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GRANULOMATOUS MENINGO-ENCEPHALOMYELITIS (GME)
& MENINGO-ARTERITIS (MENINGITIS)
WHAT IS GME AND WHAT IS MENINGITIS?
head, facial abnormalities, problems swallowing and weakness Most people have never heard of GME, meningitis or any other can be seen. This does not leave out much in the way of form of central nervous system inflammation until they have a neurological symptoms. The main clinical symptoms in dogs dog with progressive neurological disease. At Wear Referrals we with meningitis are neck pain, fever and depression. These see patients with GME or meningitis on a weekly basis and they patients tend to be mainly young (<1 year) large breed dogs. The are therefore one of the most commonly diagnosed diseases of Beagle is a smaller breed dog in which meningitis is frequently the central nervous system in dogs. We understand how diagnosed. Some dog can suffer from poly-arthritis (inflamed stressful it can be for owners when they hear that their beloved joints) at the same time as suffering from meningitis (Akita’s, pet has been diagnosed with GME or meningitis. This information sheet provides a summary of these conditions in an TYPES OF GME
There are different subtypes of GME: focal (limited to one location The general process of inflammation involves the infiltration of in the nervous system), disseminated or multifocal (involving normal tissues by cells of the immune system. These cells are like many locations in the nervous system) and ophthalmic (involving the armed police of the body. They go to the area where they are the optic nerve/eye). A patient may have more than one type called and release destructive biochemicals with the goal of at the same time. There are some breed specific encephalitis obliterating an area of invasion by infectious organisms or of types like necrotising encephalitis in the Yorkshire Terrier and dead or diseased tissues. We do not exactly know why GME and meningitis occur but they are thought to have an immune-mediated background. It is important to note that The focal type of GME typically can have a slower onset (months) both GME and meningitis are generally not infectious diseases in while the disseminated form is more rapid (sometimes days to a contrast to meningitis in humans where they tend to be viral or few weeks). Obviously, the disseminated form has a larger variety of signs within the same patient. The ophthalmic form most commonly shows up as sudden, generally permanent blindness.
Granulomatous inflammation involves infiltration by cells called It can affect one or both eyes. The disseminated form has a "mononuclear cells." These cells normally engulf and destroy particularly poor prognosis; in one (relatively old) study the debris. In GME, these cells form cuffs around the blood vessels of median survival time after diagnosis was 8 days, a testament to the brain and spinal cord (mostly in the white matter). The cuffs the rapid progression, seriousness and severity of this condition.
join at adjacent vessels forming actual masses/nodules. GME can affect all areas of the brain, the spinal cord and the membranes MAKING THE DIAGNOSIS
that surround them. In meningitis patients we see predominantly The diagnosis is made based on the patient’s history, breed, age, neutrophilic cells in the spinal fluid and these cells are located the clinical examination, bloods tests, urine analysis, radiographs, MRI and spinal fluid analysis. Blood panels and urinalysis form the foundation of evaluation and determination of what medication THE CLINICAL PICTURE OF GME & MENINGITIS
can be used, and what other body systems must be considered.
The classical patient with GME is a young to middle-aged small breed dog (terrier) of either gender although any dog can be Radiographs are taken in patients with neck pain to look for affected. What sort of neurological signs are seen depend totally obvious bony and soft tissue changes. Magnetic Resonance
on what area of the nervous system is involved. Seizures, neck Imaging (MRI) (please see MRI download) is the golden standard
pain, drunken gait, walking in circles, blindness, listlessness, tilted in neuro-imaging and it is indicated in almost every patient with 5-11 Tenters Street, Bishop Auckland, County Durham, DL14 7ADT: 01388 602707 | F: 01388 605660 | [email protected] | www.wear-referrals.co.uk suspected brain or spinal cord disease. Tapping of the GME: Immune-suppression with corticosteroids combined with
cerebrospinal fluid (spinal tap) is necessary to confirm the drugs as Cytarabine, Cyclosporine or Azathioprine) are for a period diagnosis of GME and meningitis. Both MRI and spinal taps require of at least six to twelve months. It is unusual for a patient with general anaesthetic. Prior administration of steroid (prednisolone) GME to be able to fully discontinue medication. The prognosis medication may reduce the cells found in the tap and must be with this combination treatment is vastly better compared to taken into account when interpreting the results of the spinal fluid analysis. In patients with meningitis we often see diffuse swelling of the grey matter on MRI. In patients with GME the grey matter, If seizures have been a manifestation of GME, either disseminated the white matter, the meningi and the spinal cord can be affected. or focal, anti-epileptic medication will be used to control the seizures. Ophthalmic GME also uses oral corticosteroids for A full diagnostic work-up also helps in ruling out other conditions therapy but may also employ topical ones. If glaucoma results that might present in a similar way but require different from GME then therapy for this is necessary. Again, therapy for treatments. Examples of other causes include viral encephalitis, this result of GME is addressed in a standard way; no specific GME parasitic encephalitis, fungal encephalitis, strokes and tumours. Some dogs with inflammatory disease of the central nervous system will also have inflammation of their joints Our treatment protocol is as follows;
Prednisolone long term starting at a high dose which can gradu-
MRI is able to image the brain in such detail that it is considered nearly a confirming test for GME and meningitis when combined with spinal fluid analysis. CT (CAT scanning) is significantly less Cytarabine (cytosine arabinose) injections for two days every
sensitive in diagnosing these conditions and CT scans can three weeks. Cytarabine is a strong chemotherapy drug and frequently give false negative results. The only way to confirm specifically suppresses white blood cells). GME or meningitis with 100% certainty is by biopsy though, obviously, diagnostics do not get any more invasive than brain Cyclosporin is used is a third drug where there is a recurrence of
surgery. For this reason, 100% confirmation is normally only the GME whilst the patient is on Prednisolone and Cytarabine or where the side effects of these two drug are to severe. TREATMENT
Bloods tests should be taken regularly to check liver, kidney and
The immune system needs to be much suppressed in both patients with GME and in patients with meningitis. Therefore, immune-suppressive drugs are the mainstay in treating these The main side effects of medication are the classic steroid side patients. It is important to note that most patients will effects (increased appetite, increased thirst) and side effects inflammatory CNS disease will require to be hospitalised for 2-7 related to the strong suppression of the immune system by the days as they need intensive veterinary care. combination therapy. Signs of this are vomiting, diarrhoea, Meningitis: Immune-suppression with corticosteroids (such as
prenisolone) is the choice of therapy for meningitis. Once the PROGNOSIS:
disease is controlled, one may begin to gradually drop the As mentioned above, the prognosis for patient with GME can be steroid dose until the minimum dose required to control the poor. However, it is our experience that some patients will survive disease is reached. Most dogs need to be treated for about six more than two years once they have been stabilised during the months. A second drug is added to the medication in dogs with first few weeks on medication. The prognosis in patients with 5-11 Tenters Street, Bishop Auckland, County Durham, DL14 7ADT: 01388 602707 | F: 01388 605660 | [email protected] | www.wear-referrals.co.uk

Source: http://www.wear-referrals.co.uk/GMEMeningitis.pdf