Frequent canine disorders

The scientific knowledge of dogs is extensive and has extended, especially during the past century. The UK has eight veterinary schools with dedicated programmes on canine topics and thousands of clinical papers and textbooks have been written about health disorders in dogs. In 2006, the full canine genome was sequenced (Lindblad-Toh et al, 2005).

So, it was with some soul-searching three major reports during 2008 to 2010 on welfare of purebred dogs in the UK identified, by the end of the first decade of the 20th century, we could not answer the most basic question about canine health: what are the most common disorders diagnosed in dogs in the UK? (Bateson, 2010; Rooney and Sargan, 2008; APGAW, 2009).

No reliable datasets at that time provided this type of information relating to the general population of dogs in the UK. However, the Bateson report suggested a viable route forward was to build on a pilot project at the RVC collecting clinical data directly from veterinary practices (Bateson, 2010).

This would offer a rich source of data on clinical diagnoses, along with breed and other demographic data that could greatly enhance our understanding of canine health and support improved animal welfare.

Taking action

To redress these data deficiencies on health information on companion animals, the RSPCA supported a PhD study based at the RVC from 2010 to 2013 aimed at developing a collection system for de-identified clinical records for research purposes from an array of practices. This project has become known as VetCompass (Figure 1) and is a not-for-profit collaborative programme with an underpinning philosophy the cumulative veterinary clinical experience can be harnessed to generate an evidence base to improve companion animal welfare (VetCompass, 2016).

The strengths of research based on large-scale, merged veterinary clinical records are the records made at the same time as the clinical event and by highly qualified veterinary health professionals, and can cover all episodes of clinical care for patients. This minimises selection and recall biases that limit research efforts using referral, insurance and survey data (Bateson, 2010; O’Neill et al, 2014a).

VetCompass has grown rapidly since 2010 and collaborates with 470 UK vet practices that have shared data covering 11.3 million episodes of care on 4.2 million companion animals. This data is supporting PhD, MSc and undergraduate studies, with 16 peer-reviewed papers published.

VetCompass is widely supported by veterinary and welfare bodies, including the BVA, the BSAVA, The Kennel Club, Dogs Trust and the RSPCA. It has extended to include equine practice data in the UK, with international sister projects and pilot initiatives running in Australia, New Zealand, Sweden, Denmark, Spain and Germany.

Most common canine disorders

Although VetCompass supports a wide array of research topics, the question about common disorders in dogs was a priority objective and the results were published in 2014 as an open access publication freely available online (O’Neill et al, 2014c).

The study explored a population of 148,741 dogs attending 93 clinics across central and south-east England from 1 September 2009 to 31 March 2013. The demographic data identified 78.9% were purebred, 48% were female, 41.1% were neutered, 29.2% were insured and 27.6% were microchipped. The median weight overall was 18.2kg (interquartile range; IQR 9.4 to 29, range 0.68 to 105) and the median age overall was 4.5 years (IQR 1.6 to 8.7, range 0 to 27.4).

A random sample of 3,884 of these dogs was selected and the full clinical records of each dog were reviewed to extract data on the diagnoses. Overall, 8,025 diagnosed events were recorded from the sampled dogs, identifying an average of about two events for each dog.

These events were spread across a range of 430 distinct disorders, showing the broad scope of conditions veterinary surgeons manage in dogs on a daily basis. This breadth of more than 400 disorders also highlights the complexity of reforms required to improve the health of domestic dogs and suggests tunnel-vision focus on single disorders for breeding reforms may be a suboptimal approach to improve overall health. Excessive targeting of one or few individual disorders could risk aggravating the prevalence of other non-targeted disorders.

The most common disorders recorded overall in dogs were otitis externa (10.2%), periodontal disease (9.3%), anal sac impaction (7.1%), overgrown nails (7.1%) and degenerative joint disease (6.6%; Table 1). These findings concur with the limited available publications of disorder occurrence in the wider population of dogs.

A 1997 UK study using paper-based clinical records identified the most common disorders of dogs as overgrown nails (2.7%), ascarid worm problems (2.3%), anal sac impaction (2.1%), dental calculus (1.8%), fleas (1.8%), bacterial otitis externa (1.7%), waxy otitis externa (1.2%), diarrhoea/vomiting (1%) and Otodectes otitis externa (0.9%; Edney, 1997).

These apparently lower prevalence values may be partially explained because the 1997 study (Edney, 1997) reported prevalence per consultation values, whereas the 2014 study (O’Neill, 2014c), which is the main focus of this paper, reported period prevalence per dog. A US primary care study identified dental calculus (20.5%), gingivitis (19.5%) and otitis externa (13%) as the most prevalent diagnoses in dogs, but reported the prevalence of anal sac disease at only 2.5% (Lund et al, 1999).

Basic presentations

Although any vet who has spent time in general practice will identify with these findings, the results often seem to come as a surprise when presented to other groups. There is often a tacit assumption the most common disorders of dogs must be “inherited” disorders with control programmes in place that get a lot of publicity, such as hip and elbow dysplasia, or exotic diseases with genetic tests recommended in some dog breeds.

However, unromantic as it may be, the truth is the most common disorders relate to basic presentations with sore ears, bad teeth, impacted anal sacs and arthritis. In consequence, it is these common conditions we need to ensure new graduates are equipped to manage from day one and are considered as worthy of health controls by breed groups.

It is noteworthy most of the common disorders identified in dogs were complex disorders, having multiple interacting environmental and genetic casual factors (Page et al, 2003). This suggests we should move away from the view of individual disorders being necessarily inherited or non-inherited (Bellumori et al, 2013).

In preference, we should acknowledge relevant roles for genetic and environmental components in the majority of important canine disorders (Rand et al, 2004; Wood et al, 2002; Hillier and Griffin, 2001).

This acceptance can improve the quality of decision-making on selection and development of effective disease control and breeding programmes (Mellersh, 2012).

A large body of literature supports the existence of differing patterns of disorder predispositions across dog breeds (Gough and Thomas, 2010; Summers et al, 2010; Asher et al, 2009). This suggests, while knowledge on the disorder burden in dogs can help to prioritise the main disorders affecting the overall canine population, increased focus on disease priorities in breeds is merited.

Consequently, research programmes should move towards breed-specific studies to provide evidence that specifically relates to individual breeds. Indeed, the first published of these breed-based studies covered cavalier King Charles spaniels (Summers et al, 2015).

Effective dissemination of the results of scientific studies are critical to maximising the real world impact from scientific research. Scientific research dissemination has normally been targeted towards the research and clinical community via peer-reviewed publications and conference presentations.

However, for topics such as canine inherited disease also of interest to the wider dog–owning public, the main findings of studies can also be prepared and communicated effectively via the popular press (Figure 2) or colourful infographics that appeal to social media, such as Facebook or Twitter, as well as practice websites and waiting room displays (Figure 3).

Increasing acceptance of the important roles of these wider outlets for scientific discovery should increase the impact from clinical research.