Epigenetics

Breeding animals is both art and science; if one ignores the art dimension, one robs oneself of much of the enjoyment of creativity. Ignoring the science is a ticket to a Fool’s Paradise. Remember the ad slogan “It’s not nice to fool Mother Nature”? If you want to be a dog breeder for the long haul, and leave your breed in better genetic shape than when you began breeding, you need to pay attention to advances in scientific knowledge

One of the most important recent advances in the understanding of inheritance is the field of epigenetics, the study of the variable expression of genes. Not every gene is “turned on” in every individual or at all times in the life of an individual, and genes turned on or off may be passed to o£fspring in that same mode.

Genes interact with environmental forces, not the least of which are nutrients absorbed during gestation and growth, and the microbes that live in an individual. The current scientific literature is replete with research that demonstrates that manipulating exposure to nutrients and microbes can delay or prevent the onset of disease in genetically susceptible individuals, as well as trigger onset. One recent study (Journal of Pediatrics, May 6, 2013) revealed that children of parents who sucked on their children’s dropped pacifiers to “clean” them were less likely to suffer from allergies and eczema than children whose parents did not. (See, proof positive that “Mom’s spit” can cure anything!) The researchers were quick to point out that this one behavior might have been a general indicator of attitude toward cleanliness; much other research is implicating too-rigid standards of hygiene with inappropriate reactivity of the immune system.

Be grateful for each advance that provides tests for deleterious genes; these tests are a tremendous boost to the gene pool, allowing for the breeding of carriers without risk of producing affected pups. However, be aware that there are far more genes that are under the influence of epigenetic forces. Substances in the environment, especially plastics and pesticides, have been shown to influence hormones, which can then affect fertility, behavior, development of cancer, and who knows what else. An environmental insult may “turn on” a gene in an individual (or across a breed where most individuals have the same genes – for example, cancer-prone breeds) where another dog exposed to the same lawn chemicals, kibble dog food contaminant, and so on will remain unscathed.

Breeders must be ready to do the ruthless culling (and by that I simply mean not allowing a dog to breed on) that is necessary to prevent the dissemination of genes for defects throughout a breed. However, they must be extremely careful to also avoid eliminating dogs who may be exhibiting a trait that is triggered environmentally or developmentally.

It happened to me many years ago. I kept no offspring of one of the best hunting Lakelands I’ve ever owned because at the age of 18 months she developed what I later learned was hypocalcemic tetany. It took nearly two decades to figure out that the tetanic spasms that looked like motor seizures were due to diet – most dry dog foods are formulated so that the calcium is supplied in a form that can’t be readily assimilated by some dogs, primarily terrier breeds. When switched to a meat- and bone-based diet without the plant material that makes up so much of many dry dog foods, the condition does not recur. Interestingly, that dog holds the record for the longest life span of any Lakeland in a survey conducted by the parent club, living for 18 years and four months. I so regret not having any of her descendants, but I thought 1 was doing the right thing. So far I have heard of tetany in Wires, Welsh, and Borders. I am certain there are many more examples of such environmentally triggered disorders.

I recently talked to a breeder of another terrier breed that is prone to skin issues. She has spayed and neutered all her dogs because they suddenly all developed allergies, in spite of careful genetic selection of their background to avoid just that. Are the allergies due to sheer bad luck? Something in the environment? A failure in the development of the immune system? That is what makes us tear our hair (no pun intended) – over many issues that breeders deal with. First and foremost, we don’t want to risk selling a puppy to a pet owner that could potentially lead to a situation of suffering animal and owner.

My recommendation is twofold: Keep track of as much of the science that is emerging about epigenetics, and do your best to raise your dogs as naturally as possible. You might start with a book recently published: The Royal Treatment, by Barbara Royal, DVM. Dr. Royal is president of the American Holistic Veterinary Medical Association. Of particular interest is that before she became a veterinarian she worked with zoo animals, and she is keenly aware of the ways in which animals stay “wildly healthy.”

— Pat Rock, AKC Gazette Breed Columnist · hollybriar@widomaker.com

© AKC Gazette, August 2013 · Lakeland Terrier Breed Column · Reprinted with permission