We aim in the current study to investigate the pathology and incidence of tumors that are excised surgically in Veterinary Teaching Hospital. This study collected the tissue samples from animals from 1 October 2020 until 1 April 2021. These samples were collected from animals that undergo surgical procedures to remove neoplastic growths in their body. After tissue grossing, samples were collected from tumor mass, then fixed in neutral buffered 10% formalin for 72 hours, then processed to embedded in paraffin wax. A routine Harris's haematoxylin and eosin stain were also used, histochemical stains such as Masson's trichrome and PAS techniques were used as needed. In exceptional cases, IHC protocol was used for diagnostic steps to some types of tumors included in the current study. The antibodies that were used are Vimentin for canine osteosarcoma, P53 for squamous cell carcinoma, Mdm2 for ovine pulmonary adenocarcinoma, and CD10 for neoplastic lymphocytes. The result of the current study showed that the prevalence of tumor recorded was Marek's diseases 22.8%, squamous cell carcinoma 22.8%, ovine pulmonary adenocarcinoma 15.4%, third eyelid adenoma 15.4%, canine osteosarcomas 7.4%, venereal transmitting tumors 7.4%, and feline mammary gland tumor 7.4%. In conclusion, the incidence of tumor in animals that attending Veterinary Teaching Hospital belong to the College of Veterinary Medicine, the University of Mosul was in general high in comparison to other studies in Iraq and other countries, this high incidence should pay attention to the causes of these cancerous conditions and their relation to environmental aetiology.