In the study, serum samples from 15 healthy dogs and 15 dogs with mammary tumors from Ankara and surrounding Faculty and Veterinary clinics were analyzed. From these samples the serum levels of 17β-estradiol, total cholesterol and triglyceride were determined to investigate the relationship between these parameters and canine mammary tumors.

Blood samples taken from the left front foot vena of each dog were centrifuged with 4000 revolutions for 10 minutes. The analysis of 17β-estradiol was carried out based on competitive chemilumminescent enzyme immunoassay (c-CLEIA), triglyceride on bichromatic end point technique and total cholesterol on polychromatic end point technique and performed by an autoanalyser.

In tumorous dogs, the mean serum level of 17β-estradiol was found 142,70±16,00 pg/ml, the mean level of total cholesterol was 250,10±17,60 mg/dl and the mean level of triglyceride was 106,20±7,50 mg/dl. In healthy dogs, the mean levels for the same parameters in the same order were 59,30±6,50 pg/ml, 204,90±13,20 mg/dl and 77,00±4,50 mg/dl. Control and experimental groups were compared statistically by Mann-Whitney U Test and levels of all parameters mentioned above were found higher for the dogs with mammary tumors than healthy dogs (p<0,001). In addition to this, the correlations between the control and the experimental groups were investigated by the Pearson Correlation Test. The positively linear correlation was found for the levels of 17β-estradiol and triglyceride (r=0,44 p<0,005).

Examining the average age of the dogs which took part in this study, we observed that older dogs from five to twelve years were more likely to have mammary tumors than the younger dogs.

According to observed results, it could be concluded that serum 17β-estradiol, total cholesterol and triglyceride levels play a key role for the etiology, prognosis and treatment methods of mammary tumors.