Dogs may have several congenital abnormalities affecting the urinary system, some of which may be inherited. Abnormal genes are the cause of genetic disorders present at birth. But other congenital disorders result from the fetus being affected by the illnesses and injuries the mother suffered during pregnancy or the toxins she had ingested. Some of these disorders may cause problems for the dog later. Even though congenital urinary tract disorders are rare in dogs, they may need medical attention, if present.
Kidneys Disorders in dogs
Among the several congenital disorders and inherited problems that may affect the dog’s kidneys, the most common are kidney malformations, failure to develop, and polycystic kidneys. In some cases, the kidneys may develop cysts and tumors too.
When the kidneys have not developed normally while the puppy was in the womb, it may result in malformations referred to as dysplasias. Hypoplasia is one such condition characterized by abnormally small kidneys. This disorder is found to occur in several breeds of dogs such as Alaskan Malamutes, Cocker Spaniels, Bedlington Terriers, Norwegian Elkhounds, Chow Chows, Doberman Pinschers, Soft-coated Wheaten Terriers, Miniature Schnauzers, Samoyeds, Keeshonden, Lhasa Apsos, Shih Tzus, and Standard Poodles.
The kidneys may appear pale and firm, in addition to being very small. The glomeruli occurring in the kidney’s outer region may be abnormally small also. They are involved in the filtering of blood. Dysplasia may affect both the kidneys, or it may occur in only one.
When the dog has this condition, the filtering capacity of the kidneys is greatly impaired, resulting in the accumulation of waste products in the blood. The effect of this toxin build-up usually becomes apparent when the dog is 6 months to two years old. Even before the dog becomes ill, certain symptoms such as polydipsia and polyuria may be present. Polydipsia is excessive thirst, while polyuria is excessive urination. If kidney failure occurs early in the life of the puppy, it may have stunted growth. Dysplasia and hypoplasia may be diagnosed by the veterinarian from the symptoms, the age at which these symptoms appeared, as well as the breed of the dog. However, a biopsy of the kidney is done to confirm the diagnosis.
Since no treatments are available for either hypoplasia or dysplasia, the only option is to manage the disorder by providing proper care.
Failure Of The Kidneys to Develop In Dogs
The failure of kidneys to develop is not very common in dogs, but when it occurs, the ureter connecting the kidneys and the bladder also would have failed to develop. Underdeveloped reproductive organs too usually occur along with this disorder. If only one kidney has failed to develop, the dog may not have any problems as long as the healthy kidney works well. In such cases, the disorder may not be detected at all, unless the dog is x-rayed or scanned for some other reason. On the other hand, if both the kidneys have the disorder, the puppy will not survive.
As the name implies, polycystic kidneys are characterized by multiple cysts in them. They occur in the functional region of the kidneys. They cause the kidneys to enlarge so much that they can be felt when the veterinarian conducts a physical examination. Polycystic kidneys may not cause any problems in some cases, but in others it may lead to progressive kidney failure. In some breeds such as the Cairn Terriers and the Beagles, this disorder is found to be inherited. When polycystic kidneys are detected during a physical examination, x-rays or ultrasound scans may be done to confirm the diagnosis. Occasionally exploratory surgery may be done too.
Unlike in polycystic kidneys, a single cyst may occur in the kidneys. The cause of this disorder is not known, but it usually causes no problems as normal kidney functions are carried out by the healthy portions of the kidneys. They are not usually detected unless the dog undergoes diagnostic tests such as x-rays or abdominal scans for some other purpose.
Other Kidney Disorders
A few other congenital kidney disorders found in dogs are abnormal positioning of the kidneys, occurrence of multiple renal arteries, and fused kidneys. A kidney normally has only one artery supplying blood to it, but in 5% of cases, multiple renal arteries occur. Nephroblastoma is a type of cancer affecting the kidneys. It results from the development of abnormal tissues in the kidneys of the fetus.