The diagnostic approach to asymptomatic dogs with elevated liver enzyme activities - Veterinary Medicine
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The diagnostic approach to asymptomatic dogs with elevated liver enzyme activities
What's the next step when you see an apparently healthy dog that has abnormal liver enzyme results? These clinicians help you figure out when further diagnostic testing is warranted, which tests are indicated, and what conditions to suspect.


VETERINARY MEDICINE


In patients with portosystemic shunts, twofold to threefold increases in serum ALP, ALT, and AST activities have been recorded while patients with microvascular dysplasia may have normal to mild increases in these enzyme activities.20 Microcytic red blood cells are commonly noted in cases of portosystemic shunts but are not seen in cases of microvascular dysplasia.

Gallbladder mucoceles


1. On this ultrasonogram, organized, striated, and immobile echogenic sediment can be seen within the gallbladder, consistent with a gallbladder mucocele. The possibility of perforation should be considered given the surrounding effusion.
Gallbladder mucoceles have been associated with mild to marked increases in serum activities of ALP, AST, ALT, and GGT.21 In a retrospective study examining gallbladder mucoceles, seven of 30 cases had no clinical signs of illness.21 In the 23 symptomatic cases, clinical signs were nonspecific and included vomiting, lethargy, and anorexia. The diagnosis was made on abdominal ultrasonographic examination, which revealed immobile, echogenic bile with a striated or stellate pattern within the lumen of the gallbladder (Figure 1).21 Cholecystectomy is recommended in these cases to prevent sequelae including cholecystitis, extrahepatic bile duct obstruction, and gallbladder rupture.21

CONCLUSION

Increases in serum liver enzyme activities are sensitive indicators of hepatobiliary disease, but these activities can be elevated secondary to various endocrinopathies, gastrointestinal disease, pancreatic disease, systemic disease, and enzyme induction. In asymptomatic patients, a systematic approach is required to obtain a definitive diagnosis. A careful review of the patient's history is essential to uncover vague clinical signs that the owner may have missed and to identify any potential exposure to hepatotoxic agents. A complete minimum database, including a complete blood count and urinalysis, is required to rule out an underlying extrahepatic disease. In some cases, sequential monitoring may be elected; however, persistent elevation, marked elevations, concurrent increases in serum bilirubin concentrations, or concurrent decreases in albumin concentrations warrant further investigation, including diagnostic imaging and, in many cases, hepatic biopsy.

Johanna Cooper, DVM
Cynthia R.L. Webster, DVM, DACVIM
Department of Clinical Sciences Cummings
School of Veterinary Medicine
Tufts University
North Grafton, MA 01536

REFERENCES

1. Brunson DB, Stevens JB, McGrath CJ. Pre-operative liver screen selection: a comparison for glutamic pyruvic transaminase and serum alkaline phosphatase. J Am Anim Hosp Assoc 1980;16:209-214.

2. Comazzi S, Pieralisi C, Bertazzolo W. Haematological and biochemical abnormalities in canine blood: frequency and associations in 1022 samples. J Small Anim Pract 2004;45:343-349.

3. Center S. Diagnostic procedures for evaluation of hepatic disease. In: Grant Guilford W, Center SA, Strombeck DR, et al, eds. Strombeck's small animal gastroenterology. 3rd ed. Philadelphia, Pa: WB Saunders Co, 1996;136-143.

4. Valentine BA, Blue JT, Shelley SM, et al. Increased serum alanine aminotransferase activity associated with muscle necrosis in the dog. J Vet Intern Med 1990;4:140-143.

5. Muller PB, Taboada J, Hosgood G, et al. Effects of long-term phenobarbital treatment on the liver in dogs. J Vet Intern Med 2000;14:165-171.

6. Dossin O, Rives A, Germain C, et al. Pharmacokinetics of liver transaminases in healthy dogs: potential clinical relevance for assessment of liver damage (abst), in Proceedings. Am Coll Vet Intern Med 2005.


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Source: VETERINARY MEDICINE,
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