Background: Testicular neoplasms are common in dogs, and their incidence is higher in older animals, and in cases of cryptorchidism. In general, they are benign and rarely metastasize. The aim of this study is to determine the frequency of testicular neoplasms in dogs in the Departament of Veterinary Pathology of the Universidade Federal do Rio Grande do Sul (SPV-UFGRS) in the period of January 2005 to December 2015. Materials, Methods & Results: Histopathological examination records of dogs conducted from January 2005 to December 2015 on SPV-UFRGS were reviewed searching for cases of testicular neoplasms in dogs. The general data of the dogs were analyzed, such as age, clinical history and clinical signs, when reported according to the requester. The classification of neoplasms in this study followed the histological criteria established by the World Health Organization. In the period studied, 4,764 biopsies were processed from male dogs, 305 (6.4%) of them were diagnosed with testicular neoplasms. The mean age range was 11.1 year-old. In 260 dogs, the neoplasms have affected a single testicle, and in 45, they were bilateral. From 305 dogs, 247 had a single neoplasm, while 58 dogs have developed more than one type of neoplasm, at once, totaling 415 diagnosis of testicular neoplasms. The most prevalent testicular neoplasms were Leydig cell tumor, followed by seminoma, and sertoli cell tumor, representing 50.8%, 35.2% and 14% respectively. Forty-five animals presented bilateral testicular neoplasms single or multiple, totaling 104 diagnoses. Leydig cell tumor was the most frequent bilateral neoplasm. Fifty dogs developed neoplasms in cryptorchid or ectopic testicles, representing 24.4% of cases with reported clinical data. Of these, nine were located in the inguinal region, nine in the subcutaneous, intra-abdominal 12, and in 20 cases the location was not informed. In these cases the mean age range was 9.5 year-old. Clinical signs of hyperestrogenism were reported in 4.9% of cases and histological changes of malignancy were reported in 5.5% of all diagnoses. Discussion: The frequency of testicular neoplasms in dogs in this study, and the average age, were similar to several studies. Leydig cell tumor, seminoma and sertoli cell tumor are the most common testicular neoplasms diagnosed in this paper, as described in some studies. Data relating to bilateral and multiple neoplasms cases are similar to several researchers. The combination of seminoma with Leydig cell tumor was the most frequent in this study, similar to the literature. The occurrence of cryptorchidism in dogs was described in 24.4% of cases while similar studies reported frequency of 4.5% to 56.3%. Histological changes with malignancy characteristics were described in 5.5% of all cases of this study, and were predominantly characterized by invasion of neoplasic cells into the lymphatic and blood vessels, of these, 95.6% were seminomas and 4.4% sertoliomas. This information agrees with researchers that reported that metastases occur in less than 15% of sertoli cell tumor or seminomas. Clinical manifestations of feminization were infrequent in cases of testicular neoplasms in dogs of this paper, and the sertolioma is the neoplasm most commonly associated with manifestations of hyperestrogenism. As described in literature, over 50% of dogs with sertoli cell tumor show signs of feminization, but most of the cases are asymptomatic, and often an incidental finding at the time of physical examination.Background: Testicular neoplasms are common in dogs, and their incidence is higher in older animals, and in cases of cryptorchidism. In general, they are benign and rarely metastasize. The aim of this study is to determine the frequency of testicular neoplasms in dogs in the Departament of Veterinary Pathology of the Universidade Federal do Rio Grande do Sul (SPV-UFGRS) in the period of January 2005 to December 2015.Materials, Methods & Results: Histopathological examination records of dogs conducted from January 2005 to December 2015 on SPV-UFRGS were reviewed searching for cases of testicular neoplasms in dogs. The general data of the dogs were analyzed, such as age, clinical history and clinical signs, when reported according to the requester. The classification of neoplasms in this study followed the histological criteria established by the World Health Organization. In the period studied, 4,764 biopsies were processed from male dogs, 305 (6.4%) of them were diagnosed with testicular neoplasms. The mean age range was 11.1 year-old. In 260 dogs, the neoplasms have affected a single testicle, and in 45, they were bilateral. From 305 dogs, 247 had a single neoplasm, while 58 dogs have developed more than one type of neoplasm, at once, totaling 415 diagnosis of testicular neoplasms. The most prevalent testicular neoplasms were Leydig cell tumor, followed by seminoma, and sertoli cell tumor, representing 50.8%, 35.2% and 14% respectively. Forty-five animals presented bilateral testicular neoplasms single or multiple, totaling 104 diagnoses. Leydig cell tumor was the most frequent bilateral neoplasm. Fifty dogs developed neoplasms in cryptorchid or ectopic testicles, representing 24.4% of cases with reported clinical data. Of these, nine were located in the inguinal region, nine in the subcutaneous, intra-abdominal 12, and in 20 cases the location was not informed. In these cases the mean age range was 9.5 year-old. Clinical signs of hyperestrogenism were reported in 4.9% of cases and histological changes of malignancy were reported in 5.5% of all diagnoses.Discussion: The frequency of testicular neoplasms in dogs in this study, and the average age, were similar to several studies. Leydig cell tumor, seminoma and sertoli cell tumor are the most common testicular neoplasms diagnosed in this paper, as described in some studies. Data relating to bilateral and multiple neoplasms cases are similar to several researchers. The combination of seminoma with Leydig cell tumor was the most frequent in this study, similar to the literature. The occurrence of cryptorchidism in dogs was described in 24.4% of cases while similar studies reported frequency of 4.5% to 56.3%. Histological changes with malignancy characteristics were described in 5.5% of all cases of this study, and were predominantly characterized by invasion of neoplasic cells into the lymphatic and blood vessels, of these, 95.6% were seminomas and 4.4% sertoliomas. This information agrees with researchers that reported that metastases occur in less than 15% of sertoli cell tumor or seminomas. Clinical manifestations of feminization were infrequent in cases of testicular neoplasms in dogs of this paper, and the sertolioma is the neoplasm most commonly associated with manifestations of hyperestrogenism. As described in literature, over 50% of dogs with sertoli cell tumor show signs of feminization, but most of the cases are asymptomatic, and often an incidental finding at the time of physical examination.
