ISSN 2398-2969      

Brain: neoplasia


Synonym(s): Brain tumor


  • Neoplasia secondarily involves the brain via metastasis or via direct extension from extraneural sites.
  • Primary tumors within the skull, nasal cavity or frontal sinuses can extend directly into the brain.
  • Often, signs of intracranial extension such as seizures, occur prior to or without other signs of nasal disease.
  • May be primary or secondary.
  • Usually unilateral, giving an asymmetrical picture with deficits contralateral to the side of the lesion.
  • Secondary effects, eg brain edema and herniation, may cause rapid progression of signs.
  • Cause:
    • Meningioma.
    • Gliomata (various).
    • Pituitary macroadenoma.
    • Others.
  • Signs: circling, cranial nerve deficits, related to space occupying lesion, eg seizures, depression, ataxia.
  • Higher incidence in older individuals and in brachycephalic breeds.
  • Diagnosis: confirmation of diagnosis is best carried out using computed tomography.
  • Treatment: depends on nature of tumor but may include surgical resection, chemotherapy, radiotherapy and medical control of secondary effects, eg using corticosteroids.
  • Prognosis: depends on tumor type and location.
    Print off the owner factsheet Brain tumor or cancer to give to your client.



Primary brain tumors Secondary brain tumors
  • Local infiltration from, eg skull or primary nasal tumors.
  • Metastasis from other sites.
  • Pituitary adenomas Pituitary adenoma.
  • Numerous tumors of older animals metastasize to the brain including hemangiosarcoma Hemangiosarcoma , lymphosarcoma Lymphoma , mammary gland Mammary gland: neoplasia , and other carcinomas.
  • The incidence of intracranial metastasis is often underestimated as the brain is not always examined during a routine necropsy.
  • Tumors that readily metastasize to the lungs may be more likely to metastasize to the brain.
  • The cortical gray/white junction is a common area of metastasis due to the increased vascularity, with brain stem and spinal cord metastasis less frequent.
  • Choroid plexus tumors may metastasize through the CSF to other areas in the brain or spinal cord ('drop-lets').
  • In some instances, spinal signs from choroid plexus metastasis may be the first sign of the presence of the tumor.
Secondary effects


  • Brachycephalic breed.


  • Tumors often occupy >1 anatomic division of brain and so may result in signs suggestive of multifocal disease.

Secondary effects of brain neoplasia

  • Tumor may disrupt the blood-brain barrier, causing local accumulation of fluid mostly in the white matter. This vasogenic brain edema may develop rapidly and is the most significant of the secondary effects, giving an acute clinical picture.
  • Rigid cranium does not allow expansion of contents (blood, CSF and brain tissue), so brain edema causes an increase in intracranial pressure. Raised intracranial pressure usually leads to brain herniation.
Types of brain herniation
  • Subfalcine.
  • Caudal transtentorial.
  • Foramen magnum (can cause respiratory depression).
  • Rostral transtentorial.
  • Clinical signs may be localized or multifocal depending upon the number and location of metastasis and associated pathophysiologic sequelae such as hemorrhage and edema.
  • Infarction and hemorrhage are common with CNS metastasis.


