News You Can Use May 2012

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On March 16, the FDA issued a warning to veterinarians and horse owners who have been using compounded pergolide to treat Cushing?s disease in horses. With the commercial brand Prascend Tablets FDA-approved to treat this condition in horses, the allowance for compounded and ?extra label? versions is gone.

When there is no version of a medication specifically approved for a species, the FDA will allow compounding under the ?extra-label use? rulings. This was the case with the human version of pergolide used to treat Cushing?s horses. When that human medication was withdrawn from the market due to human complications, the FDA allowed compounding pharmacies to make an equine version. However, now that there is an approved equine version of the medication, compounding is no longer allowed.

Prascend was approved in September 2011. While compounding should have stopped immediately, it appears that the FDA gave everyone a ?grace period? to allow already manufactured supplies to be used, but they now plan to enforce their rulings.

NEW RABIES STRAIN

The Central Veterinary Laboratory in Dar es Salaam, Tanzania, identified a new rabies virus strain from a civet (a cat-like mammal) that attacked a child. The viral identification came from an area of the Serengeti that has been considered to be rabies-free since 2000.

So far, the closest genetic relation for this virus appears to be a bat strain from Eastern Europe, making it likely this is a variant of a bat strain of rabies. Here in North America, rabies-positive animals can have their viral strain identified and linked to the likely source, i.e., raccoon rabies, skunk rabies, bat rabies, etc.

The concerns for our horses in North America are two-fold:

First, while tHere's no reason to worry, this shows again what a resilient virus rabies is. An area felt to be totally rabies-free truly isn?t. When bats are involved, they can fly freely across boundaries and be stowaways.? So, keep your horses vaccinated annually. Rabies is endemic in North America, meaning that the virus is here, has been here, and is unlikely to be eradicated.

Second, if you're involved in exporting horses to southern Africa or importing horses from there, the rules regarding vaccinations and quarantines may get changed.

HORSE FEED RECALL

Compared to pet-food recalls, horse-feed recalls are unusual. But, in March, Western Feeds, in Nebraska, recalled two lots of its Kountry Buffet 14% feed (lots M718430 and M720280), as it may contain monensin sodium or Rumensin. This medication is a livestock and poultry growth promotant that can be fatal to horses. Consumers who purchased this product can contact Western Feed at 308-247-2601.

According to the FDA, the bags were distributed in December, mainly in Nebraska and Wyoming.

Reports of dead horses filtered into Western Feed. Private tests revealed a potentially harmful level of monensin sodium in these lots. More testing is being conducted, but if you have these lot numbers, stop using it immediately.

The amount of monensin consumed will influence the signs shown by horses. Small amounts show up as a loss of appetite and mild colic. Larger amounts lead to full-blown colic, sweating, decreased coordination and the inability to stand. Affected horses may be stiff and sweat profusely. Cardiac damage may occur.

Article by Contributing Veterinary Editor Deb Eldredge, DVM.