Canine Cancer

There is currently a study being conducted known as the Dog Genome Project. It is a collaborative study involving doctors, veterinarians and researchers from different Universities and laboratories worldwide. The main goal of this project is to produce a map of all the chromosomes in dogs. Such a map can be used to locate the genes causing diseases in the domestic dog. Understanding the dog genome sequences, will help scientists understand the human genome as well. It was found that the dog genome is very similar in size to the genomes of humans. The human and canine genomes are 90percent similar. This project says that more than 25% or 650 million base pairs of DNA overlap between human and dog. Humans have 46 chromosomes, while dogs have 78. The American Kennel Club recognizes 150 dog breeds. This diversity makes it easier for geneticists to identify genes responsible for certain diseases. Researchers are finding dogs to be a remarkable model to study many of the diseases that also affect humans. Dogs live in the same environment as humans, breathe the same air, therefore having similar diseases, making them ideal candidates for health studies. Most of the 400 known canine diseases have human counterparts. One major disease that is being studied in the canines is cancer. Caner has always been, and continues to be a major health concern to humans. The physiology, disease presentation and clinical response of dogs mimic human cancer closely. Therefore carefully studying different aspects of cancer in dogs will help scientists reveal certain aspects of it in humans.

A program that branched off of this idea is known as The Comparative Cancer Program being conducted at Cornell University. The mission statement of this program states, "the long-term goal of the Comparative Cancer Program is to drive discovery throughout Cornell University toward advancement of new methods for prevention, diagnosis and therapeutic intervention of cancer. In order to achieve this goal the program will develop programmatic linkages from basic, applied and social sciences to the developing efforts in traditional and transgenic animal sciences ultimately bridging to clinical investigations at the Veterinary Medical Center. The intention is to develop a cancer center that provides a valuable resource for the entire Cornell research and educational environment and serves the needs of the New York state public and the Cornell veterinary medical referral community" (http://www.vet.cornell.edu/cancer/mission.html). This program clearly has many goals, in which they are already successfully accomplishing. This program focuses on comparing cancer both in cats and dogs. However, this paper will reflect only on the dog aspect of cancer. They strive to provide great services to their animal patients with cancer. Along with providing these services, one of their long term goals is to provide a great educational aspect of cancer to the outside community as well. The Comparative Cancer Program along with the oncology unit at Cornell University provides great information and services on the basics of cancer, diagnosis, prevention, different types of cancer among specific breeds, and the treatment available.

The most common cause of non-accidental deaths in dogs over 10 years in age are from cancer. Cancer is a very common problem among our pets today. Cancer is a very broad and complicated subject. The cells of canines are constantly growing and replacing themselves, and this growth gone awry is the basis of all cancer. When these cells do not grow normally, meaing they are not doing any good for the body, they are then termed as cancerous or tumorous cells. Cell growth is controlled by written instructions in DNA code in every cell. When there is a tumorous cell, this means an error has occurred in this script causing the cells to grow out of control. When these errors are minor, and the cells still look and act a lot like normal, the tumor is said to be benign. When the errors are major, they are termed to be malignant. When the cells divide out of control, the accumulation of more and more cancerous daughter cells results in the crowding out of the normal cells. The tumors basically starve the organs of the body oxygen and nutrients, which will eventually cause failure of the affected organ. Any organ or body tissue can develop cancer. Bone, breast tissue, lymph nodes, skin, and all organs can be affected. Cancer can also appear in areas not associated with any structure in particular, such as beneath the skin layer, or in the chest cavity, or the abdominal cavity. Causes of these malfunctions may be inherited or acquired. Cancer is classified into two main categories. Tumos that arise from muscle, bone and fibrous connective tissues of the body are called sarcomas. Tumors of the skin, glands or organs are known as carcinomas. Both of these tumors may metastasize. This means they can spread to other organs in the body via blood or the lymphatic system.

The diagnosis of canine cancer is very similar to the diagnosis of human cancer. First a few cells are extracted from the lump or area of infection and examined under a microscope. If abnormal cells appear, a biopsy, a surgical removal of a piece of tissue from the area, is then conducted. Examination of biopsies allows the veterinarian to determine if the tumor is benign or malignant. The tumor is also assessed as having a high grade, intermediate, or low-grade growth rate. Once this is done, other diagnostic tools are used to determine the stage of infection, the potential outcome of the particular type of malignancy, and then can devise a treatment protocol from there. Survey radiography (x-ray) is the most common diagnostic imaging tool used in veterinary oncology. Many tumors are bulky and distort the shapes of the organs they reside in making them readily apparent on x-rays. These x-rays also make it easier to determine the position, shape, and size of the tumor present. CT (computed Tomography), sometimes called CAT scan, imaging equipment is found at many large veterinary hospitals and universities, such as Cornell. CT uses special x-ray equipment to obtain image data from different angles around the body and then uses computer processing of the information to show a cross-section of the body's tissues and organs. This process is more sensitive to changes in the examined tissues and capable of imaging areas that may be hidden behind other tissues. CT imaging is favored over surgery radiography when assessing tumors of the brain and central nervous system. Magnetic resonance imaging (MRI) can also be used as a diagnostic tool. MRI uses magnetic fields and radiofrequency waves to create images of the body without the need of ionizing radiation. MRI provides a better contrast between different types of soft tissues compared to using x-rays