What do muscle wasting and weight loss tell you about a case? - DVM
  • SEARCH:
News Center
DVM Featuring Information from:

ADVERTISEMENT

What do muscle wasting and weight loss tell you about a case?


DVM360 MAGAZINE


Clinical signs Regardless of whether the brain tumor is primary or metastatic, clinical signs are usually slowly progressive over several weeks to months or may be rapid in onset and have a short clinical course. Most dogs with brain tumors will have long histories of vague signs that may be overlooked until signs of brain dysfunction are well advanced.

The clinical signs of brain neoplasms include anorexia, seizures, altered behavior, circling, head pressing, compulsive walking, altered consciousness and locomotor disturbances.

Cerebral tumors will typically cause behavior changes, seizures, visual deficits and circling. Brain stem tumors will typically cause depression, head tilt, cranial nerve deficits, weakness and ataxia. Cerebellar tumors will typically cause ataxia, head tilt, circling and tremor.

Choroid plexus tumors may also include signs of vomiting and bradycardia. Acute onset of blindness and dilated non-responsive pupils may be the only clinical signs of an intracranial tumor and are usually located in the chiasmal region.

Survey skull radiographs, cerebrospinal fluid analysis and/or special imaging techniques such as computerized tomography or magnetic resonance imaging are commonly incorporated in the clinical evaluation of a suspect dog for neoplasia of the central nervous system.

Survey skull radiographs are of limited value in the diagnosis of a primary brain tumor; however, they may be helpful in the detection of neoplasms of the skull or nasal cavity that have affected the brain by local extension. Radiographs of the skull may occasionally reveal erosion or hyperostosis of the calvarium in association with a primary brain tumor (e.g., meningioma) or document areas of mineralization within a neoplasm.

Fluid analysis Cerebrospinal fluid analysis is often helpful in evaluating dogs suspected of having an intracranial tumor, especially if the tumor communicates with the ventricles or subarachnoid space.

Although, cerebrospinal fluid changes are often nonspecific, when combined with the history and neurologic examination, such changes may provide an accurate diagnosis. Cerebrospinal fluid analysis may reveal a definitive diagnosis if neoplastic cells are visualized, but this is unusual unless its lymphosarcoma. Unless neoplastic cells are present, the cerebrospinal fluid analysis will provide only indirect evidence that a tumor exists. In general, increased cerebrospinal fluid protein content and normal to increased cerebrospinal fluid white blood cell counts are considered the typical changes seen with brain tumors.

Meningiomas are more commonly associated with a neutrophilic pleocytosis; however, pleocytosis can be seen with other tumors as well. Choroid plexus papillomas may cause dramatic increases in cerebrospinal fluid protein concentration. Primary intracranial neoplasia is usually associated with a cerebrospinal fluid white blood cell count of fewer than 50 cells/L with variable elevations of cerebrospinal fluid protein. In contrast, metastatic or invasive neoplasia is associated with higher white blood cell counts and protein concentrations in the cerebrospinal fluid.

Visualize it Because most intracranial tumors are not visible with survey radiographs, computerized tomography and magnetic resonance imaging allow for localization of tumors, facilitate brain biopsy, determine the feasibility of surgical removal of a tumor, allow for a high degree of certainty about tumor type and for localization before radiation therapy, improve the owner's ability to make decisions regarding care, and enable the veterinarian to more accurately advise owners regarding therapy and prognosis.

Computerized tomographic findings for brain tumors are:

  • Meningiomas are usually broad-based, peripherally located masses that were enhanced homogeneously with contrast material.
  • Among the brain parenchymal tumors, astrocytomas are not distinguished easily from oligodendrogliomas because both tumors have similar tomographic features of ring-like and nonuniform enhancement, and poorly defined tumor margins.
  • Choroid plexus tumors are seen as well-defined, hyperdense masses that have marked uniform contrast enhancement.
  • Pituitary tumors are distinguished readily by their location, minimal peritumoral edema, uniform contrast enhancement and well-defined margins.
  • In addition to defining primary brain tumors, computerized tomography may be helpful in identifying nasal tumors that have extended into the rostral cerebrum. These dogs may have no clinical signs of nasal disease. magnetic resonance imaging is optimal for demonstrating the amount of nasal or cerebral involvement and shows detailed anatomic features of these brain tumors.

Secondary tumor effects Control of secondary tumor effects, such as increased intracranial pressure or cerebral edema, and tumor eradication (or reduction) are the primary therapy for an intracranial tumor. Palliative therapy for dogs with brain tumors consists of the administration of glucocorticoids for reducing edema, and in some cases, for retarding tumor growth.

Some animals with brain tumors demonstrate dramatic improvement in clinical signs for weeks or months with sustained glucocorticoid therapy.

Should seizure therapy be needed, phenobarbital is the drug best suited for control of generalized seizures. Eradication or reduction of a brain tumor is the primary consideration for the long-term survival of a dog with a brain tumor. Therapy for a brain tumor may include surgery, irradiation, chemotherapy, and immunotherapy (biologic response modification).

Glucocorticoids Palliative therapy for brain tumors is administration of glucocorticoids. Glucocorticoids readily penetrate the blood-brain barrier and have some direct antitumor activity. Dexamethasone is preferred in acute and severe cases, whereas prednisone or prednisolone may be used for maintenance.

Brain tumors of any histopathologic type or location always carry a poor prognosis. Most dogs with brain tumors eventually die or are euthanized as a direct result of their tumor.


ADVERTISEMENT


Click here