Certain urinary tract abnormalities are inherited or congenital (present at birth). These abnormalities are caused by abnormal genes or produced by injury, disease, or exposure to toxic substances in the womb. They may or may not cause health problems later in your pet's life. These types of abnormalities are rare, but important to consider, if your cat has urinary tract problems.
Disorders of the Kidneys
There are many congenital and inherited problems that affect the kidneys. Among these are kidney dysplasia and hypoplasia, failure of the kidney(s) to develop, polycystic kidneys, and kidney cysts.
Kidney malformations, called dysplasias, occur when a cat's kidneys do not develop properly before birth. When the kidneys are unusually small, the condition is called hypoplasia. These abnormalities occur only occasionally in cats. Signs typically develop when cats are between 6 months and 2 years of age, and may include vomiting, decreased appetite, and increased thirst or urination. There is no effective treatment. Care for affected cats consists of managing the problems associated with the kidney failure that results from these conditions.
Failure to Develop
Rarely, one or both kidneys fail to develop. This condition is always accompanied by a lack of the tube that connects the kidney to the bladder (the ureter). The reproductive organs may also be underdeveloped. A cat in which both kidneys have failed to develop will die shortly after birth. However, a cat with one functioning kidney can live a full and healthy life. In this case, the condition is usually discovered by accident.
Polycystic kidneys have multiple cysts (enclosed, fluid-filled sacs) inside the functional part of the organ. The kidneys may be greatly enlarged, which a veterinarian may be able to feel during a physical examination. Problems caused by this condition can range from none at all to progressive kidney failure. This condition may be inherited in Persian cats and domestic long-haired cats. Your veterinarian can diagnose polycystic kidneys by examining your pet, taking x-rays, performing ultrasonography, or performing exploratory abdominal surgery.
These usually occur as a single cyst. They generally do not interfere with normal kidney function. It is unclear what causes them, and they are usually identified by accident.
Other Kidney Disorders
Other congenital problems include kidneys that are not positioned correctly, kidneys that are fused together, and nephroblastoma, a cancer that develops in the kidneys of young animals as a result of abnormal kidney tissue growth in the womb (see Kidney and Urinary Tract Disorders of Cats: Tumors).
Disorders of the Ureters
Several abnormalities can affect the ureter, the tube that connects the kidneys to the bladder. Normal, healthy cats have 2 ureters, 1 for each kidney.
An ectopic ureter is one that opens somewhere other than into the bladder. Ectopic ureters could empty urine into the urethra (the tube used for urination), or in females, the uterus or vagina. This defect can occur in cats, but it is much more common in dogs (see Kidney and Urinary Tract Disorders of Dogs: Ectopic Ureter).
Other Disorders of the Ureter
Other abnormalities of the ureter include failure to develop, the presence of more than the usual 2 ureters, and enlargement of the end of the ureter that connects to the bladder, a condition that can usually be successfully treated by surgery.
Disorders of the Bladder
The bladder is a muscular sac that stores the urine produced by the kidneys. Several congenital and inherited problems can affect the bladder.
The urachus is a cord of fibrous tissue that normally extends from the bladder to the navel. Before birth, the urachus is a tube that connects the bladder to the umbilical cord so that wastes can be removed. After birth, it normally closes and becomes a solid cord. In some animals, however, the urachus does not close properly after birth. Depending on which portion of the urachus remains open, these abnormalities are called a patent urachus or an umbilical urachal sinus. Other problems include urachal diverticula (small sac-like structures attached to the urachus) and urachal cysts. Signs include an inability to control urination, urine scalding (due to the fact that urine is acidic) of the skin near the navel, and urinary tract infections. Your veterinarian can diagnose these problems using x‑rays taken after a special dye is given intravenously. Treatment usually includes surgery and, sometimes, antibiotics.
Other Disorders of the Bladder
Other inherited or congenital bladder conditions in cats include the presence of more than one bladder, an abnormally developed or underdeveloped bladder, failure of the bladder to develop, and a bladder that is turned inside-out. Usually these problems occur along with other abnormalities of the urinary tract. Your veterinarian can diagnose these problems based on physical examination, observation of your pet while it urinates, and contrast x‑rays. Treatment varies depending on the type of problem.
Disorders of the Urethra
The urethra connects the bladder to the outside of the body. It is the tube through which urine passes when your cat urinates. Congenital urethral problems in cats are uncommon. Some of the conditions that do occur include failure of the urethra to develop, a urethra that does not open all the way or does not open at all, openings of the urethra that are on the underside or on top of the penis rather than on the tip in males, multiple urethras, urethral diverticula (small pouches that form in the urethra that become inflamed and painful), an abnormal opening between the urethra and the rectum, and an unusually narrow urethra.
Last full review/revision July 2011 by Scott D. Fitzgerald, DVM, PhD, DACVP, DACPV; Joseph W. Bartges, DVM, PhD, DACVIM, DACVN; Scott A. Brown, VMD, PhD, DACVIM; Sherry Lynn Sanderson, BS, DVM, PhD, DACVIM, DACVN; Melissa S. Wallace, DVM, DACVIM