Anatomy - Daily Dog Discoveries

I am Your Dog’s Gracilis Muscle

December 26, 2016 by Admin

You might have never heard about a dog’s gracilis muscle, but this muscle is one that certain dog owners may never forget about once their dog develops problems with it. Just as in humans, a dog’s body is made of several muscles which allow force and motion. It is thanks to your dog’s muscles after all that your dog can maintain and change posture, move about, and ultimately live his life, considering that even the heart is muscle. The gracilis is an important muscle of your dog’s hind leg that can be in certain circumstances prone to injury. So today, let’s discover more about your dog’s gracilis muscle, the role it plays and potential problems this body part may be prone to.

Introducing Your Dog’s Gracilis Muscle

Hello, it’s your dog’s gracilis muscle talking! My name derives from the ancient Latin word “gracilis ” meaning slender, thin. And if you take a look at me by taking a peek at the picture on the left, you may have a clear idea why I am called this way.

I am found in your dog’s hind limb, and more specifically, the inner surface of the thigh. I am categorized as a skeletal muscle meaning that I am a “voluntary muscle” anchored to bone and used to allow locomotion.

I Create Motion

Yes, as mentioned, as many of your dog’s other muscles, I am responsible for allowing motion. What do I do exactly? I allow adduction of the thigh, that is, movement of the limb towards the body, extension of the hip and extension of the hock. Quite a lot, for a thin muscle like me, huh?

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When Things Go Wrong

The most common type of injury affecting me, is a muscle contracture, also known as fibrotic myopathy. What exactly is a muscle contracture? The term may sound familiar but it’s different from a muscle contraction.

While a muscle contraction is the normal process of a muscle temporarily shortening when it’s being worked, a contracture is a pathological, abnormal shortening of muscle tissue, causing it to become resistant to stretching which can lead to long-term disability.

You see, when I am subjected to injury, scar tissue, under the form of fibrous connective tissue may form. However, sometimes, I may be almost entirely or completely replaced with fibrous connective tissue. Now scar tissue is less flexible than muscle fibers and therefore it leads to shortening which may limit my ability to allow a dog to to flex or extend the leg. Dogs affected by a gracilis contracture may therefore show signs of pain in the acute phases, lameness, a decreased range of motion and a characteristic gait.

The signature gait is characterized by the affected leg being raised with a jerky motion, with the hock flexed and rotated laterally, and a shortened stride due to the dog being unable to fully extend the ankle, knee, and hip joints. A video though is worth 1,000 words, so to give an idea of what happens to me when I am injured, you are better off watching it to see the gait.

In the greyhound racing business, injury caused by me is often referred to as “dropped muscle” because affected dogs may develop a bulging area in the inner area of the dog’s thigh. Generally, this type of injury is most commonly seen in German Shepherds and Shepherd related breeds, but it can be present in many other large breed dogs with an active, working lifestyle.

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“Although fibrous scar tissue provides tensile strength and plays a part in normal muscle healing, excessive scar tissue impedes muscle fiber regeneration and interferes with muscle contraction and relaxation, resulting in varying degrees of mechanical lameness.”~ Sherman O. Canapp

Did you know? Mechanical lameness refers to lameness that is not caused by pain but rather is triggered by a physical abnormality, such as presence of scar tissue, that prevents the normal motion of the leg.

As seen, I am an important structure that requires attention. If your dog is engaged in sporting events, it may help me, along with my other fellow muscles, if you could ensure proper conditioning and allow appropriate warm-ups and cool-downs. Passive stretching and massage before events is also helpful! Consult with your vet or a vet specializing in canine sports for the best ways to take care of me and prevent problems. I hope this has helped you understand me better,

Best regards,

Your Dog’s Gracilis Muscle

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog has problems with his hind leg, please see your vet for diagnosis and treatment.

References:

DVM360, Hind limb sprains and strains (Proceedings) retrieved from the web on December 26, 2016.
Vaughan LC. Gracilis muscle injury in greyhounds. J Small Anim Pract 1969;10(6):363-375.
Lewis DD, Shelton GD, Pias A, et al. Gracilis or semitendinosus myopathy in 18 dogs. J Am Anim Hosp Assoc 1997; 33:177-188.
Vet Surgery Central, Semitendinosus and Gracilis Fibrotic Myopathy, retrieved from the web on December 26, 2016
Preventing Injuries Focus on Canine Sports Medicine By Debra Canapp, DVM, CCRT, CVA and Chris Zink, DVM, Ph, retrieved from the web on December 26, 2016.

Photo Credits:

Wikipedia Anterior Hip Muscles by Beth ohara – Own work CCBY3.0

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I am Your Dog’s Gums

December 20, 2016December 19, 2016 by Admin

Unless your dog is yawning, you dog’s gums are for the most part hidden from plain view, but just because you don’t see them doesn’t mean they are a part of your dog’s body that you should neglect! “Out of sight, out of mind” is a saying that shouldn’t apply to your dog’s gums. Forget about this important body part, and the impact can have a negative effect on your dog’s overall health, sometimes even causing debilitating conditions. Your dog’s gum are an important piece of dog anatomy and can provide quite some relevant information about your dog’s overall state of health. So, don’t forget about your dog’s gums and make it a habit of paying attention to how your dog’s gums look and feel when he’s healthy so that you have a baseline to refer to as needed.

Introducing Your Dog’s Gums

Hello, it’s your dog’s gums talking! Feel free to just call us gums, but if you want to be more technical you can also call us “gingivae.” Who are we? We are simply that lining of tissue that surrounds your dog’s teeth forming a tight seal around them.

Just like in humans, we are normally a healthy pink color, but unlike most humans, it’s not abnormal if you happen to notice some pigmented spots on us.

Some dog breeds and dog mixes have black in their mouths either on our surface, roof of the mouth or tongues or generally all around the dog’s mouth. Of course though, if your dog has developed a totally new spot you have never seen before, best to have it checked out by a vet just to play it safe!

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We Play a Protective Role

When we are nice and healthy, we form a tight, firm seal around your dog’s teeth. As you already know, your dog’s mouth is used to chew and ingest food and our job is to prevent food particles and bacteria from invading vulnerable underlying tissues along with the roots of your dog’s teeth.

We Provide Hints on Health

Because we are normally slimy and vascular in nature (we’re closely related to your dog’s circulatory system), we can give you some insights into your dog’s overall health. Dogs don’t get pale skin on their faces as humans do when they are sick, but take a peek at us and we can provide several hints as to how your dog is doing. Now, this explains why your vet skips feeling your dogs’ nose when your dog’s feeling under the weather and instead goes straight to taking a peek at your dog’s mouth instead.

Normally, when dogs are healthy, we are of a nice bubble gum pink color. This pink color is great news as it means your dog is getting enough oxygen circulating in his bloodstream. Any other gum color in dogs may be a sign of trouble and in some cases even an indication that the dog needs immediate care.

