This paper describes a squamous cell carcinoma in the horn base with lung metastasis in pregnant cattle. A cow, female, Gir nine year old was treated at the Livestock Development Centre / Ruminant clinic on 2015. In the anamnesis was reported by the owner, the animal developed a wound rope at the base of the left horn did not respond to treatment. A rotation of the same being observed. Physical examination showed a large mass (16x17x8cm) with aspect of cauliflower, spongy consistency, irregular shape, fetid odor, with itching and bleeding easily. The same was located in cranioventral skin to the base of the horn and the left ear and deeply rooted inside the horn. After clinical evaluation complementary examinations were performed: blood count, radiographic examination and biopsy of the tumor mass. Blood count was observed the presence of severe anemia, hypoproteinemia and leukocytosis. Radiography showed occupation of the proximal and middle thirds of the left horn by tumor mass and prominences that surrounded the bones of the head. In histopathological evaluation was observed proliferation of atypical epithelial cells, moderately differentiated with nuclei rounded to ovoid, arranged in irregular cords and solid nests intermingled with sparse fibrous stroma presenting an infiltrative tumor manifest. Based on history, clinical signs, epidemiology and histological findings the diagnosis was closed in squamous cell carcinoma of the base of the horn. In such cases the main form of treatment is surgical resection of the tumor mass associated with dehorning. In this case due to the presence of advanced pregnancy, and poor clinical condition supportive treatment was shown to stabilize the patient until the delivery to be performed even after the surgery. After delivery, the animals showed a significant worsening of symptoms, with persistent recumbency, lack of appetite severe anemia, general weakness, showing no response to any treatment performed. After the owner's authorization was performed euthanasia and subsequent necropsy of the animal. In necropsy it was observed that the tumor emitted branches in the proximal portions and averages interior of horn and all left frontal sinus with lot of purulent fetid content and cellular debris. It was found in the caudal lobes of the lung nodules whitened of a tumor, tumor metastasis probable, and confirmed in the histopathological examination.