KC Breed Health Coordinator Conference 2012
Post date: Oct 02, 2012 7:50:29 PM
You can also view the short report here.
BREED CO-ORDINATORS SYMPOSIUM - STONELEIGH 13 SEPTEMBER 2012 by Roger Sainsubury BVM&S, MRCVS
After an introduction by Professor Steve Dene , KC Chairman and Border Terrier Breed Health Co-ordinator, in which he emphasized the need for ‘best practice’ to be shared, Ian Seath gave an overview of the new BHC tookits. the intention being that these should be available for the various areas of the BHC's activities.
BHC tookits
Two of these are currently available (and are now available on line):
Health Surveys
Guide to Health Improvement Strategy
The aim of these is to speed up the rate of improvement of the breed by means of a planned health strategy.
There is a need to be aware of what is being said, particularly on the web, about the health of a breed. Data on health needs to be collected so that this can be used to generate an initial baseline and eventually demonstrate improvements. This can then be used to engage with breeders and owners to inform them of the facts. Eventually, the breed website should be the main source of information on the actual situation in the breed.
Breed Health Websites
Simon Webb, Senior Web Developer then gave an outline of what is required for a breed website. He stressed that help was also available from the KC.
When designing a website you need to understand your audience. What are they looking for? What will they understand?
People don’t read the whole page; they scan for the bits relevant to them, then click the first helpful looking link. Pages should be designed with this in mind to enable people to find what they need.
It should be remembered
that content is king
there should be consistency with words in the text
it should be concise – write it once, then cut it in half
paragraphs should be no more than 3 sentences
people love bullet points – use them
there should be a logical heading hierarchy
the page layout should be simple – no busy backgrounds or flashing text.
We were given guidelines to Building a Website – this will be the third Toolkit. It is currently a draft, they need feedback so that the finished product can be produced.
He finished by saying that, with websites, less is more, it should always be consistent and remember that not everyone thinks the same.
Health Improvement – the French Bulldog
Penny Rankine-Parsons, French Bulldog BHC, explained their approach to health improvement in their breed. Health surveys by their breed club and the KC had identified health issues as not being simple genetic problems but they have developed from the way these dogs are constructed. These tend to be polygenic and therefore difficult to deal with (unlike a single gene mutation).
Also, registrations in this breed have increased dramatically in the last few years and this highlighted the need to deal with maintaining the health of the breed. Also, in 2009 the Breed Standard was changed.
They looked at the approach taken by other breed clubs and developed a list of priorities. They favoured a ‘carrot’ rather than a ‘stick’ approach. They identified a need to include everyone involved, including ‘volume breeders’. Peer pressure was thought to be the best way to encourage breeders and owners to take part in the scheme that they developed. Screening tests should be non-invasive, inexpensive, available and achievable without anaesthetic (problems with brachycephalic dogs).
The scheme had three levels, bronze – with fairly simple conditions to encourage entry to the scheme - then silver and gold, with increasing test requirements.
Forms were sent out for this, and these were correlated with the dogs, identified by microchip or tattoo, that were joining. After 6 months these were chased up if they hadn’t been returned. The return rate was quite high, and most of those that had not come back were still being processed.
They are pleased with progress so far and feel that peer pressure is now encouraging new entries to the scheme.
Eye Scheme Examinations
Professor Sheila Crispin, who has been carrying out BVA/KC eye scheme examinations for many years, pointed out that these used to be mainly for PRA.
There are a number of other conditions that should be included though. Schedule A covers inherited conditions and Schedule B covers other eye problems. Distichiasis, entropion and ectropion are quite common. Some of these conditions have implications for the whole litter - Collie Eye Anomaly, for instance, where one positive means that the rest of the litter may be carriers. Abnormal drainage angle conditions – where it is quite difficult to decide a prognosis – can eventually lead to glaucoma.
These conditions can lead to welfare problems for the dog because of blindness and/or pain. There is still a need, therefore, to carry out clinical eye examinations and the Eye Scheme form has been updated to include more detail on these other conditions.
Inbreeding and Outcrossing
Dr Tom Lewis is a Quantitative Geneticist at the AHT who deals with population genetics and genetic diversity. He said that inbreeding is a measurement of how genetically related individuals are. The more similar traits they have, the more closely they are likely to be related.
He pointed out that a degree of inbreeding is difficult to avoid and all individuals in a species are inbred to some extent. Highly inbred lines tend to die out, but artificial selection tends to preserve these lines, an example being the Chillingham cattle. These cattle have been genetically isolated for hundreds of years and genetically they are all almost the same. They suffer from inbreeding depression – a reduction of fertility – as did Charles ll of Spain, who had physical and mental problems. His lack of children led to the War of the Spanish Succession.
