Effectiveness of deslorelin acetate subcutaneous implantation in a domestic queen with after-spaying urinary incontinence

Abstract

A 2-year-old female ovariectomised Norwegian Forest cat with a history of post-spaying urinary incontinence was diagnosed with acquired urinary sphincter mechanism incompetence (USMI) after complete clinical and laboratory examination. Although there is no literature regarding the treatment of post-spaying USMI in cats, deslorelin acetate is successful in the treatment of post-spaying USMI in dogs. Deslorelin acetate implants have been shown previously to be effective for contraception and oestrus suppression in queens, and suppression of reproductive function in tomcats. Therefore, deslorelin acetate implant treatment was chosen for treatment of post-spaying USMI in this queen. Follow-up examinations were performed on days 8, 15 and 30 after deslorelin implant insertion. Urinary continence was restored about 25 days after implantation and maintained for at least 15 months, without treatment-related negative effects. In the present case report, the post-spaying urinary incontinence related to the acquired USMI was successfully treated with a deslorelin acetate implant. In addition, safe implantation was easy in cats and the single injection resulted in long-lasting efficacy. Further studies are needed to confirm the usefulness of deslorelin acetate treatment for post-spaying USMI in queens and to better delineate the duration of efficacy.

Case Report

A 2-year-old female Norwegian Forest cat was brought to the clinic for urinary incontinence observed by the owner. The clinical history revealed the queen was ovariectomised at the age of 15 months, after weaning her first litter. Six months after spaying the owner started to find small amounts of urine out of the litter, mainly on the cat pillow. The urinary incontinence was irregular at first, but in the following 3 months incontinence became continuous. The condition was neither investigated nor treated.

At clinical examination, the queen was healthy and in good body condition. Only a mild staining of the perivulvar area was noticeable.

With the patient handled in lateral recumbence, as part of the diagnostic procedure, an abdominal ultrasound examination using a multi-frequency linear probe array (7.5–10 MHz) (MYLab 30; Esaote) was performed, focused mainly on the urinary system. Examination revealed that both kidneys were of normal shape, size and echotexture; the cortico-medullary ratio was perfectly maintained; and no signs of pyelitis were found. The urinary tract did not appear expanded. The bladder, examined at different stages of filling, appeared to be of normal shape and position. No evidence of concretions or abnormalities of the lumen was observed.

The wall, measured at several distension stages, resulted in the normal range for thickness and echo structure. During the examination, the openings of both ureters in the bladder were evidenced. A urine sample was collected by ultrasound-guided cystocentesis in order to perform a complete urinalysis and urine culture.

In addition, a blood sample was collected for a complete haematological evaluation and for oestradiol-17β, progesterone and follicle-stimulating hormone (FSH) analysis by chemiluminescence (Immulite 2000; Medical Systems).

Urinalysis revealed a moderate number of leukocytes (seven per field of view), while urine culture showed the presence of a low number of colony forming units of Escherichia coli.

Complete blood count revealed a slight neutrophilia (19,48626/l), while blood chemistry parameters fell within the reference interval. According to the laboratory reference intervals, oestradiol-17β and progesterone plasma levels indicated anaestrus (8 pg/ml and 1.3 ng/ml, respectively), while the FSH level (112 mg/l) was in agreement with data reported for spayed female cats.

In order to rule out a possible infection aetiology, on the basis of urine culture and subsequent antibiotic sensitivity test, treatment with marbofloxacin (Marbocyl; ATI), a potent third-generation fluoroquinolone, was started at the dose of 2 mg/kg/q12h for 8 days, coupled with a bioflavonoids and dicalcium phosphate complex diet supplementation (500 mg/day, according to manufacturer’s prescription and in relation to the queen’s bodyweight).

A medical follow-up was scheduled for 8 days after the first examination. At follow-up, the owners reported that, despite therapy, urinary incontinence did not recover.

After complete clinical examination, urinary bladder ultrasound investigation and ultrasound-guided cystocentesis were repeated. Ultrasound did not show any abnormalities, nor did the urinalysis; the urine culture was sterile.

However, the antibiotic therapy was continued for 5 days and diet supplementation for 30 days. Despite the absence of obvious signs related to neurological deficiency, in agreement with the owners, a neurological examination was planned before the end of the antibiotic therapy in order to rule out a possible neurological cause for urinary incontinence. Because the neurological examination did not reveal abnormalities in the neurological control of bladder sphincter function the post-spaying, urinary incontinence related to acquired urinary sphincter mechanism incompetence (USMI) was presumed, although not supported by the literature on the condition, and of possible treatment, in the female cat.

Deslorelin acetate implant treatment was selected because of its efficacy in post-spaying USMI in dogs and on a risk–benefit estimation.

Deslorelin acetate is effective for contraception and oestrus suppression in queens and for suppression of reproduction function in tomcats,^1–3 but has no reported use for the treatment of post-spaying USMI treatment in cats. Deslorelin acetate implant therapy was recommended to the owners and performed after written informed consent was obtained.

The queen was manually restrained and no sedation was used. The implant insertion area was clipped and disinfected. A deslorelin acetate implant (4.7 mg/animal) (Suprelorin; Virbac) was then inserted in the subcutaneous tissue of the right pre-scapular region.

The clinical follow-up of the patient was scheduled for days 8, 15 and 30 after deslorelin implant insertion. At day 8 and day 15 the queen was still incontinent, and the urinary bladder ultrasound investigation did not show abnormalities, nor did the urinalysis; the urine culture was sterile. No treatment-related negative effects or local reaction were observed. At day 30 the owners reported that, since day 20 after implant insertion, the cat pillow was no longer wet and the queen, although still showing a mild urinary dribbling, restarted normal micturition in the cat litter. Starting on day 25 after implant insertion, the queen did not show any urinary dribbling and urinary continence was restored.

At the subsequent telephone follow-up, scheduled weekly for the first month and monthly for the following year, the queen remained continent. At the time of writing (15 months after deslorelin implantation), the queen remains continent. In queens, the contraceptive effect of deslorelin implants last for at least 18 months and it is expected that this queen will also remain continent for this duration.

The aetiopathogenesis of post-spaying USMI in bitches has been widely investigated, but is still not completely understood. The most suitable hypothesis is that post-spaying USMI is a multifactorial condition, involving some hormonal imbalance, as well as anatomical and functional changes of the urethral sphincter mechanism. ⁴ For these reasons, non-surgical treatments for post-spaying USMI in bitches include several different protocols, such as α-adrenergic drugs, ⁵ oestrogens ⁶ or gonadotropin-releasing hormone (GnRH) agonists in depot preparation. ⁷ Because of the required frequency of dosing with α-adrenergic drugs (effective in the bitch when administered orally every 8–24 h) and the possible side effects of oestrogens, GnRH agonist in depot preparation (effective in about 50% of bitches with post-spaying USMI) was selected. ⁷ In this clinical case, this treatment was effective in restoring continence in a queen presenting with post-spaying USMI. However, additional investigation on a larger number of affected cats is needed. In dogs, GnRH receptors are present in the urinary bladder, urethra and urethral sphincter. ⁸ The therapeutic effect of GnRH agonists could be a direct effect on the lower urinary tract. ⁸ There have not been any studies investigating the expression of GnRH receptors in the urinary tract of the cat.

Conclusions

In this case, post-spaying USMI was successfully treated with a deslorelin acetate implant without treatment-related negative effects. Urinary continence was restored about 25 days after implant administration and was maintained for at least 15 months.