Anatomy

Just in case you didn’t know, dogs have a special olfactory sense organ that plays a major role in their lives. Also known as the Jacobson’s organ, the vomeronasal organ lives quite in the shadow, secluded as it is up by the dog’s nose. Indeed, it wasn’t until 1732 that Frederik Ruysh discovered it, and then later in 1813, it was rediscovered by Ludwig Jacobson, hence this organ’s name. Interested about the role of this organ? Let’s see what the dog’s vomeronasal organ has to say!

Introducing the Dog’s Vomeronasal Organ

Hello, it’s your dog’s vomeronasal organ (VNO) talking! Yes, the introduction has it right. I am not very popular, indeed, many dog owners aren’t even aware of me. But let me tell you something, I am one important piece. Sure, I may not seem to be as important as other life-sustaining organs, but I do cover some important functions. Where am I located exactly? I am a long pouch-like structure located close to your dog’s vomer and the nasal bones (hence my name), right by the inferior part of your dog’s nasal septum and in the anterior portion of the palate. You never see me, but you can sure see me at work, when your dog is busy analyzing smells. Unlike the mucosa in your dog’s nose, I am lined with microvilli instead of cilia.

[otw_is sidebar=otw-sidebar-1]

I  Convey Messages

What is my main job? I am responsible for conveying chemical messages known as pheromones which are purposely left behind by other dogs for reproductive or other social purposes. I am lined up with olfactory receptor cells responsible for detecting these chemical messages which are then relayed to the dog’s amygdala and hypothalamus, important parts of the dog’s brain that generate emotional  and behavioral responses. To receive these chemical messages, since they’re non-volatile, it’s necessary that they make contact with me. Have you ever seen horses who lifted their lips exposing their front teeth as if they were laughing? This is known as a “flehem response” and what the horse is really doing is he’s helping those pheromones or other scents reach me.

Other animals exhibit similar behaviors such as snakes flicking out their tongues, cats opening their mouths and wrinkling their noses in a grimace and elephants using the tip of their trunks. You won’t likely see your dog exhibit a flashy flehem response as seen in horses, but dogs actually do something similar when they’re smelling something such as urine. They might push their tongue against the roof of their mouth, (tonguing) so to send some pheromones to me through special ducts found right behind the top front teeth (the incisive papilla) which connect the mouth with me. You may also notice some dogs foaming at the mouth and teeth chattering as they do this. Pssstt.. wanna see an image of an incisive papilla in a dog? Then click here and here.

A Natural Communication System

As mentioned, I specialize in relaying information deriving from non-volatile compounds and most of them of pheromones. What are pheromones exactly? According to  Karlson and Luscher (1959) they are “substances secreted to the outside of an individual and received by a second individual of the same species in which they release a specific reaction…” Where do they come from? Pheromones secreting glands are found in the dog’s ears, lips, genital/anal area, between the toes and by the inter-mammary sulcus, explains Bonnie Beaver, Diplomate of the American College of Veterinary Behaviorists in the book “Canine Behavior: Insights and Answers.”

While it may seem like your dog’s life doesn’t depend on me as much as with other life-sustaining organs such as the heart, liver or kidneys, I play an important role in reproduction and survival by generating appropriate behavioral responses. You must thank me if dogs are able to coordinate their activities with other dogs without saying a word. What type of messages do I pick up and transmit to the brain? Here are a few examples.

Reproductive Pheromones

Intact male dogs rely on me to determine the reproductive status of female dogs. When male dogs are exposed to female urine, the pheromone content can help determine if she’s receptive. The compound has been identified as methyl p-hydroxybenzoate, and according to a study, when this compound was applied to spayed female dogs, it caused male dogs to attempt to mount.

Alarm Pheromones

Alarm pheromones may be left behind by frightened dogs.  There’s belief that when dogs spontaneously empty their anal glands during fear, alarm pheromones may be secreted, explains Sarah Heath, a European Veterinary Specialist in Behavioural Medicine. Dogs in waiting rooms at the vet may pick up these pheromones and react in a stressful manner.

Territory/Information Pheromones

Why do dogs scratch the ground after they eliminated? They release pheromones from their paw pads which are detected by other dogs and may signal territory. Pheromones are also left behind in dog pee, which explains why dogs are so obsessed in marking and sniffing it. These pheromones tell a whole lot about other dogs! Dogs may react differently to pee, some just sniff it and leave the area, while some others will pee on top of it.

