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Equine Protozoal Myeloencephalitis (view source)
Revision as of 13:29, 20 July 2010
, 13:29, 20 July 2010→Treatment
*'''Sulfadiazine and pyrimethamine combination, 'Re-Balance'''': administered PO daily for a minimum of 90 days. Due to availability and ease of administration, some use an off-label regimen of trimethoprimsulfa tablets with pyrimethamine tablets. ''Mode of action'': trimethoprim, sulfadiazine, and pyrimethamine all inhibit enzymes of folic acid synthesis. ''Efficacy'': 61.5% improvement by one clinical grade.(98 in furr)''Potential adverse effects'': bone marrow suppression (mild anaemia, leucopenia, neutropenia, thrombocytopenia), fever, anorexia, depression, acute worsening of ataxiam altered reproductive performance in stallions (19 in IVIS 4), congenital defects(20 in IVIS 4) and abortion. Folic acid deficiency may also cause gastrointestinal disturbances such as glossitis.(18 in IVIS 4) Blood dyscrazias are typically self-limiting and resolve on withdrawal of treatment. (Furr)
*'''Sulfadiazine and pyrimethamine combination, 'Re-Balance'''': administered PO daily for a minimum of 90 days. Due to availability and ease of administration, some use an off-label regimen of trimethoprimsulfa tablets with pyrimethamine tablets. ''Mode of action'': trimethoprim, sulfadiazine, and pyrimethamine all inhibit enzymes of folic acid synthesis. ''Efficacy'': 61.5% improvement by one clinical grade.(98 in furr)''Potential adverse effects'': bone marrow suppression (mild anaemia, leucopenia, neutropenia, thrombocytopenia), fever, anorexia, depression, acute worsening of ataxiam altered reproductive performance in stallions (19 in IVIS 4), congenital defects(20 in IVIS 4) and abortion. Folic acid deficiency may also cause gastrointestinal disturbances such as glossitis.(18 in IVIS 4) Blood dyscrazias are typically self-limiting and resolve on withdrawal of treatment. (Furr)
*'''Ponazuril (Marquis, Bayer Animal Health)''': PO daily for 28 days, use in pregnant animals is off-label. ''Mode of action'': ponazuril is a triazinetrione antiprotozoal that targets the “apicoplast” organelle and inhibits the respiratory chain. ''Efficacy'': well absorbed PO, achieves steady state therapeutic concentration in CSF within 3 days(100 in Furr), clinical response within 10 days, 60% improvement by at least one clinical grade, 8% relapse within 90 days of stopping treatment(91 in Furr). ''Potential adverse effects'': none in a multi-centre field study (IVIS 4), no systemic toxicity even at high doses.(101 in Furr)However, the manufacturer reports signs that may have been related to treatment including blisters on nose and mouth, skin rash or hives, loose stools, mild colic, and a seizure.(IVIS 4)
*'''Ponazuril (Marquis, Bayer Animal Health)''': PO daily for 28 days, use in pregnant animals is off-label. ''Mode of action'': ponazuril is a triazinetrione that targets the “apicoplast” organelle and inhibits the respiratory chain. ''Efficacy'': well absorbed PO, achieves steady state therapeutic concentration in CSF within 3 days(100 in Furr), clinical response within 10 days, 60% improvement by at least one clinical grade, 8% relapse within 90 days of stopping treatment(91 in Furr). ''Potential adverse effects'': none in a multi-centre field study (IVIS 4), no systemic toxicity even at high doses.(101 in Furr)However, the manufacturer reports signs that may have been related to treatment including blisters on nose and mouth, skin rash or hives, loose stools, mild colic, and a seizure.(IVIS 4)
*'''Diclazuril''': PO, daily for 28 days, approved by FDA for use as top-dress tablet but not commercially available ''Mode of action'': chemically similar to ponazuril but mechanism of action unknown. ''Efficacy'': one study reported clinical improvement in 58% of cases.(98 in Furr) ''Potential adverse effects'': none found in one efficacy study.(Furr) Reported problems in a multi-centre field study included worsening neurologic status and laminitis but these were not proven to be related to treatment. (IVIS 4)
*'''Nitazoxanide, NTZ (Navigator, Idexx Pharmaceuticals)''': no longer commercially available in the US. ''Mode of action'': a member of the 5-nitrothiazole class of antiparasitics that inhibits the pyruvate:ferredoxin oxidoreductase (PFOR) enzyme dependent electron transfer reaction essential for anaerobic energy metabolism.(IVIS 4) ''Efficacy'': 60% success rate in an FDA-regulated study.(98 in Furr) ''Potential adverse effects'': adverse effects and death at high doses(98), fever, anorexia, diarrhoea, lethargy, depression and laminitis recorded at lower doses. Toxic signs usally resolve upon cessation of treatment.(Furr)'''''Caution''': 'administration of nitazoxanide can disrupt the normal microbial flora of the gastrointestinal tract leading to enterocolitis. Deaths due to enterocolitis have been observed while administering the recommended dose in field studies.''''''(IVIS 4)
Prolonged, off-license treatment is often instigated after 1 month, based on repeated clinical examination. Even successfully treated cases may remain immunoblot positive for long periods, thus aiming for seronegativity is unrealistic.(Furr) A lack of response to treatment suggests that the diagnosis should be re-assessed. Another month's worth of treatment is recommended for partial responders.(Furr)
===Ancillary medication===
===Ancillary medication===