Knowing your dog’s normal gum color and how to check your dog’s gum can turn helpful should you find yourself one day calling the emergency vet wondering if you need to take your dog in and they ask you to check the color of your dog’s gums.

Training your dog from an early age to have his mouth checked with praise and treats is extra helpful. Also because you may want to also learn how we feel. We are normally wet, slippery and slimy in healthy, well hydrated dogs. If we feel dry and sticky this can a sign of dehydration which can be seen when dogs are vomiting a whole lot or sick and in need of prompt veterinary treatment. Last but not least, don’t forget to learn how to check your dog’s capillary refill time.

When Things Go Wrong

Remember how we said that when we’re healthy we form a seal around your dog’s teeth to protect them? Well, problems start when we loosen up and that tight seal is lost. Why do we loosen up? It all starts with the presence of a sticky, bacterial bio-film.

After your dog eats, a sticky film made of a combination of bacteria, carbohydrates, food particles, and saliva forms and sticks to your dog’s teeth.

This sticky bio-film is commonly known as plaque. You can detect plaque forming on your teeth when you fail to brush your teeth on time, the same happens in dogs.

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Inflammation of Dog Gums

Unless your dog’s teeth are brushed on a routine basis, this plaque will keep accumulating and will stick around your dog’s teeth, the gingival grooves and under the gum line. When we detect this plaque getting in our way, our first reaction is to become inflamed. We will therefore become angry and red, swollen and we may even bleed, all symptoms of condition known as “gingivitis.” If the plaque is not removed in a timely manner by brushing, courtesy of minerals in a dog’s saliva, this plaque will start to harden, and in a few days, it will calcify turning into what’s known as tartar or calculus, an unsightly yellow/brown coating that is difficult to remove. The good news is that gingivitis is reversible with thorough teeth cleaning and polishing along with the owner’s daily care, as no bone loss has occurred at this stage, explains veterinary dentist Dr. Jean Hawkins.

Receding Dog Gums

Left untreated, gingivitis worsens and will develop into periodontitis, a condition that affects anything surrounding a dog’s teeth including all the structures that hold the teeth in place. So when us gums are affected, we will no longer adhere to your dog’s teeth like a cuff. Instead, we will start pulling away from your dog’s teeth (gingival recession) up to to point of exposing the roots which are normally covered by us.

Soon, since we are no longer holding on tightly to provide our protective role, bacteria will start reaching the roots of the dog’s teeth and the jawbone, releasing toxins that eat away bone tissue.

Bone loss will weaken all the dental structures that keep a dog’s teeth anchored in place such as connective tissue fibers and ligaments, providing less and less support. Next, the bone around the tooth is destroyed leading to loose, painful teeth which can affect the dog’s ability to eat properly and even digest.

“It’s not unusual for middle aged dogs to lose teeth. In most cases this occurs when there is gum disease (gingivitis) which can then spread to the tissue that holds the tooth in (periodontitis).” Dr. Pete

Did you know? According to the American Veterinary Dental College, by three years of age, most dogs have signs of periodontal disease

Systemic Disease

Remember how we talked about our importance in a dog’s health and how neglecting us can lead to serious disease? Well, here are the hard to swallow facts. Because we are very vascular, bacteria can easily gain access though us to a dog’s bloodstream and circulate throughout his body. While these bacteria may be filtered out by the dog’s liver and kidneys, tiny abscesses may develop on these organs which disrupts their normal functioning leading to liver or kidney disease. And should these bacteria happen to attach to the dog’s heart valves instead, they can cause endocarditis, a serious inflammation of the inner layer of the heart. Definitely, something to be aware of!

“As the animal chews its food, the infected and inflamed gums bleed, and a shower of very aggressive bacteria enters the blood stream. These germs are carried throughout the body and can cause infection in many areas.”~ Dr. Fraser Hale, veterinary dentist.

Lumps, Bumps and Growths

As with other parts of your dog’s body, we may sometimes have odd lumps, bumps and growths growing on us.

Sometimes we may enlarge causing a condition known as gingival hyperplasia. Epulis, also known as gum boils and viral papillomas also known as oral warts, are examples of some benign growths that may grow on us in a dog’s mouth, but unfortunately, sometimes cancerous growths may grow on us as well.

Malignant melanomas, squamous cell carcinomas and fibrosarcomas are cancerous growths that may grow on us. If your dog has a suspicious lump, bump or growth on his mouth, please have him checked out promptly.

As seen, we are important structures, meant to keep your dog’s mouth and body in good health! Keep us in good shape by protecting us from the accumulation of plaque, and while you are it, remember to take a good peek at us so to get to know our normal color so, if need be, you can readily recognize early signs of trouble. I hoped this has helped you understand us!

Best regards,
Your Dog’s Gums

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog has a problem with his gums, please see your vet for diagnosis and treatment.

Photo Credits:

Wikipedia Commons, Blausen gallery 2014“. Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. – Own work CCBY3.0

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I am Your Dog’s Chest

December 12, 2016December 12, 2016 by Admin

Unless you are in the dog show business spending lots of time studying conformation, you may have never paid particular attention to your dog’s chest. Perhaps you may have found yourself occasionally taking measurements of your dog’s chest (girth) when shopping for a harness or you may have seen your vet listening to your dog’s heart with a stethoscope through your dog’s chest wall. A dog’s chest though has much more to offer and there are many interesting facts to discover. So today, let’s discover more a bout a dog’s chest, its important functions and any associated problems with this body part.

Introducing Your Dog’s Chest

Hi there, it’s your dog’s chest talking! I am happy you are interested in hearing my story. I have a lot of little pieces of information to share with you. First, let’s start with my name. I also go by the medical name thorax, which derives from the ancient Greek word thorakos meaning “breastplate.” You might also be interested in learning more about your dog’s thoracic cavity (chest cavity) and thoracic wall (chest wall). Where am I located? I am right between your dog’s neck and his abdomen.

You may find it interesting that my length, width and depth may vary between one breed and another. You may therefore have breeds such as the greyhound equipped with very deep and narrow chests and then you may stumble on dog breeds with a very wide chest area but barely deep (for example the bulldog.)

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What does a deep chest exactly mean though? In dogs, a deep chest means that it extends to or below the dog’s elbows as seen in dobermans, dachshunds and Irish wolfhounds. A deep chest therefore depicts depth, not width, points out Carina Macdonald, in the book “Knack Dog Care and Training.” Because dogs were selectively bred to carry out different functions, my structure therefore has been morphed to meet specific needs.

Did you know? Deep-chested dogs are more predisposed to developing a potentially life threatening condition known as gastric dilatation volvulus (GDV). Why are deep-chested dogs more predisposed to bloat and (GDV)? A deep chest allows more room for the stomach to move and twist on itself. See picture below.

