By Club Health Coordinator Helen Geddes
The Club Committee has been concerned by the number of apparently incomplete health tested pups that have been bred in the past few years, and also wanted to keep abreast of the multiplicity of DNA tests available for Tollers.
This article is a collection of smaller themes that have cropped up over the past few months but go under the heading of “Beware Puppy Buyers” and “Are You Up To Speed As A Breeder?“. I have tried to indicate where I am expressing a personal opinion, which is inevitable when covering topics such as the avoidance of early death or illness in our breed.
Some of the genetic tests are now being offered by several labs mainly in the USA and European countries at widely varying prices. The Kennel Club does not recognise all these labs and does not get automatically notified of the results so it requires owners or breeders to submit the results to them for inclusion in the health registers. Some results it will not accept anyway.
Our club suggests that puppy buyers need to be sure that at least one parent is genetically clear for recessive diseases. For the pup to become ill it needs to a copy of the gene from each of its parents. “Genetically clear” means that the parent dog does not have the mutated gene.
PRA , ie earlier onset blindness, normally displaying symptoms at 5 to 6 years, but can be as earlier as 3 years. PRA – affected and blind Tollers have been born in the UK within the last 10 years despite the genetic tests having existed for close on 20 years!
DE or DEN, is a disease where the brain is gradually destroyed. The Toller becomes increasingly distressed, noise sensitive and has coordination problems and possibly epileptic like seizures. As the disease progresses they may become aggressive. Symptoms become apparent from a few weeks old to one to two years. Most sufferers are put out of their misery at 3 to 6 years.
There were several Toller litters born in 2017 from apparently untested parents and also where one parent was known to be, or at risk of being, a carrier. The worldwide stats suggest 12 % as carriers and the declared UK carriers are similar with a ten to one ratio between declared clears & declared carriers. The test is only offered by VGL, Davis University in USA, but costs about £45-50. It has recently been added as a “required test” under the assured breeder scheme with limited powers of enforcement/ assurance and test results are automatically reported in the KC records.
BE AWARE – MAKE SURE THAT AT LEAST ONE PARENT HAS BEEN TESTED CLEAR.
JADD, is another distressing disease of young Tollers that is cheaply tested for and avoided. This is a severely life limiting illness with an average life expectancy of less than 23 months. The genetics are statistically complicated in that a quarter of dogs carrying two copies of the mutant genes do not get sick, but the protective mechanism is not necessarily handed on to their offspring!
The DNA is now performed by VGL Davis under licence from (Orthopaedic Foundation for Animals) in the USA. Their overall statistics show 24% of the tollers tested were carriers, and 75% were clears. If a Toller shows clinical symptoms their DNA samples can be submitted for free determination to the genetic research lab.
We have carriers in the UK population; 18 carriers are declared to the NSDTR Club of UK Breed Browser and 268 have been declared clear. There have been no reports of deaths from JADD to our club since the test was introduced in 2012, there were 3 cases reported in the 18 months prior to the introduction of the test.
For around £50 why would this test not be used to
ENSURE THAT AT LEAST ONE PARENT HAS BEEN TESTED CLEAR.
DM. This is one of the tests included in the KC health test scheme. It is painless and is one of the causes of hind quarter paralysis in elderly dogs. Symptoms may become obvious any time after 7 years of age and typically once diagnosed the dogs are put to sleep about 2 years later due to DM. There are around 15% carriers in the worldwide toller population, and it is present in UK Tollers. The test is one of the cheaper ones and is offered at several labs, so given all the costs of a litter why would a breeder not test at least one of the parents and ensure that the litter will avoid any genetically affected pups?
CEA, is a malformation of the eye and is observable in puppies. The gene is carried by tollers at about 20% of the population. Very few Tollers are reported as being clinically or genetically affected, despite a quarter of tested dogs reported as carriers. As this is a patented test OptiGen have a monopoly and set a high price test at £168 with consequent murmurings amongst some breeders about the value of the test, especially as other testable diseases are potentially more distressing. The same lab offer their own version of the test at £48. Potential puppy buyers need to watch out and make their risk assessment if this test continues to drop out of favour, and get copies of the health test reports from the breeders or go on-line to a breed browser to check out before they commit to buy a pup.
CP1 & CPLS genetic mutations cause around 80% of cleft palette in Tollers (the carrier rate is 15% and 13 % respectively). The syndactyly bit is that the dogs carrying 2 copies of the mutation may also have toes fused together. I do wonder if this is an extreme version of the webbed feet our water-loving ginger dogs should have.
This is often seen as a breeder problem and is unlikely to cause distress to puppy buyers as pups born with cleft palette struggle to suckle and are often put to sleep in the first few days of life. Unlike the CEA above these DNA tests are relatively low cost (total for 2 test less than £100), especially if the lost revenue from one or two puppy sales in a litter is taken into account.
Puppy buyers maybe need to ask why would their chosen breeder not test for the causes of, and avoid 80% of cleft palette puppies?
Buff, Dilute gene, or D-locus is purely a coat colour issue. It is offered by many labs and costs between £27 & £60.
Dominant traits such as rear dew claws are inherited if only one parent carries the gene. Any dog carrying a dominant gene will display that trait in some degree (which may be very lightly affected to heavily expressed). A breeder can expect half the offspring of a dog with a single copy of a dominant gene will go on to inherit the trait/disease. There are very few tests available for dominant genes but recently one developed in the USA by a genetic researcher, who is also a Toller breeder, has come onto the market. It is a fairly low cost test and has been taken up by interested breeders; it is generating a good deal of discussion about how to manage the information to reduce the incidence of affected dogs whilst not losing a wide range of other beneficial genes. No doubt this will rumble on for quite a while.
