The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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YOUR GUIDE TO THE 2017 AAEP CONVENTION A12 TheHorse.com/AAEP2017 AAEP Wrap-Up THE HORSE March 2018 medically and PSHO-treated horses. They also found that all CHO-treated horses showed some improvement after surgery, compared to only 45% of medically treated horses. Additionally, 65% of CHO horses returned to previous function, compared to 12.5% of medically treated horses. "The study validates CHO as the stan- dard of care," MacKay said. A New EPM-Related Bug? Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease that has two widely accepted protozoal causes: Sarcocystis neurona and Neospora hughesi. However, recently Toxoplasma gondii, which causes toxoplasmosis (a dis- ease that's a concern for pregnant women exposed to litter boxes of infected cats), has caught EPM researchers' attention. Scientists hypothesized that T. gon- dii titers are related to horses showing neurologic signs because, "While toxo- plasmosis is not commonly considered a clinical disease of equines, previous seroprevalence studies have reported differing background rates of Toxoplasma gondii infection in horses globally," wrote the authors. They took serum samples in the fall from horses showing neurologic signs related to EPM, as well as healthy horses in California. They found the horses with neurologic signs were more likely to: ■ Have high T. gondii titers; ■ Be Warmbloods, ponies, or Quarter Horses; ■ Be 1 to 5 years old; and ■ Have lower S. neurona/N. hughesi titers. The last point, MacKay said, is surpris- ing, and he encouraged study replication. "However, this could be the first indica- tion of a third EPM disease," he said. Early EHV-1 Intervention Equine herpesvirus-1 (EHV-1) is a high- ly infectious and fast-spreading respiratory disease, especially at events where horses comingle in close quarters while under travel and competition stress, making them vulnerable to disease. The virus can also cause a deadly neurologic condition, EHV-1 myeloencephalopathy (EHM). To prevent EHV-1 disease and deaths, scientists seek early intervention ap- proaches that might prevent neurologic disease in infected horses, suppress viral shedding, and limit disease spread dur- ing outbreaks. In one study researchers investigated if a preventive course of the antiviral valacyclovir hydrochloride would be more effective than starting treatment after horses showed signs of the disease. The study included 18 aged mares divided into treatment groups before exposure to a neuropathogenic strain of EHV-1. Group 1, the controls, received a placebo; Group 2 received prophylactic (preventive) treatment with valacyclovir hydrochloride 24 hours before EHV-1 ex- posure; and Group 3 didn't receive treat- ment until onset of EHV-1 clinical signs. Horses in Groups 2 and 3 exhibited significantly lower levels of nasal viral shedding than controls. Horses in Groups 2 and 3 also had lower viral loads and, most significantly, said MacKay, they had less-severe ataxia (incoordination). That means treating horses with valacyclovir hydrochloride preventively or at onset of fever during outbreaks might prevent neurologic disease. However, prophylactic treatment or treatment at first fever didn't reduce non-neurologic clinical signs. Fungal Spores To Control Parasites? Scientists tried feeding pellets contain- ing parasite-killing fungi spores to reduce fecal egg counts (FECs) in dewormed horses. The randomized-control trial included three groups of seven horses: 1. An untreated control group; 2. Treated with ivermectin; and 3. Treated with ivermectin and the com- mercially produced pellets. They followed the horses for 64 weeks, checking FECs weekly. All group FEC av- erages were above 500 prior to the study. The control group's FECs stayed above 300. Both groups treated with ivermectin had FECs of 0 for Weeks 2 and 4. But by Week 4 the ivermectin-only group had re- turned to above 300 while the ivermectin/ spore group remained below 300. The results show that manufacturers can successfully include parasite-killing fungi spores in commercially produced pelleted feeds, and that these can biologi- cally extend ivermectin's effect. Hock Injection Accuracy In the first study Santschi recapped, researchers sought to see how accurate vets were at placing intra-articular (IA, in the joint) injections in the two lower hock joints—the centrodistal (CD) and the tarsometatarsal (TMT)—in 12 healthy horses. Vets injected 4 mL of contrast me- dium into each joint. Researchers noted needle repositioning and/or replacement, then took X rays to find out where the me- dium was located within the desired joint. The research team determined that: ■ Veterinarians successfully injected 23 of 24 (96%) TMT joints; ■ They hit the target in just 10 of 24 (42%) CD joints; ■ There was communication (leakage) between the TMT and CD joints in 26% and 20% of successful TMT and CD injections, respectively; and ■ Years of experience did not appear to impact injection accuracy significantly. Santschi said the leakage was likely due to the high injection volume, but could impact withdrawal times in regulatory settings, such as when treating racehorses with IA corticosteroids or non-steroidal anti-inflammatories before a race. Comparing Castration Contraptions The researchers behind this study analyzed two commonly used emascula- tors with different methods of action—the Serra and the Reimer—for castration. The Reimer has a "double crush" action, meaning it first crushes the spermatic DUSTY PERIN Researchers verified one surgical procedure as the standard of care for horses with THO, which causes head-tilting and facial paralysis.