Granulomatous meningoencephalitis
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'''Granulomatous meningoencephalitis''' (GME) is an inflammatory disease of the [[central nervous system]] (CNS) of [[dog]]s and, rarely, [[cat]]s. It is a form of [[meningoencephalitis]]. GME is likely second only to [[encephalitis]] caused by ''[[canine distemper|canine distemper virus]]'' as the most common cause of inflammatory disease of the canine CNS.<ref name=JAVMA>{{cite journal |author=Adamo F, O'Brien R |title=Use of cyclosporine to treat granulomatous meningoencephalitis in three dogs |journal=J Am Vet Med Assoc |volume=225 |issue=8 |pages=1211–6, 1196 |year=2004 |pmid=15521442 |doi=10.2460/javma.2004.225.1211}}</ref> The disease is more common in female toy dogs of young and middle age. It has a rapid onset. The lesions of GME exist mainly in the [[white matter]] of the [[telencephalon|cerebrum]], [[brain stem|brainstem]], [[cerebellum]], and [[spinal cord]].<ref>{{cite journal |author=Suzuki M, Uchida K, Morozumi M, Yanai T, Nakayama H, Yamaguchi R, Tateyama S |title=A comparative pathological study on granulomatous meningoencephalomyelitis and central malignant histiocytosis in dogs |journal=J Vet Med Sci |volume=65 |issue=12 |pages=1319–24 |year=2003 |pmid=14709820 |doi=10.1292/jvms.65.1319}}</ref> The cause is only known to be noninfectious and is considered at this time to be [[idiopathic]]. Because lesions resemble those seen in allergic meningoencephalitis, GME is thought to have an [[Immune-mediated disease|immune-mediated]] cause, but it is also thought that the disease may be based on an abnormal response to an infectious agent.<ref name=Braund>{{cite web|author=Vite, C.H.|year=2005|title=Inflammatory Diseases of the Central Nervous System|work=Braund's Clinical Neurology in Small Animals: Localization, Diagnosis and Treatment|url=http://www.ivis.org/advances/Vite/braund27/chapter_frm.asp?LA=1|accessdate=2007-02-15}}</ref> One study searched for viral [[DNA]] from ''[[canine herpesvirus]]'', ''[[infectious canine hepatitis|canine adenovirus]]'', and ''[[canine parvovirus]]'' in brain tissue from dogs with GME, necrotizing meningoencephalitis, and necrotizing leukoencephalitis (see below for the latter two conditions), but failed to find any.<ref>{{cite journal |author=Schatzberg S, Haley N, Barr S, de Lahunta A, Sharp N |title=Polymerase chain reaction screening for DNA viruses in paraffin-embedded brains from dogs with necrotizing meningoencephalitis, necrotizing leukoencephalitis, and granulomatous meningoencephalitis |journal=J Vet Intern Med |volume=19 |issue=4 |pages=553–9 |year=2005 |pmid=16095173 |doi=10.1892/0891-6640(2005)19[553:PCRSFD]2.0.CO;2 |doilabel=10.1892/0891-6640(2005)19[553:PCRSFD]2.0.CO;2}}</ref>
==Types of GME==
*Disseminated - This is a diffuse disease throughout the CNS. It was previously known as '''inflammatory reticulosis'''. There is an accumulation of [[monocyte|mononuclear cell]]s and [[neutrophil granulocyte|neutrophil]]s around the blood vessels (perivascular) of the CNS. [[Meningitis]] is seen with this form of GME and causes fever and neck pain.<ref name=Merck>{{cite web | title = Idiopathic Inflammatory Diseases | work = The Merck Veterinary Manual | date = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/100710.htm | accessdate = 2007-02-15 }}</ref> It has an acute progression over a few weeks. Symptoms include incoordination, [[nystagmus]], head tilt, seizures, and depression.<ref name=Braund/>
*Focal - The disease presents as a [[granuloma]], which mimics a tumor. It usually is found in the cerebrum or [[cerebellum|cerebellopontine angle]].<ref name=Ettinger_1995>{{cite book|author=Ettinger, Stephen J.;Feldman, Edward C.|title=Textbook of Veterinary Internal Medicine|edition=4th ed.|publisher=W.B. Saunders Company|year=1995|id=ISBN 0-7216-6795-3}}</ref> Symptoms may be acute or develop slowly over several months and depend on the location of the lesion.<ref name=Merck/>
*Ocular - This is an uncommon form of GME and is characterized by sudden blindness caused by [[optic neuritis]]. The disease is bilateral. Ocular GME is considered to be an extension of CNS disease. The blood vessels of the [[posterior segment]] of the eye and anterior [[uvea]] have the same infiltrates of inflammatory cells as the intracranial vessels. [[Uveitis]], [[retinal detachment]], and secondary [[glaucoma]] may be seen.<ref name=Gelatt_1999>{{cite book|author=Gelatt, Kirk N. (ed.)|title=Veterinary Ophthalmology|edition=3rd ed.|publisher=Lippincott, Williams & Wilkins|year=1999|id=ISBN 0-683-30076-8}}</ref>
==Diagnosis and treatment==
