Comparison of steroid receptor expression in normal, dysplastic, and neoplastic canine and feline mammary tissues.

Steroid receptor expression was assessed by immunohistochemistry in neoplastic, hyperplastic/dysplastic, and normal mammary tissue samples removed from 68 queens and 47 bitches, using monoclonal antibodies against human oestrogen-alpha (ER) and progesterone receptors (PR). Mammary lesions were classified according to World Health Organization (WHO) criteria, and all animals with invasive carcinomas were clinically followed for 2 years. Stromal and/or lymphatic invasion and histological grading were also recorded. In both species, ER expression was significantly higher in healthy tissues, hyperplastic/dysplastic lesions, and benign tumours than in carcinomas. The loss of ER expression was more marked in feline than in canine carcinomas. In queens, PR expression increased in dysplastic lesions and "in situ" carcinomas and decreased in invasive carcinomas, even if parts of these tumours were still PR-positive. In bitches no significant variation in PR expression was observed between normal tissue, dysplasias, and benign neoplasms, but was significantly lower in carcinomas. In both species ER and PR expression in invasive carcinomas did not correlate either with histological parameters or overall survival time. This study demonstrates several differences in steroid hormone dependency between the two species. The percentage of PR-positive feline carcinomas suggests a possible role of progesterone in promoting early tumour cell growth in queens. The low percentage of ER-positive invasive carcinomas further demonstrated the aggressive phenotype and behaviour of feline mammary tumours.

Immunohistochemical distribution of type IV collagenase in normal, dysplastic and neoplastic canine mammary gland.

The distribution of type IV collagenase (cIVase) was evaluated immunohistochemically in a series of normal, dysplastic and neoplastic canine mammary glands, as well as in lymph node metastases. In normal and dysplastic mammary tissues, and benign mammary tumours, cIVase was observed in myoepithelial cells, but in malignant tumours it was mainly localized in the cytoplasm of carcinoma cells and fibroblasts close to infiltrating neoplastic cells. No significant difference was observed between carcinomas of different histological sub-types. These results suggest that the distribution of cIVase is a potentially useful indicator of malignancy in canine mammary tumours.

BRCA1 expression in canine mammary dysplasias and tumours: relationship with prognostic variables.

BRCA1 is a nuclear phosphoprotein that participates in the regulation of the cell cycle. The role of the BRCA1 gene in canine mammary tissue and mammary tumours has not been studied. The present study examined immunohistochemically the expression and intracellular distribution of BRCA1 protein in two normal, seven dysplastic and 44 neoplastic canine mammary glands and its relationship with clinical and pathological variables and other prognostic parameters. Strong nuclear immunolabelling of BRCA1 protein was observed in the epithelial cells of the normal mammary glands and mammary dysplasias. The majority of benign tumours, and more especially of malignant tumours, showed a significant reduction in the nuclear expression of BRCA1 protein and an increase in cytoplasmic expression. Loss of BRCA1 expression was associated with high proliferation marker Ki-67 and ER-alpha negative tumours. The reduction and aberrant distribution of BRCA1 in canine mammary tumours were significantly associated with malignant characteristics. The results may indicate that BRCA1 has a role in the malignant behaviour of these tumours.

Expression of fibronectin and its integrin receptor alpha 5 beta 1 in canine mammary tumours.

Fibronectin and its integrin receptor alpha 5 beta 1 were studied by immunohistochemical methods in five normal canine mammary glands, four dysplastic glands and 18 mammary tumours. The aim of the study was to evaluate the possible changes in the alpha 5 beta 1 integrin receptor and its ligand fibronectin in relation to the metastatic capacity of canine mammary neoplasms. The immunostaining of alpha 5 beta 1 was very uniform in the hyperplastic glands but uneven in the mammary tumours. The expression of alpha 5 and beta 1 was diminished in metastatic tumours but there were some alpha 5-positive cells with pronounced features of malignancy and immaturity. Stromal fibronectin was increased in most cases and cytoplasmic staining of fibronectin was observed in epithelial and myoepithelial cells in mammary neoplasms but not in normal or dysplastic mammary tissue. There was no relationship between the content of alpha 5 beta 1 and the expression of fibronectin in canine mammary tumours.

