Acquired urinary incontinence (AUI) is an increasingly recognised and incurable condition in veterinary medicine that can lead to significant welfare issues. It is known that AUI affects up to 20% of all neutered bitches but <1% of entire bitches. As gonadectomy affects circulating concentrations of steroid and gonadotrophic hormones, it has been hypothesised that development of AUI could be affected by perturbations of the gonadotrophic axis. In this regard, it has recently been reported that, in short term trials, GnRH analogue treatment can improve AUI symptoms in up to 65% of cases.

Our previous work demonstrated significant changes in contractility and muscarinic receptor expression in the canine bladder post neutering. The aim of this study was to determine if neutering alters the expression of mRNA for GnRH and LH receptors in the urinary bladder.

Sections of bladder wall were dissected post mortem from entire and neutered, male and female dogs (ME, MN, FE, FN respectively) with informed owner consent. 2 dogs in the FN group were identified as suffering from AUI. RNA was extracted and reverse transcribed. GnRH and LH mRNA expression was quantified by rtPCR (relative to β-actin).

ANOVA indicated significant (p<0.01) effects of gender and gonadal status but no interaction between these effects, and no effect of age or weight. Neutering was associated with higher levels of mRNA expression for both LH- and GnRH- receptor in both genders. Furthermore female animals had significantly higher expression levels than their male counterparts. AUI animals had the highest LH receptor mRNA expression levels (above the 95% CI), but GnRH receptor mRNA expression was within the group range.

These results demonstrate that neutering a canine causes dynamic changes in LH and GnRH receptor mRNA expression within the bladder, which may play a role in the development of AUI in the bitch. This is substantiated by the limited data from AUI animals which showed the highest levels of LH receptor mRNA expression, which may, therefore, present a potential new therapeutic target for treatment of this debilitating condition.

Table 1. Relative expression levels of mRNA, presented as mean ± s.e. mean where n = number of dogs.