Veterinarski Arhiv

Mammary Gland Tumours in Male Dogs: A Hormonal and Tumour Marker study/Tumori Mlijecne Zlijezde U Pasa: Prikaz Hormonskih I Tumorskih Biljega


Cancer has gained considerable relevance in animals recently owing to the increased awareness among people of animal suffering and pain. The diagnosis and management of neoplasms, therefore, represents a major challenge faced by veterinary oncologists. Mammary gland tumours are among the most common canine neoplasms, but the vast majority of these tumours occur in intact female dogs (BRODEY et al., 1983; KHIMTA et al., 2010). In canines, mammary gland tumours that occur in males range from 0-2.7% (average <1%) (MOULTON et al., 1970). Sex hormones play a vital role in the occurrence of mammary gland tumours. The p53 gene over expression is an independent factor indicating worse prognosis in canine mammary gland tumours (LEE et al., 2004). The p53 may be a useful prognostic marker for evaluating malignancy in canine mammary gland tumours (ILHAN et al., 2008). There is a strong positive correlation between expression of cyclooxygenase-2 (cox-2) and the grade of malignancy in the tumour. Increased cox-2 expression is linearly related to worse prognosis and shorter overall survival of the canine mammary gland tumour patients. Canine mammary gland malignant tumours had the highest values of cox-2 expression (QUEIROGA et al., 2007). Matrix metalloproteinase (MMPs) is a family of zinc and calcium-dependent proteolytic enzymes that degrade macromolecules of the extracellular matrix. Members of this family, such as MMP-2, -9 and -7, have been shown to be associated with tumour progression and invasion in human cancer tissues. Matrilysin (MMP-7) influences the early stage of tumourigenesis (NELSON et al., 2000).

Reports of mammary gland tumours in male dogs are lacking. In this study, seven mammary gland tumours in male dogs are presented.

Materials and methods

The study was carried out on seven male dogs of different breeds and ages, with variable sizes of spontaneous mammary gland tumours, which presented at the Institute's Referral Veterinary Polyclinic. Details of these cases are given in Table 1.

Thoracic radiographs were taken in all these patients to detect the possible presence of lung metastasis. Tumour biopsy samples were collected before any therapy, fixed immediately in 10% neutral buffered formalin and processed routinely by paraffin embedding technique. Sections of 4-5 microns thickness were cut and stained by haematoxylin and eosin (H&E) for histopathological examination.

The levels of oestrogen and progesterone were estimated in serum samples with radio-immune assay (RIA) kit (Immunotech SAS-130 France). Samples and calibrators were incubated for 3 hours with 125, I-labelled estradiol, as tracer, in antibody coated tubes. After incubation, the content of the tubes was aspirated, and bound radioactivity was measured. A calibration curve was established and unknown values were determined by interpolation from the curve.

The expression of enzyme matrilysin/MMP-7 (matrix metalloproteinase) genes was assessed after collecting the tumour tissues from the affected male animal, as well as from five adult non-descript breeds of normal (CMT unaffected) male dogs by gelatine zymography and RT-PCR. The necessary permission was obtained from the animal's owner, as well as from the Institute's Animal Ethics Committee for collection of normal mammary tissue from the same location of the mammary glands in male animals. For gelatine zymography, homogenized tumour tissue was prepared using a REMI homogenizer, and the crude extract was mixed with 5X sample/gel loading buffer in a 5:1 ratio, and loaded into the wells of gel casting, fixed into vertical slab, gel electrophoresis apparatus. Electrophoresis was carried out at room temperature with constant voltage mode at 100 V This was followed by incubation of the gel in 2.5% Triton X - 100 solutions at room temperature for 3 hours, and later in developing buffer at 37[degrees]C for 18 hours. Following this the gel was stained with 0.25% coomassie blue for 2 hours and destained in deionized water. …

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