You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Kidney failure (also known as renal failure) is a common problem in both cats and dogs and early treatment is important, so owners should look out for early signs of problems

Almost all organs in the body have more functional tissue than is needed to perform it's daily tasks, and the kidney is no exception. The kidney's main role in the body is to act as a filter for the blood and waste products are eliminated in the urine, whereas "good" components of the blood such as the blood cells, proteins etc are kept in the bloodstream and are not allowed to pass into the urine to be lost from the body.

Over many years the number of functional filtration units of the kidney (called nephrons) decreases because of injury due to normal "wear and tear" or through disease. Because the kidney initially has much more tissue than is needed over two-thirds of the kidney tissue has to be damaged before it cannot do it's job as a filter properly, and over three-quarters of the functional kidney tissue has to be damaged before clinical signs are noticed.

The signs that are most commonly seen are :

• Weight loss - in part because proteins and other "nutrients" are being lost in urine
• Increased urine production - increased volume of urine is passed out, and there is an increased frequency of urination. This may result in abnormal behaviour patterns, for example the pet may suddenly start asking to go out in the middle of the night to urinate.
• Increased thirst - because the animal is losing so much water as urine. It is very important that affected animals have access to sufficient water at all times otherwise they can become dehydrated
• Animals may become pale due to anaemia - this is because the kidney has an important role in red cell production
• Sometimes the skeleton of an animal with kidney failure loses mineral from the bone because the kidney has an important role to play in regulating bone mineralisation. This leads to "rubbery" bones that bend easily - and one of the common sites to see this is the jaw bone which can become very flexible (a condition called "rubber jaw") 

Most animals with kidney failure develop the disease over a long period of time, but it is progressive and so the earlier it is identified in a patient the better so that steps can be taken to delay progression. Urine tests can identify the disease even before there are any clinical signs present - so many practices now run screening programmes for older animals to try to pick up evidence of the disease as early as possible. If you have an old dog or cat you should consider taking part in these programmes if your veterinary practice run one.

Management of kidney failure involves modifying the ration of the animal and sometimes the use of drug therapy. In some patients fluids have to be replaced by intravenous drip. These steps can greatly improve the quality of life for the animal as well as delaying progression of the disease, and so prolonging life.

In some cases kidney transplantation may be necessary.where this is available as an option.

Updated October 2013