Several canine diseases begin in the epithelial cells, including a number of kinds of cancer. Research has shown that infection of epithelial cells plays a role in canine distemper, a frequently fatal viral infection. Epithelial tissue problems in a dog’s eyes can also cause vision problems, including blindness.
Epithelial cells make up epithelial tissue, which forms the lining of body cavities, covers bodily surfaces and forms glands in animals. Three types of epithelial tissue exists in the body: squamous, cuboidal and columnar. These types of tissue are distinguished by the shape of the cells. The epithelial cells are responsible for transporting materials inside the body, secreting materials and providing protection for the internal parts of the body from the outer environment. Because they are plentiful and found throughout the body, diseases affecting these cells usually cause serious health problems for dogs.
Canine cancer frequently involves epithelial tissue. For example, epitheliotropic T-cell lymphoma is a severe form of cancer that attacks the dog's own autoimmune cells and epithelial tissue. Even with treatment, this type of canine cancer usually causes death in less than two years. Another example is adenocarcinoma, a cancerous tumor that develops in epithelial tissue inside internal organs such as the stomach and the intestines. While treatment can slow the growth of the cancer, dogs diagnosed with this disease normally do not live more than one year.
Canine distemper is a serious viral infection affecting most of the major systems of a dog's body. Although a vaccination is available, puppies and older dogs without this protection can contract the life-threatening disease by coming into contact with virus-infected feces from other dogs. No treatment can kill the virus; instead, supportive care gives the dog's immune system a better chance to fight off the infection. Studies conducted on ferrets with the virus have demonstrated that epithelial cells must be infected for affected animals to exhibit symptoms and to shed the virus. However, the same cells in dogs do not need to be infected for the canine distemper virus to begin suppressing the dogs' immune systems. Parvovirus is another serious disease affecting dogs, with a survival rate of only around 20 percent in puppies. Research on parvo has shown that the virus begins by destroying cells in the dog's small intestine, leading to epithelial tissue death, and allowing bacteria to move from the intestines into other parts of the body.
While many of the health problems affecting epithelial cells can be fatal, others can have non-life-threatening consequences. For example, one of the main causes of total retinal dysplasia is a lack of contact between the retinal pigment epithelial tissue and the retina. As a result, the retinas are not attached properly. Puppies can be born blind because of this condition. In most cases, total retinal dysplasia is caused by a recessive gene inherited from one of the puppies' parents.
- Estrella Mountain Community College: Animal Cells and Tissues
- University of Sydney Center for Veterinary Education: Epitheliotropic T-Cell Lymphoma
- petMD: Intestinal Cancer (Adenocarcinoma) in Dogs
- ASPCA: Distemper
- The Merck Veterinary Manual: Canine Parvovirus
- Journal of Virology: Canine Distemper Virus Epithelial Cell Infection is Required for Clinical Disease but Not for Immunosuppression
- Vet Street: Canine Distemper/Parvo Bordetella and Rabies Vaccine
- British Veterinary Association: Hereitary Eye Disease in Dogs
- Janie Airey/Digital Vision/Getty Images