Brain Tumors in Dogs
Introduction
Brain Tumors in Dogs Guide: Veterinary reviewed information that provides a detailed explanation of Brain Tumors in dogs. Get started and see what choices you and your vet can make to manage Brain Tumors in Dogs.
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Definition
A “tumor” has several definitions. One is simply any swelling, which is one of the hallmark signs of inflammation. Another definition of a tumor is a new growth of tissue in which cell multiplication is uncontrolled and progressive. This is also called cancer, or neoplasia. Cancer and neoplasia are interchangeable. When a tumor is cancerous or neoplastic, it is composed of new, rapidly growing cells whose growth continues even after the normal stimuli for cell growth is no longer present and serves no useful purpose for the animal.
Tumors are classified medically in several ways. The simplest classification is by the tissue of origin and whether the tumor is metastatic or benign. Tumors of the bone, fat, blood vessels and lymph tissue are typically called “sarcomas,” and they may be benign or metastatic. Tumors of the glandular tissue and organs of the mammary glands, stomach, uterus or skin are typically called “carcinomas,” which also may be benign or metastatic. “Metastatic” means that the tumor cells can transfer from one part of the body to a distant part and at the same time carry with them their ability to reproduce abnormally – in other words, they can transfer disease to areas of the body that they are not in direct contact with. “Benign” means not malignant – in other words, benign tumors do not spread disease to distant parts of the body.
Most of us think we know what the “brain” is, and in the most general sense we do. However, a bit more specific medical information will be useful to gain an understanding of brain tumors. The brain is defined as that part of the central nervous system contained inside the skull (the cranium). It is made up of the forebrain, the midbrain and the hindbrain. It is connected at its base to the spinal cord, which as its name implies runs through the bony spinal column. In the simplest of terms, the brain is a mass of soft, fleshy, pinkish and greyish nerve tissue. In the more accurate of modern terms, the brain is the most highly specialized computer that has ever existed.
Brain tumors, then, are either benign or malignant masses contained within brain tissue. They can be either primary or secondary. Primary brain tumors are those that originate from cells that are normally found within brain tissue. These include meningiomas, gliomas, choroid plexus tumors, ependymomas, medulloblastomas, olfactory neuroblastomas and primitive neuroectodermal tumors, among others. The specific details of each of these types of primary brain tumors are beyond the scope of this article.
Secondary brain tumors are either malignant neoplasms that started in tissue somewhere else in the body and ended up in the brain, usually through the blood circulatory system, such as lymphosarcoma and hemangiosarcoma. Secondary brain tumors can also be the result of local invasion of cancerous cells into the brain from areas that are adjacent to the brain, such as from primary pituitary gland tumors or from bone tumors in the skull or nasal cavity. What most people do not understand is that when their dog is diagnosed with a “brain tumor,” it does not necessarily mean that the tumor is of brain tissue origin. For example, breast cancer (neoplasia of the mammary glands) can metastasize to the brain. That is not “brain cancer.” It is “breast cancer” that has spread into the brain.
Since there are a number of different types of primary and secondary tumors that can affect the brain, there is no responsible or accurate way to describe the causes of brain tumors in general terms. In most cases, the causes of cancer remain uncertain. Heredity is thought to play a role in many tumors of the brain and other organs or tissues. Other things that have been suggested as causing or contributing to brain tumors
It is hard to say, generally or specifically, how brain tumors affect any given animal. The symptoms that they experience will depend upon the location of the mass, its size and its aggressiveness. Certainly, depending upon those things, dogs may experience any range of effects, from none to extreme pain and distress. Unfortunately, the outcome for a dog with either a benign or a malignant brain tumor is not all that different in most cases…
Any dog presenting with seizures, sudden vision problems or other signs of abnormal mentation or behavior will be given a thorough physical examination and a complete neurological work-up. Of course, a complete history of the dog’s symptoms and progression of the behavioral abnormalities will be taken from the owner. Most general veterinary practitioners can skillfully perform a basic neurological examination. In many cases, how the dog presents to the veterinarian, together with the history and
Obviously, treatment of any brain tumor must be specifically tailored to the type of tumor, whether it is primary or secondary, its location, and the extent of its invasion into surrounding brain tissue. The primary goals of treating brain tumors are to manage the potential secondary side effects of increased pressure inside the brain/skull and to try to reduce or eliminate the tumor entirely. Three general therapeutic approaches are currently available to treat brain tumors