The most common type of shunt is a single congenital shunt. This means that the animal is born with the problem. Acquired shunts may occur secondary to liver disease.

Congenital shunts occur in both dogs and cats. Most animals start showing signs by six months of age. However, shunts have been diagnosed in a adults as old as 10 years.

Shunts are more common in purebred dogs than mixed breeds. The breeds predisposed to congenital shunts include: miniature schnauzer, Yorkshire Terriers, Irish wolfhound, cairn terrier, Maltese, Australian cattle dog, golden retriever, Labrador retriever, and Old English sheepdog.

It occurs more often in female dogs, and of the affected males, there is also an increased incidence of cryptorchidism, in which one or both testicles remain undescended.

The impact of portosystemic shunt on your pet can present itself in a variety of ways. The most common clinical signs are a result of elevated toxin levels in the blood secondary to failure of removal by the liver. One of the important toxins is ammonia, which causes abnormalities of the central nervous system.

What to Watch For

Lack of appetite

Lethargy

Weakness

Disorientation

Stumbling

Circling or pacing

Apparent staring into the corner

Pressing of the head against objects

Seizures

Blindness

Behavioral changes

Excess salivation (more common in cats)

Vomiting

Diarrhea

Increased thirst and frequent urination (more likely in dogs)

Straining to urinate

Blood in the urine

Failure to grow and thrive

Weight loss

Treatment

Surgical ligation (closure) of the shunt is the treatment of choice. However, animals must be medically stabilized prior to surgery.

IV fluid therapy restores hydration deficits and corrects electrolyte imbalances.

Lactulose decreases absorption of intestinal toxins such as ammonia by altering intestinal pH.

Antibiotics alter intestinal bacteria such that ammonia production is decreased.

Feeding a protein restricted diet since protein in the diet can precipitate neurologic abnormalities.

In animals with vomiting and diarrhea, gastric protectants help reduce acidity of the gastrointestinal tract and may alleviate some of the symptoms

Anti-convulsant drugs may be necessary in animals with seizures that are not responsive to the aforementioned medical treatments.

A congenital portosystemic shunt is a condition that exists when your pet is born. This is a serious disorder because the liver  does not receive adequate blood flow, and therefore does not grow normally. Most animals with shunts have livers that are smaller than normal. Because of the inadequate blood flow and improper growth, the liver does not function properly.