Benign footrot--an epidemiological investigation into the occurrence, effects on production, response to treatment and influence of environmental factors.
Benign footrot was studied in 1 1/2-years-old Merinos on 2 farms in central Victoria from September 1987 to August 1990, inclusive. Treatment groups of 100 sheep grazed together with the remaining untreated sheep. Inspections were carried out every 3 weeks during the spring transmission period until the number of lesions greater than score 2 dropped below 3%. At each inspection, each sheep was weighed and lesion scores for each foot and digit were recorded, the treated group of sheep was treated by standing in 20% (w/v) zinc sulphate-sodium lauryl sulphate for 1 hour, and bacteriological samples were randomly collected from 5 sheep with and 5 without lesions. Dichelobacter nodosus organisms were obtained from sheep in both groups. Laboratory tests indicated benign organisms in flock A and low virulence, intermediate organisms in flock B. During the first 2 years, the number and severity of lesions were greater in flock A than in flock B. However, in the third year, with an early 'autumn break', there was a rapid and severe outbreak of footrot in flock B; 98% of the flock had lesions at the first inspection in July 1989. Flock A had a less dramatic increase in lesions of footrot. Both treated and untreated groups in flock B recovered rapidly between the third and fourth inspections. A later increase in lesions for both flocks coincided with damage caused by barely grass seeds. During this period there was a significant difference (P < 0.001) in body weight between the treated and untreated sheep on farm B.(ABSTRACT TRUNCATED AT 250 WORDS)
Glynn
T
T
Department of Agriculture, Bendigo, Victoria.
D000818:Animals; D001835:Body Weight; D005260:Female; D005535:Foot Rot / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D001467:Hordeum; D008297:Male; D015995:Prevalence; D011891:Rain; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology; D013696:Temperature; D014935:Wool