TOLLER HEALTH

Compared to some breeds the Toller is fairly healthy. The Club recommends that the following tests are carried out on all Tollers before breeding

Members should submit breeding stock for a BVA/KC Annual Eye Examination and to the Optigen screening test for genetic identification of pcrd –PRA & CEA/CH prior to mating. Please note Optigen Tests only need to be done once in a dogs lifetime.

OptiGen Testing

Breeding Strategies for prcd-PRA & Collie Eye Anomaly CEA/CH Tests

PRA the table below highlights all the desirable breedings that include at least one Normal/Clear parent. All other breedings are at risk of producing Affected pups with an extremely high probability of developing prcd-PRA during their lifetime. However, all dogs can be bred safely. It isn't necessary - or even desirable - to remove dogs from the breeding population. But when choosing pups to retain as potential breeding stock, it is important to select for Normal/Clear dogs and select against Affected dogs.

Expected results for breeding strategies using the OptiGen tests
Parent 1 Status	Parent 2 Status
Parent 1 Status	Normal/Clear	Carrier	Affected
Normal/Clear	All = Normal/Clear	1/2 = Normal/Clear 1/2 = Carrier	All = Carrier
Carrier	1/2 = Normal/Clear 1/2 = Carrier	1/4 = Normal/Clear 1/2 = Carrier 1/4 = Affected	1/2 = Carrier 1/2 = Affected
Affected	All = Carrier	1/2 = Carrier 1/2 = Affected	All = Affected

CEA/CH has been determined to be an autosomal recessive trait, inherited in the same pattern as prcd-PRA. This means that if you breed 2 dogs together that carry the gene, 1 in 4 would be affected by the disease and 50% would carry the disease gene. Although the overall carrier rate among sampling has been estimated at this time to be approximately 5%, there are situations where the rate could easily climb much higher (25 to 50%). A possibility of higher carrier frequency exists within a line with affected or carriers already identified.

The OptiGen tests can be done reliably at any age – even in young pups, and the result will be the same at any age, and will be the same whenever it is repeated. These tests therefore only need to be carried out once during the dogs life time.

Unlike Optigen Testing, this examination should be done Annually throughout the dogs lifetime by a veterinary ophthalmologist recommended by the BVA/KC. They cover all eye conditions that can possibly affect dogs. Please Note: Unaffected for GPRA on this certificate means that the dog is clinically clear of prcd-PRA at the time of testing only.

Distichiasis Distichiasis is the abnormal growth of an eyelash or several extra eyelashes. This congenital disease affects the meibomian glands along the eyelid. In some dogs, the position of the eyelash has no effect on the dog and it is likely to go unnoticed. However, if the eyelash makes direct contact with the surface of the eye, the eye may suffer from microscopic scratches and irritation. Over time, these scratches can become infected and may predispose your dog into developing a corneal ulcer.

Distichiasis is also commonly associated with tearing of the eye, squinting or a painful eye, visible scratches or white spots on the surface of the eye as well as eyelid spasms. Dogs who are showing signs of distichiasis are usually taken to their veterinarian when an eye infection is suspected. Although these dogs respond well to treatment, the infections may recur and the offending eyelash may remain hidden under the eyelid. An ophthalmic examination is often needed to reveal the eyelash, although this examination may require sedation.

The permanent treatment of distichiasis requires the removal of the offending eyelash or eyelashes. Plucking the eyelash will only result in regrowth, so other methods should be considered. Cryosurgery, or the freezing of the lid margin, can be used to prevent hair regrowth as can other surgical procedures. The surgical procedure your veterinarian proposes will be determined by the number of eyelashes and the state of the lids themselves. In some severe cases, your veterinarian may refer you to a veterinary opthalamologist for treatment.

The recommendation is not to mate together two Tollers that have/had distichiasis.

Members should submit breeding stock to the BVA/KC Hip Dysplasia Scheme for scoring before breeding

Hip Dysplasia is a term which includes a number of specific developmental and other abnormalities involving the hip joint.

All radiographs submitted to the BVA/KC Hip Dysplasia Scheme are assessed by means of scoring. The hip score is the sum of the points awarded for each of nine radiographic features of both hip joints. The lower the score the less the degree of hip dysplasia present. The minimum (best) score for each hip is zero and the maximum (worst) is 53, giving a range for the total of 0 to 106. The average score of the breed, or the 'breed mean score', is calculated from all the scores recorded for a given breed and is shown alongside its range thereby giving a representation of the overall hip status of the breed. All breeders wishing to try to control HD should breed only from animals with hip scores well below the breed mean score. BMS for Tollers at present is 11.

