Juvenile renal dysplasia, often referred to as progressive juvenile nephropathy, familial renal disease or simply renal dysplasia, is a condition whereby the kidneys fail to develop properly in the fetal puppy. Symptoms of juvenile renal dysplasia typically surface before a puppy reaches 2 years of age and include increased thirst, frequent urination, possible urine leakage, vomiting, weight loss, metallic breath odor and lethargy. Puppies may fall behind littermates in growth. The prognosis for juvenile renal dysplasia is grim, with most cases leading to chronic kidney damage and a reduced life-span. Other conditions often develop due to poor kidney function.
Due to abnormal kidney development, the kidneys fail to function as they should. The kidneys fail to process waste, and as a result, ammonia, nitrogen, acids and other waste products build up in your dog’s blood and tissues. This buildup of waste is known as uremia and symptoms include depression, loss of appetite, weight loss and dry, dull-looking hair. The tongue displays a brownish color and your dog’s breath may develop an ammoniac or metallic odor.
Renal Secondary Hyperparathyroidism
As the kidneys fail to function, resulting in chronic kidney failure, another condition that commonly develops is renal secondary hyperparathyroidism. Excess amounts of parathyroid hormone enter the body as a result of a reduced production of calcitrol. The main symptom of secondary hyperparathyroidism is bone resorption, often beginning with the teeth. Teeth may fall out and the lower jaw bone softens, resulting in a “rubber jaw,” or fibrous osteodystrophy. This condition results in drooling and the inability to close the jaw.
Similar to uremia, metabolic acidosis is the result of increased acid levels in the blood due to the kidneys' inability to excrete hydrogen ions. Symptoms include anorexia, nausea, vomiting, depression, rapid breathing, diarrhea, fever, muscle wasting and weakness, malnutrition and confusion.
Mineral abnormalities are common in dogs with juvenile renal dysplasia. Hyperphosphatemia is a condition that causes elevated levels of phosphate in the blood. When it occurs along with hypocalcemia, or low levels of calcium, dogs may experience muscle spasms and tremors. Another condition common in dogs with kidney failure is hypermagnesemia, or increased magnesium in the blood. Hypermagnesemia causes nausea, vomiting, weakness, lowered heart rate, paralysis, poor reflexes and respiratory depression. In severe cases it can lead to cardiac arrest or coma.