Stump pyometra in a spayed female dog secondary to tamoxifen.

OBJECTIVE: To describe a complication associated with the long-term use of tamoxifen for the treatment of sclerosing encapsulating peritonitis in a dog. CASE SUMMARY: A 2-year-old female spayed poodle cross was evaluated for a stump pyometra. The dog was diagnosed with sclerosing encapsulating peritonitis a year prior and was treated with tamoxifen, an oestrogen receptor antagonist, for treatment of the disease. The dog developed a swollen vulva with vulvar discharge and a stump pyometra was diagnosed on ultrasound. Hormonal testing was submitted to evaluate for an ovarian remnant and the dog underwent an exploratory laparotomy, where the uterine stump was removed. No ovarian remnant tissue was identified intra-operatively, and hormonal testing (anti-Müllerian hormone, progesterone, oestradiol) and histopathology were consistent with the absence of ovarian tissue. The tamoxifen was discontinued. The dog recovered uneventfully after surgery. NEW OR UNIQUE INFORMATION PROVIDED: This report describes a complication of treatment of a rarely described clinical disease. While most cases of stump pyometra involve ovarian remnant syndrome, this case report describes a stump pyometra in a dog without remnant tissue that was undergoing treatment with tamoxifen. Tamoxifen has been reported to cause pyometra in intact female dogs. To the authors' knowledge, this is the first case report to describe a stump pyometra in a spayed female dog, secondary to the use of tamoxifen.

Strain specific induction of pyometra and differences in immune responsiveness in mice exposed to 17α-ethinyl estradiol or the endocrine disrupting chemical bisphenol A.

Pyometra is an inflammatory disease of the uterus that can be caused by chronic exposure to estrogens. It is unknown whether weakly estrogenic endocrine disruptors can cause pyometra. We investigated whether dietary exposures to the estrogenic endocrine disruptor bisphenol A (BPA) induced pyometra. Pyometra did not occur in CD1 mice exposed to different dietary doses of BPA ranging from 4.1 to >4000µg/kg-d or 17α-ethinyl estradiol (EE; 1.2 to >150µg/kg-d). In the C57BL/6 strain, pyometra occurred in the 15µg/kg-d EE and 33µg/kg-d BPA treatment groups. At the effective concentration of BPA, histological analysis revealed pathological alterations of uterine morphology associated with a >5.3-fold increase in macrophage numbers in non-pyometra uteri of C57BL/6 mice exposed to BPA. These results suggest that BPA enhances immune responsiveness of the uterus and that heightened responsiveness in C57BL/6 females is related to increased susceptibility to pyometra.

Evaluation of adverse effects in tamoxifen exposed healthy female dogs.

BACKGROUND: Mammary tumors are among the most frequent neoplasms in female dogs, but the strategies employed in animal treatment are limited. In human medicine, hormone manipulation is used in cancer therapy. Tamoxifen citrate is a selective inhibitor of oestrogen receptors and exerts a potent anti-oestrogen effect on the mammary gland. The aim of this study was to evaluate the adverse effects when exposing healthy female dogs to tamoxifen. METHODS: Tamoxifen was administered for 120 days at a dose of 0.5 or 0.8 mg/kg/day to either intact or spayed female dogs. The effects were assessed through clinical examination, haematology, serum biochemistry, ophthalmology and bone marrow aspirate examination. Ovariohysterectomy was performed and the uterus examined by histopathology. RESULTS: Vulva oedema and purulent vaginal discharge developed with 10 days of tamoxifen exposure in all groups. Pyometra was diagnosed after around 90 days of exposure in intact females with frequencies increasing during the following 30 days of exposure. Up to 50% of dogs within the groups developed retinitis but none of the dogs had signs of reduced visual acuity. The prevalence of retinitis in each group was similar after 120 days of exposure. Haematological, biochemical and bone marrow changes were not observed. Due to the high risk of developing pyometra after prolonged exposure to tamoxifen, only spayed animals should be given this medication. CONCLUSIONS: A dose of 0.8 mg tamoxifen/kg body weight/day is recommended when treating tamoxifen-responsive canine mammary tumors. Due to the high risk of developing pyometra, ovariohysterectomy is recommended.

Pathological abnormalities after long-term administration of medroxyprogesterone acetate in a queen.

In this report, multiple abnormalities (bilateral ovarian cysts, cystic endometrial hyperplasia and pyometra (CEH-P), mammary adenoma, fibrosarcoma and cystic-papillary adenocarcinoma) identified in a queen continually administered medroxyprogesterone acetate (MPA) for 9 years are described. An 11-year-old domestic shorthair intact queen was presented for reduced appetite, polyuria, polydipsia, abdominal distension, and mammary mass. Pyometra was diagnosed based upon clinical, ultrasonographic and radiographic examinations. Mastectomy and ovariohysterectomy (OHE) were performed for treatment. Bilateral ovarian cysts were detected during OHE. Histopathologically, follicular ovarian cysts, CEH-P, and benign and neoplastic mammary lesions were identified. We suggest that, the pathological abnormalities may have been attributed to adverse effects of prolonged administration of MPA.