It stresses that in 4 out of the 5 premises investigated, the cause was not FMD but such things as the nature of the "herbage" (e.g. if very short it could be contaminated with rough stones or grit), the damage that can be caused by crunching on salt feed blocks, and stress.
The article states that this condition (referred to as OMAGOD - Ovine Mouth and Gum Obscure Disease) has not previously been described in veterinary literature! So, there exists a condition where sheep and cattle have a variety of these lesions, but are perfectly healthy with clear blood tests. The problem is that genuinely infected sheep will also exhibit superficially similar lesions.
The authors therefore urge a cautionary aproach for FMD control purposes, as lesions can obviously occur without having any link to FMD. The implication is that the correct veterinary approach to the identification of FMD when lesions are found is not to assume automatically that it is FMD, but to look for other causes for the lesions, to look for other symptons of the disease, and to carry out tests.
The article is illustrated with lots of photos of different lesions. Authors are Ayers, Cameron, Kemp, Leitch, Mollison, Muir, Reid, Smith and Sproat. P.S. Don't most livestock owners know that lesions can often occur for a variety of reasons?! "
http://www.mediavets.org.uk/lesions_vetrec.pdf (PDF format 217KB)