Mammary fibroadenomatous hyperplasia in a young cat attributed to treatment with megestrol acetate.

A male, neutered cat was presented for lethargy, reluctance to walk, and mammary enlargement after recent treatment with megestrol acetate. Mammary fibroadenomatous hyperplasia was diagnosed on the basis of history, clinical signs, and histopathological findings. Pathogenesis, clinical signs, and treatment options for mammary fibroadenomatous hyperplasia attributed to megestrol acetate treatment are discussed.

An Immunohistochemical study of HER-2 expression in feline mammary tumours.

The aim of the present study was to evaluate HER-2 expression in feline mammary tumours. Five different immunohistochemical protocols were tested with 73 feline mammary carcinomas (MCs), 10 mammary adenomas and 73 hyperplastic or dysplastic mammary lesions. The histological features of these lesions, clinical follow-up and expression of Ki-67 and p53 were also examined. With an optimized immunohistochemical protocol, HER-2 overexpression was detected in only four of the 73 (5.5%) MCs and did not correlate with histological classification or with the 1 year post-surgical clinical outcome. No correlation was found between the expression of Ki-67 or p53 and HER-2. Five of the 73 (6.8%) hyperplastic or dysplastic lesions and one of the 10 (10%) mammary adenomas were HER-2 positive. These results suggest that HER-2 may not play as significant role in mammary carcinogenesis and prognosis in cats as it does in human patients.

Feline reproduction: problems and clinical challenges.

AUDIENCE: Many veterinarians are closely involved with pedigree cat breeding and have become familiar with the unique characteristics of feline reproduction and breeding management. However, even veterinarians who do not have involvement with the pedigree cat fancy require a basic knowledge of the reproductive problems that are most likely to be encountered in working with non-breeding pet cats as well as stray and feral cats. CLINICAL CHALLENGES: This article reviews reproductive problems and challenges in both sexes - namely, ovarian remnant syndrome, mammary fibroadenomatous hyperplasia, congenital anomalies of the reproductive tract and pregnancy diagnosis in the queen, and cryptorchidism and low libido in the tom. EVIDENCE BASE: Feline reproduction has not received the amount of investigation and attention that has been directed at canine reproduction. The result is that less data is available both for description of normal reproduction and for management of common problems. This article reviews most of the available evidence for the conditions discussed. Efforts should focus on making information more readily available to the practitioner and expanding the knowledge base in this important area of feline medicine.

Sparse and wavy hair: a new model for hypoplasia of hair follicle and mammary glands on rat chromosome 17.

Mutant animals in the skin and hair have been used to identify important genes in biomedical research. We describe a new mutant rat, sparse and wavy hair (swh), that spontaneously arose in a colony of inbred WTC rats. The mutant phenotype was characterized by sparse and wavy hair, which was most prominent at age 3-4 weeks, and was inherited in an autosomal recessive manner. The swh/swh rats showed impaired gain of body weight, and their hair follicles were reduced both in number and size, associated with hypoplasia of the sebaceous glands and the subcutaneous fat tissue. Female swh/swh rats were unable to suckle their offspring. Their mammary glands were hypoplastic, and differentiation of mammary epithelial and myoepithelial cells was impaired. Linkage analysis of 579 backcross rats localized the swh locus to a .35-cM region between D17Rat131 and D17Rat50 in the distal end of rat Chr 17. The swh locus spanned the 3.7-Mb genomic region where 24 genes have been mapped and corresponded to the centromere region of the mouse Chr 2 or the region of the human Chr 10p11.1-p14. None of the genes or loci described in mouse or human hair and skin diseases mapped to these regions. These findings suggest that the rat swh is a novel mutation associated with impaired development of the skin appendages, such as hair follicles, sebaceous glands, and mammary glands, and will provide an experimental model to clarify a gene and mechanisms for development of skin appendages.