As with people, brain surgery is performed on animals for a variety of ailments, including surgical removal of brain tumors, correction of brain anomalies (e.g., Chiari malformation), removal of blood clots (e.g. subdural hematoma), and placement of shunts in patients with hydrocephalus.
Surgical Removal Of Brain Tumors
The most common reason that brain surgery is performed in dogs and cats is to remove a brain tumor. A tumor is defined as an abnormal growth of cells and may be classified as primary or secondary. A primary brain tumor originates from cells normally found within the brain and its surrounding membranes. Examples include meningioma, astrocytoma, oligodendroglioma, ependymoma and choroid plexus tumors. A secondary brain tumor is either cancer that has spread to the brain (a process known as metastasis) from a primary tumor elsewhere in the body, or is a tumor that affects the brain by extending into brain tissue from an adjacent non-nervous system tissue, such as bone or the nasal cavity.
In both dogs and cats, the most common brain tumor is a meningioma, a tumor of the membranes which surround and protect the brain and spinal cord.
While a brain tumor diagnosis is frightening, it is important to note that animals do quite well with treatment. Typically, animals tolerate brain surgery, radiation therapy, and chemotherapy better than people, with fewer side effects.
The most common indication of a brain tumor in dogs is a seizure, especially seizures that begin for the first time in a dog older than five years of age. Other signs suggestive of a brain tumor include abnormal behavior (e.g., increased aggression), altered consciousness, hypersensitivity to pain or touch in the neck area, vision problems, propulsive circling motions, uncoordinated movement, and a “drunken,” unsteady gait. Non-specific signs such as inappetence, lethargy, and inappropriate urination may also be seen.
In cats, surgical removal of a meningioma can be curative. In dogs with meningioma, and in both dogs and cats with other types of brain tumors, brain surgery can provide patients with improved quality of life, especially when followed by radiation therapy.
The neurologists and neurosurgeons at Southeast Veterinary Neurology have many years of experience with surgical treatment of brain tumors. Successful outcomes depend not only the experience of the surgeon, but also on the availability of state of the art equipment such as ultrasonic aspirators (photo), on-site MRI for post-operative imaging and 24 hour nursing care.
Pre-Operative MRI In Dog With Brain Tumor
Post-Operative MRI In Dog With Brain Tumor
Foramen Magnum Decompression
A specialized catheter is used to drain fluid from the ventricular system of the brain into the peritoneal cavity (abdomen). The catheter travels under the skin from the head to the belly. A valve (fluid pump) is positioned between the portion of the catheter in the brain and the portion that goes to the peritoneal cavity. When extra pressure builds up within the brain, the valve opens, allowing excess fluid to drain into the abdomen. This helps lower intracranial pressure.
Ventriculoperitoneal shunting is performed most frequently in puppies with congenital hydrocephalus, however, it is occasionally performed if there is a mass causing obstruction of CSF flow.
The prognosis is favorable. Many puppies can do quite well with shunt placement. The main complications include obstruction of the shunt, shunt infection and dislodgment of the shunt.
Rarely, brain surgery is indicated for head trauma to evacuate blood clots, skull fractures or foreign bodies (bullet, broken tooth, dirt/debris). Prognosis depends on the severity of the injury and MRI findings.
MRI image of a small dog with head trauma after being bitten by a larger dog. Note the bone fragment (single arrow) that is within the brain parenchyma. The double areas show the defect in the skull