Truth In Advertising: Breeder Self‑Regulation
By John C. Cargill, MA, MBA, MS
Reprinted from Giant Steps © Vol. I 1990-91
Originally printed in Dog World © July 1009
When looking through the various dog magazine and your eye is caught by a publicity photo of a good‑looking dog‑presented well, scrubbed clean, alert and taking the points or BOB. What do you really see? Plastic wrapper‑that is all!
We know that wins are not all the same, though I do not know anyone who has turned down even a one pointer. Just what do you see when you look at the photograph? Probably, you see a nice‑looking animal. You learn of the breeder or owner (useful information). You may even learn something of the pedigree. Beyond that, usually, there is nothing, not even details of the “big win” depicted in the photograph. The essential information is lacking. Then, there may even be potentially misleading information.
If you do not own the animal in question, you are interested in it for one reason: breeding. You are considering breeding to it or to its progeny or siblings. You should have many questions. Most of us recognize there are health problems of major concern in many AKC‑recognized breeds. Putting it all in perspective, we have to recognize the AKC‑approved genetic pool is very limited and that we, as breeders, further restrict the gene pool by our breeding selection practices.
For example. given that the eye color is linked to some degree with coat color (much as eye color is linked to hair color in humans), restricting breeding to darker‑eyed animals in most breeds further reduces the size of the genetic pool. Similarly. other selections have further reduced the effective size of the genetic pool. In some breeds, such as the Akita, AKC has closed the stud book and actually refuses to register new animals brought in from Japan, the Akita's country of origin. Fortunately, the number of possible genetic combinations is still quite large. Large is a relative term; however, we have already started to see genetic problems in part attributable to a small gene pool. The old concept “line‑breed for type; out cross for hybrid vigor” applies. The problem now is how to out-cross. Virtually every dog of breeding quality registered under AKC is somewhat related to the other dogs available, and many of them are genetically deficient. This is a strong statement, but it is intended to make a point. The short-term impact of line/inbreeding is most felt in relatives within three generations; however, the long‑term impact must extend well beyond that to genetically transmitted health problems and some conformation faults, especially for recessive traits.
So what are some of the essential elements of missing information? First, a short list and discussion of each: Thyroid disease/imbalance, von Willebrand's disease (vWD), hip dysplasia and Progressive Retinal Atrophy (PRA) are probably the major elements that can be genetically screened with reasonable ease. (There is an argument to be made that screening for cardiomyopathy has become necessary in some breeds: however, that discussion is beyond the scope of this article.)
Thyroid disease‑Baseline levels of thyroid hormones are one of the premier breeding selection criteria because familial autoimmmune thyroid disease has become characteristic of many AKC breeds.(1‑7) Testing for thyroid function is essentially testing for hybrid vigor. Thyroid is to the body as clock speed is to a computer. As the clock cycle regulates the internal functions of a computer, thyroid levels regulate the operating of internal bodily functions of the dog (people, too). Whenever there is an irregular clock, system interfaces break down. Whenever there is a thyroid dysfunction, other system responses are affected.
For example, when thyroid levels are low, the immune system is depressed. Put another way, homeostasis, the body's dynamic equilibrium is threatened. Every system functioning correctly has a normal operating range or homeostasis There is a point estimate or mean (average) value in this range. The further away you get from this measure of central tendency, the closer you are to the edge of the range. Beyond the edge is instability and increased vulnerability to system collapse (entropy) or system runaway (eutrophication). Just as your automobile has a normal operating oil pressure range and a normal water temperature range, every higher-order vertebrate mammal has its own normal operating range for the various aspects of thyroid function.