I House Important Organs

I am home to your dog’s heart and lungs which are critical to your dog’s life. Mother Nature has made sure to protect these vital organs enclosing them in a cage made out of ribs. In an animal crafted for sprinting at high speeds such as the greyhound, I was purposely crafted to allow maximum expansion of the lungs. That’s why I am so deep and narrow in this running breed.

Learning how to perform chest compressions is something that all dog owners should learn how to do and is a must for those dealing with dogs on a daily basis such as pet sitters, dog trainers and dog walkers. Chest compressions entail pushing down on the unconscious dog’s chest in hopes of getting his heart pumping. When artificial respiration is given along with chest compressions it’s called cardiopulmonary resuscitation, or CPR. CPR classes for pets are often taught in veterinary offices, pet stores, training clubs and are sometimes even organized by the Red Cross.

When Things Go Wrong

While I am overall pretty sturdy, I can only take so much. Traumatic injuries to the chest wall are unfortunately not uncommon in dogs. They may stem from being hit by car, kicked by a horse or a stab/impalement wound such as running into a branch, but in many cases the trauma to the chest area area in animals is due to bite wounds sustained by small dog breeds.

Thoracic trauma may lead to complications such as broken ribs and penetrating wounds may affect the pleural lining of the thorax (a thin sheet of tissue that lines the chest and wraps around the dog’s lungs) leading to pneumothorax, hemothorax, diaphragmatic hernia and pleural or pericardial effusion.

I can sometimes accumulate fluids within my cavity. When fluids collect, they either collect within the lungs or between the chest wall and the lungs, explains veterinarian Dr. Hunt. An X-ray can help differentiate them. Accumulation of fluids in the dog’s chest cavity may be due to bacterial or viral infections, pneumonia or heart failure. In some cases, a swollen chest may be a sign of low protein due to an underlying liver problem. If your dog is showing symptoms of chest congestion or fluid accumulation, he or she definitely needs checked out by a vet.

As seen, I play quite an important role in your dog’s life! Please keep your pal safe from injury and see your vet promptly if you see any signs of problems.

Yours truly,

You Dog’s Chest

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog is sick or not acting right, please see your vet for proper diagnosis and treatment.

References:

Knack Dog Care and Training: A Complete Illustrated Guide to Adopting, House-Breaking, and Raising a Healthy Dog, by Carina Macdonald, Globe Pequot Press; 1 Original edition (July 15, 2009)
DVM360, Pulmonary contusions and other thoracic trauma (Proceedings) retrieved from the web on December 11th, 2016
DVM360, Pleural space disease and chest taps and tubes (Proceedings) retrieved from the web on December 11th, 2016

Photo Credits:

Photo By Ruth Lawson. Otago Polytechnic.The original uploader was Sunshineconnelly at English Wikibooks – Transferred from en.wikibooks to Commons by Adrignola using CommonsHelper. CCBY3.0
The greyhound in 1864: being the second edition of a treatise on the art of breeding, rearing, and training greyhounds for public running …By John Henry Walsh Edition: 2 Published by Longman, Green, Longman, Roberts, & Green, 1864 Public Domain

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I am Your Dog’s Carpal Bones

December 5, 2016December 5, 2016 by Admin

Among the variety of bones your dog has, the carpal bones are particularly important, and something to be aware of especially if you are the owner of a performance dog who is engaged in various doggy sports. Your dog’s carpal bones are known for forming several joints. A joint is simply the place where two bones meet and allow movement. Joints typically consist of bones, muscles, ligaments and cartilage, and in order to stay flexible and well working, they are lubricated with joint fluid. So today, let’ s discover a thing or two about the dog’s carpal bones, their role in movement and the medical conditions these bones may be subjected to.

Introducing Your Dog’s Carpal Joint

Hello, it’s us, your dog’s carpal bones talking! We consist of several small bones that make up your dog’s wrist. Our name indeed derives from the Latin word “carpus” meaning wrist.

What bones are we? There are actually seven of us, strategically aligned in two rows, parallel to each other. The ones displayed on the first top row are given individual names; whereas, the ones on the bottom row are given numbers rather than names.

Here is the list of our names: radial carpal bone, ulnar carpal bone, accessory carpal bone, first carpal bone, second carpal bone, third carpal bone and fourth carpal bone.

We are basically located in between the lower portion of your dog’s radia and ulnar bones and the top of the metacarpal bones. We work together to form three articulations; your dog’s antebrachiocarpal joint, the middle carpal joint, and the carpometacarpal joint.

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“Each bone of the carpus has a convex or concave side that matches a curve on the adjacent bone. These seven bones fit together like fieldstones that are used to build the walls of a house. ~Dr. Christine Zink

We Carry Several Functions

Located at the bottom of Rover’s legs, we play an important role in bearing weight. You might find it interesting learning that dogs tend to carry the majority of their weight in their front legs.

If you’re looking for more details on distributions, consider that it’s estimated that about 60 percent of a dog’s weight is carried by the front legs and 40 percent by the rear.

Carpal bones also allow movement and flexibility of the dog’s wrist.

Did you know? Along with your dog’s carpal pad, carpal bones act as sock absorbers for your dog’s leg during weight bearing actions. As you can see in the picture, the carpal pad touches the ground when the dog is running and also when he’s landing from a jump where it acts like a bumper.

When Things Go Wrong

While we help ear weight and absorb shock, we can only do so much. As mentioned, we are prone to injury, something that is quite common in performance dogs, such as dogs engaged in the sport of agility.

Dogs not enrolled in canine sports though can be vulnerable too, especially when running over uneven fields with rabbit holes or jumping or falling from a certain height.

Injury to us is most likely the result of some acute traumatic event or the result of chronic, repetitive strains over a certain period of time. Since we have a relatively loose fit, we’re for the most part supported by ligaments that join us one to another, but these ligaments are subjected to sprains.

Sprains are simply injuries to the ligaments that connect bones.. The sprains can be of different degrees. A grade one sprain is just the ligament overstretching. A grade two sprain is a partial tear of the ligament. A grade three sprain is the complete tear of the ligament due to hyperextension of the limb or hyperflexion with rotation which causes the joint to become unstable. This injury can cause lameness in the dog and reluctance to bear weight on the leg. In severe cases, the carpus may appear to have dropped to the ground. Left untreated, ligament injuries can cause arthritic changes to us, carpal bones. Veterinarian Christine Zink explains that in the past years she has seen several canine athletes suffering from carpal arthritis. Fractures are also a possibility.

“With so many carpal bones that don’t tightly interlock with the adjacent bones, the ligaments of this joint can be easily stretched and even torn when torque (twisting) is applied to the leg. The dewclaws have the important function of reducing the torque that is applied to the front legs, especially when dogs are turning at a canter (the main gait used in agility).”~Dr. Christine ZinK

Did you know? Carpal hyerxtension also occurs to a certain degree from slow degeneration of the dog’s ligaments as part of the aging process. As it happens to older dogs, they becomes progressively palmigrade (walking with the palm touching the ground), explains Nacho Calvo, Senior Surgeon at Fitzpatrick Referrals in Surrey.

