Concentrations of estrogen (ER) and progesterone (PR) receptors were measured by radioreceptor assay in tumor (n = 319) and normal (n = 166) mammary tissue from 248 bitches. Correlations between ER and PR and between receptor expression in tumor and normal mammary tissue from the same bitches were evaluated. The influence of tumor, clinical, or hormonal variables on receptor expression also was studied. Approximately 80% of tumor and 95% of normal mammary tissue expressed detectable concentrations of ER, PR, or both. Direct correlation was found between ER and PR concentrations in normal and tumor tissues. Median ER concentrations were significantly higher (46 +/- 47 fmol/mg of cytosolic protein vs 27 +/- 24 fmol/mg of cytosolic protein; P = 0.0002) in normal than in tumor tissue. On the other hand, PR concentrations were significantly higher (57 +/- 52 fmol/mg vs 77 +/- 99 fmol/mg; P = 0.03) in tumors (especially benign tumors) than in normal tissue. Poorly differentiated malignant tumors expressed lower concentrations of receptors than did benign or well differentiated malignant tumors. The ER and PR concentrations decreased with increasing size of the lesion. Hormonal status of the bitch significantly (P < 0.05) influenced receptor expression in normal tissue: bitches in the luteal phase of the estrous cycle had higher concentrations of ER (69 +/- 62 fmol/mg) than did ovariectomized bitches (24 +/- 19 fmol/mg) or bitches in anestrus (38 +/- 45 fmol/mg) or the follicular phase (13 +/- 7 fmol/mg).(ABSTRACT TRUNCATED AT 250 WORDS)

A retrospective case/control study was performed in order to evaluate the influence of hormonal history on the risk of mammary tumor development in the dog. We particulary studied the effect of ovariectomy, contraceptive treatments with depo-medroxyprogesterone acetate, pseudopregnancy and pregnancy. We also evaluated the influence of those parameters on the age of detection, the number and the histology of the lesions. 405 bitches with mammary tumors and 274 control bitches supported this study. A protective effect of ovariectomy was confirmed. It is stronger for bitches sterilized early in life but remain significant also in old bitches. Frequent progestative treatment leads to a slight increase of the risk but does not significantly influence the number or the histology of the lesions. Frequently treated bitches are affected earlier thant non treated bitches. Pseudopregnancy seems also to increase the risk. A similar but not significant tendency is observed in parous bitches. We conclude that ovarian hormones and progestagens have a promotor effect on mammary tumor development in dogs either directly or indirectly.

Receptors for oestrogen (ER), progesterone (PR) and epidermal growth factor (EGF-R) are found in normal mammary tissue (NMT) and/or mammary tumours (MT) from all species studied, including dogs. The aims of this study were to define the possible influences of mammary histology, age, location in the mammary chain and of hormonal status and cycle stage in the expression of ER, PR and EGF-R in mammary tissues from healthy dogs and from dogs with MT. Carcinomas that had lost their glandular structure had significantly lower amounts of receptors. NMT either from healthy or affected dogs had significantly higher amounts of ER than MT. PR levels were significantly higher in benign lesions than in NMT. Steroid receptors in NMT from healthy dogs varied significantly with age (older dogs having more ER), location (posterior glands having higher ER concentrations) and cycle stage (the highest ER concentrations being found in the mid-luteal phase and the lowest PR concentrations in the early luteal phase). In NMT from affected dogs, higher steroid receptor concentrations were found in posterior glands; as in healthy dogs, ER concentrations were low in the follicular phase and high in the luteal phase and PR were high in anoestrus. Steroid receptor content in MT did not vary significantly with age, location or cycle stage or with hormonal status, but tended to vary with cycle stage in a manner similar to that found in NMT from the same dogs. In dogs affected with MT and treated with medroxyprogesterone acetate (MPA), NMT had low concentrations of PR but MT from the same dogs had high PR concentrations. EGF-R were found in the majority of the samples (+/- 65% of MT and +/- 85% of NMT) but there was no significant relation between the concentrations and the parameters studied. Nevertheless, EGF-R content was higher in NMT in the proliferative stages (oestrus, early and mid-luteal phase) than in the non-proliferative stages (early pro-oestrus and anoestrus). EGF-R and ER were significantly and positively correlated only in malignant tumours. There is no apparent difference between affected and healthy dogs in the regulation of ER, PR and EGF-R expression in NMT; on the other hand, some differences between NMT and MT are observed in the regulation of PR (for example under the influence of MPA) and in the correlation between EGF-R and ER expression.

Developments in understanding the pathophysiology of urinary incontinence caused by urethral sphincter mechanism incompetence (SMI) are reviewed. SMI is a multifactorial condition; affected bitches have shorter urethras, reduced urethral tone and more caudally positioned bladder necks than continent bitches. Other factors thought to be important in the aetiology of SMI include neutering, breed, body size, docking and obesity. Most of the recent developments in the understanding of SMI have resulted from radiographic and urodynamic investigations of normal and affected bitches. The urodynamic technique of urethral pressure profilometry is discussed and its contribution as an investigative tool reviewed.