Jejunal hemorrhage syndrome (JHS) is an acute, highly fatal enterotoxemic disorder in dairy cattle that has been reported during the last few decades. No specific cause of this syndrome has been identified; however, several studies have revealed a strong association between JHS and infection with Clostridium perfringens type A. A common mold, Aspergillus fumigatus, has also been implicated as a potential causative agent in this disease syndrome. Clinical signs of JHS (including sudden decreases in feed intake and milk production, rapid loss of condition, a right-sided ping audible during simultaneous auscultation and percussion of the abdomen, abdominal distension, and melena or bloody feces) usually develop early during lactation when cattle receive rations that are high in energy and low in fiber. Appropriate preventive strategies have not yet been determined, and intensive medical management with or without surgical intervention is rarely successful. The use of commercially available vaccines that are directed against C perfringens types C and D is of questionable efficacy and not likely to be helpful as a preventative measure. This article highlights the potential etiologic and risk factors, describes common clinical signs, outlines relevant diagnostic testing, and summarizes treatment options and their outcomes.
Objective—To determine prevalence of anthelmintic
resistance in cyathostome nematodes of horses in
the southern United States.
Animals—786 horses on 44 farms and stables in
Georgia, South Carolina, Florida, Kentucky, and
Procedure—Fecal egg count (FEC) reduction tests
were performed on 44 large farms and stables. Horses
on each farm were treated with an oral paste formulation
of fenbendazole, oxibendazole, pyrantel pamoate,
or ivermectin at recommended label dosages. A mixed
linear model was fitted to the percentage reduction in
FEC, accounting for differences among farms, states,
ages, treatments, and treatment by state interactions.
Results—By use of a conservative measure of resistance
(< 80% reduction), the percentage of farms with
anthelmintic-resistant cyathostomes was 97.7%, 0%,
53.5%, and 40.5% for fenbendazole, ivermectin, oxibendazole,
and pyrantel pamoate, respectively. Mean percentage
reductions in FEC for all farms were 24.8%,
99.9%, 73.8%, and 78.6% for fenbendazole, ivermectin,
oxibendazole, and pyrantel pamoate, respectively.
Pairwise contrasts between states for each treatment
revealed that in almost all instances, there were no significant
differences in results between states.
Conclusions and Clinical Relevance—The prevalence
of resistance found in this study was higher than that
reported previously, suggesting that anthelmintic resistance
in equine cyathostomes is becoming a major problem.
Furthermore, data from these 5 southern states,
which are geographically and physiographically distinct,
were remarkably similar. This suggests that drug resistance
in cyathostomes is highly prevalent throughout
the entire southern United States and probably nationwide.
(J Am Vet Med Assoc 2004;225:903–910)