Abstract :
Our objective was to determine whether breed differences existed in response to exposure and treatment of virulent foot rot.
Dorset (DS), 1/2 Dorper (DX), 3/4 or greater Dorper (DO), Gulf Coast Native (GC), Katahdin (KA), and St. Croix (SC) mature
sheep and lambs were exposed to virulent foot rot in spring 2003. Treatment for foot rot was initiated in 132 lambs and 262 mature
sheep in late July. There were eight pasture groups treated, two of which were minimally exposed to foot rot. Treatment included
hoof paring, foot bathing with 10% zinc sulfate with surfactant, allowing the zinc sulfate to dry on the foot and moving to a small
paddock that had not been exposed to small ruminants for more than 14 d. Foot bathing was repeated every 7 d for a maximum of five
treatments. Animals that had not responded (odor or any indication of persistent infection) by then were culled from the flock. As
an indication of severity of foot rot for each animal, the number of areas on the foot (interdigital and two digits for each foot), a foot
score (0 = no infection found; 1 = infection of digits only; 2 = infection of interdigital area and could include digits), and presence
of characteristic odor was recorded. Least squares means for number of areas infected were greater for mature than growing sheep
(2.07±0.16 versus 0.88±0.31; P < 0.001), for highly than minimally exposed groups (2.89±0.17 versus 0.05±0.29; P < 0.001),
and DX compared with other breed types (P < 0.03). Percentage of sheep with odor was similar between age groups, was greater
in the highly exposed groups (11.4±1.9 versus 2.1±3.4; P < 0.02), and greater in DO compared with DS, KA, and SC breeds
(P < 0.001). Foot score was similar among breeds and greater in the highly exposed groups (age by group, P < 0.05). Percentage
of sheep culled for failure to respond to foot bath treatment was greater for the highly than minimally exposed group (22.9±2.3
versus 0.0±3.9; P < 0.001) and greater for mature sheep compared with lambs (P < 0.001) and similar among breeds. In November,
four ewes in a large group and two lambs in a small group were determined to have foot rot and were immediately culled. The two
groups containing these ewes were re-treated for 2 weeks and were determined to be free of foot rot (no further signs of lameness).
Response to foot rot eradication appeared to be similar among breeds examined.
Published by Elsevier B.V.