Did you know? Some puppy potty training pads or pee posts are sometimes treated with synthetic pheromones for the purpose of grabbing the pup’s attention and hopefully enticing him to soil on them next time nature calls.

Calming Pheromones

Some pheromones make dogs alarmed, while others calm them down. When mother dog gives birth, she releases special pheromones which are meant to comfort her puppies. Today, a synthetic form of dog appeasing pheromones (DAP) is made to craft special dog appeasing pheromone plug-ins and collars. These DAP products have been found to calm down anxious dogs even if adult.

As seen, I do a whole lot! So next time your dog is sniffing, think about me, and how fascinating it is that I relay information left from other dogs even after they’re gone! I hope this has helped you understand my important roles better, have a good rest of your week and send some lovely pats to your dog.

Sincerely,

Your Dog’s Vomeronasal Organ

References:

• Karlson P., Lüscher M. Pheromones: A new term for a class of biologically active substances.Nature. 1959;183:55–56.
• Veterinary Nursing Journal, Volume 22, Issue 9, 2007, Understanding pheromones, by Sarah Heath
• Wikipedia, Vomeronasal Organ, retrieved from the Web on March 14th, 2016
• Wikipedia, Flehem Response, retrieved from the Web on March 14th, 2016

Photo credits:

Flehmen response in a horse by Brandinian – Own work, sjp horse, public domain

Just like us, our dog’s spinal column is composed by several vertebrae, and just like us, dogs may suffer from several problems such as misalignment, pinched nerves and herniated discs. Not surprisingly, there are also chiropractors for dogs to help get relief from achy neck and back problems! Getting more acquainted with a dog’s spine is not only interesting, but also educational so we can understand what may be going on when dogs develop neck and back pain. So let’s let our dog’s spinal column do the speaking so we can get to know him better.

Introducing the Dog’s Spinal Column

Hello, it’s your dog’s spinal column talking! I am also known as vertebral column or simply backbone, and as mentioned, I am structured in a quite similar fashion to your spinal column. I am a tubular structure, running  from the base of your dog’s skull to the end of his tail, but I am not at all rigid, I am quite flexible courtesy of several irregular bones known as vertebrae. For ease of explanation, I am divided into five regions: the cervical (composed of  7 neck vertebrae ), thoracic  (composed of  13 chest vertebrae), lumbar (composed of  7 abdominal vertebrae), sacral (composed of 3 pelvic vertebrae) and coccygeal (composed of  6 to 23 highly mobile tail vertebrae).

[otw_is sidebar=otw-sidebar-1]

In between my vertebrae are several intervertebral disks that provide cushioning  and act as shock absorbers so your dog’s vertebrae aren’t rubbing against each other. Other than making your dog’s back flexible, the vertebrae  also protect your dog’s spinal cord, a bundle of nerves responsible for relaying information between your dog’s brain and his body.

When Things Go Wrong

When all goes well, I am well aligned and allow your dog to make fluid and smooth movements. Your dog is a happy camper with no signs of problems. However, things can sometimes go wrong, either because of aging, trauma or hereditary conditions. To get an idea, imagine your dog’s intervertebral discs as jelly donuts, with the dough being the fibrous covering and the inside being the gelatinous nucleus, suggests veterinarian Dr. Fiona. As the dog ages, the jelly substance becomes chalky and hard. All it takes is a bit of force for the disc to herniate, extruding its chalky contents, in what’s known as a herniated disc. A herniated disc is painful as it compresses the soft tissues and nerves (hence the term dog “pinched nerve”) of the dog’s spinal cord.

The condition where the discs of a dog’s neck, middle back, or lower back degenerate, is generally referred to as “intervertebral disk disease” 0r “IVDD” Some dogs breeds with long backs and short legs such as dachshunds, basset hounds, beagles and Corgis are particularly predisposed to back problems due to their “chondrodystrophic“conformation which causes their vertebrae to degenerate prematurely.

Signs of Herniated Discs in Dogs

When my discs herniate, I cause symptoms in dogs which are often confused with other conditions. Affected dogs will be reluctant to move and when they move they’ll assume unusual postures and their movements are often not well-coordinated. Pinched nerves in the dog’s neck cause lots of pain and affected dogs may vocalize as they get up or turn their head. When the nerves of the dog’s back  are affected, dogs may be unable to walk on their hind legs and may even lose control of their bladder and bowels.