The purpose of the Hip scheme is to reduce the incidence of the disease in dogs used for breeding. The minimum age of the dog at the time of radiography is 12 months; there is no upper age limit. Dogs may not be scored under the scheme more than once.

SRMA (Steroid Responsive Meningitis Arteritis) MUA (Meningoencephomyelitis of unknown aetiology)

The club accepts that there are auto immune mediated problems within the UK toller population and in conjunction with Robert Foale BSc BVetMed DSAM DipECVIM MRCVS and ECVIM Diplomat in Small Animal Medicine the club is doing all it can to identify the genetic and environmental factors. The current state of knowledge is that there are family tendencies with a probable environmental trigger, but we would stress that research is ongoing at present. Breeders should be willing to discuss this with any prospective purchasers.

After several enquires Re: Haplotype Testing the Club contacted Dr Jeff Sampson at the KC, he passed me on to Cathryn at the AHT, who gave the Club her official viewpoint on the matter of haplotype testing as it pertains to auto-immune disease. This is what we have already been told by other prominant geneticists and that is why at this present time the UK Club decided not to use this test until further details became available.

My understanding of the test is that it looks at the region of the canine genome called the Major Histcompatibillity Complex (MHC) and investigates whether the dog being tested has two different copies of the MHC region or two identical copies. Haplotype is just another word for 'version', so when I talk about copies or versions you could substitute the word haplotype instead. You can think of this simplistically as whether the dog has two copies of this region of DNA that are the 'same colour' or two copies that are different colours. Within a breed there will be a number of different coloured versions (haplotypes) of the MHC segregating. The DNA test won't give the results in terms of colours, it will give the different haplotypes different names or numbers, but I like to think of things as simply as possible and colours work for me!

The reasoning behind Genoscoper's test is that dogs are more likely to suffer from auto-immune diseases if they carry two copies of the MHC that are the same colour, and less likely if they have different coloured copies. So their advice is to find out what an individual dog has and choose a mate that has different coloured versions of the MHC. For example, if your dog has a green haplotype and a blue haplotype then mate it to a dog that has a red haplotype and a yellow haplotype, rather than a dog that has two green haplotypes.

This concept is fine, and makes sense. I do however have reservations about planning a breeding strategy on a single region of the genome, for several reasons. The main reason is that two dogs can be very closely related but, by chance, have quite different MHC haplotypes. For example, if a dog has red and blue haplotypes and is mated to a bitch with yellow & green haplotypes it is perfectly possible for puppies in the resulting litter not to share a haplotype at all. One puppy could inherit red from the sire and yellow from the bitch and another puppy could inherit blue from the dog and green from the bitch. Genoscoper's DNA test would suggest these two puppies would be ideal mates as they have completely different MHC haplotypes (red & yellow) and (blue and green) but in fact they are full siblings, are thus likely to share about half of all their DNA and would obviously not be ideal mates at all.

It is MUCH safer to base this type of analysis on much larger numbers of markers, that are dispersed over the entire genome, so that a bigger picture is obtained. My colleague, Sarah, is developing a system that uses pedigree information to optimise breeding strategies, and eventually I believe DNA analysis will be included. This is a much better way to choose mates than basing the decision on a single region of the genome.

Obviously DNA tests that assay for the presence or absence of a single mutation are only analysing a single position of the genome, but these mutations are usually 'causal' in that they always cause disease when they are present, or when two copies are present, whereas the MHC DNA test is a risk factor test - dogs with two identical copies of the MHC region are thought to be at increased risk of developing auto-immune disease, and that increase in risk might be quite modest.

BVA/KC scoring scheme for elbow dysplasia (ED) was launched in 1998. Dysplasia means abnormal development, and the degree of elbow dysplasia present is indicated by a grade assigned to each elbow on a scale of 0 to 3 (0 being the best and 3 being the most severe). Only the highest grade of the two elbows is taken as the elbow grade for that dog. The minimum age for elbow grading is one year, and each dog is only ever graded once under the scheme. Advice to breeders is wherever possible to use only those dogs with grades of 0 or 1 for breeding.

Find the Health Test Results for your dogs Sire/Dam by pressing the button below

TOLLER HEALTH

Members should submit breeding stock for a BVA/KC Annual Eye Examination and to the Optigen screening test for genetic identification of pcrd –PRA & CEA/CH prior to mating. Please note Optigen Tests only need to be done once in a dogs lifetime.

OptiGen Testing

Breeding Strategies for prcd-PRA & Collie Eye Anomaly CEA/CH Tests