We have been breeding disease resistant cattle for years, yet little attention has been paid to such a process in dogs. When the immune system is depressed one can stand by for a whole series of other diseases. With thyroiditis or hypothyroidism (the end stage of the thyroiditis process), it may not be advisable to give multi-valent (combination) vaccines, especially of the modified live type vaccines, because of the possibility of overly suppressing the immune system and leaving the animal susceptible to disease or of over‑stimulating the animal and producing an abnormal immune reaction. (8) Instead of causing the immune system to protect specifically against the infective agent, these vaccines may even induce immunologic disease. The jury is still out to some extent on the ability of a particular vaccine type to increase the specificity of the immune system response to a given threat. This goes for distemper, hepatitis, leptospirosis, parainfluenza, parvovirus and coronavirus. See the problem? When the thyroid level goes, so does protection against immunologic imbalance and disease. It get worse!
Von Willebrand's disease- If hypothyroidism and its associated problems are just a run‑of‑the‑mill time bomb, then von Willebrand's is an atomic version of the same. VWD is threatening to wipe out the show‑quality breeding stock in Dobermans. This is no exaggeration. It has been reported that more than 70 percent of Dobermans tested have reduced levels of von Willebrand factor and close to 20 percent are referred for abnormal bleeding. (11) Many breeds are not far behind. There is a link between vWD and thyroid imbalance levels. (1,8,11,12) In combination, vWD and thyroid imbalance constitute a formidable threat.
There are three vWD types. Type III is found only in Scottish Terriers, Chesapeake Bay Retrievers and possibly in Shetland Sheepdogs. Type II is found so far only in German Shorthaired Pointers. Type I vWD, the most common and the one of concern in this article, may be inherited or acquired. A common cause for acquired vWD is hypothyroidism (low thyroid function).(11,12)
If a puppy receives a carrier gene from each of its parents, it most likely will not live. Normally, it will be aborted or resorbed in the early phases of the pregnancy. Ever hear of lines with a high incidence rate of very small litters? Beware! You should consider that vWD or thyroid disease is present in a population of small litters. As with hypothyroidism, other diseases can affect the vWD carrier more severely. Yet, few breeders are testing for vWD and eliminating from their breeding program animals that test positive or borderline. If you still do not consider vWD a major threat, consider the following:
VWD mating types:
Normal x Carrier/heterozygote = 50 percent normal puppies; 50 percent carrier/heterozygote puppies.
Carrier/heterozygote x Carrier = 25 percent normal puppies; 25 percent homozygote puppies (dead or severely affected); 50 percent carrier/heterozygote puppies
It does not take much of a mathematician to figure out what could happen in just a few generations of show animals if testing is not done and carriers are not eliminated from breeding programs. In a worst‑case scenario, it might be possible to reconstruct a breed from genetically clean scrubs in backyards that were not affected. Test breeding, would be needed to determine clear stock. It would be along uphill battle coming back. Many parent breed clubs, as organizations, would not be able to survive. The dog fancy would have lost many, many years of work to stabilize the many AKC breeds. This holds true, of course, for thyroid problems. If you think this is far‑fetched, consider the long‑term test breeding program that was required to reduce the incidence rate of dwarfism in Alaskan Malamutes.
Most of us use antibiotics, various worm medications and flee and tick sprays and dips on a fairly routine basis. The majority of these are immuno‑suppressant That means that if your dog has a low thyroid level, he is more likely to get sick. Some of the commonly used drugs documented to cause immunologic or other reactions in susceptible dogs are: trimenthoprim‑sulfa antibiotics (Tribrissen™, Bactrim™, Septra™, TMZ™); phenylbutazone (Butazolidin™); nitrofurans (Furazone™, Furadantin™); phenobarbitol; diethylcarbamazine‑mxybendazute (Filaribits‑Plus™); and ivermectin (Heartgard‑30™).(7,9) Even praziquantel (Droncit™) can cause extensive swelling at the site of injection in some thyroid‑imbalanced animals. Virtually every flea and tick killer on the market contains an anti‑cholinesterase agent. Immune‑imbalanced animals can be affected by anti‑cholinesterase agents.
How do you tell if a flea or tick spray or shampoo contains an anti‑cholinesterase agent? It will usually have a statement that PAM‑2, 2-PAM Chloride or Atropine is antidotal. Military nerve gas agents (VX. GA, GB, GD) are no more than stiff concentrations of this class of pesticide. (10) Any toxin that must be eliminated by the liver can alter immune‑system responses. Therefore, an animal with a low thyroid level is further threatened by flea and tick pesticides, even at concentrations normally considered safe.