Fortunately, when treatment is sought in a timely manner, there are chances that I may recover. Surgery can help remove the disc material that has herniated and is compressing me. If the vet thinks, it’s worth a shot, he may skip the surgery and try to handle things conservatively by allowing the dog to rest and recover. This means strict confinement and cage rest for several weeks so to give my discs time to heal.  To help the dog cope with the pain and reduce inflammation, pain relievers and nonsteroidal anti-inflammatory drug (NSAID) are often prescribed. More and more veterinarians are offering chiropractic care and acupuncture for dogs suffering from the chronic effects of pinched nerves in their neck and spine.

As seen, I am a very important structure! To sum it all up, I support your dog’s body and skull, I allow flexible movements of your dog’s head, neck, back and tail. I protect your dog’s spinal cord and all those internal organs enclosed within your dog’s rib cage. I offer a place where your dog’s muscles, ligaments and tendons may attach and my vertebral discs act like shock absorbers. With all these important functions, it’s important that you take good care of me! Here are a couple of ways you can help me out, according to the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. 

Four Ways to Help Prevent IVDD in dogs:

1. Feed your dog a balanced diet.
2. Keep your dog lean so to reduce stress on the neck and backbone.
3. Invest in a harness rather than a leash to put less strain on the dog’s neck.
4. Prevent jumping by keeping steps next to the bed or couch.

So do your best to take good care of me and report to your vet at once should you notice any signs of  neck or back trouble in your dog. Respectfully yours,

Your Dog’s Spinal Column

References:

• UC Davis Veterinary Medicine, Disc Disease, retrieved from the web on March 7th, 2016.
• Pet Education, Intervertebral Disc (Ruptured Disc) Disease in Dogs, retrieved from the web on March 7th, 2016
• Veterinary Practice News, Non-Surgical Options For IVDD? Keeping Hope, And Dogs, Alive, retrieved from the web on March 7th, 2016,
• College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, Intervertebral Disc Disease in Dogs, retrieved from the web on March 7th, 2016

• Vertebral column of a goat. By Ruth Lawson, CC BY 3.0
• Stages of spinal disc herniation, public domain

[otw_is sidebar=otw-sidebar-1]

It’s Monday Marvels and today’s place of honor is reserved to the dog’s lungs. We often take a dog’s lungs for granted except when they trigger coughing or wheezing, making us worry about our dog’s health. The dog’s lungs are vital organs, and as such, they require great care to ensure they function and continue to function properly. There are many disorders out there that can affect the lungs, so it’s best to take good care of them and immediately report to the vet any changes. But let’s allow the dog’s lungs to do the talking, so we can get better acquainted with them.

Introducing the Dog’s Lungs

Hello, it’s your dog’s lungs talking! There are two of us, the right lung and the left one, and just like in humans, they’re divided into several lobes. If you look closely at my air passages, you’ll notice that  they appear like an upside-down tree. My larger branches are the bronchi, and then there are the finer branches which are my bronchioles. Then, if you were too look at things microscopically, you would notice that my bronchioles end into these teeny tiny structures known as the alveoli which are like grape-like bunches of air. Each alveolus is covered with capillaries that receive blood from the heart.

I am an Oxygen Supplier

My biggest job is to allow your dog to breathe well. When your dog inhales, fresh air enters his nose or his mouth, then it reaches the pharynx, the larynx and the trachea, also known as the windpipe. As the name implies, the windpipe is a tube that carries the air from the nose all the way down to me through the bronchi and bronchioles. At the level of the alveoli, the fresh oxygen-rich air is absorbed, while the used air is discarded by passing through (this time in reverse order) from the bronchi all the way back to the nose where it is exhaled. Right beneath me is the diaphragm, a dome-shaped muscle that helps your dog inhale and exhale effectively.

[otw_is sidebar=otw-sidebar-1]

I am an Exchange System

I do much more than supplying oxygen, I also work as an important exchange system replacing carbon dioxide with oxygen. When the heart sends me the dark blood composed of carbon dioxide, I replace it with bright red, oxygen-rich blood that is then sent to all parts of your dog’s body giving vital energy to his cells. Cells though produce carbon dioxide, a waste gas, that needs to be removed, which happens when your dog exhales. Every day, your dog inhales and exhales hundreds of times. According to Dr. Debra Primovic, the average breathing rate in dogs is estimated to be 10 to 30 breaths per minute.

