Abstract
Background:
Equine papillomavirus type 1 (EcPV-1) causes cutaneous papillomatosis in horses, which is characterized by benign, proliferative epithelial lesions. Despite its global presence, the prevalence and characterization of EcPV-1 in Arabian horses in Saudi Arabia have not been previously reported.

Aim:
This study is the first to identify and comprehensively analyze EcPV-1 in four Arabian horses presenting with multiple raised, verrucous lesions around the muzzle and lips.

Methods:
This study involved clinical examination, skin biopsy collection, histopathological examination, and molecular analysis.

Results:
Clinical examination revealed non-painful, nonpruritic growths ranging in diameter from 2 to 8 mm. Histopathological analysis of skin biopsies showed thickening and hyperplasia of all epidermal layers, accompanied by acanthosis, hyperkeratosis, and the presence of koilocyte within the stratum spinosum and granulosum. Molecular analysis using polymerase chain reaction (PCR) confirmed the presence of EcPV-1 DNA in all affected horses, with 384 bp amplicons corresponding to the E4 and L2 genes of the viral genome. Gel electrophoresis revealed clear bands in samples from affected horses, whereas viral DNA was not detected in normal control samples.

Conclusion:
This study provides the first molecular and histopathological evidence of EcPV-1 infection in Arabian horses in Saudi Arabia, highlighting the need for further epidemiological studies to understand the distribution and impact of EcPV-1 in the region. These findings also underscore the importance of integrating molecular diagnostics with clinical and histopathological evaluation for the accurate diagnosis and management of equine papillomatosis.

Key words: Equine papillomavirus (EcPV-1), Arabian horses, Cutaneous papillomatosis, Viral DNA detection, Veterinary dermatology