EN
The study was based on biopsy and necropsy materials obtained from 405 dogs, of which 258 were females and 147 males. Tumors appeared almost throughout the whole period of dog’s life, but they were most prevalent in adulthood or old-age, with an average of about 10 years. The highest breed prevalences, of about 79% of all tumors examined were noted in 5 breeds of dogs: Mongrels, Boxers, Poodles, German Shepards and Cocker-spaniels. From a set of 544 tumors examined in this study the most susceptible to neoplastic process appeared to be the mammary gland where up to 35.9% of the total number of tumors examined was diagnosed. The skin and its appendages, with 26.8% of the total number of neoplasms studied formed the second most frequent tumor predilection site. Malignant tumors — 60.8% occured more frequently than benign ones — 39.2%.