Updated: Sep 26, 2020
Compared to how much we are increasingly realizing we do not know, humans understand relatively little about the interplay of nurture (environment) and nature (genetics) in determining outcomes for puppies. However, research from the past few decades in the field of epigenetics has taught us that we do not need to wait for slow evolutionary processes to dramatically alter genetic outcomes in dogs. Collectively, these findings represent astronomically enhanced responsibility and opportunity for breeders.
A 2003 study illustrates this perhaps most impactfully. Consider the below two mice. They are the same species and the same age.
The mouse on the left is almost orange in color, is quite overweight, and actually is significantly more predisposed to cancer, obesity, and diabetes than the mouse on the right. What drives these differences? Genetics? Environment? In this case, there is a single variable of difference between these two mice. The mice are in fact genetic clones. They have the same genes, and have been raised the same way in the same exact environment. The only reason they look so different and have such widely varied outcomes in quality of life is what their mothers ate while pregnant. The mother of the mouse on the right was fed an enriched diet including folate, choline, vitamin B12, and other supplements. As a result, the mouse is leaner, better adapted phenotypically to its environment, and has enhanced longevity and health expectancy.(1)
How can clones turn out so differently? This occurs because of epigenetic alterations to what is actually expressed of their identical DNA. While we would expect evolution to slowly alter DNA across generations to produce the dramatic disparities between the mice above, it turns out that factors as varied as environment, experience (particularly early in life), and nutrition can have arguably the same effect. While the DNA itself is not changed, how that DNA is expressed can be dramatically altered in a single generation. As one of the study authors put it in a later interview: "Epigenetics is proving we have some responsibility for the integrity of our genome. Before, genes predetermined outcomes. Now everything we do—everything we eat or smoke—can affect our gene expression and that of future generations. Epigenetics introduces the concept of free will into our idea of genetics."(2) To put it simply, we are increasingly learning that breeding is so much more than pairing two ideal dogs: everything from how breeding stock are fed to the experiences their breeders provide them matters. A lot.
There are multiple studies in a variety of mammals with similarly shocking results as the above. For example, obese male mice on an enhanced fat diet produced pups that inherited their fathers' health problems: they were unable to produce sufficient insulin. In this case, methyl groups attached to the DNA in the males’ sperm were different due to their obesity, yet again modifying the activity of the DNA if not its actual sequence.(3)
In a way, what we do to and for our dogs is arguably as powerful as changing DNA itself. It is as if we can immediately affect evolutionary development.
Not just nutrition, but an animal's experiences also interact with its genetic code to impact critical factors such as capacity to handle stress. The quality and quantity of maternal care has been demonstrated in many mammals to be of paramount importance to their offspring's adult physiology. Methyl patterns in the brain cells of mice pups that are licked by their mothers vary significantly from those who are neglected by their mothers, and as a result the licked pups are more competent in the face of stress later in life. Specifically in dogs, maternal care appears to impact puppies' predispositions for social and physical engagement and abilities, and even traits and behaviors that most people perceive as "aggression".(4)
Critically, these changes can be passed down through multiple subsequent generations, effecting entire bloodlines ("transgenerational epigenetic effects").
Returning to the impact of nutrition, in humans, mice, and worms, for example, the experience of starvation or food abundance early in life seems to be encoded in DNA and passed through to subsequent generations, ostensibly to prepare them for the environment their ancestors encountered.(5) This has been observed in natural experiments (such as famine in human populations), as well as replicated multiple times in laboratory investigations. In a recent study in worms, transgenerational effects of famine lasted at least through the third generation.(6)
The list of startling research goes on an on in this relatively new and exciting field of epigenetics. Yet another study demonstrated that the offspring of mother rats living in enriched environments were better able to problem solve than offspring of rats that did not. In dogs, it's been demonstrated that supplementation of a mother dog's gut microflora using FOS, pro- and pre-biotics enhances immune system development and activity in her puppies.(7) Similarly, adequate provision of DHA (an omega-3 component lacking in most modern human and canine diets) impacts the "intelligence" and "trainability" of puppies.(8) Pictured here is supplementation for the diet of one of our currently pregnant dams in her first trimester. Sardines are an excellent source of highly bioavailable Omega-3 (DHA & EPA), although you will also see fish oil to achieve the necessary ideal daily value. Raw beef organ and muscle mix provides highly bioavailable sources of iron and zinc. Combined with the egg, this provides an ideal protein and amino acid source - the building blocks of canine bodies. Folic acid is supplemented, as well as antioxidant powder and pro/pre-biotic. This particular raw beef formulation is also blended with blueberries, spinach, apples, and carrots - all of which provide sources of trace vitamins and minerals in a maximized state of bioavailability for canines. (Keep in mind that pregnant females need balanced carbohydrate and calcium sources appropriate for their stage of pregnancy.)