The problem is that a change in one location in DNA may lead to the protein being produced by the gene this DNA is part of being the wrong shape. This may have a reduction in the function of this protein. As there are two copies of each gene, the other gene will produce normal protein and this may, therefore not be a problem. With inbreeding, though, the chance of both copies of the DNA, and hence the protein, being abnormal are increased, and this could have serious implications for the animal.
All animals carry some defective genes. Each human has about 250, so this is a potential problem for all of us.
A measurement of inbreeding is the Coefficient of Inbreeding (CoI). This measures the probability of both copies of a gene being the same. Breeding siblings give a coefficient of 25%, half siblings 12.5%, first cousins 6.25%.
Cesky Terriers have an average CoI of 17.1% and Bearded Collies 15.3%.
These figures can be found in the Mateselect pages in the KC’s website.
The Rate of Inbreeding is important. A rapid increase is bad and may lead to problems for the breed, even if the CoI appears to be OK. This could happen because many breeders use one popular sire. This can lead to a high CoI in one part of the population even if the average for the breed is low. Monitoring the use of sires and perhaps limiting the use of popular sires would prevent this.
The Effective Population Size is a measure of the genetic diversity of a breed – a breed with a high effective population size would have a large variety of different gene combinations – the opposite of the Chillingham cattle where all the animals have almost the same DNA.
Increasing the breed diversity can be done by outcrossing or importing – bearing in mind the pedigree of the imports, who must not be from the same original recent gene pool. Care must be taken, of course, that the import doesn’t become a popular sire, thus negating the object of the exercise.
Outcrossing may be needed to increase the genetic diversity, but also to introduce a trait or characteristic. This will give ‘hybrid vigour’ – but only in the puppies resulting from the initial outcross.
DNA Tests – how to spot a good one
Dr Cathryn Mellersh said that there are large numbers of new DNA tests being introduced worldwide. These are tests for DNA associated with a particular trait (usually a disease, but may be coat colour, length etc.). Currently, these are mainly simple Mendelian inheritance traits where the mutation causing the disease is in a single recessive gene.
An example is Hereditary Cataract where
The DNA should be -c-c-c-c-c-c-c-c-c-c-
But is -c-c-c-c-c-c-c-c-c-c-c- with 1 extra c
Mutations may be small (maybe only 1 base pair, as above) or large (thousands of base pairs), and they may be caused by
Insertion (extra DNA – as above)
Deletion (DNA missed out)
Or Substitution (DNA replaced with different DNA)
Tests can identify these genetic differences from the normal. The test is useful if the genotype predicts the phenotype – i.e. if the test is positive the dog will have the disease.
New ‘Risk Factor’ tests are being introduced. Most genetic disease is complex – may be caused by more than one gene or gene abnormality, plus environmental factors, and these tests predict the probability of the animal having the disease. Care needs to be taken to assess how good or useful these tests are. We need to consider:
Has the mutation been associated with the disease in your breed?
How common is the mutation?
What is the mode of inheritance?
What is the frequency of the mutation?
Is there a need to test?
Is the test simple or complex?
Will it tell us, or just predict a probability?
Has the lab got a good reputation for accuracy?
Were they involved in the research that found the gene?
Has the research on the gene been peer reviewed?
In all cases, control of genetic disease has to balance the needs of the breeder which are to eliminate the disease, with the needs of the breed – to reduce the gene frequency and also to maintain the genetic diversity.
So, the breeder wants the next litter to be healthy.
The breed needs to retain its diversity.
There is a need, therefore, to eliminate the gene, but slowly and carefully.
Advice should be customised for the condition – whether a test is needed, and advice about breeding from carriers etc.
The frequency of the gene in the population is an important factor in decisions as to the action to take, but care is needed initially as research samples are biased to diseased animals and their relatives.
If the mutation frequency is 2% then the probability of being affected is 0.02 x 0.02 (i.e. a puppy gets the gene from both parents), which is 0.0004, or 4 in 10,000 dogs.
If the gene frequency is greater than 0.01 (or 1 in 100 dogs) then they recommend breeding from carriers. The reason for this is that the disease mutation is not the only mutation the dog has (human >50 mutations, dog similar) and breeding only from clear dogs will increase the inbreeding coefficient. This may lead to other serious genetic problems in the breed, which would be highly undesirable.