Strangles On The Rise
trangles appears to be on a rise this year, making this a true health alert for all horses, especially those traveling and competing or in barns with a lot of horse traffic. Some of the outbreaks have indeed been Strep equi, the strangles bacterium, while others are a closely related strain, Strep zooepidemicus. Some of the zooepidemicus strains are highly antibiotic-resistant, including the two most commonly used, penicillin and trimethoprim/sulfa.
Symptoms with both organisms are similar and include high fevers, purulent discharge, lymphatic involvement and an incidence of purpura hemorrhagica in 10% of the cases.
The intranasal strangles vaccination (Pinnacle I.N.) is currently the best protective strategy available, but it may not provide protection against strains different from those used in the vaccine, or against Strep zooepidemicus.
Horses showing any signs suspicious of strangles should be isolated immediately and all horses in the barn monitored carefully for temperature elevations, discharge and appetite changes. Cultures of purulent discharges should be done immediately to identify the strain and its antibiotic sensitivity.
While many veterinarians prefer to hold off on antibiotics for fear they will slow the maturation and drainage of abscesses, horses severely off feed or showing any early signs of a purpura reaction (e.g. edema) should be aggressively treated with the appropriate antibiotic.
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Anti-Slaughter Legislation
Federal legislation to ban the slaughter of horses for human consumption, as well as both domestic and international transport of live horses intended for slaughter for human consumption, has been introduced to the House by Rep. John Sweeney, N.Y., cochairman of the Congressional Horse Caucus, and Rep. John Spratt, Jr., S.C.
The legislation is titled the American Horse Slaughter Prevention Act (AHSPA), house bill H.R. 857. Those interested in ending this practice should contact their representatives in the House and Senate to voice their support. Letters, faxes and phone calls carry more weight than e-mail. Detailed contact information can be found at: www.saplonline.org/congress.htm.
The slaughter of horses for meat has dropped in recent years, but the two plants presently operating in Texas continue to receive horses transported from 47 states.
The Texas plants are operating in violation of existing state law and were ordered to close, but they’re challenging the validity of the law in court. California has already outlawed the transport and slaughter of horses for meat. Legislation is also pending in Illinois, where the third U.S. equine slaughter plant is poised to reopen following reconstruction after a fire two years ago.
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Drugs In The Hair
Hair sampling has been used as a method of drug-use detection in people for quite some time. Now it may have potential for horses, too. A German study appearing in the Equine Veterinary Journal showed that a 10-day course of clenbuterol was detectable in mane and tail hair for up to a year. Clenbuterol is a potent bronchodilator that is also used as an anabolic for “bulking up” horses for sales. In addition, a United Kingdom study looked for drug residues in the hair of horses known to have received omeprazol, procaine penicillin, trimethoprim/sulfa or metronidazole. All drugs except the omeprazol were easily detected.
Hair testing won’t replace urine and blood for competition horses because it takes too long. However, it may be useful at a prepurchase exam or to test for unscrupulous drug use should the horse go lame after they buy him. Hair-drug analysis can tell you if a drug was given in the past and when.
The German study tested for clenbuterol serially over a year and found that the drug-positive segments grew out with the hair, so that the drug first appeared in segments taken close to the roots then traveled down the hair shaft over time. The technique may be useful for drugs whose effects last well beyond their current detection times, like EPO, and for late testing should evidence surface after a horse has competed.
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Sidebone Note
Many horsemen avoid a horse with ringbone, but they’ll give a horse with sidebone a try, figuring it’s not likely to affect the horse’s soundness — at least not soon. It may be time for a change in thinking.
According to a study published in Equine Veterinary Journal, researchers from the Department of Veterinary Clinical Studies at the University of Helsinki determined sidebone may indeed be significant in horses with a vague lameness. The researchers looked at bone scans, X-rays and lameness histories in 21 horses.
While all the horses had some ossification, four had obviously different bone scan radionucleotide uptake in one wing and a mild lameness that disappeared with anesthesia to the nerves supplying that area. Two horses had no obvious lameness on exam but had a history of being “stiff” or gait problems. X-rays revealed the ossified portion of involved cartilage was wider and more irregular than calcifications in other lateral cartilages of the same horse. Ossification of the collateral cartilages is most likely to occur in hooves that are narrow or contracted.