“Count the number of breaths your pet takes in one minute. Avoid counting when your dog is panting. A good time to count the normal breathing rate is when your dog is asleep.” ~Dr. Debra Primovic

 I am a Cooling System

You might already know that your dog doesn’t sweat as effectively as you do. Humans sweat a lot through their skin. While dogs sweat a bit from their paws, their main cooling system is provided by panting. When your dog pants, he is breathing faster, and therefore is removing the warm air from his body (ever felt how warm that air is when he pants in your face?). As the warm air is removed, it’s replaced with the cooler air from the outside.  If the air outside though is very hot and humid, I might be unable to help your dog cool down, so be careful not to overheat your dog! And what about when your dog romps in the yard or chases a squirrel? When your dog exerts himself, the brain tells me to work faster. Let him lie down though to snooze, and the brain will tell me to slow down.

When Things go Wrong

Everyday I risk being exposed to triggers that could lead to problems. Bacteria, viruses, fungi, dust, chemical particles, you name it. Luckily, most are trapped by the mucous lining of the nasal passages before they reach me. Cilia, special mucous-covered hairs that resemble a field of grass as seen in the picture, also help trap foreign particles and germs before the particles make it to me. Not to mention, the immune system also attempts to destroy certain microorganisms. However, sometimes these harmful entities still manage to make it my way. When this happens, I get irritated, even inflamed. Coughing or sneezing may sometimes help expel these entities, but sometimes this isn’t enough. Some small particles may still make it through and wreck havoc.

Fungal Infections

You see, dogs like to use their powerful sniffers, and sometimes, the may inhale spore-like particles of harmful fungi that inhabit the soil. Because these particles are tiny, they are able to reach me and cause great havoc. Histplasmosis, blastomycosis and coccidioidomycosis are some fungal infections dogs may get if they live in areas where these harmful fungal spores thrive.

Bacterial/Viral Infections

Normally, the dog’s immune system should keep harmful bacteria and viruses out of my way, but if the immune system is for some reason weak, as often seen in puppies, and sometimes in older dogs, bacteria may reach the respiratory system. The distemper or parainfluenza virus may weaken the immune system enough to cause serious problems. Affected dogs may develop a sudden onset of a runny nose, sneezing, fever, lethargy and general malaise.

Other Problems

There are many things that can go wrong with me. You see, my alveoli are meant to fill up with air, but if they end up filling up with fluid, this leads to problems as it prevents oxygen from being absorbed into your dog’s bloodstream. How does fluid end up in the wrong place? It can happen with aspiration pneumonia, heart disease, drowning just to name a few. Because I am a vital organ, Mother Nature made sure to protect me by shielding me with a strong  ribcage, but if a dog gets hit by a car, I may still get damaged. If a rib fractures and punctures me, air can escape from the area around me causing me to collapse, a condition known as pneumothorax.

Signs of Trouble

If your dog for a reason or another is unable to breathe well, his body may not receive enough oxygen. Carbon dioxide may accumulate causing signs of trouble. If your dog’s gums appear pale, gray or blue, that’s a sign they lack oxygen. See your emergency vet immediately if you notice abnormal gum color in your dog. Trouble breathing and coughing in dogs is often associated with respiratory disease, but it can also be a symptom of something else such as congestive heart failure.

As seen, I play a very important role in your dog’s health! From the day your dog was born, I will be working hard day and night.  Make sure you protect me as much as you can. Keep your dog away from excessive dust, and don’t forget about smoke. Dogs suffer from the effects of second-hand smoking just as humans do! Don’t forget to keep your dog’s teeth in good shape. According to VCA Animal Hospitals, dental disease ups the chances for bacteria to reach me and cause a serious secondary infection. And of course, see your vet promptly at the first signs of trouble!

I hope this helped you get more acquainted with me! Living out in the boonies makes people often forget about me, but I am always here, diligently doing my work from your dog’s first breath, to his very last.

Respectfully,

Your Dog’s Lungs

Did you know? The dog’s respiratory system is divided in the upper respiratory tract comprising the nose, nasal sinuses, throat and trachea, and lower respiratory tract comprising the bronchi and bronchioles and the alveoli.

References:

• Pet Education, Respiratory System: Anatomy & Function in Dogs, by Race Foster DVM, retrieved on February 29th, 2016
• Merck Veterinary Manual, Introduction to Lung and Airway Disorders of Dogs, retrieved on February 29th, 2016

Photo credit:

• Ciliated and non-ciliated cells on lungs, public domain.
• Lungs diagram with internal details, by Patrick J. Lynch, medical illustrator – Patrick J. Lynch, medical illustrator, CC BY 2.5

[otw_is sidebar=otw-sidebar-1]

Dog tails: we often take them for granted, sometimes we even chop them off as if they were useless appendages at the end of the vertebral column, when instead they have many functions that go far beyond the classical tail wag.

