Follicular cysts and prolonged oestrus in a female dog after administration of a deslorelin implant.

CASE HISTORY

A 7-year-old female Bernese Mountain dog was presented for treatment to prevent oestrus. One 4.7-mg deslorelin implant was injected S/C between the shoulder blades. Three months later, the dog was re-examined because of prolonged oestrus.

CLINICAL FINDINGS

Ultrasound showed multiple thin-walled cysts on both ovaries. Blood samples were taken at various intervals during the following weeks. Concentrations of oestradiol and vaginal smears indicated pro-oestrus. Follicle stimulating hormone (FSH) and luteinising hormone (LH) remained at basal concentrations.

DIAGNOSIS

Follicular cysts and prolonged oestrus.

TREATMENT

Two treatments of 360 IU human chorionic gonadotrophin (hCG) were administered 42 days apart, that induced a partial or complete degeneration of the cysts. However, concentrations of oestradiol rose again within a few weeks. After the second treatment with hCG the bitch developed pyometra. After successful conservative treatment with antibiotics and aglepristone the dog underwent ovariohysterectomy.

CLINICAL RELEVANCE

Slow-release biocompatible implants containing deslorelin provide an opportunity for effective contraception for male dogs. Some authors describe deslorelin also as safe and efficacious for the use in female dogs but those recommendations are derived from few studies, with a small number of animals. Based on the outcome of this case and the experience of other authors we suggest a complete gynaecological examination be performed before implanting deslorelin, and weighing the risks against the advantages in controlling fertility. It is well known that the risk of induction of oestrus can be reduced when implants are administered at concentrations of progesterone in plasma of ≥16.0 pmol/L. The implant should be administered S/C, cranial and close to the umbilicus, to have the option of relocation and excision if necessary.