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Liver Biopsy in Small Animals

By

Sharon A. Center

, BS, DVM, DACVIM, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University

Last full review/revision May 2015 | Content last modified May 2015

Hepatic needle true-cut biopsies (especially 18-gauge) collected under ultrasonographic guidance may yield samples too small and fragmented for accurate diagnosis because of a lack of representative acinar units (at least 15 portal triads should be sampled). Furthermore, needle biopsies are usually only collected from the more safely sampled left-side lobes, which may miss lesions differentially affecting liver lobes (eg, cholangiohepatitis in cats). Blind-needle biopsies done without ultrasonographic guidance are hazardous and ill advised in animals with suspected hepatic hilar or mesenteric lymphadenomegaly; involvement of the common bile duct, gallbladder, intestines (eg, inflammatory bowel disease, infiltrative disease), or pancreas; or multiple organ abnormalities. An exploratory laparotomy is more appropriate. When possible, wedge biopsies or laparoscopic cup forcep biopsies are preferred, because samples of adequate size can be easily and safely acquired from multiple liver lobes, ensuring accurate disease representation. These methods also permit assessment of the gross appearance of the liver. Notably, laparoscopic methods are not recommended when disease of the common bile duct or gallbladder is suspected that may necessitate a decompressive biliary procedure, cholecystectomy, or cholestotomy. Liver biopsy should always be done even if an obvious biliary abnormality is the predominant disease process, because underlying histologic liver lesions may indicate another primary disease process. It is also important to biopsy grossly normal liver when focal lesions are identified. This practice ensures 1) characterization of "normal" liver histology, 2) determines whether an underlying liver disease coexists, 3) investigates histology of liver distant to the gallbladder in animals undergoing cholecystectomy, and 4) provides multiple liver lobe samples needed to confirm suspected MVD (because this lesion is variable among liver lobes)..

Routine biopsy evaluation should include examination of a cytologic imprint, Gram stain (if suppurative or pyogranulomatous inflammation is cytologically detected), routine H&E staining and interpretation, as well as staining with a reticulin stain (discloses sinusoidal collapse of the supporting scaffolding of the liver), Masson's trichrome (to confirm presence and severity of fibrillar connective tissue deposition), Prussian blue to identify iron retention in Kupffer cells (fixed macrophages) and hepatocytes (helps confirm lobular involvement in inflammation, Kupffer cell activation, presence of rare hemochromatosis), rhodanine stain for copper (confirms and can be used to quantify copper with digital scanning of the rhodanine-stained section), aerobic and anaerobic bacterial cultures of liver and bile, and quantification of liver metals (copper, iron, and zinc concentrations because these values can help evaluate risk of oxidative injury and need for zinc supplementation). A tissue sample (formalin fixed) should also be reserved for other special case-specific studies such as special immunohistochemical stains or for PCR testing for infectious agents.

Before biopsy, bleeding tendencies should be evaluated by careful review of the history, physical examination, blood smear (to confirm platelets ≥100,000/μL), routine coagulation profile (prothrombin time [PT], activated partial thromboplastin time [APTT]), von Willebrand factor (vWF) activity in high-risk breeds, and a buccal mucosal bleeding time. Routine coagulation assessments have low reliability to detect bleeding risk. The buccal mucosal bleeding time is more relevant when performed immediately before the procedure. Animals suspected to have bleeding tendencies should be treated with vitamin K1 (0.5–1 mg/kg, SC or IM) at 0, 12, and 24 hr before tissue sampling. If buccal mucosal bleeding time is >5 min, a fresh frozen plasma transfusion is indicated, as is administration of desmopressin acetate (DDAVP, 0.3–1 mcg/kg diluted in saline), which increases plasma vWF 2-fold over baseline within 1 hr as well as plasma activity of Factor VIII. DDAVP can initiate a hemostatic effect in dogs with type 1 vWF (partial quantitative deficiency) but not in dogs with qualitative defects or complete vWF deficiency. In many people with liver disease, DDAVP has improved coagulation ability, although the exact mechanisms remain incompletely clarified.

OTHER TOPICS IN THIS CHAPTER

Hepatic Disease in Small Animals
Overview of Hepatic Disease in Small Animals
Hematology in Hepatic Disease in Small Animals
Coagulation Tests in Hepatic Disease in Small Animals
Enzyme Activity in Hepatic Disease in Small Animals
Other Serum Biochemical Measures in Hepatic Disease in Small Animals
Hepatic Function Tests in Small Animals
Imaging in Hepatic Disease in Small Animals
Cholecystocentesis in Hepatic Disease in Small Animals
Liver Cytology in Small Animals
Liver Biopsy in Small Animals
Pathologic Changes in Bile in Small Animals
Nutrition in Hepatic Disease in Small Animals
Fulminant Hepatic Failure in Small Animals
Hepatic Encephalopathy in Small Animals
Portal Hypertension and Ascites in Small Animals
Portosystemic Vascular Malformations in Small Animals
Acquired Portosystemic Shunts in Small Animals
Other Hepatic Vascular Disorders in Small Animals
Hepatotoxins in Small Animals
Infectious Diseases of the Liver in Small Animals
Feline Hepatic Lipidosis
Biliary Cirrhosis in Small Animals
Canine Cholangiohepatitis
Canine Chronic Hepatitis
Lobular Dissecting Hepatitis in Small Animals
Canine Vacuolar Hepatopathy
Metabolic Diseases Affecting the Liver in Small Animals
Hepatocutaneous Syndrome in Small Animals
Nodular Hyperplasia in Small Animals
Hepatic Neoplasia in Small Animals
Miscellaneous Liver Diseases in Small Animals
Diseases of the Gallbladder and Extrahepatic Biliary System in Small Animals
Cholecystitis in Small Animals
Canine Gallbladder Mucocele
Other Disorders of the Gallbladder in Small Animals
Other Disorders of the Bile Ducts in Small Animals
Extrahepatic Bile Duct Obstruction in Small Animals
Cholelithiasis in Small Animals
Biliary Tree Rupture and Bile Peritonitis in Small Animals
Feline Cholangitis/Cholangiohepatitis Syndrome
Hepatobiliary Fluke Infection in Small Animals
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