Oestrogen receptors in a case of hydrometra in a bitch

HYDROMETRA – the accumulation of fluid in the uterine lumen – alone is uncommonly observed in bitches. McAfee and McAfee (1976) reported a case of hydrometra in a young bitch that was presented for elective ovariohysterectomy. Other reports of hydrometra have associated the condition with cystic endometrial hyperplasia (CEH) which evolves with a high degree of mucous hydration (Kennedy and Miller 1992). In other species, hydrometra has been associated with chronic stimulation of oestrogen receptors by exogenous substances (Biolatti and others 1994, Re and others 1995). Granulosa cell tumours are one possible source of endogenous oestrogens. However, they do not always induce uterine disease. These tumours are common in bitches, but their endocrine secretion is not constant and may vary between tumours and with the stage of tumour development (Cotchin and others 1961, Norris and others 1970, McEntee 1990). Several studies (De Cock and others 1997, Dhaliwal and others 1997, Vermeirsch and others 1999) have demonstrated that the number and distribution of oestrogen receptors in the uterus varies within the oestrous cycle, and have correlated the expression of oestrogen receptors with the concentrations of oestrogen and progesterone in the blood. This short communication describes a case of hydrometra in a bitch in which the macroscopic and microscopic features differed from those associated with the CEH/pyometra complex. A 10-year-old Yorkshire terrier cross bitch was presented for examination with a history of depression, anorexia and vomiting, dark faeces with an abnormal consistency, polyuria and polydipsia; the owner also described trembling and muscular weakness that rendered the dog incapable of climbing up stairs. According to the owner, its last heat had been one month previously. On admission, the bitch was conscious but lethargic, and the rectal temperature was within normal values. The conjunctival mucosa was slightly pale, but the capillary refill time was normal. The respiratory rate was normal; cardiac auscultation revealed a heart murmur. Signs of pain were evident on abdominal palpation. The results of a complete blood count indicated mild anaemia, but the leucogram was normal (Table 1). Serum biochemical analysis revealed that biochemical variables were within normal range limits, with the exception of albumin, which was very close to the lower end of the range (Table 1). No haematological signs of disseminated intravascular coagulation were present. Ultrasonographic examination revealed enlargement of the uterus, atrophy of the uterine wall and hypoechogenic contents, which led to a presumptive diagnosis of CEH/pyometra complex. The dog received supportive therapy, including lactated Ringer’s solution supplemented with glucose and potassium chloride, enrofloxacin, ranitidine and metaclopramide. Once the dog’s condition had been stabilised it underwent ovariohysterectomy. The dog was premedicated with 0·2 mg/kg diazepan (Bialzepan; Bial) and 0·4 mg/kg butorphanol (Turbogesic; Fort Dodge) intravenously, and then anaesthetised by intravenous administration of 2 mg/kg propofol (Diprivan; AstraZeneca). After intubation, the anaesthesia was maintained with 2 per cent isoflurane (Abbott Laboratories). Within 10 days after surgery, the bitch recovered from its clinical signs and showed normal PCV values and also normal serum albumin and calcium levels. The uterus presented a bilateral increase in the dimensions of the horns (11·5 cm in length and 2 cm in diameter) and its wall was very thin but had no ulcers or cysts (Fig 1), and had normal transverse folding. The fluid content of the uterus was watery and slightly yellow, and no particles in suspension were observed. The ovaries had a smooth surface; one ovary measured 1·5 x 1 x 0·5 cm, and had an apparently normal consistency, the other measured 1 x 0·8 x 0·5 cm and had a soft consistency, and a massive, white structure was present in one of the poles of the ovary. The ovaries and uterus were fixed in 10 per cent buffered formalin, embedded in paraffin wax, sectioned at 2 μm and stained with haematoxylin and eosin. Uterine sections were also stained with periodic acid-Schiff and alcian blue for staining mucopolysaccharides. For immunohistochemical characterisation, a mouse monoclonal antibody that binds to human oestrogen receptors (Clone CC4-5; Novocastra Laboratories) was used. The tissues were sectioned, placed on a slide, deparaffinised and hydrated. Antigen retrieval was performed in a pressure cooker at above 100°C for two minutes in a citrate buffer at pH 6, and then hydrogen peroxide inactivation and immunohistochemistry were performed. The primary antibody was applied at a dilution of 1:40, overnight at 4°C. The expression of oestrogen receptors in the uterine tissue was Veterinary Record (2006) 158, 487-489