Chronic cat kidney disease is a common condition of old cats. Up to 49 percent of elderly cats over 15 years old have some degree of kidney disease. However, the cause is rarely diagnosed. It isn’t known why nearly all elderly cats suffer kidney damage, but it’s thought to be the result of a lifetime of work.
Cat Kidney Disease: Symptoms, Diagnosis, And Treatment
Kidney disease refers to a number of conditions that damage the organs and result in impaired kidney function. Normally, kidneys work as an organic filtering system that screens waste products from the bloodstream and excretes them into the urine. Kidneys also regulate the body’s fluid composition and the nutrient content of the blood, as well as producing hormones that control red blood cell production and blood pressure.
Kidney disease is characterized as acute (of recent origination) or chronic (of long duration). Kidneys are able to work quite well even when severely damaged, and cats typically show few symptoms until 75 percent of kidney function is gone. Consequently, owners rarely notice anything is wrong until the disease is quite advanced. Untreated kidney failure results in death.
Signs Of Kidney Disease
One of the earliest signs is increased thirst and urination. This happens because when the kidneys lose their ability to concentrate urine, the cat must drink more and more water to compensate for excessive water loss. Cats in kidney failure may seek water in unusual locations, like the toilet bowl, fish tank or sinks. Owners also often notice a refusal to eat, weight loss, depression, and weakness, or even dehydration.
As kidney disease progresses, the cat may develop a brownish discoloration on the tongue, and sores in the mouth. The breath may smell like ammonia. Finally, the cat falls into a coma and then dies.
How Kidney Disease Is Diagnosed
Diagnosis is based on signs of disease, along with blood tests that measure levels of creatinine and BUN (blood urea/nitrogen) and analysis of the urine. X-rays, ultrasound or other specialized examinations of the kidneys may be necessary. Creatinine levels are influenced by lean body mass, though, and a lean or underweight cat in kidney failure may have normal creatinine levels, so the diagnosis may be missed in these cases.
A new test from IDEXX Laboratories screens for symmetric dimethylarginine (SDMA), which is a new biomarker for kidney function. This test offers a good estimate of glomerular filtration rate (GFR), an indicator of how well the kidneys are working. Research has shown that SDMA can identify chronic kidney disease an average of nine months earlier in dogs and 17 months sooner in cats. The SDMA biomarker test is recommended as a screening test for cats age six and older.
The prognosis depends on how far the disease has advanced. Some cats live with kidney disease for several years if the condition is mild to moderate.
Many cats have kidney disease, hypertension (high blood pressure), and hyperthyroidism at the same time. About one in four cats with chronic renal failure or hyperthyroidism also develop hypertension. Hypertension as a result of kidney failure can cause a stroke at worst, and erratic behavior and yowling at night at best. In fact, increased blood pressure is one of the major factors causing the disease to progress. The Doppler blood-pressure monitor is currently considered the most accurate machine for use on cats. An inflatable cuff is placed on the cat’s foreleg, and a transducer reads reflected ultrasound signals bouncing off moving red blood cells.
Getting an accurate reading can be tough, though. Stress from going to the hospital can make the cat’s blood pressure go higher and cause an inaccurate reading. Sedation also interferes with accuracy. Often, multiple readings over several days must be averaged to get the best picture of the cat’s situation.
Treating Cat Kidney Disease
Compromised kidney function in extremely advanced kidney failure makes it difficult for the cat to filter the waste produced from protein metabolism. For that reason, traditional therapy includes changing the cat’s diet to a high quality but lower protein ration.
Cats with kidney failure also are unable to get rid of extra phosphorus, and the excess can result in a number of secondary problems. Special diets for kidney disease typically reduce phosphorus levels. Some diets also adjust the amount of dietary salt. Your veterinarian can recommend an appropriate diet for your individual cat’s needs.
Most cats with renal failure lose their appetite, and these diets may not be palatable to your cat. If your cat refuses to eat the therapeutic diet, offer other brands and try to find a kidney diet your cat will accept. In many cases, though, you must give in to the cat’s preferences, and let him eat something rather than let him starve.
VeritasDVM shows a video of a cat owner’s guide to kidney diseases-Part 1:
Are there other symptoms, diagnosis, and treatment for your cat kidney disease you know of? Let us know in the comments section below.