Dr. Al Townshend
The reason one pet develops cancer and another pet does not is complex. There is no one answer to the question. It primarily involves the environment, diet, genetics, and how these three items interact with individual animals.
Previous articles have discussed the role that lifestyle, the environment and diet can play in causing cancer, and in helping to prevent the disease. It’s all about the choices we make for our lives and the lives of our pets.
When it comes to genetics, the choices involve understanding how heredity can increase the risk of a pet developing cancer and avoiding as many of those genetic risks as possible when selecting a pet.
It is essential to understand the terms used when discussing genetics and pets.
- Heredity is the passing on of physical or mental characteristics genetically from one generation to another.
- Genetics is the study of heredity and the variation of inherited traits.
- Genes are a unit of heredity which is transferred from a parent to offspring and determines some characteristic of the offspring.
The Right Genes
Selecting a pet with the right genes can play a significant role in lowering the risk of cancer.
Breed: Some breeds are known to have a higher incidence of certain cancers than other breeds. For example, Golden Retrievers have a greater risk of developing two types of cancer, lymphoma, and Hemangiosarcoma. Mast cell tumors are more common in the Boxer breed.
Make sure to check with the breed association websites for more information on specific breeds and their risk of cancer.
Family within the breed: It is also important to know that individual families within a breed can be more likely to develop cancer. An example again would be the Golden Retriever. Goldens in the US have a significant risk of developing cancer, and yet, in Great Britain, cancer in Golden Retrievers is very uncommon.
Discussing the history of cancer within a trusted breeder’s specific blood-lines is vital to be assured that cancer is not a common problem within their family of dogs
Mixed Breeds: Thanks to their mixed genes, mutts are less likely to have received a high dose of any particular breed’s genes. Because of this, many mixed breeds have a lower rate of health conditions, such as hip dysplasia, spinal diseases, knee problems, certain cancers, and heart disease, than their purebred counterparts.
Cats: Less breed-specific information exists on the cancer risk in cats. However, purebred cats are generally believed to be more susceptible to cancer than mixed-breeds. There is some evidence to suggest Persians, Bengals, and Siamese cats appear to suffer from cancer at increased rates.
In general, cats don’t seem to have as great a risk of cancer as there is in the general dog population.
Size: It seems that larger dogs and larger breeds have a higher incidence of cancer. The larger Greyhound, which is similar genetically to the much smaller Whippet, has a greater risk of bone cancer.
Color: Darker colored dogs seem to have a higher incidence of certain types of skin cancer, whereas white cats have an increased risk of the same cancers of the skin.
Trying to understand the genetic risk of cancer to reduce the overall risk becomes even more complicated when one considers how diet and the environment seem to interact with the pet’s genetic makeup.
The Interaction Between Risk Factors
Simply put, cancer is the uncontrolled growth of a normal cell that has mutated. Some genes affect the potential for cancer cells to develop.
As scientists have begun to unravel the genetic code of humans and many animals, we have only just started to understand how genes express themselves, and what factors besides the gene itself also affect how a specific gene is expressed. The interest in this interaction between a gene and other factors is just in its infancy. Still, it has sparked many questions about how those outside factors can either depress or activate how a gene is expressed.
The primary factors of interest by researches seem to be the environment and food. Two new disciplines, Epigenetics and Nutrigenomics, have grown to investigate these factors and how they can be used to slow or even prevent cancer in a pet that is at risk of the disease.
For example, when it comes to cancer, if a Golden Retriever has a gene for one of the common cancers seen in the breed, can we use the environment and food to depress the actual development of that cancer?
For now, feeding a protein-based, biologically appropriate, natural diet and providing a natural, safe environment seems to be the best way to reduce the risk of cancer, especially in those pets at greater risk.