Arteriovenous Malformation of the Liver in Cats

 

Intrahepatic arteriovenous (AV) fistula is generally a congenital based condition, which causes abnormal passages to develop between the proper liver (hepatic) arteries and the inner liver (intrahepatic) portal veins. It can also develop through surgical injury, trauma, and abnormal tissue or bone growth (neoplasia). Although this condition is uncommon in cats, it does occur.

 

This severe illness can be addressed with fair results when a proper diagnosis has been settled on. Most treatment will be on an outpatient basis and will include a planned diet, dietary restrictions, and long term observation.

 

Symptoms and Types

 

Cats suffering from AV fistula may show lethargy, anorexia, vomiting, diarrhea, weight loss, excessive thirst (polydipsia), dementia, and abdominal swelling. There are several other signs of AV fistula, such as:

 

• Ascites (fluid in the abdomen)
• Congenital heart malformations
• Hemorrhages
• Abnormal portal vein coagulation (thrombosis)
• Protein loss in the kidney (nephropathy)
• Intestinal abnormality (enteropathy) hypertension
• Liver disease, cirrhosis of liver

 

The central nervous system may also be affected by this condition. Symptoms can include:

 

• Distemper and other infectious disorders
• Lead poisoning, water on the brain (hydrocephalus)
• Idiopathic epilepsy
• Metabolic disorders
• Brain degeneration associated with liver failure (hepatic encephalopathy)

 

Causes

 

There is no particular breed that shows a higher predisposition than another. Hepatic AV is a vascular (vessel) malformation that is genetically determined during the embryonic stage of development - also referred to as embryologic anlage. Most conditions begin to show at an early age. In some cases of AV, surgical injury, trauma, or tumor growth (neoplasia) can lead to the problem.

 

Diagnosis

 

The disorder can be tested for by conducting a complete blood count (CBC), biochemistry, and urinalysis techniques, as well as coagulation tests, abdominal (peritoneal) fluid analysis, and an evaluation of bile acids (digestive secretion from the liver). X-rays, ultrasounds, liver biopsies, and explaratory laparotomies (incision into the abdominal wall) are other exams that may help to diagnose the liver malformation.

 

  

 

Treatment

 

While some cats will require surgical care, most can be treated at home with proper nursing care. Modifications to the diet will often include dietary restrictions on nitrogen and sodium. Hydration and electrolyte disturbances will also be addressed and treated. Drugs that rely on liver biotransformation should be avoided, along with any drugs that will react with GABA-benzodiazepine receptors (the transmitters that inhibit anxiety and over excitement). Veterinarians commonly prescribe histamines for blood pressure reduction, and diuretics (furosemides) to relieve excess fluid.

 

Living and Management

 

It will be important for your veterinarian to monitor your cat's biochemistry every few weeks, and then every few months following the initial treatment routines. Prognosis is fair when AV is properly treated, although your cat will require ongoing monitoring and treatment to address any related health issues that may arise.

 

Prevention

 

As the health issue is mostly congenital in nature, there are no preventative measures to consider.