Over the last few weeks, your nine-year-old Bullmastiff girl has been on your mind. She is drinking more than normal and asking to go out to urinate in the middle of the night. While that in itself is not alarming, it’s the weight loss and overall lethargy that have you truly concerned. The last straw was when she started vomiting. You took her to the vet the next morning for a full workup, but his diagnosis floored you: chronic renal disease. How could her kidneys be so far gone without you noticing until now?
The early stages of renal disease are often hard to detect, as many symptoms are benign and can be attributed to advancing age.
Symptoms of Kidney Problems in Dogs Include:
- Drinking excess water
- Frequent urination
- Urine that does not concentrate, resulting in a pale color with little odor
- Leaking urine (more common in females)
- Vomiting
- Weight loss
- Anorexia
- Lethargy
- Muscle weakness
Once blood and urine samples are analyzed, the doctor will find:
- An elevated blood urea nitrogen (BUN) and creatinine
- High levels of protein in the urine
- Urine that does not concentrate
Most owners do not notice their pet’s decline until vomiting begins and the dog refuses to eat. When a dog with a usually insatiable appetite suddenly won’t eat its favorite food, alarm bells go off for unsuspecting owners. Unfortunately, by the time symptoms become noticeable, the kidneys are already functioning at below twenty-five percent of their full capacity, ringing alarm bells for the vet.
Our kidneys filter our blood and produce hormones that stimulate red blood cell production, help regulate calcium, magnesium, and phosphorus levels, and maintain normal blood pressure. They are filled with thousands of tiny funnels called nephrons, which work to filter and balance fluid levels in the body. When they malfunction, it affects the entire body, not just urine output. Fortunately, nephrons are resilient, and both canine and human bodies have an abundance of these microscopic structures. It is not until the level of functioning nephrons drops below 25% that they can no longer keep up with the demands of clearing toxins from the blood and maintaining proper fluid balance. As the number of functioning nephrons declines, the remaining ones cannot compensate, leading to the development of symptoms. However, if the disease progresses slowly enough, the remaining nephrons can adjust to the increased workload.
There are two types of renal disease: chronic and acute. Chronic renal disease has a slow onset, often caused by old age. While it is not entirely reversible, its progression can sometimes be slowed. Acute renal disease, on the other hand, is usually caused by trauma, poisoning, infection, cancer, or autoimmune diseases. If an animal survives a traumatic incident, such as being hit by a car or falling, the next big hurdle is surviving the damage done to the kidneys when the animal goes into shock. Shock kills more animals than any other condition once they survive the initial incident. While reversing acute kidney failure is possible, it depends on the severity of the disease and how quickly the correct treatment is initiated.
Although various toxins can cause acute renal failure, the most common poisonings are from ethylene glycol in antifreeze and calciferol in rat poison. As little as a teaspoon of ethylene glycol can cause crystals to form inside the nephrons, shutting down renal function entirely. This is typically fatal unless treatment begins immediately, such as inducing vomiting after witnessing the animal lick the antifreeze. Calciferol increases calcium levels in the body, leading to mineral deposits that can damage the kidneys. Additionally, certain medications and treatments for other diseases can harm the kidneys, so always consult your veterinarian before administering anything to your pet.
Due to the insidious onset of chronic renal failure, many professionals recommend yearly baseline urine and blood tests starting at age three for large dogs and at age five for small dogs. This practice can catch kidney disease well before symptoms appear and gives your vet an idea of what ‘normal’ levels are for your pet (baseline testing is recommended for many other diseases as well, not just renal disease).
Treatment for both acute and chronic renal disease is similar, primarily focusing on supporting the kidneys until they either begin to function normally again or the remaining nephrons hypertrophy, each taking on more of the workload.
As toxin levels rise throughout the body, additional treatments may be needed to support other organs. Treatment can include medications to reduce irritation of the stomach lining, antacids, and phosphate binders to control mineral levels, as well as drugs to manage high blood pressure or hypertension. Non-medicinal treatments may involve sodium restriction if diet alone does not control blood pressure and introducing vitamin B complex and C to replenish lost vitamins. Diet plays a crucial role in treating both forms of renal failure, and thankfully, there are low-protein, low-phosphorus diets available through your veterinarian. Encouraging your dog to drink is also vital; dogs suffering from any form of renal disease should have access to clean, fresh water at all times.
Kidney problems in dogs are common and serious, but with prompt treatment and lifestyle changes, many dogs can continue to lead long, normal, and happy lives. Have your dog tested during their next visit for vaccinations, and remember that early detection is the best way to ensure your companion stays by your side for years to come.
