Renal disease is a general term for the dysfunction, impairment or failure of the kidneys. The kidneys are responsible for filtering nitrogenous and other waste products out of the body. They also help regulate blood pressure, red blood cell volume and the metabolism of calcium and phosphorus.
How Kidney Disease Affects Cats
The affects on cats from kidney disease result from the body's attempt to compensate for the kidneys' diminishing ability to flush toxins out of the body in urine. Among the early signs are dramatically increased water intake and urine output. Other signs are anorexia, weight loss, vomiting, diarrhea, lethargy, bad breath, seizures, collapse, abdominal discomfort, oral ulceration, bleeding problems, poor hair coat, weakness, depression and altered states of consciousness. In severe cases, affected cats can develop high blood pressure as well. Unfortunately, in most cases, the effects of chronic kidney disease are not noticed by owners until the damage has become largely irreversible. The signs of acute-onset kidney disorders closely parallel those caused by chronic kidney disease.
Causes of Kidney Disease in Cats
Generally speaking, kidney disorders in cats are classified into those that are chronic and those that are acute. Chronic renal disorders result from long-term insult to the kidneys which, over time, damages their ability to adequately concentrate urine and remove waste products from circulation. Chronic kidney disease can be caused by trauma, congenital abnormalities, urinary tract obstruction or infection, kidney stones, polycystic kidney disease, exposure to toxins, lymphoma, advancing age and a number of other disorders. The signs of acute kidney disorders appear abruptly. If appropriate treatment is provided quickly, it is possible to avoid permanent damage to the kidneys in cases of acute-onset disorders. Acute kidney disorders can be caused by venomous snake or insect bites, shock, bacterial and viral infections and exposure to or ingestion of renal toxins such as antifreeze, among other things.
Preventing Kidney Disease in Cats
One of the most troubling aspects of chronic kidney disease is that affected animals usually do not show clinical signs until the kidneys have been severely damaged. The best prevention is to have your aging cat get annual veterinary examinations to assess kidney function and overall health. Owners also can help manage the risk of kidney disease by feeding their cat a high-quality, nutritionally balanced diet, of course with free access to fresh water at all times. Potential poisons or other toxins should be kept well out of reach of all companion animals to prevent acute kidney damage.
Cats with chronic renal disease usually will be put onto a protein-restricted diet. It is very important that they have free access to fresh water at all times.
Kidney disease, which is potentially life-threatening, can occur in cats for many reasons and tends to develop as cats advance in age. However, regardless of the cause, the symptoms of kidney disease are the same, and they usually are nonspecific. In most cases, kidney disease cannot be cured but often can be managed with early diagnosis and prompt, lifelong medical treatment. Early diagnosis and intervention may help curb further damage to the organs in acute cases. However, particularly in chronic cases, the kidneys typically are severely and irreversibly damaged by the time clinical signs appear.
Symptoms of Kidney Disease
The kidneys are responsible for filtering nitrogenous waste products from circulation and excreting them in urine, regulating the concentrations of hydrogen, sodium, potassium, phosphate and other components of bodily fluids and producing essential hormones. Once a significant portion of functional kidney tissue has been damaged, the cat becomes increasingly unable to filter and excrete waste products in its urine, and toxic levels build up in the blood, causing signs of disease.
The most consistent and common clinical signs of kidney disease are polyuria (markedly increased urination) and polydipsia (markedly increased water consumption). These signs are a result of the body's attempt to flush toxic wastes out of circulation. Owners will report unusually frequent visits by their cat to the litter box. As the kidneys progressively deteriorate, the urine becomes less concentrated and lighter in color. Other common signs of renal disease include depression, appetite loss, weight loss, lethargy, weakness, possible tooth discoloration, vomiting, diarrhea, dehydration, oral ulcers, bad breath (halitosis), reluctance to exercise, pale gums, shivering, seizures, muscle wasting and abdominal discomfort. Kidney disease can also cause high blood pressure, which can result in blindness. Owners may notice a drastic change to the appearance of their cat's eyes, such as enlarged pupils and an overall cloudy appearance.
Chronic kidney disease cannot be cured. However, in many cases it can be controlled with medication, diet and other supportive therapies that will help clear the body of waste build-up.