[[Cerebrospinal fluid]] (CSF) analysis shows a large number of [[white blood cell]]s. Typically small mature [[lymphocyte]]s are the majority of cells seen, with [[monocytes]] and neutrophils making up the rest.<ref>{{cite web | last = Vernau | first = William | title = Cerebrospinal Fluid Analysis in Dogs and Cats | work = Proceedings of the 50° Congresso Nazionale Multisala SCIVAC | date = 2005 | url = http://www.ivis.org/proceedings/scivac/2005/Vernau5_en.pdf?LA=1 | format = PDF | accessdate = 2007-02-18 }}</ref> A [[computed tomography|CT scan]] or [[magnetic resonance imaging|MRI]] will show patchy, diffuse, or multifocal lesions. Treatment is with immunosuppressive drugs such as [[corticosteroid]]s, [[azathioprine]], and [[cyclophosphamide]].<ref name=Ettinger_1995/> [[Procarbazine]], [[ciclosporin|cyclosporine]], and [[cytarabine|cytosine arabinoside]] have also been used successfully. Treatment with [[radiation therapy]] for focal GME gives the longest periods of [[remission (medicine)|remission]].<ref name=JAVMA/> The condition is rarely cured. The animal usually dies within a few months.<ref name=Ettinger_1995/>
==Pug Dog encephalitis==
'''Pug Dog encephalitis''' (PDE) is an idiopathic inflammatory disease primarily affecting the prosencephalon (forebrain and thalamus). It is also known as '''necrotizing meningoencephalitis'''. The disease may be inherited in [[Pug]]s and [[Maltese (dog)|Maltese]].<ref name=Ettinger_1995/> It differs in [[pathology]] from GME by more tissue breakdown and increased [[eosinophil granulocyte|eosinophil]]s. CSF analysis is also unique among inflammatory CNS diseases in dogs in that the cells are predominately [[lymphocyte]]s instead of a mixed population of mononuclear cells.<ref name=Kent>{{cite journal | last = Higginbotham | first = Michael J. | coauthors = Kent, Marc; Glass, Eric N. | title = Noninfectious Inflammatory Central Nervous System Diseases in Dogs | journal = Compendium on Continuing Education for the Practicing Veterinarian | volume = 29 | issue = 8 | pages = 488–497 | publisher = Veterinary Learning Systems | date = August 2007 }}</ref> In Maltese and Pugs there is extensive necrosis and inflammation of the [[grey matter|gray matter]] of the cerebrum and subcortical white matter. The most common early symptoms are related to [[prosencephalon|forebrain]] disease and include seizures and [[dementia]], and later circling, head tilt, and blindness with normal [[pupillary light reflex]]s may be seen. Corticosteroids may improve symptoms, but the dog almost always dies from the disease.<ref name=Ettinger_1995/>
==Necrotizing leukoencephalitis==
In Yorkies, [[Chihuahua (dog)|Chihuahua]]s, and [[Shih Tzu]]s there can be severe mononuclear inflammation of the brainstem and [[Ventricular system|periventricular]] cerebral white matter. Because the condition in these breeds affects only the white matter, it has been called necrotizing leukoencephalitis. Symptoms of brainstem and central [[Vestibular system|vestibular]] disease predominate.<ref>{{cite web | last = Garosi | first = Laurent S. | title = CNS inflammatory (UK) problems: The neurologist’s viewpoint, clinical approach and treatment | work = Proceedings of the 53° Congresso Nazionale Multisala SCIVAC | date = 2006 | url = http://www.ivis.org/proceedings/scivac/2006/garosi3_en.pdf?LA=1 | format = PDF | accessdate = 2007-02-18 }}</ref> As in Pug Dog encephalitis, corticosteroids may improve symptoms, but the dog almost always dies from the disease.<ref name=Ettinger_1995/>
==Other types of noninfectious meningoencephalitis==
*'''Steroid-responsive meningoencephalitis''' is any noninfectious meningoencephalitis that responds well to [[corticosteroid]]s and usually has an excellent [[prognosis]]. This could represent mild forms of GME or PDE, but there are two separate conditions recognized also.
**'''Steroid-responsive meningitis/arteritis''' , also known as '''necrotizing vasculitis''', is seen most commonly in [[Beagle]]s, [[Boxer (dog)|Boxer]]s, [[Bernese Mountain Dog]]s, and [[German Shorthaired Pointer]]s younger than two years of age.<ref name=Chrisman_2003>{{cite book|author=Chrisman, Cheryl; Clemmons, Roger; Mariani, Christopher; Platt, Simon|title=Neurology for the Small Animal Practitioner|edition=1st ed.|publisher=Teton New Media|year=2003|id=ISBN 1-893441-82-2}}</ref> Many cases have fever, loss of appetite, and severe neck pain without other neurologic symptoms, although longterm cases may have incoordination and limb weakness or paralysis. CSF analysis shows predominantly neutrophils. In Beagles this condition is also known as '''Beagle pain syndrome'''.<ref name=Braund/>
**'''Eosinophilic meningoencephalomyelitis''' is seen mainly in [[Golden Retriever]]s.<ref name=Chrisman_2003/> CSF analysis shows predominantly eosinophils.
*An acute progressive '''pyogranulomatous meningoencephalomyelitis''' is seen in mature [[Pointer (dog breed)|Pointer]] dogs. There is monocytic and neutrophilic infiltration of the [[meninges|leptomeninges]]. Symptoms include incoordination, reluctance to move, and neck rigidity.<ref name=Merck2>{{cite web | title = Meningitis and Encephalitis: Introduction | work = The Merck Veterinary Manual | date = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/101600.htm | accessdate = 2007-02-15 }}</ref>
==See also==
*[[Encephalitis]]
*[[Meningitis]]
==References==
<div class="references-small"> <references/> </div>
[[Category:Dog diseases]]
[[de:Granulomatöse Meningoenzephalitis]]
[[es:meningoencefalitis granulomatosa]]