Epigenetics. Epi = on top of; genetics = that class you barely passed in school. In short, the term describes recently updated concepts that profoundly change the way we understand heredity and health. Dramatically improved technology in the last couple of decades has allowed scientists to gain fresh insight into the way cellular DNA functions. Without a doubt
—this is way beyond the X’s and Y’s of your high school pea plant crosses.
Maybe you remember (or maybe not) learning many years ago that one parent has a set of genes that mixes during reproductive processes with the other parent’s genes. This results in an offspring with a certain mathematical chance of carrying and expressing particular characteristics of each parent. For instance, the pups of two Labrador Retrievers might be different colors, depending on the parents’ color, but no one would expect to see a poodle in the mix.
What epigenetics tells us, however, is that many more important factors aren’t quite so etched in stone. We now know that there are mechanisms by which parts of the DNA molecule can be turned on or off in response to environmental and nutritional influences. This means that the conditions experienced by the parents during the time before conception has a significant influence on the health, behavior and overall well-being of the offspring.
One of the most primal imperatives of any animal is to ensure the successful propagation of its species. Epigenetics gives flexibility to the genetic code, thus offering the best chance for the survival of an animal’s offspring. Take, for example, a wild animal that experienced a succession of exceptionally dry summers with less to eat. The animal’s offspring would be born with metabolic changes mediated by chemical “switches” on the parent’s DNA, allowing it to better survive such harsh conditions. It has been speculated that increased levels of type 2 diabetes in some human populations in Europe may be due to epigenetic changes from centuries ago, where higher blood sugar levels allowed individuals to survive and reproduce during long periods of famine.
In a recent experiment, rats that were genetically inclined to obesity were divided into two groups. One group was fed a conventional rat diet, and the other group was fed a diet with supplements known to alter certain chemical tags affecting DNA functionality. The conventionally fed rodents gave birth to rats that became obese as expected, but the nutritionally supplemented group had offspring that never became overweight. Amazingly, the diet of the adult rats affected the body weight tendencies of their offspring. In another experiment, the adverse effects of emotional stress on breeding rats was shown to result in offspring that were more anxious and less social than normal. When these offspring were bred, their babies were also more fearful than normal rats. This suggests that the effects of extreme stress, as well as nutritional factors, can be passed down from generation to generation.
Our new understanding of the adaptability of DNA isn’t confined to heredity alone. The double-helix-shaped molecule inside every living cell is central to maintaining life itself. Human health matters aside, what this means in a very practical sense to health and well-being of the animals in our care is this: what we feed our pets, what pesticides or toxins we expose them to, what emotional stresses they experience… all can profoundly affect the most basic of cellular functions that tip the balance between health and disease.
The newly discovered concepts of epigenetics can give us comfort as pet owners. To know that just because a particular breed of dog or cat has a genetic tendency to develop a certain disease, doesn’t mean that that it will actually occur. A multitude of tests are now available for a wide variety of diseases that have a genetic component in both dogs and cats. While these tests may be of value in some situations, it is overall more important to realize that disease is never completely predetermined, and that a proactive approach to your pet’s care can make a profound difference. A nutritious diet, good exercise, an emotionally supportive living situation and avoiding exposure to toxins and unnecessary vaccines can all support health at the most basic cellular level.
Dr. Judkins is the owner of Animalkind Holistic Veterinary Clinic in Jacksonville
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