CDDY is a test of one of the causes of dwarfism in dogs. The gene involved causes early hardening of the cartilage at the growth plates and vertebral discs of young Tollers. It is present in other breeds. It does not explain the “Queen Anne” legs where the front feet turn outwards.
The physical effects are that Tollers carrying 2 copies of the mutant gene will have much shortened legs than they would have had all other, and Toller’s with just a single copy of the mutated gene will have somewhat shorter legs. Normal dogs will not have leg length shortened by this specific gene, but there are other factors that contribute to leg length so not all the variability in Toller height is explained by this mechanism. This is an example of semi-dominance.
The other disease associated with this mutation and also tied into the cartilage calcification is with vertebral disc disease, IVDD. One copy of the mutation leaves a Toller much more at risk of getting disc type back problems. It is not the only cause of these problems, but is the inherited one. Being a geek I have been tracking (working with two or three others in Europe and north America) dwarfism, genetic status which can be further deduced from test results of parents or progeny, and incidence of back problems and disc disease. The table below shows the results to date, but needs to be read with a “health warning” that this is based on voluntary declarations of back issue/disc problems in Toller’s made by their owners and/or breeders in the public domain and is likely to be an under reporting.
|BACK PROBLEMS||POPULATION STATS|
|GENES||NUMBER||NUMBER||%||% WITH 1 OR 2|
COPIES OF CDDY
|%||WITH 1 OR MORE
COPIES OF CDDY
|CDDY / CDDY||34||7||20.6%||8.0%||7.5%||52.4%|
Note: “back problems” is any comment re stiffness, hydrotherapy as well as diagnosed disc disease
In summary worldwide Toller’s are likely to have a 4-5% likelihood of having some form of back problems during their lifetime. If their genetic profile is wild type (as in wolves) with no copy of the CDDY gene this is around a 1% likelihood of back problems and disc disease, rising to 6 % for a single copy of the dominant gene and 21% for the double dose. As this is based on over 400 dogs it is getting to be statistically sound. However it is based on i) any type of back issue and not specifically disc disease; and ii) on voluntary reporting by predominantly breeders with a natural bias to under reporting this issues.
It is up to puppy buyers to inform themselves and decide how important this is to them. My personal opinion is to avoid matings that might produce double copies, given that a fifth of pups may go to develop back problems. And I think it is logical to maintain genetic diversity but through time try to reduce this gene if we do see this early scenario does represent the reality within our breed; I would not exclude matings that might produce pups carrying a single copy of the gene. It goes without saying that we are interested in reports of back problems and specifically disc disease, or of Toller’s that have no back problems whatsoever.
KC Assured Breeder Scheme
Having worked professionally in certifying Quality, Health and Safety and Environmental Management Systems I do have a degree of scepticism about such schemes. The title lulls us into a sense of expert knows best and this has to be better than puppy farming! Well yes it does, and is better than no scheme at all …BUT the devil is in the details.
Puppy buyers beware! Look at the words as there are very few sanctions in the scheme.
Both dogs have to be:-
If these are not in place the KC may not register the litter of an assured breeder. There have been cases of assured breeders having litters refused for registration, and nothing to stop a breeder resigning from the scheme to get a litter registered!
It is recommended that:-
You might be surprised to realise there are no sanctions associated with these latter recommendations, nor do any of these conditions (requirements & recommendations) apply to stud dogs owned by assured breeders.
In the world of professional standards this is a very low level of customer assurance with very light level of enforcement.
There are some very good breeders have joined the scheme because they feel it is better than nothing and a start. I do agree with them. However I hear from puppy buyers who feel it gives a guarantee of puppy health and breeding quality. Beware and inform yourself and make your own mind up before committing to your adorable bundle of ginger fluff.
BVA/KC Hip scoring: https://www.bva.co.uk/Canine-Health-Schemes/Hip-Scheme/
prcd-PRA – Progressive rod cone degeneration – progressive Retinal Atrophy: http://www.optigen.com/opt9_test_prcd_pra.html
CEA/CH – Collie Eye Anomaly/Choroidal Hypoplasia: http://www.optigen.com/opt9_test_cea_ch.html
DE -Degenerative Encephalopathy: https://www.ofa.org/diseases/dna-tested-diseases/degenerative-encephalopathy
DM – Degenerative Myelopathy: http://www.laboklin.co.uk/laboklin/showGeneticTest.jsp?testID=8158D
BVA/KC annual eye testing: https://www.bva.co.uk/Canine-Health-Schemes/Eye-Scheme/
BVA/KC Elbow scoring: https://www.bva.co.uk/Canine-Health-Schemes/Elbow-Scheme/
JADD – Juvenile Addison’s Disease: https://www.vgl.ucdavis.edu/services/dog/NSDTRTests.php#JADD
CLPS – Cleft Lip/Palate and Syndactyly: https://www.vgl.ucdavis.edu/services/dog/NSDTRTests.php#CLPS
CP1 – Cleft Palate: https://www.vgl.ucdavis.edu/services/dog/NSDTRTests.php#CP1
CDDY – Chondrodystrophy: https://www.vgl.ucdavis.edu/services/dog/NSDTRTests.php#CDDY
Buff – Dilute: https://www.vgl.ucdavis.edu/services/dog/dilute.php