Diagnostics should include biochemical tests (SDH, AST, LDH, ALP, GGT, serum bile acids, serum or plasma bilirubin) to determine
whether there's liver involvement.
Photo 1: An ultrasonogram of the liver next to the spleen in a horse with cholangiohepatitis. Sludge can be seen in the bile
duct. (Image courtesy of Dr. T.J. Divers, Cornell University.)
Transabdominal ultrasonography is another tool that can help diagnose cholangiohepatitis (Photos 1-3). While ultrasound-guided
liver biopsy is required to make a definitive diagnosis, repeat ultrasonographic evaluations of the liver can also be useful
in assessing the success of therapy.
Photo 2: An ultrasonogram of a distended bile duct in a horse with cholangiohepatitis. (Image courtesy of Dr. T.J. Divers,
"Ultrasound can reveal the presence of abscessation or neoplasia, dilation of bile ducts, presence of stones and an assessment
of the hepatic texture or changes in the liver lining consistent with nodular formation," says Byars.
Photo 3: An ultrasonogram of a stone in the bile duct casting a shadow in a horse with cholangiohepatitis. (Image courtesy
of Dr. T.J. Divers, Cornell University.)
Ultrasonographically, cholangiohepatitis may appear with both dilated bile ducts, reflecting reduced bile flow, and textural
changes to the hepatic parenchyma. However, the findings may be highly variable in many horses that appear relatively normal
but have abnormal chemistry results, according to Byars.
"Many veterinarians will skip a full chemistry, maybe just run a CBC, looking for infection, etc.," says Byars. "Practitioners
should take the clinical complaints, combine those with a complete blood chemistry panel and use ultrasound. A biopsy would
be definitive. If you have 100 suspected liver-involved horses in the field, maybe 10 percent get biopsied, but those at referral
hospitals typically are biopsied."
Recognizing certain liver enzymes that are failing to be cleared appropriately in conjunction with increased liver-specific
enzymes (GGT and AP) would help to support a diagnosis of cholangiohepatitis.