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Why Are Random Source Dogs and Cats Needed?
Animal models of disease offer an important means towards finding cures for many diseases. A disease model should be an animal species with biological features that make it susceptible to a condition that resembles the disease being studied. Dogs and cats have served as models of many diseases, but they have been particularly important to the study of cardiovascular, digestive, musculoskeletal, and neurological diseases. They also provide good models for several kinds of cancer, including lymphoma and breast cancer. In addition, dogs and cats are essential for veterinary research.
The vast majority of research animals—perhaps upwards of 95%—are specially-bred mice and rats. Dogs and cats combined represent a fraction of 1%. About two-thirds of these dogs and cats are specially bred for research. The rest are non-purpose bred, or “random source,” animals, also known as “out bred” or mongrel animals.
Class “A” dealers, or breeders, sell dogs and cats that are young and come from a limited genetic stock. Factors such as age and inbreeding are important considerations in designing research models. The characteristics that are typical of purpose-bred dogs and cats are ideally suited for some kinds of research, but not for others. For instance, many cardiovascular, digestive, and musculoskeletal diseases affect humans as they age. Since purpose-bred animals are young, they may not make good research models for some of these conditions. Genetic inbreeding, which is the other hallmark of purpose-bred animals, is a desirable trait for some studies, but it can also be an undesirable one because inbreeding can produce shared traits that bias the research.
By contrast, non-purpose bred dogs and cats come from genetically diverse backgrounds and represent a wide spectrum of ages. Although they comprise a minuscule fraction of animals in medical research, non-purpose dogs and cats nonetheless play a significant role.
- Non-purpose bred animals are important in cardiovascular research and surgical training because their greater anatomical variation parallels that of humans better than inbred animals. Virtually all drugs, devices, and surgeries for heart disease were developed or tested at some point in random source dogs.
- Non-purpose bred cats and dogs are the most suitable models for the study of type 2 diabetes and insulin resistance. These conditions, which occur naturally as humans age, also occur in aging dogs and cats.
- Their physiological similarities to humans make non-purpose bred dogs and cats valued for digestive disease research including colitis, inflammatory bowel disease, gastro-esophageal reflux, swallowing disorders, and nausea associated with cancer treatments.
- Older and genetically diverse dogs and cats are needed to study muscular dystrophy, and the decline in skeletal strength associated with aging.
- Cats that have developed Feline Immunodeficiency Virus (FIV) naturally (as opposed to artificially induced disease of purpose-bred cats) are valuable for both veterinary and medical research into retroviruses.
About 3–5 million unwanted dogs and cats each year are euthanized by pounds and shelters. Fewer than one percent of these are needed each year for potentially life-saving medical research. Because many states and localities prohibit the sale of pound animals for research, for a growing number of research institutions, USDA-licensed Class “B” dealers are the last remaining source for non-purpose bred dogs and cats. Without these animals, important research will be stymied.