I hope this article has helped you understand us! We are small and live in the shadow, but we are quite important allowing locomotion and flexibility to your dog’s legs. Take good care of us by ensuring that your dog is kept always in good shape and lean and prevent injuries by not letting your dog run on uneven surfaces.

Best regards,

Your dog’s carpal bones

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog is lame or you suspect your dog is showing signs of a problems with his carpal bones, consult with your vet for proper diagnosis and treatment.

References:

DVM360, Carpal and tarsal sports-related injuries (Proceedings) retrieved from the web on December 5th, 2016
Dogs in Canada September 2003, With A Flick of the Wrist by Chris Zink, DVM, PhD retrieved from the web on December 5th, 2016
Veterinary Orthopedic Sports Medicine Group, Carpal and Tarsal Injuries, retrieved from the web on December 5th, 2016

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I am Your Dog’s Amygdala

November 28, 2016November 28, 2016 by Admin

Among the various structures of the brain, your dog’s amygdala plays a primary role in the way your dog interacts with the world. Your dog’s brain is ultimately the boss of his body and it cannot be denied that it runs the show, controlling everything your dog does even when he’s deep asleep curled up in a ball. The amygdala is only a small component of your dog’s brain but it plays a big role in your dog’s life. Learning more about this structure may provide you with a deeper understanding of how your dog views and experiences the world around him. So today’s let’s discover more about the dog’s amygdala, what it does and some problems it may encounter.

Introducing Your Dog’s Amygdala

Hello, it’s me, your dog’s amygdala talking! Actually, as with many other parts of your dog’s body we come in pairs. For those word nerds out there, the plural of amygdala is amygdalae, and the word “amygdala” derives from the ancient Greek word “amygdale” meaning “almond.”

Apparently, since we are shaped like almonds, somebody with a touch of creativity decided to call us this way. How cool is that? We are are also sometimes affectionately nicknamed “the neural nugget” considering that we are made of clusters of nuclei.

We’re the primitive part of your dog’s limbic system, a collection of special brain structures specially involved in emotions. We are therefore surrounded by some fascinating neighbors such as the pineal gland and your dog’s hippocampus.

If you’re looking for us, you can indeed find us right at the end of the hippocampus, a structure with which we exchange information.

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We Work as a Threat Detection System

When you think of us, think about the word “threat.” It’s is thanks to us that your dog is intimidated by threats and reacts accordingly in a fearful manner. You may think, why should I be thankful that my dog has fear?

Being fearful is not always a bad thing, it’s actually good if your dog is fearful of things that can actually pose a threat to his life and well being. “Is that thing in the distance a piece of rope or a poisonous snake?” If your dog startles, it is because we gave him the signal of alarm that makes him jump. Imagine not having fear for one moment…

An experiment was once done on rats where researchers, through a procedure known as deep lesioning were able to remove the amygdalae (ameygdalectomy) of rats. Deprived from us, the rats started no longer having fear and exhibited some serious, non-species-specific behaviors. They no longer feared cats as the removal of their amygdalae, resulted in their fear memories being swiped away for good. Of course, this is not good and one can imagine how these poor mice must have been fun for the cat to play with!

So yes, fear is important as it protects dogs (and any other living being) allowing self-preservation and protection of the species. If all mice weren’t scared of cats, imagine how quickly they would quickly become extinct!

We therefore play a role in fear conditioning. If your dog has started to show fear of the stairs because he heard a loud noise while climbing them, we are responsible for creating that fearful response. We gain information from the dog’s senses and then work in unison with our next door neighbor the hippocampus. The hippocampus is responsible for storing memories of traumatic events so it sends us alert messages that causes us to react. Our teamwork therefore helps orchestrate the fear response.

“The amygdala attaches emotional significance to the information coming into the brain, and has been called the command center of the emotions of surprise, rage and fear.”~Patricia McConnell, Ph.D.

When Things go Wrong

Our goal is to ultimately keep your dog safe; however, sometimes things may get out of hand. If we happen to regularly overreact, we create fertile grounds for an anxiety disorder to set in.

” It has been hypothesized that fear is, in part, due to chronic amygdala over-reaction and, or failure of the amygdala to turn off after the threat has passed” says Karen Overall, board-certified veterinary behaviorist.

Things can get complicated because we are not really a thinking part of the brain, our job is to become alert from bad memories and just react, triggering the dog’s hypothalamus to initiate the fight and flight response. So there is no way you can really “reason” with your dog telling him it’s OK while we are in full blast alert mode.

There are schools of thought though that we can be trained to not react through exposure. The belief is that through gradual exposure, where nothing really negative happens to the dog, we might come to “learn” that there’s no threat and therefore stop going unnecessarily on alert.

Richard LeCouteur, a board-certified veterinary neurologist believes that the our reaction can at least be overridden. When the vet sticks a thermometer up a dog’s bum, “that’s in the amygdala forever,” says LeCouteur. The dog therefore develops anxiety when he goes in the car and knows he is going to the vet clinic. So does this mean that the dog will be forever frightened of going to the vet because the amygdala tells him so? Not all is lost it seems. According to LeCouteur. “The cortex can change its mind through conditioning and experience, and it can override the amygdala’s memory. Fear extinctions are stored in the cortex.”

Joesph LeDeoux, American neuroscientist says “Once your emotional system learns something, it seems you never let it go. What therapy does, is teach you how to control it—it teaches your neocortex how to inhibit your amygdala. The propensity to act is suppressed, while your basic emotion about it remains in a subdued form.”

At times, we can also be an area for seizure activity. The onset of intense and irrational fear may suggest this activity. Fortunately, affected dogs respond to anticonvulsant therapy. “A seizure focus in the amygdala should produce inexplicable and intense fear. I have seen such cases, one confirmed by EEG and responding positively to anticonvulsant therapy,” says Nicholas Dodman for Veterinary Practice News.

