Overview:

Also known as liver shunt, portosystemic shunt is caused by an abnormal development of the blood vessels draining the gastrointestinal tract. They usually go from the intestines to the liver, but in the case of a portosystemic shunt, the liver is bypassed & is unable to perform many of it's usual metabolic functions.

Due to the lack of normal detoxification performed by the liver, neurologic disturbances are a problem in cats with a portosystemic shunt.

Portosystemic shunts may be congenital or acquired, most shunts in cats are congenital & cats demonstrate clinical signs within 12 months of age. Persians, Himalayans & Siamese are more represented than other breeds & it is seen more commonly in males.

Symptoms of portosystemic shunts in cats:

Central nervous system disorders are commonly seen in cats with a portosystemic shunt. Common clinical signs include:

• Poor growth
• Excessive drooling
• Lack of appetite
• Seizures
• Depression
• Vomiting
• Diarrhoea
• Tremors
• Intermittent blindness
• Mental & neurological abnormalities such as sudden aggression, mental dullness, pressing head against objects
• Straining to urinate due to ammonia biurate bladder stone formation
• Blood in urine due to ammonia biurate bladder stone formation
• Copper coloured irises

Diagnosis of portosystemic shunts:

• Complete blood count
• Biochemical profile
• Urinalysis
• Liver function tests such as Bile acid test & ammonia tolerance test
• Ultrasound & X-rays
• Portography

Treatment of portosystemic shunts:

• Surgical ligation (tying off to stop blood flow) is the treatment of choice for single, extrahepatic shunts.
• A prescription diet which is restricted in protein may be recommended.
• Supportive care, where necessary.