Effect of parenteral selenium administration to sheep on prevalence and recovery from footrot.
BACKGROUND
Insufficient intake of selenium (Se) is common in many regions, and can contribute to increased susceptibility to and prolonged recovery from infectious diseases.


OBJECTIVE
To determine the effect of Se administration in decreasing the severity and prevalence of footrot in sheep.


METHODS
Thirty-eight footrot-affected and 19 nonaffected sheep from a commercial flock of known high incidence of footrot.


METHODS
Placebo-controlled, prospective, 15-month clinical trial. Footrot-affected sheep were randomly assigned into 2 groups (n = 19) and injected with either 5 mg Se (footrot [FR]-Se) or saline (FR-Sal) at 1-month intervals for the duration of the study. Unaffected sheep (controls) received no treatment. Sheep feet were examined, trimmed, and scored for footrot with a scale of 0 (no footrot) to 4 (extensive) at 0, 3, 6, 9, and 15 months. Sheep were also bled at time 0 and then at 3, 6, and 15 months to assess whole blood Se concentrations.


RESULTS
At time 0, control sheep (255 +/- 11 ng/mL) had higher (P < .05) whole blood Se concentrations compared with FR-Se (205 +/- 12 ng/mL) and FR-Sal (211 +/- 14 ng/mL) sheep. By 6 months, FR-Se sheep (317 +/- 9 ng/mL) had whole blood Se concentrations greater (P < .05) than both control (281 +/- 14 ng/mL) and FR-Sal (277 +/- 16 ng/mL) sheep. FR-Se ewes showed a faster decline in highest lesion score at 3 (P= .012) and 6 (P= .0036) months, and a greater decrease in the number of feet with foot score >0 at 6 (P= .020) months compared with FR-Sal ewes. Sheep with blood Se concentrations <300 ng/mL were at 3.5 times greater risk (1.1-12.1 confidence interval, odds ratio) for FR, although this relationship was only significant (P= .04) at 6 months of the study.


CONCLUSIONS
In sheep with footrot, improved Se status in conjunction with routine control practices result in more rapid improvement of foot lesions.
Hall
J A
JA
Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Dryden Hall 206, Corvallis, OR 97331-4802, USA. jean.hall@oregonstate.edu
Bailey
D P
DP
Thonstad
K N
KN
Van Saun
R J
RJ
D000818:Animals; D020376:Dichelobacter nodosus / Q000254:growth & development*; D005260:Female; D005535:Foot Rot / Q000097:blood / Q000188:drug therapy* / Q000382:microbiology / Q000517:prevention & control; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D015995:Prevalence; D011446:Prospective Studies; D012643:Selenium / Q000008:administration & dosage* / Q000097:blood; D012756:Sheep; D012757:Sheep Diseases / Q000097:blood / Q000188:drug therapy* / Q000382:microbiology / Q000517:prevention & control
D012643:Selenium