Hepatobiliary Diseases of Horses Flashcards
What is Theiler’s Disease?
idiopathic acute hepatic disease, most commonly caused by administration of tetanus antitoxin or other equine products 4-10 weeks prior –> AKA acute serum hepatitis
- most common cause of acute hepatitis in horses
What clinical signs are indicative of Theiler’s disease?
- depression, anorexia
- severe icterus
- photosensitization
- hepatoencephalopathy
- pica
What changes to the liver are seen with Theiler’s disease?
widespread hepatic necrosis and inflammatory cell infiltrate with mononuclear cells and neutrophils in portal areas + bile ductile proliferation
What treatment is recommended for Theiler’s disease?
non-specific supportive therapy
- fluids
- dextrose supplementation
- anti-inflammatory therapy
- nutritional support
- control of hepatoencephalopathy
What is prognosis of Theiler’s disease like?
- favorable if no severe signs of encephalopathy
- poor with signs of bleeding or hepatic encephalopathy
What necropsy findings are most common with Theiler’s disease?
- decreased liver size
- severe icterus
What is chronic active hepatitis in horses? What are 4 possible potential causes?
chronic inflammatory response of the liver to unknown stimulus
- plant/chemical toxins
- environmental chemicals
- ascending infection from biliary tract
- immune-mediated disease
What clinical signs are seen in cases of chronic active hepatitis in horses?
- progressive weight loss
- intermittent fever
- icterus
- inappetence
- photosensitization
CHRONIC in nature
What changes to the liver are seen in cases of chronic active hepatitis in horses?
- varying degrees of fibrosis in the portal areas
- cellular infiltrate
- biliary hyperplasia
- hepatocytes may appear normal
What treatments are recommended for horses with chronic active hepatitis in horses? What is prognosis like?
corticosteroids + supportive care + fluids + antibiotics if bacterial cholangiohepatitis is present
- fair to good if early and mild fibrosis
- poor if chronic changes and/or hepatic failure
What is pyrrolizidine alkaloid toxicity? What are the 3 most common etiologies?
chronic progressive intoxication resulting from the consumption of plants containing pyrrolizidine alkaloids
- Senecio
- Crotalaria
- Heliotropium
What are 4 steps to the pathophysiology of pyrrolizidine alkaloid toxicity?
- toxin is absorbed through the GIT and transported to the liver where hepatocytes metabolize it into pyrroles
- pyrroles cross-link DNA, causing an anti-mitotic effect
- hepatocytes can no longer divide and form megalocytes as cytoplasm expands without nuclear division
- cells due and are replaced by connective and fibrous tissue
What clinical signs are seen in cases of pyrrolizidine alkaloid toxicity?
- weight loss
- icterus
- photosensitization
What change to the liver is seen in cases of pyrrolizidine alkaloid toxicity?
fibrosis + megalocytes + bile duct hyperplasia
What treatments are recommended in cases of pyrrolizidine alkaloid toxicity? What is prognosis dependent on?
- remove PA-containing plants
- provide supportive care
degree of hepatic change