In a past blog, we discussed factors that have a role to play in determining an individual dog's temperament. For example, in utero exposure to stress can create puppies that are literally born anxious. Similarly, the association of electric shock with stimuli can pass down fear of those stimuli to several successive generations (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3923835/). This landmark study rocked the animal behavior scientific community, and should be reviewed closely by breeders, trainers, and other dog professionals.
Besides being fascinating, this research indicates that how we produce and raise puppies - the nutrition of those puppies and their mothers, not only their own health and experiences but also those of their ancestors - greatly impacts their longevity, health, happiness, and behavioral and physical wellness. For prospective owners, this further proves that where you get your puppy matters. For breeders, it means that we have even greater power over our puppies than we expected - and all the concomitant responsibility that entails.
At Ca' Rigada, we believe breeders have an ethical obligation to maximize outcomes for puppies and their owners by going above and beyond ensuring the best genetic stock. One of the reasons we breed drahthaar is to take advantage of the health and performance testing required for generations by its breed authority. We combine this with commensurate emphasis on nutrition, experiences, exercise, health, and overall lifestyle that optimizes outcomes for our owners, our individual pups, and subsequent generations. While we will visit these in successive posts in more detail, we are pleased to discuss our methods in detail with our owners, and how you can continue to build upon your puppy's carefully crafted foundations to ensure your pup achieves his or her maximum potential.
(1) Waterland, R. A. and Jirtle, R. L. (2003), Transposable Elements: Targets for early nutritional effects on epigenetic gene regulation. Molecular Cellular Biology, 23: 5293-5300. http://web.as.uky.edu/Biology/faculty/cooper/Bio350-Spring%202020/folicAcid.pdf
(3) Fullston T, Ohlsson Teague EM, Palmer NO, DeBlasio MJ, Mitchell M, Corbett M, et al. (2013), Paternal obesity initiates metabolic disturbances in two generations of mice with incomplete penetrance to the F2 generation and alters the transcriptional profile of testis and sperm microRNA content. FASEB J. 27: 4226–4243. 10.1096/fj.12-224048. See also, Fullston, T., Ohlsson-Teague, E. M., Print, C. G., Sandeman, L. Y., & Lane, M. (2016), Sperm microRNA Content Is Altered in a Mouse Model of Male Obesity, but the Same Suite of microRNAs Are Not Altered in Offspring's Sperm. PloS one, 11(11), e0166076. https://doi.org/10.1371/journal.pone.0166076
(4) Lezama-García, K., Mariti, C., Mota-Rojas, D., Martínez-Burnes, J., Barrios-García, H., & Gazzano, A. (2019). Maternal behaviour in domestic dogs. International journal of veterinary science and medicine, 7:1, 20–30. https://doi.org/10.1080/23144599.2019.1641899 See also Foyer, P., Wilsson, E. & Jensen, P. (2016), Levels of maternal care in dogs affect adult offspring temperament. Scientific Reports 6: 19253. https://doi.org/10.1038/srep19253.
(5) Kaati G., Bygren L.O., Pembrey M., Sjöström M. (2007), Transgenerational response to nutrition, early life circumstances and longevity. European Journal of Human Genetics 15: 784-790. https://www.nature.com/articles/5201832/.
(6) Rechavi O, Houri-Ze'evi L, Anava S, et al. (2014), Starvation-induced transgenerational inheritance of small RNAs in C. elegans. Cell 158(2): 277-287. doi:10.1016/j.cell.2014.06.020. For a discussion in layman's terms, see https://www.medicaldaily.com/starvation-and-epigenetics-dna-can-hold-memory-starvation-three-generations-and-now-297054
(7) Adogony, V., Respondek, F., Biourge, V., Rudeaux, F., Delaval, J., Bind, J.‐L. and Salmon, H. (2007), Effects of dietary scFOS on immunoglobulins in colostrums and milk of bitches. Journal of Animal Physiology and Animal Nutrition, 91: 169-174. doi:10.1111/j.1439-0396.2007.00688.x
(8) Morse, N.L. (2012),Benefits of Docosahexaenoic Acid, Folic Acid, Vitamin D and Iodine on Foetal and Infant Brain Development and Function Following Maternal Supplementation during Pregnancy and Lactation. Nutrients 4: 799-840. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407995/