“We are not, thankfully, completely at the mercy of the whims of our hippocampus and amygdala, subject to uncontrollable fears based on past bad experiences. We have some ability to take a step back and calm ourselves down. One of the parts of the brain involved in this higher-order cognition is the prefrontal cortex (PFC). This region of the brain has direct connections to both the hippocampus and the amygdala and appears able to mediate some of the signals coming from those two regions.”~Jessica Perry Hekman DVM

As seen, we play an important role in keeping your dog out of danger. OK, sometimes we may overreact, but we ultimately mean good. However, here’s some important piece of advice for you. When your dog starts developing signs of anxiety and fear, consult with a professional as soon as you can. The quicker you nip fears in the bud, the better chances those fears are prevented from putting roots and establish, insidiously wrecking havoc in your dog’s life. I hope this has helped you better understand your canine friend,

Best regards,

Your Dog’s Amygdalae

References:

Goleman, NYTimes, Brain’s Design Emerges As a Key to Emotions, retrieved from the web on November 28th, 2016
Veterinary Practice News, Complex Partial Seizures Or Compulsive Behavior? retrieved from the web on November 28th, 2016
Brain Made Simple, Amygdala, retrieved from the web on November 28th, 2016
Calm Clinic, How to Amygdala Affects Anxiety, retrieved from the web on November 28th, 2016

Photo Credits:

Location of the Amygdala in the Human Brain User Washington irving on en.wikipedia –CC BY-SA 3.0

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I am Your Dog’s Meninges

November 21, 2016November 21, 2016 by Admin

Your dog’s meninges are structures your dog may hopefully never have a problem with, but as with other dog body parts, there are always some fascinating things to discover. For instance, did you know that your dog’s brain, on top of being protected by the skull, is also protected by several layers of tissue? These layers of tissue are basically your dog’s meninges. Meninges have several functions and just as other dog body parts they are predisposed to medical conditions and problems. So today, let’s discover more about a dog’s meninges, what their purpose is and when things go wrong.

I am Your Dog’s Meninges

Hello, it’s your dog’s meninges talking! Our name comes from the ancient Greek word “meninx” which means membrane. As our name implies, we are membranes that envelop your dog’s brain.

Imagine your dog’s brain as being an onion while we are the layers. There are three layers of us actually covering the brain: the dura mater, the arachnoid mater and the pia mater. Let’s take a closer look at these layers individually, shall we?

Coming from the Latin word for”tough mother,” the dura mater is a thick membrane that is found closest to the skull.

The arachnoid mater, discovered in 1664 by the Dutch anatomist Gerardus Blasiusm, is the layer that is sandwiched in the middle. Its name derives from the the Greek word “Arachne” (“spider”) because of its spider-web like appearance.

Finally, the last layer is the pia mater, coming from the Latin word for “tender mother.” This is the most delicate membrane. This structure adheres to the surface and contours of the brain and spinal cord.

In between the layers of the arachnoid and pia mater, there is a space that is filled with cerebrospinal fluid.

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We Protect the Central Nervous System.

As you can imagine, we play a protective role. Together, we protect your dog’s central nervous system including the brain and spinal cord. The dura mater is quite thick, and as the name implies, the”tough mother” acts like a mother protecting her child (the brain.) The arachnoid mater provides also provides cushioning for the central nervous system while the pia mater on the other hand, contains blood vessels and small capillaries which are meant for providing nourishment to the dog’s brain.

When Things Go Wrong

We are susceptible to the effects of trauma. When the trauma is forceful enough, affected dogs may develop a subrachnoid hemorrhage, meaning that there is bleeding under the arachnoid. A hematoma, a collection of blood from torn veins, may also form between the arachnoid layer and the dura mater layer.

As with other structures, we also prone to getting inflamed. Fortunately, though this doesn’t happen as often as in other body parts courtesy of the protective barriers of the nervous system such as the blood brain barrier.

However, when these barriers weaken and we do get inflamed, the condition is known as meningitis. This inflammatory condition can be caused by viruses, protozoa, rickettsia, and fungi. Affected dogs develop an elevated temperature, neck pain, muscular spasms and rigidity. Left untreated, meningitis can progress and cause serious neurological problems such as seizures, paralysis and even death.

In some cases, we can also develop tumors, and these are referred to meningiomas. Meningiomas are likely the most common cause of seizures affecting dogs over the age of six, explains veterinarian Wendy C. Brooks. On top of causing seizures, these tumors can cause a dog to walk in circles, drag toes, and walk in a drunk-like gait. Since, most menangiomas in dogs develop in the front part of the skull, where the olfactory lobes are located, an altered sense of smell may also occur.

Meningioma tumors grow from the skull inward, which makes them more advantageous for surgical removal compared to growths set deep in the brain. Not all meningiomas are malignant, actually most tend to be benign, meaning that they do not spread to other areas. However, any growths in this area can be problematic, considering the limited amount of space within the dog’s skull. For this reason, prednisone is often prescribed to reduce the problematic swelling. Anti-seizure meds are also often prescribed, but these are only palliatives, a more definitive treatment involves surgical removal of the growth and/or radiation therapy.

As seen, we are quite important structures! Think about what a good job we do in preserving your dog’a brain and spinal cord! Yours truly,

Your dog’s meninges.

Disclaimer: this article is not meant to be used as a substitute for veterinary advice. If your dog is sick, please see your vet for proper diagnosis and treatment.

References:

Merck Veterinary Manual, Meningitis and Encephalitis in Dogs, retrieved from the web on November 20th, 2016

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I am Your Dog’s Prostate Gland

November 14, 2016November 14, 2016 by Admin

The dog’s body shares several similarities with humans and therefore it’s not surprising for dogs to also have a prostate gland. Of course, prostate glands are only present in male dogs, and just as in humans, it has reproductive purposes. Also, just like in humans, dogs also share some disorders that affect their prostate glands. So today, we’ll be discovering more about a dog’s prostate gland,where it is located, what functions it serves, and some disorders this body part is prone to.

Introducing Your Dog’s Prostate Gland

Howdy, there, it’s your dog’s prostate gland talking! My name dates back from the 1640s and derives from the ancient Greek word “prostates” which means “leader, ruler, guardian; “the one standing in front”. I am called this way because of my position at the base of the bladder, just by the dog’s rectum.

I am just a small bi-lobed gland that communicates with the dog’s urethra, a tube that carries Rover’s urine from his bladder to the outside so that he can effectively urinate on your neighbor’s mailbox.

I am ovoid in shape and considered quite large for the size of a dog, but that’s most likely because, unlike in humans, in dogs I am the only male accessory gland. On average expect me to measure anywhere between one and two inches in diameter in a forty pound dogs.

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However, my size for a good part depends on whether your dog is neutered (had testicles surgically removed) or not. In intact males I am larger, whereas, in dogs neutered before the onset of puberty, I will just develop to a tiny budge of tissue. And if your dog is neutered when he is mature, I will instead shrink to a fourth of my former size.

Did you know? According to VCA Animal Hospital, intact Scottish terriers are known for having a prostate that is about four times greater in weight compared to other dog breeds.

I Help Manufacture Puppies

I play a big role when it comes to the manufacturing process of puppies. When Rover mates with his girlfriend Missy, he will ejaculate several fluids created by me in three distinct fractions: first comes the pre-sperm which consists of just a small volume of clear fluid, next comes the cloudy, sperm-rich fluid and then comes an abundance of clear prostatic fluid once the dogs are stuck in a tie. Since my ducts communicate with the dog’s urethra, expect these fluids to travel outside Rover’s body and then right into Missy. Quite a trip there, huh?

What’s the purpose of this fluid? It add volume and helps sperm travel so to successfully reach its destination (yup, talk about motility!) and it’s also believed to have some special antibacterial properties.

