The signs of kidney disease (renal failure) relate to the inability of the diseased or damaged kidney to perform its normal functions. The most easily recognized symptoms are excessive drinking and urinating (polydypsia and polyuria) caused by an inability to concentrate the urine. Animals with renal failure will often be dehydrated despite the polydypsia. This can be easily assessed by a skin fold test. The skin is pulled up into a fold and released. Normal skin will rapidly return to place whereas a dehydrated animal's skin is slow to return or remains folded. Withholding water will also fail to produce more concentrated urine in these animals.

The range of compounds filtered out of the body by the kidneys includes breakdown products from protein, muscle and bacteria, trace elements and minerals. When these compounds reach a level which causes clinical signs of poisoning the animal is considered to be uremic. Gastrointestinal signs (gut) of uremia are the result of damage to the lining of the mouth, stomach, and intestine. Vomiting and diarrhea sometimes with blood may occur while visible ulcers may be seen in the mouth leading to drooling and difficulty eating.

Uremic animals have a reduced ability to clot their blood leading to bouts of bleeding especially into the intestine. This is due to changes to the platelets which are blood cells involved in the clotting process. Damaged kidneys also produce less erythropoietin lowering production of red blood cells and ultimately can result in anemia (low red cells in the blood). Pale gums are a common sign of anemia. Other blood cells also effected by uremia are the white blood cells which form part of the immune system. The damage to the immune system leaves the animal open to infection which can be an important factor in death of animals with kidney failure. As the uremia becomes more severe especially where the amount of functional kidney reduces to a very low level the brain can become effected by the build up of toxins leading to signs of tremors, seizures, and abnormal behavior.

Diagnosis of renal failure can be confirmed by a number of tests. Blood test involve measurement of the breakdown products normally filtered by the kidneys. Urea from protein metabolism (blood urea nitrogen - BUN) and creatinine from muscle breakdown are most commonly assessed. Although not necessarily conclusive, significant increases in these compounds suggest less than 25% of the kidney is functioning. The concentration of the urine (specific gravity) can also be measured to assess kidney function. Very dilute urine even when the animal is deprived of water supports a diagnosis of renal failure.

Treatment of renal failure depends on both the severity of the case and the cause. The kidneys can be damaged both by external factors such as infection and toxins, or internal factors including tumors and the aging process (degeneration). Symptoms can also be acute appearing suddenly or build up over a period of time. Where the underlying cause can be treated such as infection using antibiotics, this is undertaken. General treatment however is designed to stimulate the functioning kidney to work better to filter out the toxins responsible for the signs of uremia. Diuretics such as Frusemide and Hypertonic glucose are the drugs used to increase the filtering rate of the kidneys. Animals on diuretics are often initially place on intravenous fluids (drip) to ensure they have adequate fluid intake while being treated.

Where treatment is successful in reversing the uremic state maintenance and prevention is based around feeding high quality, low residue protein diets which reduces the amount of wastes which need to be filtered out by the kidneys.