Studies on canine mammary tumours. I. Age, seasonal and breed distribution.

The incidence as well as age, seasonal and breed distribution of canine mammary tumours (n = 521) were studied at the Clinic of Obstetrics and Gynaecology of the University of Veterinary Science, Budapest, between 1985 and 1989. In 39 cases of mammary tumour, blood plasma oestradiol (E2) and progesterone (P) concentrations were also determined. Of all dogs referred to the clinics of the University in 1985, 0.7% had mammary tumour. On the average, 104 +/- 9.3 cases of mammary tumour were recorded at the Clinic of Obstetrics per year. This number did not increase after the Chernobyl atomic reactor catastrophe of 1986. The age distribution of canine mammary tumour found in this study shows good agreement with earlier data of the literature: mammary tumour showed the highest incidence in 10 years old dogs. The incidence of mammary tumour kept increasing with age until the 14th year of life (as expressed in per cent of animals of identical age). The number of mammary tumours was markedly higher in the spring (April-May) and autumn (September). This seasonality was demonstrable in 11 to 16 years old bitches, too. On the basis of the blood plasma E2 and P profiles, 61.5% of the clinically anoestrous animals were found to be cycling. The strikingly high ratio of pulis among dogs with mammary cancer was suggestive of a breed disposition.

Studies on canine mammary tumours. II. Oestradiol and progesterone receptor binding capacity and histological type.

Tissue samples taken from the mammary gland of 42 dogs (age: 6 to 12 years) were examined. Thirty-eight samples showed neoplasia: 36 were epithelial while the remaining 2 proved to be connective tissue tumours. Thirty-four % of the neoplasms were new benign tumours (most frequently adenoma and fibroadenoma) and 66% were malignant ones (mainly adenocarcinoma). The oestrogen receptor (ER) and progesterone receptor (PR) binding capacity was determined on 21 tissue samples using the method of EORTC (1980). The connective tissue tumours and non-tumourous tissues contained no sexual steroid receptor. 71.4% of all tissue samples contained receptors. 61.9% of the samples was ER+, 42.8% was PR+, 33.3% contained both receptors, 28.6% was only ER+ and 9.5% only PR+. The average ER and PR binding capacity was 120.3 (5.0-622.8) and 266.7 (92.3-475.0) fmol/mg cytosol protein, respectively. No difference in receptor positivity was demonstrable between the benign and the malignant tumours. PR negativity accompanied by ER positivity was more common in the case of benign tumours. ER binding capacity tended to be correlated with age: this correlation could be described with a hyperboloid regression curve (r = -0.5931; 0.06 > p > 0.05).

Long-term effect of incubation temperatures on production parameters and changes in luteinizing hormone and gonadal steroids during the onset of lay in the hen.

Earlier studies demonstrated that different incubation temperatures (33.8 or 37.8 C) from Day 17 of incubation until hatching resulted in differences in postnatal growth rate and hormonal parameters. These studies were repeated and extended to the reproduction period. The onset of egg laying was significantly delayed by 5 days in the 33.8 C group compared to the 37.8 C group. No differences in percent egg production were found between the groups after 3 or 5 months of production: however, mean egg weight was significantly reduced in the 33.8 C group by 1.9 and 1.8 g over 3 and 5 months of production, respectively. Serum concentrations of luteinizing hormone (LH), estradiol (E2), estrone (E1), progesterone (P4), and testosterone (T) were measured weekly at the same time of day approximately 4 weeks before to 4 weeks after the onset of lay. The changes in levels of all hormones over the period studied were identical for both experimental groups. Luteinizing hormone, T, and E2, but not E1 and P4, were different before and after onset of lay in both groups. There were no significant correlations between hormonal levels before onset of lay and production traits for individual hens. In the 33.8 C group, after onset of lay, significant positive correlations were observed between serum E2 and egg production and serum LH and egg production; however, these correlation coefficients were not significant in the 37.8 C group. Significant negative correlation coefficients were observed in both groups between serum E2 after onset of lay and age at first egg.