Evaluation of Coccidioides antigen detection in dogs with coccidioidomycosis

Area of Science:

• Veterinary Mycology
• Diagnostic Immunology
• Canine Infectious Diseases

Background:

• Coccidioidomycosis is a significant fungal disease in dogs, often diagnosed via antibody detection.
• Coccidioides antigen detection methods, successful in human diagnostics, had not been evaluated in canine cases.
• Evaluating novel diagnostic approaches is crucial for improving canine coccidioidomycosis management.

Purpose of the Study:

• To assess the utility of Coccidioides antigen detection in canine serum and urine for diagnosing coccidioidomycosis.
• To compare the sensitivity of antigen detection with antibody-based diagnosis in a canine cohort.
• To determine if antigen detection could serve as a viable diagnostic tool in veterinary medicine for this specific mycosis.

Main Methods:

• Sixty dogs diagnosed with coccidioidomycosis (based on antibody titers ≥1:16) were tested for Coccidioides galactomannan antigen using enzyme immunoassay in urine and serum.
• Control groups included dogs with other fungal infections (histoplasmosis, blastomycosis), non-fungal diseases, and healthy canines.
• Antibody testing was conducted by commercial veterinary laboratories.

Main Results:

• Coccidioides antigen was detected in urine or serum of 20% of dogs with coccidioidomycosis.
• Antigen was found in urine only (3.5%) and serum only (19.0%) in affected dogs.
• Antigen detection showed low sensitivity, with serum exhibiting higher sensitivity than urine for diagnosing canine coccidioidomycosis.

Conclusions:

• Coccidioides antigen detection is an insensitive method for diagnosing coccidioidomycosis in dogs, particularly when antibody titers are the primary diagnostic criterion.
• Serum antigen detection demonstrated higher sensitivity compared to urine antigen detection in this canine study.
• Further research may be needed to explore antigen detection's role or refine its application in canine coccidioidomycosis diagnostics.