Comparison of serum creatine kinase and aspartate aminotransferase activity in dogs with Neospora meningoencephalitis and noninfectious meningoencephalitis.

BACKGROUND

Creatine kinase (CK) and aspartate aminotransferase (AST) activity can be increased with myositis associated with Toxoplasma and Neospora infection in dogs.

HYPOTHESIS/OBJECTIVES: Serum activity of CK and AST can be used as a rapid screen for predicting positive serology in meningoencephalitis caused by Toxoplasma gondii or Neospora caninum in dogs compared to dogs with noninfectious meningoencephalitis.

ANIMALS

Eighty dogs with meningoencephalitis based on magnetic resonance imaging and cerebrospinal fluid analysis.

METHODS

Retrospective case-control study. Serological cutoffs (≥1:800 immunofluorescence for Neospora and ≥1:400 IgG or ≥1:64 IgM or both for Toxoplasma) categorized dogs as infected (n = 21, all neosporosis) or noninfected (n = 59). Activities of CK and AST between infected and noninfected groups were compared using a Mann-Whitney U test and receiver operating characteristic curve analysis.

RESULTS

No dogs were diagnosed with toxoplasmosis. Serum CK and AST activities were significantly increased (P < .001) in dogs with positive serology for Neospora (CK: median, 1334 U/L; range, 281-3633 U/L and AST: median, 124 U/L; range, 59-333 U/L) compared to noninfectious cases (CK: median, 215 U/L; range, 69-683 U/L and AST: median, 36 U/L; range, 19-139 U/L). A CK cutoff of 485 U/L had 95.24% sensitivity and 96.61% specificity with a negative predicative value of >99%. An AST cutoff of 57 U/L had 94.44% sensitivity and 85.71% specificity with an estimated negative predicative value of 99%.

CONCLUSIONS AND CLINICAL IMPORTANCE

High serum CK and AST activity can increase suspicion for neosporosis while awaiting serological tests for dogs with meningoencephalitis.