  • Usually insidious onset over weeks or months.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Snyder J M, Shofer F S, Van Winkle T J & Massicotte C (2006) Canine intracranial primary neoplasia: 173 cases (1986-2003). J Vet Intern Med 20, 669-675 PubMed.
  • Abate O et al (1998) Cytological, immunocytochemical and biochemical cerebrospinal fluid investigations in selected central nervous system disorders of dogs. Zentralbl Veterinmed B 45 (2), 73-85 PubMed.
  • Bagley R S et al (1998) Seizures as a complication of brain tumors in dogs. Clin Tech Small Anim Pract 13 (3), 179-184 PubMed.
  • Bagley R S et al (1998) Clinical features of trigeminal nerve-sheath tumor in 10 dogs. JAAHA 34 (1), 19-25 PubMed.
  • Kraft S L et al (1997) Retrospective review of 50 canine intracranial tumors evaluated by magnetic resonance imaging. J Vet Inten Med 11 (4), 218-225 PubMed.
  • Morozumi M et al (1997) Computed tomography and magnetic resonance findings in two dogs and a cat with intracranial lesions. J Vet Med Sci 59 (9), 807-810 PubMed.
  • Sheppard B J et al (1997) Primary encephalic plasma cell tumor in a dog. Vet Pathol 34 (6), 621-627 PubMed.
  • Kraus K H et al (1996) Identification and management of brain tumors. Semin Vet Med Surg (Small Anim) 11 (4), 218-224 PubMed.
  • Moore M P, Bagley R S, Harrington M L et al (1996) Intracranial tumors. Vet Clinic North Am 26 (4), 759-77 PubMed.
  • Nakaichi M et al (1996) Primary brain tumors in two dogs treated by surgical resection in combination with postoperative radiation therapy. J Vet Med Sci 58 (8), 773-775 PubMed.
  • Tucker R L & Gavin P G (1996) Brain imaging. Vet Clinic North Am 26 (4), 735-58 PubMed.
  • Gavin P R, Fike J R & Hoopes P J (1995) Central nervous system tumors. Seminars Vet Med Surg 10 (3), 180-9 PubMed.
  • Bindal R K, Sawaya R, Leavens M et al (1993) Surgical treatment of multiple brain metastases. J Neurosurg 79 (2), 210-6 PubMed.
  • Davidson M G, Nasisse M P, Breitschwerdt E B et al (1991) Acute blindness associated with intracranial tumors in dogs and cats - Eight cases (1984-1989). JAVMA 199 (6), 755-8 PubMed.
  • Heidner G L, Kornegay J N, Page R L et al (1991) Analysis of survival in a retrospective study of 86 dogs with brain tumors. J Vet Int Med 5 (4), 219-26 PubMed.
  • Dimski D S & Cook J R (1990) Carmustine-induced partial remission of an astrocytoma in a dog. JAAHA 26 (2), 179-82 VetMedResource.
  • Fenner W R (1990) Metastatic neoplasms of the central nervous system. Seminars Vet Med Surg 5 (4), 253-61 PubMed.
  • Foster E S, Carrillo J M & Patnaik A K (1988) Clinical signs of tumors affecting the rostral cerebrum in 43 dogs. J Vet Int Med 2 (2), 71-4 PubMed.
  • Bailey C S & Higgins R J (1986) Characteristics of cisternal cerebrospinal fluid associated with primary brain tumors in the dog - A retrospective study. JAVMA 188 (4), 414-7 PubMed.
  • Carrillo J M, Sarfaty D & Greenlee P (1986) Intracranial neoplasm and associated inflammatory response from the central nervous system. JAAHA 22 (3), 367-73 VetMedResource.
  • Turrel J M, Fike J R, LeCourteur R A et al (1986) Computed tomographic characteristics of primary brain tumors in 50 dogs. JAVMA 188 (8), 851-6 PubMed.
  • Palmer A C, Malinowski W & Barnet K C (1974) Clinical signs including papilloedema associated with brain tumors in twenty-one dogs. JSAP 15 (6), 359-86 PubMed.
  • Geib L W (1966) Ossifying meningioma with extracranial metastasis in a dog. Pathol Vet 3 (3), 247-54 PubMed.

Other sources of information

  • Bagley R S, Kornegay J N, Page R Let al(1992)Central nervous system neoplasia.In: Slatter D H (ed)Textbook of Small Animal Surgery.3rd edn Philadelphia: W B Saunders. pp 2137.
  • Fulton L (1991)The use of lomustine in the treatment of brain masses.In:Proceedings of the Ninth Annual Veterinary Medical Forum, New Orleans. pp 827.

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