Dog tails are indeed full of life! Their muscles allow a wide range of motion so to allow the dog to lift the tail upwards, move it side-to-side, or lower it between the hind legs. Tails are composed of skin, nerves, tendons, muscles and bones consisting of several vertebrae. Think dog tails are just for wagging? Think again! Following are six surprising ways dogs use their tails that your dog wants you to know. Yup! Straight from your dog’s mouth!

My Balancing Act

It’s true, you likely won’t ever see me at a circus walking on a tightrope, but rest assured that my tail plays a big role in maintaining my balance. Just like the tightrope walkers use that horizontal pole, my tail helps me out when I am accelerating, braking, walking along narrow structures (think agility A-frames, catwalks and teeter-totters) and turning at fast speeds.

If you were to watch me in slow motion as I jump up to catch a Frisbee or jump over an obstacle, you may notice how may tail lowers as I take off, then flicks up in mid-flight, and ends up lowering again as I touch the ground. All these well orchestrated tail movements are meant to adjust my center of gravity so I can balance myself and avoid drastic falls. Sure, my friends with bobtails may still be able to jump, but they’ll need to make some adjustments in their jumping styles to make up for the balancing effects our tails provide.

[otw_is sidebar=otw-sidebar-1]

Meet my Rudder

Boats aren’t the only things that comes with rudders, us dogs have tails that act like rudders too! Many of my doggy friends, who were selectively bred to swim a lot, have webbed feet and these thick, strong tails that are also very flexible, allowing them to effectively thread through the water at a nice pace. You see, when we swim, we keep our tails straight out just below the surface of the water, but the moment we decide to turn, our tails swing to our sides so that we can turn effectively. Pretty amazing, huh? We sure are proud of our rudders! Just make sure though that after we swim, you keep us safe from cold drafts. Limber tail is a painful condition that results in a flaccid, limp tail that’s sometimes seen in dogs after swimming.

Tales of Tails

You may use hand gestures to add some emphasis to your speech, us dogs instead rely on our tails. Keep an eye on my tail’s position and movement, and you may get a glimpse on how I may be feeling. Many of my emotions are indeed expressed through my tail. Is my tail  moving side-to-side in fast sweeping motions? Most likely, I am happy, but don’t just take my word for it. When looking at a dog, look at the rest of his body. Does the dog look overall relaxed and friendly? Not all tail wags are friendly!

Relying on a wagging tail as a sign of friendliness is a big mistake that causes many people to get bitten! If  you’re unsure and no owner is around to ask if it’s fine to pet me, you might not want to approach. Oh, and that day you take me to the vet, don’t worry if my tail goes missing in action. I may tuck my tail tight because I might feel frightened, and while I’m at, I may also try to keep my private area protected from that invasive thermometer!

Did you know? A recent study suggested that dogs tend to wag their tails  to the right when looking at something they wish to approach and wag their tails to the left when confronted with something they wish to back away from!

A Whiff of Scent

You see us dogs wag our tails often, but have you ever wondered why dogs wag their tails in the first place? Well, you know those two anal glands we have under our tails? They’re not there just because. My sweeping tail wags help these anal glands give off scent so that I can use it for communicative purposes. Most likely, you don’t smell anything when I do this (if you get a whiff of fishy smell though have me see the vet to get those glands checked), but rest assured, my doggy friends at the dog park know all about it. Dogs who are reserved and wish to fly under the radar instead, will often keep their tails tucked as a way to cover up their scent.

“Most people think when a dog wags its tail it means its friendly and happy – but, in fact, experts will tell you it’s about scent communication. Dogs wag their tails to spread their scent around.” ~Sarah Whitehead

Keeping Things Put

If you think all this isn’t enough to prove how important my tail is to my physical and emotional well-being, take a peak at dogs who have suffered damage to the nerves in their tails. These dogs may have trouble with fecal and urinary incontinence. In other words, they poop or pee on themselves. You see, my tail is an extension of my spine, and those tail muscles and nerves play a role in the correct functioning of my hind body as a whole. When my nerves that control urination and defecation are injured, my tail gets flaccid and I risk losing bladder and bowel control.

When it comes to urinary incontinence, our tails also play a big role.  According to a study by Holt and Thrusfield urinary incontinence mostly seems to affect my old English sheep-dog, Rottweiler, Dobermann, Weimaraner and Irish setter friends the most. Why is that? It looks like docked breeds are more likely to develop urinary incontinence than undocked dogs of the same breed.

