Noteworthy: 10/03

Time Your Vaccinations
ou may want to pay a little more attention to when you schedule your vaccinations in terms of exercise and deworming schedules. At least that’s what two different studies at the Louisiana State University School of Veterinary Medicine seem to indicate.

Researchers looked at protection provided by an influenza vaccine in resting ponies compared to ponies that were heavily exercised.??The rested ponies seemed to get full disease protection from the vaccination. However, the exercised ponies showed a depressed immune response to a challenge of virus and weren’t protected.

Obviously, you should always avoid exposure to infectious disease in stressed horses, even if the horses are vaccinated. However, the impact of heavy-exercise stress on the horse’s immune system can be underestimated, especially at vaccination time.

Gradually conditioning your horse for the level of exercise you expect and avoiding sudden, unaccustomed increases in exercise demands are important.??

Working horses will also benefit from generous levels of antioxidant vitamins and minerals to support their immune function. An adequate dietary provision of branched chain amino acids and glutamine is also indicated to avoid dangerous depletion of these amino acids with negative effects on the immune system.

And The Worms …
Worms can affect immunizations, too. Parasites not only rob your horse of nutrients and potentially injure the bowel, they’re also a constant drain on the immune system.

Ponies with light worm burdens showed a slight enhancement of their response to vaccines, probably as a result of low-level nonspecific stimulation of the immune system. However, ponies with moderate or heavy worm burdens showed significantly depressed responses in terms of both antibody levels and immunity.


Penicillin Stronger Against Pus
Trimethoprim/sulfadiazine oral antibiotics are a popular alternative to injectables,widely used to treat many equine infections.??However, if there’s pus, you might want to consider penicillin instead.

A study at the University of Utrecht and published in the Journal of Veterinary Pharmacology and Therapeutics compared the effectiveness of trimethoprim/sulfadiazine to penicillin injections in an experimental Strep zooepidemicus infection (similar to strangles).??The researchers concluded penicillin is a better choice when pus is present in an infection.

The test ponies treated with the oral timethoprim/sulfa showed only limited reduction in live bacteria, and all eight developed abscesses. However, seven of eight ponies treated with penicillin had the infection completely eliminated.

The authors attributed the difference to trimethoprim/sulfa being unable to penetrate pus well. They concluded that even when organisms show culture results that indicate the organisms should be sensitive to either trimethoprim/sulfa or penicillin, veterinarians should choose penicillin in conditions with pus.


West Nile Vaccine Competition
As we said in May 2003, Fort Dodge applied for permission to field test a DNA vaccine for West Nile. Now Merial has applied for permission to field test an equine recombinant DNA vaccine for West Nile.?? The technology used to prepare this vaccine is the same as that being used for the human vaccine currently in development.??Selected portions of WNV DNA are inserted into a canarypox virus, which does not cause disease in horses.?? Vaccines of this type have replaced the killed-virus vaccines — like the currently available West Nile vaccine — for use in people.


Heat Therapy For Backs
Back and rump-muscle soreness can plague any hard-working horse.??You know heat’s the key, as it’s soothing and relaxes spasmed muscles, but this is a difficult area to get it to.??Try soaking an oversize heavy bath towel in steaming water with Epsom salts and/or liniment added. Place the hot towel on the horse’s back, then place a lawn/leaf-sized plastic garbage bag on top of the towel. The plastic bag will conform to the horse and trap heat for about 30 minutes. We recommend you tie or hold your horse during the therapy.

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