Prevalence of Lesional and Nonlesional Dermatophytosis in Shelter/Rescue Guinea Pigs (Cavia porcellus) in Southern California, USA.

BACKGROUND

Dermatophytosis is a contagious, zoonotic disease caused by fungal infection of keratinised structures of the skin, hair and nails. Transmission can be from newly acquired pets, including guinea pigs (Cavia porcellus).

OBJECTIVES

The primary objective of this study was to determine the prevalence of dermatophytosis in guinea pigs before adoption from shelters/rescue organisations. Secondarily, test results were compared by modality for agreement.

ANIMALS: Samples were collected from 85 guinea pigs between 17 February and 27 September 2025 from five shelter/rescue locations in Southern California.

MATERIALS AND

METHODS

Each guinea pig was sampled by acetate tape preparation, superficial-to-deep skin scraping, trichogram, fungal culture, PCR and next-generation sequencing (NGS).

RESULTS

None of the 85 guinea pigs (0%) had abnormal trichogram findings. One animal (1.18%) was positive for Trichophyton benhamiae by culture and also was positive on PCR and NGS. PCR detected dermatophyte DNA in 54 of 85 animals (63.5%); NGS in six of 85 (7.06%), with four of 85 (4.71%) positive on both. Of those positive on at least one test, only three (of 56, 5.36%) had skin lesions consistent with dermatophytosis. Six animals had compatible lesions yet tested negative on all assays. Two animals (2.35%) harboured Gliricola porcelli.

CONCLUSIONS AND CLINICAL RELEVANCE: Active dermatophyte infection was uncommon based upon culture results, yet positive genetic material testing suggests that many animals had potential dermatophyte environmental exposure. Poor agreement among diagnostic tests underscores the need for clinical interpretation and careful test selection in suspected dermatophytosis cases.