“The movement of the tail during the act of defecation has a direct
influence in evacuating the rectum and anal canal of the last part of the faecal bolus.  If the tail is removed from an immature puppy the muscles of the tail and pelvis may fail to develop to their full  potential.~Anti-docking Alliance.

Keeping Warm

OK, not all of us may rely on our tails to stay warm, but some of my good arctic friends have found a way to put their tails to good use when they want to take a nap. Those nice bushy, plumed tails you see in Siberian huskies and Alaskan Malamutes are covered with long dense fur. When sled dogs sleep, they sleep curled up in a ball and use their tails to cover their noses, trapping the heat against their bodies, explains Dr.  Susan Whiton, a veterinarian and owner of  Dream a Dream Iditarod Sled Dog Kennel.

As seen, there’s more to wagging a tail, and us dogs sure have many uses for it! If we didn’t, wouldn’t you think Mother Nature would have turned our tails into a vestigial structure and our tails wouldn’t have made it so far? Instead, our lovely tails are still here, lively, strong and proudly carried over our backs! Yes, tails are here to stay!

A dog wags its tail with its heart. ~Martin Buxbaum

References:

• Seeing Left- or Right-Asymmetric Tail Wagging Produces Different Emotional Responses in Dogs, Current Biology, Vol. 23, Issue 22, November 2013
• Peak Performance EBook: Coaching the Canine Athlete, by Canine Sports Productions, September 15, 2011
• Pet Place, Structure and Function of the Tail in Dogs, retrieved from the web on February 26th, 2016.
• VCA Animal Hospitals, Tail Injuries in Dogs, retrieved from the web on February 26th, 2016.

Photo credits:

• Ano-Genital-Kontrolle, by Hundehalter, CC BY-SA 3.0
• Guillaume Baviere, Flickr, Creative Commons

[otw_is sidebar=otw-sidebar-1]

It’s Monday Marvels and today we’ll be discovering more about our dog’s marvelous kidneys. We often take our dog’s kidneys for granted and it’s unfortunate that we usually only acknowledge them when they start giving problems. Regular check-ups can help keep tabs on the health status of this important organ. There are also many things that can be done to keep a dog’s kidneys in good shape. Let’s see what our dog’s kidneys have to talk about.

Introducing the Dog’s Kidneys

Hello, it your dog’s kidney talking! Like several others organs you have met in our past series, I am not very appealing when it comes to looks. I am a paired organ (yes, there’s two of us!) that is reddish brown in color and shaped like a kidney bean, but hey, looks are not everything! I am part of your dog’s urinary system and serve many important functions when it comes to your dog’s health. Indeed, I am so important, Mother Nature has gifted your dog (and you!) with two kidneys, one on the right side, and one on the left side, just to cover the eventuality that one might no longer work as it should.

I am a Filtration System

I am mainly known for my state-of-the-art filtration system. Sorting non-recyclable waste from recyclable waste is something I do on a daily bases, 24 hours a day, 7 days a week. You see, blood passes through me continuously and my job is to clean and filter it, removing waste products that otherwise would be deadly. In some sort of way, I work in a similar fashion as a water filter. Filtration of blood occurs thanks to my hundreds of thousands of nephrons, special filtration elements that work diligently in filtering all the bad stuff out. My nephrons are quite tough cookies, just consider that should 75 percent of them no longer work, I will still be able to function. Yes, your dog can well live with only one kidney!

[otw_is sidebar=otw-sidebar-1]

Minerals, vitamins and all the goodies your dog gets from food, I make sure they are absorbed, but if there’s anything in excess, or notice things that shouldn’t be there, I send them down to my neighbor, the bladder, a storage unit that will hold urine. Urea is a big waste product I have to deal with quite frequently. It’s produced from the digestion of protein. If I fail to remove urea properly, uremic poisoning can take place.

I am  a Monitoring System

I am a monitoring system that keeps an eye on your dog’s electrolytes such as sodium and potassium, sugars, and proteins and make sure they are in the right amounts. I also make sure that your dog’s blood isn’t too acid or alkaline. Oh, and if your dog isn’t drinking too much, I take a conservative approach. Your dog’s brain sends a hormone my way that informs me about the outage of water, so I’ ll hold on to fluids by concentrating your dog’s urine at least until he starts to drinks more. “Homeostasis” is what vets call the work I do to ensure that the fluids in your dog’s body are balanced correctly. Luckily, I can discard anything in excess by dumping it in the urine so your dog is out of harm’s way.

