Introduction
Kidney disease is one of the most common health issues affecting cats, especially as they age. It occurs when the kidneys become damaged and can no longer effectively filter waste products from the blood. The two main types of kidney disease in cats are acute kidney injury and chronic kidney disease (CKD). Acute kidney injury comes on suddenly, while CKD is a gradual decline in kidney function over months or years.
According to the American Veterinary Medical Association (AVMA), CKD affects more than 1 in 3 cats over the age of 15[1]. The early stages of CKD often go undetected because cats are excellent at hiding signs of illness. Symptoms like increased thirst and urine output don’t become obvious until over two-thirds of kidney function has already been lost. This makes CKD easy to miss in routine vet exams, allowing it to progress to an advanced stage before being diagnosed. However, early detection and management of CKD is key to slowing its progression and preserving kidney function.
[1] https://www.avma.org/javma-news/2021-02-01/creating-brighter-futures-cats-chronic-kidney-disease
Symptoms of Kidney Disease
As kidney function declines in cats with chronic kidney disease (CKD), it leads to an accumulation of waste products in the bloodstream. This buildup of toxins causes a variety of symptoms that often progressively worsen over time. The most common symptoms of CKD in cats include:
Increased thirst and urination – With failing kidneys, cats are unable to concentrate their urine properly, leading to increased water intake and urine production. Many owners report their cat is drinking significantly more water and urinating larger volumes more frequently.
Weight loss – Poor appetite, nausea, and metabolic changes make weight loss common in kidney disease. Muscle wasting and cachexia can occur as the disease advances.
Poor appetite – Toxins in the bloodstream often cause nausea and changes in taste perception. This leads many cats to eat less food over time.
Vomiting and diarrhea – The buildup of waste products can irritate the digestive tract and cause vomiting. Some cats have episodes of diarrhea as well.
Bad breath – Uremic breath, or a metallic/ammonia odor, is common as nitrogenous waste products accumulate. Kidney disease can also cause ulcers and oral inflammation.
Other symptoms like lethargy, depression, mouth ulcers, hair loss, and itching can occur. In advanced CKD, anemia, heart issues, and neuropathy may develop. Early detection and treatment is key to slow progression and minimize symptoms. (Source: https://vcahospitals.com/know-your-pet/kidney-failure-chronic-in-cats)
Risk Factors
Certain cats are more prone to developing chronic kidney disease (CKD) than others. Older cats are at higher risk, with more than half of cats over 15 years old having CKD to some degree (Finch et al., 2016). Male cats are also 1.6 times more likely to get CKD compared to females (Roura, n.d.).
In addition, cats with pre-existing chronic conditions have increased risk. Hyperthyroidism is strongly associated with CKD, with 25-30% of hyperthyroid cats also having concurrent kidney disease (Finch et al., 2016). Other conditions like chronic infections, dental disease, and lower urinary tract disease are also risk factors.
Diagnostic Testing
Veterinarians use several diagnostic tests to evaluate kidney function and look for signs of kidney disease in cats. Blood and urine tests are commonly used as initial screening tools. These can detect elevated levels of waste products like creatinine and blood urea nitrogen (BUN) that indicate the kidneys are not adequately filtering the blood. Urinalyses check for increased protein in the urine, which signals kidney damage. The urine protein-to-creatinine ratio is particularly useful for quantifying protein loss through the kidneys.
Imaging techniques like radiographs and ultrasound allow veterinarians to visualize the size, shape and architecture of the kidneys. This can reveal abnormalities suggestive of disease. Ultrasound-guided kidney biopsies are sometimes performed to examine kidney tissue under a microscope. This can confirm a diagnosis and help determine the underlying cause of kidney dysfunction.
Results from a combination of bloodwork, urinalysis, imaging and biopsy inform the diagnosis of kidney disease in cats. Ongoing monitoring of clinical signs and laboratory tests are needed to stage the degree of kidney impairment and guide treatment.
