Research News: 08/04

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Powerful New Topical NSAID
Your veterinarian will soon be able to offer you something new in the war on your horse’s inflammation.

The FDA granted equine approval for a topical form of the NSAID drug diclofenac.??Surpass, manufactured by Idexx Laboratories, is suspended in fatty beads called liposomes that enhance uptake through the skin and control the rate of absorption.?? Research has shown low circulating levels of the drug, but high levels in the tissues under the application sites.??The advantage compared to oral or injectable anti-inflammatory drugs is lower blood levels, which means less risk of side effects.??

However, diclofenac is an extremely potent NSAID. Dosage instructions must be carefully followed or side effects like ulcers and colic can occur.?? Like all NSAIDs, this drug is best used for short periods of time only, during the acute inflammatory stage following an acute injury or flare up of an old injury.?? It is not intended for long-term use.

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’Ware Pheasant’s Eye
A new plant poisoning in horses has been identified by the University of California Davis. Three horses died after consuming hay that contained the plant summer Pheasant’s Eye (Adonis aestivalis). The plant is a member of the buttercup family and closely resembles a buttercup, except that the flower is bright red. This plant is likely to be found in New York, California and the Northwest.

The horses had symptoms of colic before their death and on postmortem examination were found to have damage to their hearts. Symptoms had started to appear with 24 to 48 hours of eating the contaminated hay, and the horses had been euthanized because of the severity of their symptoms within one to four days after first becoming ill.

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Impacted Horses And Electrolytes
Veterinarians vary in their approach to impaction colics with dehydration, some focusing heavily on intravenous fluids, others on oral fluids. They also have differences in regard to using stool softeners or other additives in oral fluids. A study performed at the Marion duPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, may help determine what’s best.

Researchers compared intravenous lactated Ringer’s solution alone to several oral treatments and found only the oral treatments effectively increased the moisture content of the colonic contents and/or manure.

Both plain water and sodium sulfate caused electrolyte disturbances. Magnesium sulfate (Epsom salts) was not effective. The balanced electrolyte solution was best.

Intravenous fluids are usually indicated to correct dehydration in horses with impactions but aren’t necessarily going to help with the impaction itself. According to this study, tubing the horse with balanced electrolyte solution rather than plain water is the best way to go.

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Injectable Banamine Works Orally
Most veterinarians carry injectable flunixin meglumine, or Banamine, with them, but they may not have an oral version when needed.

A University of Pennsylvania study published in the June 2004 Journal of Veterinary Pharmacology and Therapeutics found that giving the injectable form orally resulted in detectable blood levels as quickly as 15 minutes after dosing, then responsded similarly to regular oral flunixin. The authors or the study concluded that giving the IV form of Banamine orally is fine.

Due to the nature of drug bioavailability, the 10 cc usual IV dose should be increased to about 13.3 cc if you’re going to give it to the horse orally.

Even with the higher dose, there’s a price advantage to using the injectable solution orally rather than the granular form that amounts to about 50?? per dose. If you use a generic flunixin rather than the brand name Banamine product, the savings are even higher.

Note: Just like phenylbutazone, giving flunixin to a horse that has been eating hay delays absorption significantly and can lead to erratic patterns of absorption that could give you poor results when you first start using, and potentially toxic overdoses later on. These drugs are best given in the early morning, before feeding hay, either orally by a dose syringe 15 to 20 minutes before feeding, or mixed into a very small amount of grain.

However, since neither one is particularly appealing it’s best to go with giving it by dose syringe. Either drug can be given suspended in some milk of magnesia to help decrease the chance of any local irritation. Make up with your horse by giving him a small handful of grain right after dosing, but wait 15 to 20 minutes before giving the horse a full feed.