Did you know? When a intact male dog cocks his leg to urine mark a lamp post, urine isn’t the only thing coming out. According to Tim Glover, author of the book “Mating Males: An Evolutionary Perspective on Mammalian Reproduction” prostatic fluid is discharged as well and dogs produce quite an amount of it!

“Dogs have no other accessory sex glands and, therefore, no other source of seminal fluid; all fluid present in the ejaculate arises from the prostate. Prostatic fluid is secreted at all times, whether the dog is being used for breeding or not. Most accumulates in the urinary bladder and is voided with the urine. Some runs down the urethra and accumulates at the opening of the prepuce, forming the mass of greenish discharge that often is visible on intact male dogs. “~Dr. Peggy Root Kustritz

When Things Go Wrong

While most of the problems listed below affect older intact male dogs, don’t count your blessings yet if you own a neutered dog. Neutered dogs may also occasionally suffer from prostate problems too.

Benign Prostate Hyperplasia

Just as in men, as intact male dogs start to age, I start enlarging. Yes, dogs are prone to benign prostate hyperplasia (BPH) too! Statistics assume that 100 percent of adult intact dogs over the age of 7 will develop BPH. What causes me to enlarge are the hormonal changes associated with aging. While in men, the tell-tale sign of prostate problems is difficult urination since I end up pressing against the bladder, in dogs, I am more likely to cause painful defecation. So when I enlarge, I am known to cause poor Rover to strain and act constipated. And if you notice ribbon-like or pencil-thin stools in an intact male dog, suspect problems with me too. On top of causing trouble defecating in dogs, when I enlarge I may also cause straining during urination and sometimes I may even cause affected dogs to walk in an unusual gait, taking short steps as if walking on eggs. For persistent cases causing significant enlargement, most vets suggest neutering the dog considering that once testosterone is removed, I will shrink and things get better from there.

“As the prostate increases in size, it expands backwards in four-legged animals, that means toward the spine. If there’s significant enlargement, it can obstruct the rectum, causing straining during defecation, constipation, and even fecal impaction. Once in a while, an enlarging prostate pushes forward rather than backward, pressing on the urethra. This can cause a dog to strain while urinating.”~Dr. Karen Becker

Did you know? There is no prostate-specific antigen blood test in dogs as there is in humans, explains veterinary Betsy Brevitz. Dogs are therefore subjected to the humiliating rectal exam with the vet’s gloved finger and other diagnostic tests.

Prostate Infection

At times, I may also get infected. When this happens, the dog is said to have developed prostatitis. After BPH, this is the second most common condition of the prostate affecting dogs. It is estimated that about 45 percent of dogs will get an infection of the prostate at 7 years. How do I get infected? These infections may stem from the dog’s blood stream or from the urinary tract. Fortunately, a course of the right type of antibiotics (they must be able penetrate into the prostate gland) and for the right amount of time (often several weeks or months) will help me feel better.

Prostate Cancer

And then there is cancer, yes, this can affect me too. The most common types of cancer affecting me are transitional cell carcinoma and prostatic carcinoma. However, the good news is that unlike in humans, cancer of the prostate is less common so on this I can count my blessings. When it happens though, prostate cancer in dogs is quite an aggressive cancer that can metastasize (spread to many organs) and wreck havoc.

Did you know? According to a study published by the August, 2007 issue of the journal “Prostate” it was found that male dogs who had been neutered had a higher risk for transitional cell carcinoma.

As seen, I am quite important for intact dogs meant for passing on their genes, while in neutered dogs, well, to put it bluntly, let’s just say I am pretty much quite useless. While many problems with me are more common in intact male dogs, consider that neutered dogs may also occasionally have problems too. So keep an eye for problems with me and report promptly to your vet upon noticing them.

Kind regards,

Your Dog’s Prostate

References:

Glover, Tim (2012) Mating Males: An Evolutionary Perspective on Mammalian Reproduction Cambridge University Press, page 31. ISBN 9781107000018.
Young W.C. – Sex and internal secretions, 1961, Third Edition, vol. 1, Ed. The Williams&Wilkins Co., Baltimore
Pet Education, Prostate Enlargement in the Dog, retrieved from the web on November 14th, 2016
CANINE PROSTATE PATHOLOGY GABRIELA KORODI, VIOLETA IGNA, H. CERNESCU, C. MIRCU, ILINCA FRUNZĂ, RENATE KNOP Faculty of Veterinary Medicine Timişoara Calea Aradului 119, 300645 – Romania
A population study of neutering status as a risk factor for canine prostate cancer. Bryan JN, Keeler MR, Henry CJ, Bryan ME, Hahn AW, Caldwell CW.Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri, USA. Prostate. 2007 Aug 1;67(11):1174-81

Photo Credits:

Wikipedia, Created by US government agency National Cancer Institute – Permission details public domain
Flickr Creative Commons, Luca Conti Cani sposati CCBY2.0

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I am Your Dog’s Ribs

November 7, 2016November 7, 2016 by Admin

Your dog’s ribs are what provide structure and shape to his chest cavity along with important protection for many vital organs. You might not really pay much attention to your dog’s ribs, but you may have noticed at some time the rise and fall of your dog’s rib cage when your dog inhales and exhales. Chances are high that your dog may never develop any problems with his ribs, but it’s still an interesting part of your dog’s body that deserves some attention. So today, let’s discover more about your dog’s ribs, what they do and some potential problems that they may develop.

Introducing Your Dog’s Ribs

Hello, it’s your dog’s ribs talking! You may not be familiar with how we look, but hey, animal anatomy is quite similar, so when you’re at a restaurant and order a rack of ribs, you kind of get an idea of what we look like.

We are basically those curved bones that form your dog’s rib cage giving your dog’s abdomen its familiar barrel-like shape. On the top, we attach to your dog’s vertebral column or spine which keeps us in place by the back area. We then basically spring away from the spine at the top in a wide curve and then curve back at the bottom where some of us attach to the sternum (breastbone).

The first sets of us that connect directly to your dog’s sternum are known as “true ribs” while the ones that are not directly connected to the sternum are called “false ribs.”While you have 12 pairs of us, for a total of 24 ribs, your dog has 13 pairs of us, for a total of 26 ribs.

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Did you know? Unlike the rest of your dog’s ribs, the cartilage of your dog’s last rib doesn’t connect to anything at all and is therefore called a “floating rib.”

We Provide Protection

If you look at our shape, we are similar to the bars of a cage which have an important protective function: enclosing and protecting your dog’s vital organs, such as your dog’s lungs and heart.

On top of protecting the heart and lungs, we also provide protection to your dog’s stomach, spleen, and kidneys from any external injury.

In addition to acting like a protective shield, we provide your dog with a framework onto which the muscles of your dog’s chest, back, upper abdomen can attach.