Sources:
https://vcahospitals.com/know-your-pet/kidney-failure-chronic-in-cats
https://www.petmd.com/cat/conditions/urinary/kidney-disease-cats
Misdiagnosis Reasons
Kidney disease in cats can often go undiagnosed or misdiagnosed for a few key reasons:
Vague Symptoms – The signs of kidney disease like increased thirst, weight loss, poor coat quality, and vomiting can also indicate many other conditions. This makes it easy for vets to miss kidney issues and focus on other potential causes.1
Focus on Other Diseases – Since kidney disease shares common symptoms with other illnesses, vets may prioritize testing for hyperthyroidism, diabetes, cancer etc. Kidney function can get overlooked while pursuing other diagnostic paths.2
Mild Changes in Tests – Early blood and urine tests often show only minor abnormalities that could indicate kidney issues but aren’t definitive. Vets may repeat testing over time rather than diagnosing CKD based on subtle changes.3
Consequences of Misdiagnosis
Misdiagnosing kidney disease in cats can have serious consequences as the disease progresses unchecked. Without proper treatment and management, kidney function will continue to deteriorate leading to a poor quality of life for the cat (VC Animal Hospitals). As toxins build up in the bloodstream, cats experience symptoms like vomiting, diarrhea, decreased appetite, weight loss and lethargy (Pethealth Network). Untreated kidney disease also puts cats at higher risk for other issues like high blood pressure, heart disease and urinary tract infections. Ultimately, misdiagnosis shortens a cat’s lifespan often by years. Detecting kidney disease early and beginning treatment is critical to slowing progression of the disease and extending a cat’s life.
Prevention of Misdiagnosis
There are some key ways to help prevent the misdiagnosis of kidney disease in cats:
Routine screening blood and urine tests starting at age 7 help catch early kidney changes before they become advanced (1, 2). Annual senior wellness exams allow vets to monitor at-risk cats, like those with hyperthyroidism or high blood pressure, which can damage kidneys over time. Using multiple test methods like blood tests, urinalysis, imaging, and biopsy provides a more complete picture than relying on just one (3).
Monitoring urine concentration is important, as dilute urine is an early red flag for kidney dysfunction. Testing urine protein levels can also help screen for early damage. Trending kidney values over time with consistent labwork gives more insight than one-off tests.
Finally, partnering with a vet who specializes in kidney disorders can help optimize diagnostic accuracy. Staying vigilant with senior cats allows early intervention and better outcomes.
Sources:
(1) https://www.reddogbluekat.com/post/why-kidney-diets-don-t-work-part-2
(2) https://vcahospitals.com/know-your-pet/kidney-failure-chronic-in-cats
(3) https://www.petmd.com/cat/conditions/urinary/kidney-disease-cats
Treatment
Treatment for kidney disease in cats focuses on several key areas:
Fluids – Providing extra fluids, usually subcutaneously, helps flush toxins from the body and support kidney function. Vets often recommend giving 100-150 mL per day. Fluids help correct dehydration and electrolyte imbalances.
Diet change – Prescription kidney diets restrict phosphorus and provide increased quality protein. Reducing phosphorus is important since diseased kidneys cannot properly excrete it. High protein aids muscle maintenance despite uremia.
Phosphorus binders – Medications like aluminum hydroxide bind to phosphorus in food, preventing absorption. This supplements dietary phosphorus restriction.
Blood pressure medications – Hypertension frequently accompanies kidney disease and damages vessels further. Drugs like amlodipine help control blood pressure.
Other medications may be prescribed to control vomiting, anemia, acidosis, and secondary hyperthyroidism. The treatment plan depends on the cat’s specific condition and test results. With treatment, cats can live comfortably with kidney disease for months to years.
Prognosis
The prognosis for cats with kidney disease depends significantly on the underlying cause and severity of the condition. According to the Cornell Feline Health Center, “Some cats respond very well to treatment for CKD while others do not, so the prognosis for CKD in affected cats is quite variable.”
If kidney disease is caught in early stages, the prognosis is more positive. With proper management and treatment, cats can live with chronic kidney disease for months or years. According to a 2008 study, cats in stage 2 kidney disease had a median survival time of 2 years with treatment.
However, the prognosis worsens considerably in advanced stages of kidney failure. The study found stage 4 cats had a median survival of only 1.16 months. At end-stage kidney disease, most cats will require euthanasia within weeks to months.
The key to maximizing longevity is catching kidney issues early and beginning fluid therapy, diet changes, and medication as soon as possible. With diligent monitoring and treatment, many cats can live a good quality of life despite kidney disease.
Takeaways
Kidney disease in cats can often go undiagnosed or misdiagnosed due to the subtlety of symptoms in early stages. However, early detection and management of kidney disease is crucial for maximizing quality of life and longevity. Cat owners should monitor for symptoms like increased thirst and urination, weight loss, poor coat quality, vomiting, and bad breath. Annual vet exams with blood and urine tests are important for cats over 7 years old. If kidney disease is suspected, further testing like imaging and biopsy may be needed for an accurate diagnosis. With proper treatment of underlying causes, diet changes, fluids, medication, and regular monitoring, many cats can live comfortably with chronic kidney disease for months or years.
