31 Aug 2021
Figure 1. The Irish red setter had the highest breed prevalence (32.3%) for incontinence in bitches. Image: Diane Pearce and The Kennel Club
Urinary incontinence describes involuntary leaking of urine from the bladder. The direct welfare impact on dogs includes increased risk of urinary tract infection and urine scald.
For many years, increased risk of urinary incontinence in bitches had been attributed to neutering, but the evidence for an association between neutering and urinary incontinence was weak until recently (Beauvais et al, 2012).
This problem can also be hugely distressing for owners, resulting in feelings of anger, disappointment and frustration. Therefore, due to the welfare implications, the potential impact on the owner-animal bond and the importance for decision-making on neutering, a deeper understanding of the epidemiology and role of neutering in the development of urinary incontinence is important. Research based on first opinion clinical records offers the ideal resource to fill critical knowledge gaps relating to the wider dog population such as these.
The VetCompass programme at the RVC aims to improve animal welfare by providing better and more relevant evidence for primary care veterinary professionals.
An early VetCompass paper in 2017 explored the prevalence and risk factors associated with urinary incontinence in bitches, showing that the disorder affects 3.1% of bitches in England (O’Neill et al, 2017). In total, 100,397 bitches attending 119 veterinary clinics across England were included in that cross-sectional study and the research revealed strong breed variation in susceptibility to the condition.
The levels of predispositions were eye-raising in certain breeds. For example, almost one third of Irish red setter bitches were recorded with urinary incontinence during the study period – this is 10 times the average across all dogs.
The most predisposed breeds were:
The research also showed the value of big data resources such as VetCompass to improving our understanding of veterinary practice. For example, because veterinary teams see a lot of cases of urinary incontinence in Labrador retrievers, it would be easy to conclude in general practice that Labrador retrievers are predisposed to urinary incontinence.
However, after taking account of the popularity of Labrador retrievers (has been the most common breed in the UK for many years), their risk was no different to the overall average – 3%.
Good data can change our perceptions; beliefs generated in the absence of good data can be wrong. Simply put, a lot of Labrador retrievers with urinary incontinence exist in general practice just because a lot of Labrador retrievers exist in general practice.
Naturally, we are also interested to explore the welfare impact of urinary incontinence. One option to assess the welfare impact is to explore the need for medical treatment. In the case of urinary incontinence, almost half of all the cases (45.6%) received medical treatment, suggesting that urinary incontinence has a highly clinical relevance to the owners and the veterinary teams.
When we looked at the bitches that died during the study period, urinary incontinence was recorded as either a contributory or main reason for death in 16.7% of these deaths.
The early study provided proof of concept that first opinion records could answer important questions on urinary incontinence. This confidence supported the development of a Master of Research (MRes) project, funded by PetSavers, that explored the associations between neutering and urinary incontinence in greater depth.
This MRes study led to two papers revealing that both neutering per se and the age at neutering were key risk factors for urinary incontinence (Pegram et al, 2019a; 2019b). These findings provide a strong evidence base – allowing veterinarians to enhance their clinical recommendations, treatment and overall animal welfare – for higher risk bitches.
The first of these MRes papers described a case-control study (Pegram et al, 2019b). The study included 427 cases and 1,708 controls that presented between November 2014 and October 2017. Prior neutering was associated with three times increased risk of urinary incontinence. Increased risk of urinary incontinence was additionally associated with:
Increasing age, With bitches aged older than 12 years at 4.1 times the risk of urinary incontinence compared with bitches aged younger than 3 years.
Increasing bodyweight, with bitches greater than or equal to 30kg at 3.2 times the risk of urinary incontinence compared with bitches less than 10kg.
Although age and bodyweight are important risk factors to assist with our index of suspicion for diagnosis, we have less control over these as humans. Neutering, on the other hand, is very much a human decision that affects our dogs and is therefore much more amenable to change.
In the UK, neutering is a routine and normalised clinical procedure, but this view is not universally accepted. In many Scandinavian countries, for example, neutering of dogs is not the norm (Von Heimendahl, 2011). So, if adverse consequences are likely from neutering, we have an obligation as veterinary professionals to be aware of these and to share this information with our clients to contribute to informed decision-making.
Among the observational study design types, cohort studies provide the best level of evidence for risk factors that change over time, such as neuter status (Burns et al, 2011). Therefore, the case control study was followed by a more exacting cohort study to dig deeper into the associations between neutering and urinary incontinence (Pegram et al, 2019a).
The cohort study followed 72,971 bitches in the VetCompass records from 2010‑18, during which 492 bitches developed urinary incontinence. These cases were defined as “early-onset urinary incontinence” (that is, first diagnosed before eight years of age) to avoid conflating effects between neutering with cases of urinary incontinence that were primarily associated with senescence.
This study highlighted the complexity of the relationship between neutering and urinary incontinence. After accounting for confounding factors, such as breed and bodyweight, increased risk of early-onset urinary incontinence was identified in:
Neutered bitches, with the risk of urinary incontinence in neutered bitches increasing with age.
Bitches neutered before 6 months, compared to those neutered at 6 to less than 12 months, within the first 2 years following neutering.
Therefore, both the neuter status itself and the age at neuter are important risk factors for urinary incontinence.
The decision to neuter a bitch is based on many factors, not just urinary incontinence risk alone. However, the contribution to decision‑making driven by an awareness of the risk of urinary incontinence may need to be greater for the high-risk breeds and bitches with larger bodyweights.
These results also suggest that decisions on early-age neuter (less than six months) should be carefully considered, particularly in high-risk breeds and bitches with larger projected bodyweights.
More information about VetCompass and access to the papers is available at www.rvc.ac.uk/vetcompass
