Some urinary system problems in dogs are congenital (present at birth) and/or inherited (passed down through the genes). Congenital problems can be caused by abnormal development before birth or by exposure to harmful substances in the womb. Congenital and inherited problems are rare, but they can matter if your dog develops urinary signs.
Congenital and Inherited Kidney Disorders in Dogs
Congenital and/or inherited kidney problems in dogs include kidneys that don't form correctly, failure of a kidney to form at all, kidneys with many cysts (pockets of fluid), and simple kidney cysts.
Kidney Malformations in Dogs
Sometimes, a dog's kidneys don't develop normally before birth. When the kidneys develop with an abnormal structure or contain immature or disorganized tissue, this is called renal dysplasia. A specific kind of kidney dysplasia, called renal hypoplasia, is when the kidneys are smaller than normal because they didn't develop fully. These problems occur in many breeds, including Alaskan Malamutes, Bedlington Terriers, Chow Chows, Cocker Spaniels, Doberman Pinschers, Keeshonden, Lhasa Apsos, Miniature Schnauzers, Norwegian Elkhounds, Samoyeds, Shih Tzus, Soft Coated Wheaten Terriers, and Standard Poodles.
Dogs with congenital kidney abnormalities are often very thirsty and urinate a lot. Because of decreased kidney function, waste products can build up in the blood, which is called azotemia (see Chronic Kidney Disease in Dogs). Puppies with kidney dysfunction that begins early in life might have stunted growth.
Diagnosis of congenital kidney malformations is based on the dog's breed, age, blood and urine test results, and sometimes a kidney biopsy (sampling a piece of the dog's kidney to analyze it under a microscope).
Treatment focuses on managing kidney dysfunction, similarly to how chronic kidney disease is managed.
Missing Kidneys in Dogs
In rare cases, one or both of a dog's kidneys don't develop at all. The ureter on the same side as the absent kidney might also be missing, and the dog's reproductive organs might be abnormal. Dogs missing both kidneys die soon after birth. With one normal kidney, however, a dog can often live a normal life, and the missing kidney might be discovered only by accident when the dog undergoes testing or surgery for an unrelated issue. An undeveloped kidney is more likely to occur in certain breeds, including Beagles, Shetland Sheepdogs, and Doberman Pinschers.
Polycystic Kidneys in Dogs
A kidney containing many cysts (pockets of fluid) is called polycystic ("poly-" meaning "many"). Dogs with polycystic kidneys might also have cysts in their liver. The kidneys are often enlarged. Some affected dogs show no symptoms, but others will develop worsening kidney dysfunction.
Polycystic kidneys are detected by physical exam, x-rays, ultrasound, or exploratory surgery. This condition is inherited in Beagles, Bull Terriers, West Highland White Terriers, and Cairn Terriers.
Simple Kidney Cysts in Dogs
Some dogs are born with single kidney cysts that don't affect kidney function. These simple kidney cysts are often found by accident when the dog is undergoing tests or surgery for an unrelated condition.
Other Congenital and Inherited Kidney Disorders in Dogs
Other congenital and/or inherited kidney problems can occur. For example, a dog might have extra arteries supplying a kidney, or the kidneys might be in an abnormal location or be joined together. Nephroblastoma, a type of cancer of the kidney, is linked to abnormal kidney tissue that develops before birth.
Congenital and Inherited Ureter Disorders in Dogs
The ureters carry urine from the kidneys to the bladder (see diagrams in The Urinary System of Dogs). Dogs normally have two, one for each kidney.
Ectopic Ureter in Dogs
A ureter is considered "ectopic" if it opens somewhere other than into the bladder. It might drain into the urethra or, in females, into the uterus or vagina. This problem usually occurs in young dogs, especially females. Certain breeds are at higher risk for ectopic ureters, including West Highland White Terriers, Siberian Huskies, and Labrador Retrievers.
A common sign that your dog has an ectopic ureter is constant urine dribbling. Skin irritation and inflammation around the vulva (the external opening of the vagina) can also occur. Some dogs can still urinate normally if one ureter is normal.
A veterinarian typically uses x-rays to identify an ectopic ureter. The problem is fixed with surgery to relocate the ureter so it drains into the bladder. In severe cases, the ureter and the kidney might need to be removed altogether. Some dogs still leak urine after surgery, but medication can often help.
Other Congenital and Inherited Ureter Disorders in Dogs
Other congenital and inherited ureter problems in dogs include failure of a ureter to form, extra ureters, and ureterocele, which is an enlargement where the ureter enters the bladder. Depending on the problem and its severity, surgery might be needed.
Congenital and Inherited Bladder Disorders in Dogs
A dog's bladder stores its urine until it is ready to urinate. Dogs can be born with abnormalities of the bladder, some of which can be inherited.
Urachal Problems in Dogs
The urachus is a cord connecting the bladder to the umbilical cord before birth. It normally closes after birth. If it doesn't close properly, several defects can occur, including a patent (persistently open) urachus, a urachal sinus (an abnormal pocket or channel), urachal diverticula (pouchlike outgrowths), and urachal cysts (pockets of fluid).
Signs that your dog has problems relating to the urachus can include urine leakage, skin irritation near the navel (belly button), and urinary infections. A veterinarian can usually diagnose these problems using x-rays. Surgery is typically needed to correct the issue, and sometimes antibiotics are prescribed.
Other Congenital and Inherited Bladder Disorders in Dogs
Other rare defects of the bladder in dogs include more than one bladder, an underdeveloped bladder, failure of the bladder to form, or a bladder that is turned inside out. Diagnosis can involve a physical exam, watching the dog while it urinates, and x-rays. Treatment depends on the defect.
Congenital and Inherited Urethral Disorders in Dogs
A dog's urethra carries its urine from the bladder out of the body. Congenital and/or inherited urethral problems are uncommon.
Hypospadias in Dogs
Hypospadias is a disorder of male dogs in which the urethral opening is located before the tip of the penis. The penis or testicles might also be underdeveloped. Signs of hypospadias depend on the location of the opening and can include urine scald (skin irritation from being in constant contact with urine) and urinary infections. Dogs with this condition can be treated with surgery.
Urethrorectal and Rectovaginal Fistulas in Dogs
A fistula is an abnormal connection between two parts of the body that normally aren't connected. A urethrorectal fistula connects the urethra and rectum (the last part of the large intestine, before it opens to outside the body at the dog's hind end), whereas a rectovaginal fistula connects the rectum and vagina. These types of fistulas are more common in English Bulldogs than in any other breed.
Dogs with these problems often get urinary infections and might have blood in their urine or painful urination. Some may pass urine from the rectum.
Surgery is usually needed, and the treating veterinarian might prescribe antibiotics.
For More Information
Also see professional content regarding congenital and inherited disorders of the urinary system in animals.
