Friday, January 11, 2008

No beneficial effect of treament

Opinions on the importance of tapeworms (Moniezia sp.) to sheep (and goat) health and growth are controversial. Researchers in Germany used two flocks of sheep and several breeds of sheep to determine the effect of treatment (with praziquantel) for tapeworms.

tapeworm segments in sheep fecesIndividual fecal flotations were performed (using a combination of zinc chloride and sodium chloride). Lambs were assigned to treatment (n=117) or control (n=117) groups. The treated animals received a commerical 2.5% solution of praziquantel at 3.75 mg/kg orally, repeated every six weeks for up to 4 treatments. All lambs, treated and control, received oral moxidectin on the same schedule, at the labeled dosage, to remove possible effects of nematodes on lamb health.

At the beginning of the trial, in June-July, 28 to 45% of lambs were positive for tapeworm eggs. The percentage dropped off markedly in both the treated and untreated lambs, such that 0 to 7% of treated animals and 0 to 9% of control lambs had detectable eggs at the last sampling before slaughter, up to 140 days after the beginning of the trial. There was no significant differences in body weight between the groups. In fact, the animals that remained infected with tapeworms were often heavier than the average of the uninfected lambs.

lamb passing a tapewormReinfection presumably occurred on pasture as 11 of 22 lambs last treated 30-36 days before slaughter had juvenile tapeworms in the intestine as did 5 of 45 necropsied up to 29 days after the final treatment. 29 of the 67 control lambs contained juvenile tapeworms.

In this study, the researchers found no clear evidence for pathogenicity. A beneficial effect of treatment for tapeworms could not be demonstrated in this trial.

Source: Wool & Wattles, AASRP Newsletter, October-December 2007.

About praziquantel
Praziquantel is considered to be more effective at removing tapeworms than albendazole (Valbazen®), which is more effective than fenbendazole (SafeGuard®). Praziquantel is marketed in the U.S. primarily for cats and dogs as Droncit®. Some horse dewormers contain praziquantel: Zimecterin® Gold Paste, Equimax™ Paste, and Quest® Plus Gel.

Read article on tapeworms.