ABSTRACT. Chacur M.G.M., Agostinho B.F., Pessoa V.M. & Yamasaki L.P. [Clinical and laboratory evaluation of squamous cell carcinoma of the prepuce with the invasion of the spinal cord in a horse. A case report.] Avalia- ção clínica e laboratorial do carcinoma das células escamosas no prepúcio com invasão da coluna vertebral em equino. Relato de Caso. Revista Brasileira de Medicina Veterinária, 36(1):24-28, 2014. Departamento de Clínicas e Reprodução Animal, Universidade do Oeste Paulista, Rod. Raposo Tavares, Km 572, Campus II, Presidente Prudente, SP 19067-175, Brasil. E-mail: firstname.lastname@example.org The squamous cell carcinoma is a malignant tumor that originates in the epidermal layer skin from the differentiation of keratinocytes. It has high incidence in dogs, cats, horses and cattle. Horses often occur in mucocutaneous junctions, areas like penis and foreskin are the most affected. The incidence is higher in castrated equines with more than 16 years old. This case describes a castrated crossbred horse, actually with 7 years old. The animal presented a mass in foreskin region with evolution of three months. Diagnosed as squamous cell carcinoma by aspirative cytology and biopsy. Surgical tumor mass excision was chosen as treatment. Two months after surgery there was local recurrence of tumor. Euthanasia was performed and a necropsy later in which was found the tumor invaded the adjacent musculature extending from the spine in sacral region between vertebres S1 and S2. Therefore is important to perform tests such as aspirative cytology and biopsy to diagnosis of squamous cell carcinoma. To prognosis the presence of metastasis must be investigate.