I am a Production System

I produce a substance that helps with the creation of new red blood cells and I also manufacture certain types of hormones. And of course, as you already know, I produce urine which is delivered to the bladder through two ureter tubes, one attached to the left kidney and one attached to the right one. At night, I fortunately slow down my urine productivity, otherwise you would have to take Rover on frequent trips to potty preventing you from getting enough sleep. Again during this time, I will retain all the water I can to keep your dog still hydrated during this time. This is why your dog’s morning urine is normally more concentrated.

When Things Go Wrong

When I get sick, vets talk about “renal disease” which is just another name for kidney disease. There are several things that can go wrong with me. Usually, I start giving signs trouble as dogs begin to age, causing the onset of chronic kidney disease, but sometimes dogs can get into things they shouldn’t, and when that happens, I suddenly cause severe symptoms that are associated with acute kidney disease. Here are a few details about these disorders.

Chronic Kidney Disease

As mentioned, when dogs age they are more prone to having problems with me. You see, as I age along with the dog, I may start failing and lose my ability to concentrate urine, which leads to dogs producing large quantities of diluted urine. When this happens, dogs lose a lot of fluids and become dehydrated which causes them to drink more. Dehydration may also cause dogs to develop loss of appetite. Because I can’t longer excrete waste products as before, these may accumulate in the blood and this can make dogs quite ill. Affected dogs may develop vomiting, diarrhea, weakness and anemia. Other than aging, any type of damage occurring to me may also put a dent in my ability to work well. Remember how I said that I can still work decently even if several of my nephrons have been damaged? Well, while this is remarkable, there’s a big down side, I show signs of kidney disease when 2/3 of my nephrons in both kidneys have been lost. Unfortunately, at this point things get critical. All that can be done is slow down the progression of the disease.

Acute Kidney Disease

While chronic kidney disease in dogs causes me to deteriorate gradually, acute chronic failure develops abruptly and I cause severe symptoms that will hopefully alert dog owners so they can get help in time. Things can get critical when a dog laps up antifreeze in the winter as dogs are attracted by its sweet taste. Infections, chemical poisons and trauma are other potential culprits that have damaging effects on me. Vomiting, lethargy, diarrhea, loss of appetite, dehydration, neurological signs and urinating in small amounts or not urinating at all are symptoms of problems.

Monitoring my Health

Luckily, there are several diagnostic tests that may reveal signs of trouble. A urinarlysis for example can tell a whole lot about me.  Are there abnormal amounts of protein in your dog ‘s urine? There should not be, this may be a sign that I am not doing a good job in removing stuff. Most likely my filters are letting some escape from the blood. Are there casts in your dog’s urine? The presence of casts in dog urine sediment is know as “cylindruria” and may also indicate a kidney issue. Blood tests may be helpful too. Abnormal levels of BUN in your dog’s blood, which stands for blood urea nitrogen, can be indicative of problems. Again, the presence of abnormal levels of nitrogen-containing urea compounds in the blood is a sign that I am not working well, as I would normally excrete these. Creatinine in the blood is also a sign of trouble. I am the only organ that excretes this substance, so if it’s in high levels in the dog’s blood, it’s again a sign of me not doing my job.

Keeping me In Good Shape

You can keep me in good shape by ensuring your dog has always access to fresh, clean water. I love water! Feeding your dog a high-quality diet can help keep me in top shape. Medications such as non-steroidal anti-inflammatory drugs can make me work harder, so if your vet has your dog on certain medications, make sure to follow his advice of getting me checked out every now and then. And of course avoid exposure to toxins and anything harmful! Antifreeze, grapes and raisins are just a few things out of a long list of toxins that can cause renal failure, cautions veterinarian Dr. Lorie Houston.

As seen, I play a very important role in your dog’s health! People should re-think featuring hearts on Valentine’s Day cards as the heart isn’t the only vital organ. I hope they may feature me too one day! In the meanwhile, keep me in your thoughts and safe from harm as much as you can, your dog and I will thank you!

Today we’ll be discovering some interesting stuff about the dog’s third eyelid. Yes, that’s right, dogs have actually three eyelids, but where on earth is the third one? Last time you checked, you only saw two, the top one and the bottom one, so where is the third one hiding? No need to run a treasure hunt. Tucked out of sight, at the inner corner of your dog’s eye, the third eyelid isn’t normally visible. You may have likely seen it occasionally when your dog sleeps or wakes up after catching some Zzzs, but not seeing it much is a good thing. A third eyelid showing on other occasions may be indicative of some underlying problems. So today, let’s get more acquainted with our dog’s third eyelid, shall we?

