Cranial diseases in dogs involve the brain and brain stem, the spinal cord, and the primary and peripheral nerves of the brain. The brain governs automatic and voluntary impulses including breathing, heart rate, behavior, movement and sensation. When disease occurs in the canine brain and surrounding tissues, every aspect of the animal's life can be changed. Cancerous tumors, various spinal cord illnesses and neurological disorders alter the dog physically and can compromise his life expectancy.
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Brain Neoplasias
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According to researchers at the North Carolina State University College of Veterinary Medicine, the most common types of brain neoplasia (cancer) seen in dogs include glioma, meningioma, pituitary adenosarcoma and choroid plexus papilloma.
Gliomas occur when the inner, supportive brain cells overgrow and become malignant tumors. Poorly differentiated (hard to separate from surrounding brain tissue), they commonly affect short-nosed breeds, such as the boxer, French and English bulldogs, and the Boston terrier.
Meningioma develops in the meninges--the membranous lining between the brain and the cranium. These tumors compress and eventually invade the brain tissue and can be treated successfully, although some malignancies do occur. Meningioma is most usually found in the long-nosed breeds such as German shepherds and golden retrievers.
Pituitary adenosarcoma tumors arise in the dog's pituitary gland, a small gland attached to the hypothalamus that produces specific hormones and corticosteroids necessary for the health of the dog. A tumor in this location is the primary cause for Cushing's disease in dogs.
Choroid plexus papilloma tumors grow in the part of the dog's brain where cerebral spinal fluid develops. They can block drainage of the fluid into the spinal cord and cause severe neurological symptoms.
Spinal Cord Diseases
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Meningitis is an inflammation of the meninges. Usually caused by some sort of bacterial infection, meningitis in dogs is most often the result of the spread of the canine distemper virus, infectious hepatitis virus, toxoplasmosis and the rabies virus. Canines commonly show severe neurological symptoms by the time of diagnoses and usually need to be euthanized.
Hydrocephalus is a congenital disease occurring most often in the toy and short-nosed breeds such as the toy poodle, pug, Lhasa apso, Chihuahua and Boston terrier. A build-up of cerebrospinal fluid in the spinal cord and ventricular system of the brain, it is most commonly diagnosed in newborns and after head trauma in adults.
Neurological Disorders
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Canine epilepsy causes the animal to have seizures--often losing consciousness, paddling or running in the air, and chomping or salivating. The cause of epilepsy is unknown in veterinary medicine but is suspected to be related to an uncontrollable discharge of brain neurons, according to CanineEpilepsy.com, the website of the Canine Epilepsy Resource Center.
Dogs with narcolepsy show symptoms of sudden muscular weakness and will suddenly fall asleep at inopportune times. A fairly rare idiopathic disease, narcolepsy affects only humans, dogs and horses.
Vestibular disease centers around the nerves and the part of the brain that controls equilibrium. The disease is commonly called "old dog vestibular disease", and patients have difficulty standing up and may have a pronounced head tilt that causes them to walk in circles or fall over. While there is no known cause for this disease, veterinary care centering around treating for ear infections will often resolve the issue with time.
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