We know many diseases are caused by genetic mutations. Over 400 diseases have been recognized to be genetic in nature in the dog. Some of the conditions are caused by one gene’s action, but others such as osteoarthritis are influenced by the collective action of many genes.

Likewise, it is commonly recognized that nutrition has direct affect on health. Of the 50 or so specific nutrients essential to maintaining health in dogs, the deficiency of one or more can trigger disease. Some of the essential nutrients are capable of causing problems when they are present in excess as well, resulting in toxicity.

Apart from nutrition and genetics, environmental variables play a role in health and disease. Toxins, chemicals, parasites, viruses and bacteria all impact the maintenance of health in a dog or puppy. Stresses caused by climate, housing, breeding and management can open the way for opportunistic pathogens to take hold.

All of these influences interact to express cumulative affect. The easiest elements to control include housing, and therefore climate, management, exposure to chemicals, toxins and pathogens, and nutrition. As we learn more about genetics, knowledgeable breeders can directly impact disease prevalence within a breed. While it may be impossible to totally eliminate a disease from a breed, we can decrease the occurrence, the progression and the severity of many genetically caused diseases through nutrition.

To better understand this emerging science, let’s review some basic information about genetics, or the study of genes. The gene is the basic unit of inheritance from parents to offspring. Any given animal receives half of its genes from each parent. Each gene carries the information for the implementation of a single step in a biological process. Most processes are made up of more than one step, and are often very complicated.

Each gene is the master copy of an instruction manual on how to produce a specific protein, which will have a specific action. The master copy is replicated, much like making a photocopy, which is then used to dictate the production of the needed proteins. These proteins serve many different roles within the cell and communicating with other cells and organs.

The general rule is that many genes control the expression of a single trait, such as coat color. Some genes make different colored pigments in the coat, some genes act to suppress the expression of color by other genes, and yet others will dictate color patterns within individual hairs as well as over the entire body.

All animals have hundreds of thousands of genes. Any gene is vulnerable to mutation, resulting in a new version of itself. Sometimes that change results in the inability of the gene to function at all. Other changes may modify the action of the new version of the gene, but it still functions. Some changes appear not to affect the functionality of the gene at all.

Each version of a gene that directs a specific action is called an allele. An individual animal normally can carry only two alleles for any given gene, regardless of the number of allele versions available. It receives one allele from each parent. If the two alleles present are identical, it is referred to as homozygous. If the two alleles are different, it is called heterozygous.

In the heterozygous pairing, if one has a stronger expression or activity, it is said to be dominant. An allele that has a weaker expression, or does not express itself at all, is referred to as recessive. The only time an animal will express the weaker allele is if both alleles present are the same, or homozygous.

The pairs of alleles clump together with potentially hundreds of other allele pairs to make up a gene, and thousands of genes then clump together to create a chromosome. Dogs have 39 pairs of chromosomes. One pair of those chromosomes is dedicated to the sex of the animal, and all that entails, while the other 38 direct all the necessary chemical biological activities for life.

Genes direct the creation of proteins that act as enzymes and polypeptides, according to a specific template sequence of amino acids, which are the building blocks of proteins.

It has long been recognized that manipulation of nutrients, and therefore diets, can impact an animal’s physiologic activity. A good example of this is the situation of Type II diabetes in people, which can be controlled thru diet and exercise. It has been stated that disease occurs when the normal action of a gene malfunctions, even if that genetic activity is from a bacteria or virus. It is through the interaction of nutrients and genes that influence can be exerted to encourage the activity of so-called “good” genes and suppress the action of “bad” genes.

As more research is completed, we will increasingly understand why certain breeds have a higher incidence of certain diseases, and that information will illuminate ways in which we might treat and prevent those illnesses.