As reported by Dr. W. Jean Dodds (and many others), thyroid levels tend to be low in some 42 AKC breeds (1), with the very predictable result that immune‑system problems are more frequently noted. (1‑7) Yet I know of a number of Top 10 dogs in several breeds on thyroid treatment that have been used extensively for breeding. Folks, we are creating a time bomb. Some day it will go off and we will be scrambling to pick up the pieces
There have been those who suggest, even advocate, the breeding of thyroid‑deficient animals given that they perform well on thyroid treatment and are otherwise excellent specimens. This is not a gray area. We have an AKC‑restricted breeding pool and cannot afford to lose vigor. It is wrong. Genetics, stress, hormones and infective agents impact the immune system. Anything depressing the self‑compensating properties of the organism makes for a weaker animal. Note: Even giving thyroid replacement therapy is not always safe‑while T4 is very forgiving, T3 can be easily toxic! (11) In summary, 42 of the 54 AKC breeds known to have vWD are also predisposed to hypothyroidism and a host of related immune-mediated diseases.
Many researchers have written openly about the problem associated with hypothyroidism and vWD. Specifically recommended for ease of comprehension are those by Dr. W. Jean Dodds, the internationally recognized expert on the subject. Read and heed. The action you take may just save your beloved breed. If you do not have Dr. Dodds' work, your “dog” library is incomplete. It is well worth your time to obtain copies and to refer to them when considering various breedings. You do not have to be well‑versed in genetics, biology, immunology, etc., to understand and benefit from this body of academic literature. If you are not alarmed after doing some reading in this area, please note that recessive and incompletely dominant genes are the most difficult to eliminate in a breeding program. Then note that Type I vWD is incompletely dominant with variable penetrance.(13) Only conscientious selection for breeding will eliminate the problems we are encountering with increased frequency today. (14)
Hip dysplasia‑It is only in recent years that we have started to test for hip dysplasia. As with thyroid functions and vWD, hip dysplasia has a hereditary component. There are some breeders who would dispute this, who feel that it is solely the result of a nutritional problem, etc., but the preponderance of evidence and veterinary opinion speaks otherwise. There is a simple rule: Test for hip dvsplasia; send x‑rays to the Orthopedic Foundation for Animals for radiographic analysis and comparison against norms for the breed. In the United Kingdom, hip dysplasia is also recognized as a very serious problem and the rating system there is considered by some to be significantly stricter than the OFA Excellent, Good. Fair and Dysplastic rating scheme.
The British Veterinary Association/ Kennel Club new system, implemented in 1984. scores hips numerically from 0‑10, with a lesser score indicating a lesser degree of dysplasia.(15) A total score of 0‑4 (with no more than 3 for one hip), is equivalent to the old “Pass Certificate.” A score of 5‑8 (with no more than 6 for one hip) is equivalent to the old “Breeders Letter.” Dysplasia is a painful and crippling condition. There is no sense in giving it a bigger foothold on your breed than it already has.
Progressive Retinal Atrophy-Think blind. Think hereditary. Think about this trait being introduced to your line. As with the other testable problems above, it is easier to avoid introduction than to eliminate it once you have it. Remember the 50‑50 percent and 25‑25‑50 percent proportions from genetics? It is simple: Breed only to PRA‑clear animals. The Canine Eye Registration Foundation differs from OFA in that while OFA staff members actually conduct the radiographic studies, CERF only registers the opinions of board‑certified veterinary ophthalmologists.
One of the great characteristics of numerous AKC‑recognized breeds is that they have excellent eyesight. Let's keep good eyes wherever we can. Working dogs and gazehounds need good eyes. Jack‑of‑all‑trades dogs need good eyes. One word of caution: PRA and other eye diseases may not show up for many years. Different breed and different hoes within a given breed may exhibit different ages at time of onset of PRA.
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