HEELER HEALTH FACTS
I am just starting to give you heeler health facts, the right ones the swanndale web site is not a flashy site but one which has been hard work for many years.
We have always told anyone the truth about heeler health but when you are at the top in anything you will always get people that are envious of your success.
HEALTH UP DATES SOON.
1.Coat colours in small popolation in dog breeding.
2.Aggression in dogs.
10 Heart Murmur.
UP DATE FROM THE LABS AT THE ANIMAL HEALTH TRUST
IN TO THE D.N.A RESEARCH INTO P.L.L
From Cathryn Mellersh.
Thank you for your message about our Lancashire Heeler research. The work is well underway as we employed someone [ his name is Dave Withers ] back in september who works 25 houre per week soley on PLL project.
Unfortunately the nature of this type of research is that is increments - so although Dave is working very hard we dont have any
monumental announcement to make yet. He has been steadily examing markers from all over the canine genome [DNA ] to
see if any appear to be inherited in the same pattern as the disease- this would be an indication that the marker was located close to the gene that is causing PLL.
Analysing all the markers [ about 400 of them ] is a time - consuming chunk of work that Dave has nearly finished- once he has finished we will analyse the results carefully and hopefully that is the stage at which we will identify markers linked to the disease.
So although i cant tell you we have found the mutation [ i wish i could ] the work is all progressing in the right direction, [ and on
schedule ] so i am hopeful sometime in the new year we will have good news for you all.
I hope this will help.
Coat Colours and Small Populations In Dog Breeding
The main goal for any dog breeder would be to rear both physically and mentally viable and healthy dogs. With this in mind it is also of great interest to produce dog of different types and mental capabilities.
There are two main obstacles in the way when trying to reach the main goals of dog breeding. The first one is that some types are so physically extreme that they cannot possibly be combined with normal physical health. The second one is the temptation to standardize living creatures into artifacts, ie. being too similar.
Standardisation is easier to achieve if only a few animals are used as breeding animals THe reason is that there are fewer genes in a small group of animals and thus less "risk" of genetic variation amongst their progeny.
The problem combined with loss of genetic variation by use of few breeding animals is however that not only the genes one wishes to standardise will become similar, the entire gene system of the animals will loose diversity at the same time.
This inevitably causes standardisation (doubling) also of some deleterious genes with loss of viability as one of the main consequences.
There are some very simple and basic rules to apply if one wishes to avoid the negative consequences of too far reaching standardisation of the gene system of dogs, or of any other species.
The number of effectively breeding animals should always be kept above a critical level of about 100 individuals, with at least 25 males and 3-4 females per male. In such a small populations one should make efforts to allow most of the litters to contribute equally to the next generation of breeding animals.
It is important to realise that the number of male used for breeding is of great importance if genetic variation, and thus viability, is to be preserved in the stock. The effective size of the stock will never exceed about 4 times the number of males used, unless very special breeding plans are applied.
Thus strong efforts should be made within any breed to keep the number of actually breeding males well above this level and to make sure that all the males are used to approximately the same number of bitches.
Studies undertaken in sweden demonstrates very clearly that dog breeders normally are not aware of the often extremely narrow breeding base of their breeds and that very little joint planning is taking place on most breeds. The next figure shows the number of registered dogs per year in some of the breeds studied and their effective population sizes.
Effective populations size is defined as the number of dogs needed, both sexes equally represented, to produce that same amount of inbreeding per generation if randomly mated as one has found in the real population of breeding dogs.
It is of special interest to note the rather small differences in effective size between such a popular breed as the English Cocker Spaniel and the much less numerous Canadian Duck Tolling Retriever or even the Chinese Crested.
Thus, irrespective of the number of puppies registered per year the loss of genetic variation, or rate of inbreeding, is very similar independent of the number of dogs reared in different breeds. The picture is very similar for all breeds so far studied.
Only two breeds, the German Shepherd and the Finnish Hound, have effective populations sizes large enough to keep genetic variation on safe level for more than some few decades.
True inheritance of some special fur colour is one of the breeding goals in many dog breeds. It is normally easy to achieve a standardisation of coat colour since many colour variants have a fairly simple genetic background. Deviant fur colours, in comparison with breeds standards, should however be looked upon as minor problems compared to the risk of scattering about a lot of deleterious gene I a too small population.
Strong precautions should thus be taken to avoid that the breeding for specified colours reduces the number of available and acceptable breeding males. I a situation of conflict between the to goals, viable and healthy dogs or colour standardised dogs viability should always be the main goal amongst responsible dog breeders.
If there is a desire, as in the Lancashire Heeler, to reduce the frequency of other colours than pure black and tan, especially liver and tan and blue and tan, this can be rather easily done without to strong restrictions in the breeding program. The frequency of recessive phenotypes such as the liver (bb) or blue (dd) will be halved in each generation just by the simple measure of not breeding from such animals and avoiding the overuse of other males irrespective of their genotype.
The only way to actually raise the number of an unwanted recessive genes in a population is to mass produce progeny from some special male dog who carries the gene in question. If such overproduction is always avoided the general rule applies, affected dogs are halved in numbers each succeeding generation.
It is almost impossible ever to guarantee, with any breeding method to get totally rid of unwanted genes in a population. When such genes become very low in frequency the cost of finding them and selecting against them will be overwhelmingly large.
Thus they will normally have to stay there and will do no harm again unless some breeders start to overproduce puppies from some single breeding animal again.
The consequences of what has been said is that, to preserve the viability and health of a dog population in which one would like to change some characteristics by breeding, one should make changes slowly to avoid losses of valuable genes. Personally I cannot find coat colour such an important matter in breeding that it is worth to endanger the health of dogs to get rapid changes in colour frequencies.
In most cases I would actually recommend the breeders' societies to reconsider the value of colour standardisation, especially if their breed is less numerous and thus there might be large difficulties to keep the population on an acceptable effective sizes for breeding purposes.
I cannot resist to repeat the answer I once got from the well known geneticist and dog breeder, Dr Marca Burns. She had retired from office and was breeding English Cocker Spaniels on her small farm in the Lake District when I visited her and asked her why of all breeds she reared just Cocker Spaniels. Very compressed her answer was "In the UK all colours are permitted for Cocker Spaniels.
Thus every puppy born will be individually distinguishable from the date of birth. Thanks to that I know every dog as an individual from the first day of life. How do you distinguish at a distance between your Riesenschnauzer puppies which are all alike as if they were produced at a factory?"
Professor in Animal Breeding and Genetics.
Swedish University of Agricultural Sciences.