Intrahepatic arteriovenous (AV) fistula is a rare congenital condition found in cats and dogs, although it can also develop due to surgical injury, trauma, or abnormal tissue or bone growth (neoplasia). It involves the formation of abnormal passages between the hepatic arteries and the intrahepatic portal veins within the liver.
When present, this acute condition requires a thorough diagnosis for appropriate treatment. Typically, treatment can be managed on an outpatient basis and includes a tailored diet, dietary restrictions, and ongoing observation. Both dogs and cats can be affected by this condition or disease.
Symptoms and Types
Dogs affected by AV fistula may display various symptoms, including lethargy, loss of appetite, vomiting, diarrhea, weight loss, increased thirst (polydipsia), confusion, and abdominal swelling. Additionally, other indicators of AV fistula may include:
- Ascites
- Congenital heart abnormalities
- Hemorrhages
- Abnormal coagulation of the portal vein (thrombosis)
- Protein loss in the kidneys (nephropathy)
- Intestinal abnormalities (enteropathy)
- Hypertension
- Liver disease
- Cirrhosis of the liver
Furthermore, symptoms may extend to affect the central nervous system, manifesting as distemper and other infectious disorders, lead poisoning, hydrocephalus (accumulation of fluid in the brain), idiopathic epilepsy, metabolic disorders, and brain degeneration associated with liver failure (hepatic encephalopathy).
Causes
There is no particular breed that exhibits a greater predisposition to hepatic AV fistula than others. This condition is a vascular malformation that is genetically determined during the embryonic stage of development, also known as embryologic anlage. While most cases manifest in young dogs, in certain instances, the issue can arise due to surgical injury, trauma, or tumor growth (neoplasia).
Diagnosis
The condition can be evaluated using complete blood count (CBC), biochemistry, and urinalysis techniques. Coagulation tests, analysis of abdominal (peritoneal) fluid, assessment of bile acids (digestive secretion from the liver), X-rays, ultrasounds, liver biopsies, and exploratory laparotomies (incision into the abdominal wall) are additional examinations that may aid in diagnosing the liver malformation.
Treatment
While surgical intervention may be necessary for some pets, most can be managed with home care and nursing. Dietary modifications often involve restrictions on nitrogen intake and sodium. Management of hydration and electrolyte imbalances is also essential and will be addressed accordingly. Medications that rely on liver biotransformation should be avoided, as well as any drugs that interact with GABA-benzodiazepine receptors, which regulate anxiety and excitability. Veterinarians typically prescribe histamines to reduce blood pressure and diuretics (such as furosemide) to alleviate excess fluid.
Living and Management
Regular monitoring of the dog’s biochemistry is crucial, initially every few weeks and then every few months after initiating treatment protocols. With proper treatment, the prognosis for the dog is generally fair. However, ongoing monitoring and treatment are necessary to address any potential health issues that may emerge.
Prevention
Since the health issue is primarily congenital, there are no preventive measures to take into consideration.
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