The kidneys are the body’s filtration organ, filtering the blood and removing the toxic by-products of metabolism and excretes them harmlessly through the urine. Renal failure is a degeneration of the kidneys where there is not enough active filters available to be able to handle the all the blood which passes through the kidneys. Renal failure in dogs is usually due to aging. The onset of renal failure is dependent on the size of your dog – larger breed dogs reach senior status much sooner than smaller breed dogs. Larger breed dogs can experience renal degeneration from 7 years of age, where early signs occur at about 10-14 years of age in small breed dogs. Some breeds have a genetic predisposition toward renal failure, but mostly, it is a senior dog disease. Renal failure occurs when 70% of the nephrons (individual filters that make up the kidney) are lost due to degeneration, or toxicity. This can be acute (sudden onset, due to non-aging, repairable) or chronic (degenerative, non-repairable). Acute cases are usually due to the ingestion of toxins, such as ethylene glycol (antifreeze) and some poisonous plants. Acute renal failure is still very serious and can be life-threatening if not treated by a veterinarian, but the kidney damage is mostly reversible. Chronic renal failure is non-reversible, but your pet can live happily for years with early diagnosis, careful treatment, and regular veterinary checks.
When the filtration process by the kidneys become ineffective, blood flow to the kidneys is increased, to improve the filtration of toxic products. Because of this, there is more urine being produced, and therefore the body’s stores of water are going to decrease. As a result, your dog will increase the amount of water he/she drinks, to prevent dehydration from occurring. These are the first two clinical signs of early kidney failure. When kidney failure becomes more advanced, more toxins are going to build up in the bloodstream, as they aren’t being excreted properly. This usually causes nausea, depression, vomiting, bad breath, and diarrhoea. Sometimes advanced kidney failure may cause ulcers in the mouth, which may affect eating habits. In severe cases, seizures may be seen as the toxic substances overload the brain.
Treatment for Kidney failure
After diagnosis of kidney failure, treatment will start immediately. In some cases, the kidneys are so badly damaged that they cannot be revived. However, intravenous fluid therapy may revive the filters in the kidneys so that they can continue to function. The first step is to flush out the kidneys. Intravenous fluids given in high volumes over a few days helps to stimulate the kidney cells to start functioning again. If enough of these cells remain to perform the body’s requirement for waste removal, your dog’s kidneys will resume function and will continue to function for a few weeks to a few years.
If there are not enough functioning cells remaining then your pet may respond to the initial fluid therapy treatment, or may not respond at all. In situations such as these, kidney function may return for a short period of time, but will rapidly degenerate as soon as the treatment stops, or kidney function will not return at all.
If intravenous fluid therapy is successful, and your pet is now feeling better, there are some medical and nutritional treatments which will help to decrease the stress on the kidneys.
- A good quality, low protein diet, formulated for kidney disease. When protein is metabolised by the body, toxic substances result, which require elimination from the body. If the kidneys are ineffective at eliminating these substances, the substances end up in the bloodstream, causing your pet to feel very ill. Dogs which are experiencing renal failure will often have a decreased appetite, and their food intake will be lower. Diets targeted for dogs with renal issues will often have a high fat content, making the diet more palatable and more enticing, and a higher carbohydrate content, for energy. Also, they will include supplements like fatty acids, which increases the blood flow to the kidneys, eliminates minerals like sodium and phosphorus, slowing the progression of degeneration, and increases the amount of soluble fibre which lowers the urea level in the blood. Diets like Hills k/d and Eukanuba Renal plus are suitable formulas.
- A phosphate binder. The kidneys remove phosphorus from the bloodstream and excrete it through the urine, and if renal function is impaired, phosphorus accumulates in the blood, contributing to lethargy and poor appetite. Phosphate binders will affect the intestinal tract to prevent the absorption of phosphorus into the bloodstream, reducing the workload of the kidneys.
- Other drugs may be prescribed that regulate the parathyroid gland and others to stimulate the bone marrow to produce new red blood cells. The parathyroid gland will release hormone in response to increased phosphorus, which strips calcium from the bones, making them brittle. Kidneys will also produce erythropoeitin, a hormone which stimulates bone marrow production of red blood cells. In patients with kidney failure, a low red blood cell count, or anaemia, may result if there is insufficient erythropoeitin levels.