Parenteral Selenium Supplementation Benefits Foot Rot-Affected Sheep
ACVIM 2008
J.A. Hall1; R.J. Van Saun2
1Oregon State University College of Veterinary Medicine, Corvallis, OR, USA; 2Pennsylvania State University College of Agricultural Sciences, University Park, PA, USA

The purpose of this study was to determine the clinical effectiveness of selenium (Se) supplementation on foot rot (FR) prevalence and recovery in sheep. A prospective, 15-month, placebo-controlled clinical trial was undertaken in a commercial sheep flock.

FR-affected sheep were randomly divided into 2 groups (n=19). An additional control group of 19 sheep without FR (Control) were identified. Sheep feet were examined, trimmed, and scored for FR using a scale of 0 (no lesions) to 4 (extensive lesions). Half the FR-affected sheep were treated with 5 mg injectable Se (FR-Se) at 1-month intervals for the duration of the study; the other half were given saline injections (FR-Sal). Controls received no treatment. Sheep feet were reexamined, trimmed and rescored at 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. Whole-blood Se data were analyzed by ANOVA for repeated measures; foot scores were assessed by nonparametric analyses with main effects of month and treatment.

At time 0, Control sheep (255 ng/ml) had higher (P<0.05) whole blood Se concentrations compared with FR-Se (205 ng/ml) and FR-Sal (211 ng/ml) sheep. By 6 months, FR-Se sheep (317 ng/ml) had whole blood Se concentrations greater (P<0.05) than both Control (281 ng/ml) and FR-Sal (277 ng/ml) sheep. FR-Se ewes showed a faster decline in highest lesion score at 3 (P=0.05) and 6 (P=0.03) months, a greater decrease in the number of feet with foot score >0 at 6 (P=0.02) months, and a tendency for a lower total severity score at 6 (P=0.07) 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 CI, Odds Ratio) for FR, though this relationship was only significant (P=0.04) at 6 months of the study.

In sheep with FR, Se supplementation results in higher whole-blood Se levels and more rapid improvement of foot lesions compared with saline treatment.

Speaker Information
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Jean Hall, DVM, PhD, DACVIM
Corvallis, OR

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