“Best of Health” No. 6 published in Our Dogs today

Ian_and_PolaTackling complex diseases

In my last article I mentioned a couple of webinars that Aimee Llewellyn (Genetics and Health Information Manager at The Kennel Club) had presented on thewebinarvet.com.  I’ve now had a chance to watch the second webinar which is “Avoiding Inherited Diseases: tackling complex diseases”.

This was aimed at providing the veterinary professional with advice and guidance for their clients and explaining what resources are available for testing for complex diseases.  Aimee also explained the inheritance of complex diseases i.e. those which are multi-factorial (including genetic and environmental factors) and for which no simple DNA test exists.  Aimee said that complex conditions include those such as Heart Disease, Epilepsy and Hip Dysplasia.  The KC’s development of Estimated Breeding Value (EBV) tools was one of the major areas of discussion in this webinar.  EBVs estimate the genetic risk of complex diseases and area  more efficient way of estimating risk and breeding away from undesirable traits than by looking at individual dogs’ screening results alone

As with the first webinar (“Simple Genetic Diseases”), there are some excellent visuals to help people get to grips with the principles and practices of dealing with complex genetic conditions. For example, there’s a good explanation of why a puppy bred from two parents with low hip scores might end up with poor hips.

Currently the KC’s Mate Select website provides EBV information for 15 breeds.  These tools provide more flexibility for breeders to balance and prioritise different health considerations such as temperament, DNA test results, health screening results, genetic diversity and conformation.

An EBV can only be calculated for a breed if enough individual dogs across the breed have been scored. The KC says that EBVs will become available for more breeds when there are enough scores within the breed to make the calculations.

For those breeds where (lack of) genetic diversity is currently a challenge, Aimee talked about some of the options available.  These include:

 

  • Reducing the relatedness of sires and dams (use of the COI calculator within Mate Select is a key tool here)
  • Limiting the number of offspring from individual dogs; i.e. avoiding the Popular Sire Syndrome
  • Make use of all the available healthy stock in a breed with randomised selection of sires and dams
  • Inner-breed crossing, for example “working” and “show”lines
  • Make use of overseas bloodlines (assuming these don’t originate from the same stock)
  • Make smart outcrossing decisions (an example would be the LUA Dalmatians)

I can imagine some breeders having apoplectic fits at the thought of some of these, given that their whole breeding strategy for years has been the complete opposite.  Aimee talked through an example of the Otterhound to illustrate how focusing on resolving one particular condition (epilpesy) could actually make things worse for the breed by reducing genetic diversity. She ended by saying “sometimes you have to take really creative solutions into consideration”.

What’s your Breed Health Survey telling you?

I’ve had an interesting conversation with one of the Breed Health Coordinators who is just putting the finishing touches to the report from their recent Breed Health Survey.  I won’t name the breed as the results haven’t been published yet, but they’re not the first and they won’t be the last to find themselves in a similar situation.

For many breeds, their first survey may well be a fairly quick and simple one designed to achieve two main objectives: firstly, to get some quantitative data on what health issues there might be in the breed and secondly, to get owners used to the idea of supporting health surveys and seeing the benefits.  The KC’s Breed Health Survey Toolkit describes this as a “Level 1” survey.

The question is “what should the breed do if only a relatively small number of surveys were returned and the results don’t appear to show any major health issues?”  The answer (and more questions) lies in the raw data.

If the breed only has a small number of annual registrations, then that clearly impacts on how many dogs are likely to be reported on, irrespective of the enthusiasm or otherwise of people in the breed.  So, my first questions would be what are the annual registrations and what is the average life expectancy of the breed?  My breed, Dachshunds, has about 5000 registrations per year and they live, on average to 12.  That suggests there’s a UK population of around 60,000 KC Registered dogs.  Our 2012 Health Survey got a response of 1500 dogs which represents 2.5% of the population.  It doesn’t sound like a big proportion, but it was big enough to allow us to draw statistically valid conclusions, with known confidence intervals.

Performing the same calculation on the breed in question’s survey showed that they had probably achieved a response rate that equated to something like 10-15% of the KC Registered population, which then actually looks quite good.  That’s a reason to be pleased with their first survey.

Rather than dive into the detailed numbers of dogs with particular conditions, I then wanted to know what proportion of the dogs had reported conditions.  More good news: nearly half the responses were for dogs with no health problems reported at all.  Just under a third had reported one health condition, but nearly one third of those were Kennel Cough, which is clearly something that any dog of any breed might catch.  So, overall, 2 in 5 dogs had reported a health condition that the breed club might be interested in understanding more fully.

The breed club had (sensibly) used the same categories for recording health conditions as the 2004 KC survey so that opens up the possibility of making comparisons with ten years ago.

When I looked at the health category data I found that two-thirds of the reports were associated with just 5 categories.  Of those, the musculo-skeletal category was by far the most significant (probably not a surprise for this breed) and worthy of further analysis.  It’s then useful to look for patterns associated with factors such as age, sex and neuter status.  Half the musculo-skeletal reports were in dogs aged 7 or younger which might suggest some further investigation is needed to explore the contributory factors (genetic and lifestyle – remember Aimee Llewellyn’s webinar about complex diseases).

It’s usually also worth looking at the patterns being reported for the Cancer category. In this breed’s case, all the reports were in dogs over the age of 7 which probably mirrors the general canine population with many cancers being related to older age.

I was really pleased to receive an e-mail from the Breed Health Coordinator saying “you’ve made our apparently uninteresting data suddenly very interesting”.

Overall, this particular breed looked pretty healthy at the level of individual conditions, which is obviously good news.  The main issue I’d be looking to explore in any future survey is age of diagnosis. Here, they only had the age of the dog which might be quite different to the age of diagnosis of any condition it has.  It’s probably also worth gathering age/cause of death data.

I’ve written before about the value of the data being analysed and reported by the RVC’s VetCompass project. It’s getting to the point where this is a really valuable resource for breed clubs to refer to when they design and analyse their own health surveys.

A Health Survey is a key part of every breed’s Health Improvement Strategy and it’s perfectly valid to “start simple”.  Even the simplest survey (provided it’s well designed) should help provide a focus on what the breed needs to do next.  Every breed’s Health Strategy will be unique to that breed. There is no “one size fits all” solution.  A numerically small breed with few current health issues will need a totally different strategy to a breed with a large gene pool and multiple, complex conditions.

Mastiff and Molosser Breeder/Owner Day

The Bullmastiff Breed Council is holding a Molosser Breeder/Owner Day in conjunction with Nottingham University School of Veterinary Medicine and Science on Saturday the 29th November 2014, at the University.

This is a joint venture between the Bullmastiff Breed Council and the Vet School to run this specific seminar for owners and breeders of Bullmastiffs, Mastiffs, Neapolitan Mastiffs Dogues de Bordeaux and other Molosser breeds to look at some of the health related problems in these breeds.  The discussions of clinical problems raised by attendees will be gathered during the day and the most important ones will form the basis for future health improvement projects.

There’s a highly participative agenda which should make for an informative, but informal day at a cost of just £15.

For further information about the day please contact Mrs P. Jeans-Brown. Tel:0121 779 2692 or e-mail : Pamela@bourgueil.co.uk or billybrittle@aol.com

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