What is CRF – Chronic Renal Failure?
Chronic renal failure (CRF) is the most common kidney disease found in old dogs. Dogs are considered old above the age of 7.5 years. However, in the case of large dogs (above 20 kg) and giant dogs (above 40 kg), old age appears earlier than 7.5 years. An awareness of different aspects of this disease leads to early detection.
Role of kidneys?: The role of kidneys is to form urine, excrete waste products, regulate the volume and composition of fluids in the body and act as an endocrine gland.
Old age and kidney disease?: A dog’s vulnerability to kidney disease increases with the appearance of old age. This does not mean that a younger dog will not get this disease but the incidence is very low among them. Our observation in respect of dogs coming to our clinic during the last 10 years is that 95 percent of the incidence of CRF has been in old dogs and compared to various other diseases appearing in old dogs, this disease is very prevalent.
What is chronic renal failure?: Chronic renal failure (CRF) is the term applied to the persistent impairment of renal function of such severity that the kidneys can no longer maintain a healthy internal environment and if not detected, treated and managed properly, death of the dog is inevitable. CRF is a progressive condition and appears in four phases.
Phase-1: Loss of renal reserve?: During this phase, there is loss of renal reserve. The reserves of nephrons (a nephron is the basic functional unit of the kidneys) are lost as the kidney ages. Despite the losses, the kidneys maintain the ability to concentrate the urine and excrete waste products. The affected dogs do not show any signs of illness or abnormality.
Phase-2?: Renal insufficiency?: During this phase, two-thirds of the total nephrons are lost.
The ability of the kidneys to concentrate urine becomes less, but still there are no clinical signs except an increase in the frequency of urination and quantity of urine output.
Phase-3?: Renal failure?: As the CRF advances to this phase, three-fourths of the nephrons are lost, the dog loses his urine concentrating ability and there is accumulation of waste products in the blood and this is manifested as lethargy, loss of appetite, weight loss, dehydration, vomiting and diarrhoea.
Phase-4?: Advanced renal failure?: This is the final stage and a return from this stage to normalcy is extremely difficult. In this stage, more than nine-tenths of the nephrons of the kidney are lost leading to retention of excessive quantities of protein metabolic by-products leading to a uraemic state. The affected dogs in this stage show oral ulceration, profound weight loss, continuous vomiting and total loss of appetite. Nervous signs such as incoordination and inability to stand are also seen. Most of the affected dogs also become very anaemic and develop other complications such as pulmonary and gastro-intestinal tract diseases. Uraemic coma (dog goes into coma because of high urea level in the blood) follows, ending in death/euthanasia. The parameters of kidney function are elevated several times the normal values especially, blood urea nitrogen, serum creatinine and phosphorus.
Prevention of CRF?: Early detection of the disease is crucial for preventing the disease from progressing to stage of renal failure. To be successful, the disease should be detected before the beginning of the third phase. An old dog showing excessive urination without any other symptoms (including diabetes) could be a case of advanced renal insufficiency progressing to renal failure and merits a detailed examination by the vet including a detailed lab examination of blood and urine and treatment depending on the findings. This followed by sound nutritional management can halt/slow down the progress of the disease. Aim of nutritional management is to reduce the accumulation of protein waste products by reducing the percentage of protein, phosphorus and sodium levels. A phosphate binder such as calcium acetate or carbonate in the daily feed can reduce absorption of the dietary phosphorus. Prescription diets, specially formulated for CRF cases are also available.
Practical difficulties in prevention of CRF?: Unfortunately, the disease is seldom detected at an early stage. By the time the owner takes his pet to the vet, the stage becomes critical.
General therapeutic and managemental measures to deal with chronic renal failure?: Therapeutic measures are aimed at controlling infections, discontinuing injurious drugs, correcting fluid, acid-base balance and metabolic problems. The vets will assess the case and a therapeutic regimen will be decided to suit the needs of the particular case. An awareness of the different aspects of this disease will help the owners to be on the lookout for early signs and getting it examined by the vets including laboratory tests.
(Dr. J J Rappai and Dr. K V Rappai can be contacted at JRG Vet Clinic, 24 Damodar Shopping Complex, Sector-37, Noida. Ph : 95120-2430521)