Absence of three known benzimidazole resistance mutations in Trichostrongylus tenuis, a nematode parasite of avian hosts

Benzimidazole (BZ) resistance is widespread in nematode parasites of livestock, but very little is known about the levels of BZ resistance in parasites with avian hosts. We investigated BZ resistance in Trichostrongylus tenuis, a nematode parasite of red grouse, Lagopus lagopus scotica. BZ anthelmintics had been in use in this system for up to 15 years, yet existing phenotypic evidence for resistance was inconclusive. We screened 1530 individuals from 14 populations at the principal β-tubulin locus for BZ resistance (isotype 1, residue 200) and 940 of these at two further resistance sites (isotype 1, residue 167; isotype 2, residue 200). No BZ resistant genotypes were found. Alternative mechanisms may be responsible for BZ resistance in this system, or the method and timing of treatments may reduce selection pressure for BZ resistance by creating substantial refugia for susceptible genotypes.     

Use of a flexed dorsoplantar radiographic view of the talocrural joint to evaluate lameness in two dogs.

A flexed dorsoplantar radiographic view of the talocrural joint was a useful additional view to diagnose abnormalities of the lateral trochlear ridge of the talus of 2 dogs. This view outlined the subchondral bone of both trochlear ridges of the talus and the apposing cochlea tibiae of the distal portion of the tibia. The tarsus was flexed at the level of the talocrural joint, and an x-ray beam was centered on the joint. With this additional view, fractures of the lateral trochlear ridge were readily diagnosed. This view would help to demonstrate osteochondral lesions of the lateral trochlear ridge.