Did you know? By placing your hands over your dog’s rib cage, you can tell whether he’s overweight. If you feel the ribs easily, your pet is normal weight, but if the ribs are hard to feel or you can feel a layer of fat between the skin and ribs, your pet might be overweight, according to a handout by Dr. Ernest Ward Jr.

When Things Go Wrong

As with other bones and structures, we are prone to a variety of problems. These problems may not be as common as others that dogs may be predisposed to, but they may happen on occasion.

Bone Cancer of the Dog’s Rib

Perhaps the most worrisome of all problems affecting us, is osteosarcoma, an aggressive and malignant form of bone cancer that is prone to spreading (metastatize). When this type of cancer affects us, there is often a visible or at least a palpable mass on us. Some dogs may shows front-leg lameness when one of the first four of us are affected and the mass is compressing nerves that travel to the leg.

If the mass is large or the cancer has spread to the lungs, it can cause trouble breathing. Treatment consists of surgical removal of the affected rib, as well as the unaffected ribs in front and behind. Fortunately, dogs tolerate well the removal of such a large portion of the rib cage, explains Daniel A. Degner, a board-certified Veterinary Surgeon.

Fracture of Dog’s Rib

As other bones in your dog’s body we are prone to breaking. When we fracture it is usually the result of a car accident or some sort of blunt force such as a strong kick or a large dog biting and shaking a smaller dog. Usually, if we stay in place and the structures around us are undamaged, we generally heal on our own as long as we’re taped by a vet and the affected dog is as prescribe a pain reliever, but if we are out of place, affected dogs may deal with complications. For instance, when we brake, we may cause bruising to the dog’s lungs and this can lead to trouble breathing. A punctured lung may cause free air in the dog’s chest and a collapsed lung is a serious issue. When we break and the dog develops a change in his breathing and pale gums appear, this is indicative of the dog not getting enough oxygen. A vet should be seen ASAP!

As seen, we are on duty 24/7 for all your dog’s life, protecting all his vital organs from injury. And we do quite a good job at that, considering that it really takes quite a blow to harm us! As always, keep us in mind, as you marvel at the great body your dog was gifted with it.

Yours truly,

Your Dog’s Ribs

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If you suspect your dog has a broken rib or some other health problem, please see your vet immediately.

References:

Vet Surgery Central, Chest Wall Tumors – Rib Tumors, retrieved from the web on November 7th, 2016

Photo Credits:

By Ruth Lawson. Otago Polytechnic. The original uploader was Sunshineconnelly at English Wikibooks – Transferred from en.wikibooks to Commons by Adrignola using CommonsHelper. CC BY 3.0

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I am Your Dog’s Thyroid Gland

October 31, 2016October 31, 2016 by Admin

Your dog’s thyroid gland is a neat little masterpiece that’s responsible for many functions. Among the thyroid gland’s functions one of the most important and well known is its ability in regulating the dog’s metabolism by producing thyroid hormones. Any disruption in this gland’s correct functioning may result in several complications that may affect a dog’s physical and mental well being. So today’s let’s learn more about a dog’s thyroid gland, where it’s located, its many functions, and some signs suggesting something may be wrong and require veterinary attention.

Introducing Your Dog’s Thyroid Gland

Hello, it’s your dog’s thyroid gland talking! Yes, I am quite a neat little masterpiece. I am a small gland consisting of two lobes that are found in your dog’s neck area, just underneath his voice box, also known as the larynx.

As my name implies, I am gland, which means that I produce special chemical substances, that are known as hormones. You see, I am composed of tens of thousands of follicles from which hormones are produced. What hormones do I produce? Thyroxine (T4) and tri-iodothyronine (T3) are produced by me and sent to your dog’s bloodstream.

A third hormone called TSH (thyroid stimulating hormone,) is produced by the pituitary gland found at the base of the dog’s brain. How much of this hormone is produced depends on how many thyroid hormones are in the bloodstream. Therefore, expect more TSH to be produced when the thyroid hormones I produce are are on the lower end.

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Do you see the four little dark circles in the picture above? Those are parathyroid glands, little fellows that play an important role in maintaining optimal levels of blood calcium in dogs. These glands though deserve their own little story, so let’s move on to learning more facts about me and what I do.

I am The Boss of Metabolism

I am the boss of your dog’s metabolism. The several hormones I produce help transport energy to every cell in your dog’s body and they play a vital role for making your dog feel happy and healthy. Need an example? My hormones play a main role in the development of your dog’s nervous and musculoskeletal system and it’s thank to the hormones I produce that your dog gets to enjoy a normal cardio-respiratory function.

I also help regulate your dog’s temperature and work like a thermostat. You see, the hormones I produce allow your dog to generate heat and maintain an ideal temperature. If your dog is mostly kept outdoors, that means extra work for me, as I will have to increase your dog’s metabolic rate to keep him warm. Hopefully, owners of outdoor dogs will keep this in mind and feed their dogs more food to compensate for all the burned nutrients used to accomplish all this!

Oh, and if your dog has a nice coat, you must thank me as my hormones help with the anagen growth phase of your dog’s hair cycle.

When Things Go Wrong

When I produce just the right amount of hormones, everything is fine, but sometimes I may produce too many or too little hormones. Cats are notorious for having an over reactive thyroid gland (hyperthyroidism), while in dogs, the opposite is true,as they are mostly affected by an under active thyroid gland (hypothyroidism).

What happens in this case? Most often, this condition arises when the dog’s immune system attacks me, and ends up killing my cells, leading to a condition known as autoimmune lymphocytic thyroiditis. However in some cases, I may atrophy for unclear reasons or cancer may be the culprit to my destruction.

Sometimes, certain medications are known to lower my production in thyroid hormones. For instance, moderate and high doses of glucocorticoids and sulfa antibiotics are known to lower T4 concentrations while phenobarbital has shown to lower T4 levels in 40 percent of dogs taking this drug.

Regardless of what slows me down, the effects on the dog’s body remain almost the same. Since I reach all tissues of your dog’s body, when I get sluggish and stop working as I should, I cause a vast array of symptoms such as hair loss, lethargy, weight gain, recurrent skin infections, intolerance to cold, slow heart rate, dry coat and behavior changes. In some cases, I may cause drooping skin of the dog’s chin, neck and face, which is known as “tragic face” as it gives affected dogs a sad look on their faces, explains Dr. Ralston. You can see an example of this in the picture on the left.

Diagnosing dogs with hypothyroidism requires a blood test to check for signs of me not working as I should. Your vet may offer several tests, but if you are looking for the most comprehensive test in the market, you can’t go wrong with the Thyroid Profile 5™ produced by Hemopet. What the treatment for hypothyroidism in dogs? Since I am not producing hormones as I should, dogs are often placed on a daily dose of a synthetic thyroid hormone such as levothyroxine that will need to be taken for the rest of the dog’s life.

