As they age, dogs may have an increased risk of developing cancer of the brain. A brain tumor is most common in older dogs. Brain tumors in dogs often go undiagnosed because diagnostic tests such as an MRI may be required to confirm the diagnosis. The prognosis for dogs with brain tumors may vary as there are many different types of tumors that can develop in dogs. Some tumors may be treatable whereas others are not.
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Identification
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According to The North Carolina State University College of Veterinary Medicine, a brain tumor is a mass located inside the brain. The term "brain tumor" is most commonly used to refer to a cancerous mass, but there are brain tumors that are not malignant. There are two types of tumors. Primary brain tumors begin in the brain, forming from cells inside a dog's brain and its lining. Secondary brain tumors are the result of cancer elsewhere in a dog's body, which has metastasized (spread) to the brain.
Types
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The most common primary brain tumor in dogs is the meningioma. This tumor develops from the membranes that line the brain. Meningioma occurs most often in dogs with long noses such as the golden retriever. This tumor is usually treatable because it is slow-growing. Other types of primary tumors in dogs include the pituitary adenoma, glioma, the choroid plexus papilloma, and the adenocarcinoma. Secondary brain tumors may include melanoma, mammary carcinoma, and the hemangiosarcoma. Secondary brain tumors can carry a more dire prognosis because the cancer is already located elsewhere in the dog's body before it spread to the brain.
Symptoms
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The symptoms of brain tumors in the forebrain of dogs may include increased thirst, increased appetite, depression, pacing, circling, decreased vision on one side of the body, pain, and seizures. Tumors that develop in a dog's brain stem may produce symptoms such as head tilt, abnormal eye position, vomiting, loss of appetite, drunken gait, circling, and leaning to the side. Brain tumors located in the cerebellum may cause symptoms such as head tremors, drunken gait, wide stance, swaying of the trunk, and head tilt.
Diagnosis
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In order to diagnose a brain tumor in your dog, your veterinarian will perform a full physical and neurological evaluation. Diagnostic tests such as a CBC (complete blood count), chest X-rays, a CT scan, or an MRI may be performed. If a tumor is detected on a CT scan or MRI, the veterinarian may perform a biopsy of the tumor in order to identify which type it is.
Treatment
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The treatment of brain tumors in dogs largely depends on the type of tumor and the severity of illness. Removal of a tumor may be performed to cure the disease or reduce the symptoms associated with it. Brain tumors may only be removed if they are easily accessible to a veterinarian. Dogs with tumors that lie deep inside the brain may not be candidates for tumor removal. Radiation therapy may be performed to slow tumor growth. Chemotherapy may be recommended on certain types of tumors, such as the glioma.
Prognosis
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It is important to understand that brain tumors in dogs may be treated but not cured, which means that treatment may not eliminate the brain tumor but may give your dog an improved quality of life for the time he or she has left with you.
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