Urinary and Kidney Health in Dogs | Explained by a Vet

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Cleaning up your dog’s puddles may seem like a chore to do, but when you think about how crucial a healthy urinary system is to their survival, you’ll celebrate every time they take a leak.

Urinary problems, particularly those that affect the kidneys, can spell the difference when it comes to life span and quality of life. So as dog owners, it is important that we provide our four-legged friends with everything they need to maintain a fully functional urinary system.

Function of the canine urinary system

The urinary system is important because it sorts out what gets to stay in the body and what should be removed from it. Blood goes through the kidneys for the biological version of deep cleaning. A complex process of filtration and reabsorption commences, allowing the body to take back the appropriate amount of electrolytes, nutrients, and water it needs, while eliminating metabolic wastes, toxins, drugs, and other unneeded materials. The end result is the fluid we know as urine. The rest of the urinary system is involved in the storage and delivery of urine out the body and into the authorized pee spot (ideally).

The kidney also secretes hormones that affect the blood. Renin plays an essential role in correcting low blood pressure, while erythropoietin stimulates production of red blood cells from within the bone marrow.

With this function, it’s easy to see why the kidneys and associated organs are among the bodily systems at the forefront of maintaining homeostasis. The urinary system allows the body to maintain a very specific set of conditions for cell survival and function. Any fluctuations outside the narrow range of normal pH, volume, and fluid osmolarity will manifest as clinical symptoms that may appear systemic.

Whether these symptoms show up overnight or over the years, one thing is for sure: failure to treat urinary system problems will lead to problems for the entire body.

Factors affecting the canine urinary system

Blood flow

While every organ in the body is affected by impaired blood flow, the kidneys are particularly sensitive. After all, they receive up to 25% of the oxygenated blood that the heart pumps out every single minute for the entirety of your dog’s life. That’s a whole lot of blood in a small amount of time. But while it may sound like a lot of work, the kidney thrives under these circumstances--in fact, it can’t do its work properly without that amount of blood and pressure.

Problems in blood flow are among the principal causes of renal problems in dogs. It could be because of a decrease in the amount of circulating blood--as in severe dehydration, bleeding from injuries, or leakage out of fluid from blood vessels into tissues. It could also be because of problems in blood pressure--as in issues with heart pumping, imbalances in hormones that control blood vessels, and improper use of anesthetic drugs that depress the circulatory system.

Without proper blood flow, kidney cells sustain cellular damage and do not have what they need to produce Adenosine triphosphate (ATP). This is bad news for the rest of the body, because the kidney needs ATP to filter and reabsorb some very important molecules. The circulating blood will have too much of this or too little of that, which affects all other organs of the body. Kidney malfunction also means that metabolic wastes are not efficiently cleared out, so they accumulate in the body and wreak havoc.

Urolith formation (Stones)

Um…what is that? Uroliths are aggregates of minerals that clump together and form “stones”. These occur because there is a high concentration of a particular mineral in the urine. Canine uroliths can be made out of one of several mineral compounds, and each has their own predisposing factors.

For example, the occurrence of urate stones have been associated with Dalmatians, a breed that seems to have problems converting urate to allantoin. On the other hand, calcium oxalate stones occur because of increased absorption of calcium from the diet, or derangements in hormones that regulate calcium levels. Meanwhile, struvite stones form as a sequela to urinary tract infection of bacteria that cause the normally acidic urine to turn basic.

In dogs, uroliths occur most frequently in the lower urinary tract, particularly the bladder and the urethra. Multiple small stones or big stones can partially or completely block the passage of urine or cause injury to the mucosal lining, making for difficult and painful potty sessions.

Nephrotoxic substances

Nephrotoxicity refers to the ability of a substance to damage the cells of the kidney. This is often dependent on the duration and/or amount of exposure, but there are exceptions to the rule.

Certain classes of antibiotics, pain relievers, cancer therapeutics, and anesthetic drugs have been known to cause kidney problems. Veterinarians often screen for renal injury and malfunction before giving these medications, and take the risk into consideration in the dosage and duration of treatment.

The tendency of dogs to eat things they shouldn’t also poses a risk of nephrotoxicity. Household chemicals like antifreeze and rat poison are extremely dangerous to dogs and should be kept out of their reach. Evidence of kidney damage has long been documented after ingestion of grapes, raisins, and currants, although why this happens in dogs is not yet fully understood. Plants like pothos, oleander, and castor beans have also been known to cause kidney problems.

Urinary tract infection

The production and storage of urine is normally a sterile, bacteria-free process. However, there are times when bacteria or fungi make their way into the urinary system by way of ascending infection.

The most common culprits in canine UTIs are microbes that are normally found on the skin and gastrointestinal system. They come in from the external opening and often proliferate in the lower urinary tract, at times infecting the closely associated genital organs.

How to keep your dog’s urinary system strong

Provide an appropriate, balanced diet.

A balanced diet supplies the appropriate amount of macronutrients and micronutrients for the animal’s health status and age. We all know the dangers of giving too little, but all too often ignore the dangers of giving too much.

Giving food that provides too many nutrients relative to what the dog needs results in problems such as obesity and joint disease. For the urinary system, excessive protein and minerals are most damaging, particularly if the kidney has already experienced degenerative changes due to old age, or sustained damage from other disease processes. A defective urinary system has trouble filtering out toxic byproducts of protein metabolism and adjusting the electrolytes in the blood. Specially formulated renal diets are available for canines with existing kidney problems.

To keep the urinary system from working overtime unnecessarily, it is important to feed your dog a balanced diet that is appropriate to age, life stage, and existing health issues. Here is a collection of diets that are particularly well-suited for urinary health in dogs.

Keep your dog hydrated.

Giving your dog access to water 24/7 is an easy way to make sure that their urinary system (and the rest of their body!) stays healthy. Water makes up a big chunk of blood and urine volume, and lends the two substances their fluidity. The urinary bladder empties out when the stretch receptors in its walls detect a certain volume of urine, so drinking lots of water helps prevent urine stasis. Your dog’s body is able to flush out any ascending bacterial infection and excess minerals that, if allowed to stay stagnant, will tend to clump together.

Pay attention to potty time.

If you know what to look for, your dog’s potty habits can reveal a lot about their health. Changes in the frequency, amount, and general appearance of their urine are all clues that will help you tell if something is wrong as early as possible.

Symptoms of urinary problems vary from the subtle (such as increased frequency of drinking and urination) to the obvious (straining to pee, bloody urine, or no pee at all). Small, gradual changes can be reported to your veterinarian during the next visit, where they can investigate further if there is cause for concern. Overt signs of urinary disease are emergency cases that should be brought to the clinic right away.

Strictly follow drug prescriptions.

Medically-induced renal disease happens when nephrotoxic drugs are used inappropriately. So if your dog needs to take medication for any illness, be sure to follow your veterinarian’s prescription to a T. This way, you can give just the right amount – enough to resolve the medical condition, but not enough to cause problems with the kidneys.

If you do notice changes in their urine schedule and appearance, general behavior, and appetite after using prescribed drugs, make sure to mention it to your doctor to check if it is out of the ordinary. Healthy kidneys will often tolerate medications very well, but degenerating and damaged ones will be sensitive ones to any additional stress.

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Danny Schumann