Premium
Residual effects of Mycobacterium avium infection on susceptibility of sheep to copper toxicity and efficacy of treatment with tetrathiomolybdate
Author(s) -
Suttle N. F.
Publication year - 2012
Publication title -
veterinary record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.261
H-Index - 99
eISSN - 2042-7670
pISSN - 0042-4900
DOI - 10.1136/vr.100716
Subject(s) - glutamate dehydrogenase , toxicity , copper , copper toxicity , lactate dehydrogenase , medicine , superoxide dismutase , zoology , gastroenterology , hay , chemistry , microbiology and biotechnology , biology , enzyme , biochemistry , glutamate receptor , receptor , organic chemistry
Posthaemolytic copper poisoning (post‐HCP) in one of six, one‐year‐old, uninfected sheep (group O) on a Mycobacterium avium experiment prompted an evaluation of copper status and hepatotoxicity in 17 surviving cohorts. Group O had higher mean plasma Cu and δ‐glutamyl transferase (GGT) activity and more variable bile acid (BA) concentrations and glutamate dehydrogenase activities (GDH) than two groups infected with M avium soon after birth. Ammonium tetrathiomolybdate (TTM; 3 x 1.7 mg/kg LW) was given subcutaneously over seven days and the pelleted, complete diet replaced by hay, low in copper. Plasma BA immediately declined and was followed by GDH, but erythrocyte superoxide dismutase activity (ESOD) became severely inhibited and took 18 days to recover. Plasma BA and GDH rose sharply after 18 days in uninfected sheep and they became hypercupraemic. TTM treatment was repeated from day 42 and had removed all group differences by day 110 but only after further inhibition of ESOD. M avium infections probably lessened the severity of pre‐HCP by reducing copper retention but may predispose grazing livestock to hypocupraemia. The capacity of TTM to reduce liver Cu has probably been overestimated and side effects on cuproenzyme activity underestimated.