Liver disease and treatment in dogs and cats (Proceedings)
Canine and Feline liver disease diagnosis and treatment has improved dramatically over the last 20 years due to clinicians working to obtain a definitive diagnosis with improved diagnostic procedures. Knowledge gained over the years with more definitive diagnoses available has allowed clinical diseases to be separated into categories of infectious, inflammatory, immune-mediated, neoplastic, nutritional and toxic liver disease. Treatment aimed at the specific disease has improved outcome in our patients. Diagnostical procedures for more accurate diagnosis of liver disease includes physical exam findings, clinical pathology, radiology, scintigraphy, abdominal ultrasound (U/S), U/S guided fine needle aspirates and tissue biopsies and laparoscopy and exploratory celiotomy and tissue biopsies. Treatment is most successful if the primary cause can be eliminated however supportive care for complications of liver disease and hepatoencephalopathy can also be of great value as the liver heals.
Clinical Signs of Liver Disease
Patients often have non-specific signs of liver disease with a decreased appetite, anorexia, lethargy, weight loss, intermittent vomiting/diarrhea, and PU/PD. More specific signs of liver disease are icterus and ascites with a low protein content. Some patients have a chronic history while others have an acute history depending on the underlying condition and whether more than 80% of the liver has been affected and not functioning properly. Although clinical signs can be present before this occurs, most patients show signs of clinical disease at this stage.Bacterial Liver Disease
Bacterial liver diseases are usually due to ascending infections from the GI tract via the portal vein or bile duct. The hepatic artery can also bring systemic bacteria to the liver such as leptospirosis. Gram positive, Gram negative and anaerobic bacteria are normal flora of the liver and can cause infectious diseases when the liver is overwhelmed by bacteria from the GI tract or the liver suffers a major insult in some way such as a toxin. Feline Suppurative Cholangitis/Cholangiohepatitis,in the first phase of the complex, canine cholangitis/cholangiohepatitis, hepatic abscesses, toxoplasmosis and leptospirosis are the most common presentations for bacterial liver disease.
It is ideal to have a liver biopsy to culture the tissue for the specific bacteria and antibiotic sensitivity. Aerobic and anaerobic cultures should be submitted. Antibiotics can empirically be chosen based on the known bacterial flora of the liver. Ampillicin, cephalosporins, enrofloxacin, metronidazole (low dose 7mg/kg) and clindamycin and chloramphenicol are good choices in combination to cover the broad spectrum of bacteria.
Inflammatory Liver Diseases
Feline non-suppurative cholangiohepatitis in the second phase of the complex, canine chronic active hepatitis (CAH), canine copper hepatotoxicity, and possibly granulomatous hepatic disease are the most common diagnoses for inflammatory liver disease. Diagnosis by tissue biopsy is essential to identify the inflammatory cells present. Culture of liver tissues is also essential to eliminate bacterial disease as a component.
Anti-inflammatories: prednisone, azathioprine (Imuran®), cyclosporine (Atopica®), and chlorambucil. Antioxidants have been shown to improve chronic hepatocyte damage that causes oxidative damage/ Vitamin E (alpha-tocopherol) has proven to be effective in humans with chronic hepatitis and it is suspected to be helpful in dogs and cats as well. Milk Thistle (Silymarin) and S-adenosylmethionine (Denosyl SD4) have also been shown to protect heptic damage due to toxins and corticosteroid induced hepatopathy. Denosyl provides the hepatocyte with glutamine which is necessary for metabolic reactions within the hepatocyte to maintain function of the liver. Anti-fibrotics may prevent collagen deposition during inflammation and stimulate collengenase activity to prevent cirrhosis which is the end-stage of liver inflammation and is irreversible. Colchicine is used often for this purpose however effectiveness in dogs has not been studied. Cholerectics such as Ursodeoxycholic Acid (Actigall®) replace "bad" bile acids (hydrophilic) with "good" bile acids (hydrophobic) in the intestine so that the "bad" bile acid does not cause hepatocyte damage during cholestasis. There are clinical reports in dogs that show improvement in liver enzymes and histopathology with its use.