Did you know? Hypothyroidism is the most common endocrine disorder affecting dogs, and up to 80 percent of cases are caused by autoimmune (lymphocytic) thyroiditis, explains Dr. Jean Dodds.

As seen, I am quite important and can wreck all sorts of problems when I stop functioning well. You may want to take extra good care of me, by having your dog see your vet if you notice any vague symptoms, especially if you dog is middle-aged and ranging between mid-size to large. Also, you may want to be extra careful about what equipment you use to walk your dog as collars (especially choke and prong collars) can do quite some damage to me. Dr. Erin O’Connor, an AVCA animal chiropractor, found that pressure on me can cause dogs thyroid issues. If your dog is an avid puller or if you deliver collar corrections, you may want to change your ways and be more gentle with your dog, and perhaps consider investing in a harness instead. With that being said, I hope you found it interesting learning more about me!

Kind regards,

Your Dog’s Trachea

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog shows signs of a thyroid problem, please consult with your vet.

References:

DVM360, Progress in the diagnosis and management of canine hypothyroidism (Proceedings), by Peter Kintze, DVM, DACVIM retrieved from the web on October 31st, 2016
Clinical Veterinary Advisor: Dogs and Cats, By Etienne Cote, Mosby; 3 edition (December 23, 2014)

Photo Credits:

Wikipedia, Thyroid and parathyroid. Public Domain

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I am Your Dog’s Mast Cells

October 24, 2016 by Admin

Your dog’s immune system is always working around the clock to keep your dog protected from insidious diseases. In particular, white blood cells, the cells of your dog’s immune system, play the role of soldiers actively protecting the fortress (your dog’s body) against infectious diseases and foreign invaders. Mast cells, even though having a bad rap due to allergies, anaphylaxis and cancer, are a type of white blood cell which also have a protective role. Today, let’s take a closer look into a dog’s mast cells, what they do, how they work and the things that can wrong.

Introducing Your Dog’s Mast Cells

Hello, it’s your dog’s mast cells talking! As mentioned, we are a type of white blood cell. Actually, to be more descriptive, we are granulocytes, a sub-type of white blood cells that are known for having granules in their cytoplasm. Many of our granules are rich in histamine and heparin, an anticoagulant, along with other substances. We were first described by Paul Enrich in 1878, who noted our distinguishing feature of having large granules.

We are born in your dog’s bone marrow and then distribute in most tissues of your dog’s body, but we’re mostly like to stick around the skin, digestive tract, respiratory tract, mouth, nose and eye area. In healthy dogs, we normally populate body tissues only, and only very rarely are we detected into the blood stream.

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We are equipped with special storage sacs which house powerful molecules called mediators which are released in specific circumstances and that produce local responses.

We Stand Guard

As mentioned, we are guardians who protect the body from perceived invaders and actively respond to the presence of allergens and inflammation. Since we are located by the skin, mouth, eyes and nose, we play a prime role in detecting allergens. We are basically pretty inactive beings when all is well, but the moment we detect an allergen in your dog’s body, we rapidly degranulate, releasing histamine. This explains why your dog gets all itchy when he eats a food he’s allergic to!

When histamine is released, it can lead to swelling, redness, itching, welts and even anaphylaxis, a severe systemic reaction to an allergen such as from bees stings and drugs. In dogs, skin allergies are more common rather than the classic allergy symptoms seen in humans such as sneezing and developing a watery nose and eyes. Antihistamines are helpful in keeping allergy symptoms under control.

“Histamine is useful in the body at certain levels. Mast cells release histamine which helps attract other white cells to an area or an invader to help clean up the area, or mount an immune system reaction… Histamine is important in immunity. However, too much histamine is not good for the body.” ~ Dr. Demain Dressler

When Things Go Wrong

Yes, there can be too much of a good thing. While we are master immune regulators and infection fighting cells, things can get out of hand at times, such as when there are too many of us or we “misbehave” causing severe symptoms and disorders.

Mast Cell Tumors

We are probably mostly known for wrecking trouble as it happens with mast cell tumors. Fortunately, malignant mast cell cancer can be often ruled out or confirmed through a fine needle aspirate. Remember how we said earlier that we rarely appear in the bloodstream? Well, when a mast cell tumor is highly malignant, it may spread and appear in the blood stream. An advanced mast cell tumor can therefore be detected with a blood test by looking at the “buffy coat.“

When it comes to the malignant, aggressive forms, mast cell tumors are often referred to as “the great imitators,” because it can take many different forms which can be confused with other skin problems. Sometimes they may present as a solitary bump or in groups on the dog’s skin, and often look like innocuous masses. This is why when your dog develops any unusual looking lumps, bumps or lesions, you should have them checked out by the vet, especially if they grow and change appearance. Mast cell skin tumors may appear as lumps that stay the same size for a while and then start growing. Mast cell tumors can be seen in any dogs, but boxers and Boston terriers are particularly affected.

When caught early and affecting only the skin (grade 1) mast cell tumors can be surgically removed, with wide and clean margins, and the cancer can be kept at bay. Things start getting progressively worse through with grade 2 and 3. Treatment options therefore vary based on the grade of this tumor. Because we release histamine, heparin, and other enzymes when we’re damaged, we can cause major disruptions. Too much histamine can cause the dog’s stomach to produce too much acid, which is why antihistamines and antiacids are often prescribed to dogs with mast cell tumors. On top of increased acidity, the release of histamine, heparin, and other enzyme may also have negative effects on the dog’s heart rate, blood pressure, and other important body functions.

While mast cell tumors most commonly affect the dog’s skin (cutaneous mast cell tumors) at times, they may even affect internal organs (visceral mast cell tumors) which can produce vague symptoms such as loss of appetite, vomiting and lethargy. Skin mass cell tumors may also affect the skin only at first and then metastasize to internal organs as they advance and spread.

“It is not possible to tell with the naked eye alone whether a specific skin growth is a malignant mast cell tumor or not, and therefore, some diagnostic tests are always necessary to confirm whether a skin growth is a mast cell tumor.”~ Etienne Cote

Did you know? Mast cell tumors commonly affect a dog’s skin and subcutaneous tissues and account for 7 to 21 percent of dog skin tumors. (Source, References 1)

References:

Pergamon Press Ltd. 1992, “Skin tumors of the dogs and cat,” by M.H. Goldschmidt & F.S. Shofer
Clinical Medicine of the Dog and Cat, Second Edition, edited by Michael Schaer
Mast Cell Tumors in Dogs, TEXTBOOK OF VETERINARY INTERNAL MEDICINEClient Information Series Mona P. Rosenberg, DVM DACVIM
Pet Education, Mast Cell Tumors, retrieved from the web on October 24th, 2016

Photo Credits:

Kidz Search, author Kauczuk, Photo of skin mast cells at 100X using an oil immersion lens and an olympus digital camera. The cells are stained with Tol Blue, and might appear slightly degranulated as they were activated using an artificial antigen during the course of an experiment.

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