Introducing Your Dog’s Third Eyelid

Hello, it’s your dog’s third eyelid talking!  I am also known as the nictitating membrane or haw. You may not know me too well, as I tend to not show up much often. I am that membrane that you may occasionally see partially drawn across a part of your dog’s eye. In other animals such as certain reptiles, birds and sharks, you may see me fully drawn across the eye, in some cases covering it completely. In humans, I am just a vestigial remnant known as the “plica semilunaris.”  I have basically lost my original function during evolution, so I shrunk into a small fold that’s found on the inside corner of your eye. See picture for correct location of the plica semilunaris in humans.

[otw_is sidebar=otw-sidebar-1]

In dogs, I am more functional, covering the eye when your dog is asleep. Like you car’s wiper blades, I help wipe any mucus or debris from across the surface of your dog’s eyes. According t o the American College of Veterinary Ophthalmologists, I also play an important role in maintaining normal tear production. I have a gland that’s responsible for about 40 to 50 percent of your dog’s tear production.  Last but not least, my lymphoid tissue has an immunological function producing antibodies to help fight infections.

Third-Eyelid Showing

As mentioned, you don’t normally see me other than when your dog sleeps with his eyelids semi-open or you see me for a split second as I retract when your dog wakens up suddenly from a deep sleep. You see, I cover your dog’s eyes when your dog is sound asleep so to prevent his eyes from drying up too much. Your dog doesn’t blink in his sleep so I’ll take over the role of keeping those eyes nice and moist. So yes, it’s a good thing if you notice your dog’s “red eyes” when he’s sleeping. What you are seeing is basically me doing my job. You need to worry instead when I do not normally retract when your dog’s eyes are open and your dog is wide awake, as this can be a sign of something wrong.

If you see me when your dog is wide awake, under the form of a pinkish triangle covering the inner corner of one eye,  it could mean an eye problem. The dog’s eye may be painful or injured or a nerve may have been damaged, explains veterinarian Betsy Brevitz in the book ”  The Complete Healthy Dog Handbook: The Definitive Guide to Keeping Your Pet Happy, Healthy & Active.” There are no muscles attached to me, so my range of motion is completely passive. If the eyeball sinks in, I will automatically cover the eye. When you see me in both eyes, unless both eyes may have been injured, something more systemic may be going on. Third eyelids showing in both of a dog’s eyes could be a sign of dehydration, illness or pain. Consult with your vet for proper diagnosis and treatment.

Prolapsed Nictitans Gland 

My gland responsible for making tears (nictitans gland) is located on the side that lies against the eye, so it’s normally not visible. Sometimes though, a small ligament responsible for holding the gland in place, may stretch or break for unknown reasons, explains veterinary ophthalmologist Rhea V. Morgan. When this happens, my gland will prolapse, leading to a visible reddish mass in the corner of the eye that is commonly referred to as “cherry eye.”

You see, this mostly happens in certain dog breeds that are prone to it such as cocker spaniels, basset hounds, lhasa apso, shih-tzu, poodle, beagles, Newfoundlands, Chinese shar-pei, Saint Bernards and bulldogs. To correct this, I need surgery to get that gland replaced so that it can continue to produce tears as it was meant to and to prevent the emergence of complications such as a chronic dry eye.

As seen, I perform several duties! I hope this guide has helped you understand me better! I sometimes feel like I live in the shadow, tucked out of sight as I am. Out of sight though doesn’t mean out of mind, so hopefully today you’ll cherish the work I do to keep your dog’s eyes healthy and bright. And if I ever show up when your dog is awake and active, please have me checked out by your vet to see what’s going on.  Yours dearly,

Your dog’s third eyelid.

References:

• Betsy Brevitz, ”  The Complete Healthy Dog Handbook: The Definitive Guide to Keeping Your Pet Happy, Healthy & Active.” Workman Publishing Company; 1 edition (April 16, 2009)
• Christine C. Lim, “Small Animal Ophthalmic Atlas and Guide”, Wiley-Blackwell; 1 edition (February 2, 2015)

Photo credits:

• Prolapsed gland of the third eyelid (cherry eye) in a dog, by Joel Mills, CC BY-SA 3.0
• The plica semilunaris of conjunctiva, by Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body, public domain

[otw_is sidebar=otw-sidebar-1]