Effect of breed on response to foot rot treatment in mature sheep and lambs
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 P P P P P P P
Genetic and phenotypic aspects of foot lesion scores in sheep of different breeds and ages.
Footrot is a costly endemic disease of sheep. This study investigates the                    potential to decrease its prevalence through selective breeding for decreased                    lesion score. Pedigreed mule and Scottish Blackface (SBF) ewes were scored for                    lesions on each hoof on a 0 to 4 scale for up to 2 (SBF ewes) or 4 (mules) times                    over 2 years. One score was obtained for SBF lambs. An animal was deemed to have                    lesions (severe lesions) if at least one hoof had a score of at least 1 (2). The                    prevalence of lesions was 34% in lambs, 17% in SBF ewes and 51% in mules. The                    heritability of lesions (severe lesions) analysed as repeated measurements of                    the same trait in a threshold model was 0.19 (0.26) in SBF ewes and 0.12 (0.19)                    in mules. Estimates for the sum and maximum of scores as well as the number of                    feet affected were much lower, as were estimates for permanent animal effects                    (i.e. non-genetic effects associated with an animal). When successive scores on                    the same animal were analysed as correlated traits, heritability estimates for                    most traits tended to be higher, except for severe footrot in mules where                    estimates varied greatly over time. The phenotypic correlations between                    successive scores in SBF ewes were close to 0, genetic correlations were                    moderately positive (0.18 to 0.55). Correlations in mules were generally of a                    similar size, but some genetic correlations were higher (up to 0.92). There was                    a clear trend for heritabilities for lesions and severe lesions to increase with                    higher prevalence of lesions, even when analysed in a threshold model.                    Heritability estimates for traits that combine scores over several events in                    mules, identifying the more persistently affected animals, ranged from 0.12 to                    0.23 with the highest estimates for the average number of feet that were                    (severely) affected in animals scored for a minimum at two events. The                    heritability of all lesion traits in lambs was estimated as 0. It is concluded                    that selection for lower lesions is possible in ewes but not lambs, and that a                    simple binary score at an animal level is at least as effective as a                    comprehensive score at hoof level. Given the low repeatability of lesion scores,                    repeated measures over time will improve effectiveness of selection. Selection                    across environments (flocks, seasons) with different prevalences of lesions                    scores will need to take account of variation in the heritability.
Formaldehyde allergy. Incidence and patch test problems.
Conflicting reports on formaldehyde allergy led us to analyze our clinical and patch test data. While patch-test positive formaldehyde allergy occurred in less than 5% of our eczematous patients, when present it was usually clinically significant. In three patients formaldehyde allergy caused garment contact dermatitis. Patch tests with formalin require critical evaluation as false-positive irritant responses may occur, especially if 4% or 5% formalin is used. The high incidence of so-called latent formaldehyde allergy found in some studies probably represents an artifact from misinterpretation of irritant reactions. The patch test with 2% formalin is a useful procedure in the investigation of contact dermatitis.