New Websites Offer Latest Information on Equine Protozoal Myeloencephalitis and West Nile Virus

SUMMIT, N.J. – Feb. 28, 2012 – Merck Animal Health Unveils New Websites to Help Horse Owners Understand these two devasting diseases.

Equine protozoal myeloencephalitis (EPM) and West Nile virus (WNV) – two diagnoses veterinarians don’t want to give and horse owners dread hearing. To help horse owners in the United States stay up-to-date on the latest information regarding these devastating diseases, Merck Animal Health has developed two new comprehensive websites – and – EPM resource center

EPM is a progressive and potentially fatal infection of the central nervous system, which is caused by the single-celled protozoal microorganism,Sarcocystis neurona (S. neurona). Because the disease is progressive, early detection and veterinary intervention are critical to the horse’s chance of recovery. offers a centralized location for horse owners to research EPM and learn to recognize the early onset of the disease.

The website provides owners with:

  • Up-to-date disease information and research through webinars, videos, fact sheets, educational brochures, etc.
  • News and events surrounding EPM
  • Management strategies to aid in prevention of EPM
  • Treatment options to discuss with their veterinarian

The website also offers information on Merck Animal Health’s new EPM treatment product, PROTAZIL® (diclazuril) 1.56%. PROTAZIL is the only FDA-approved, alfalfa-based, pelleted EPM treatment product on the market.

“EPM can cause irreversible damage to the horse’s brain or spinal cord and is more likely to cause permanent damage if the disease is not detected early,” said Wendy Vaala, V.M.D., Dipl. ACVIM, senior equine technical services veterinarian for Merck Animal Health. “Although EPM only affects less than 1 percent of horses, it is critical that owners know what to do, just in case. Owners can increase their horse’s chance of a full recovery by talking to their veterinarian and educating themselves through websites like”

To stay informed on the latest EPM and PROTAZIL information, visit – WNV information and more

Though less evasive than EPM, West Nile virus infection is still a threat in the United States. provides horse owners with many educational resources on WNV, as well as information on vaccines that aid in helping prevent this disease.

“We see cases of West Nile virus in horses every year in the United States,” said Craig Barnett, D.V.M., senior equine technical services veterinarian for Merck Animal Health. “West Nile is still a threat to our horses and it is important for owners to understand the disease and, more importantly, understand the need for prevention.”

In addition to providing horse owners with information on WNV, also includes information on vaccinations and other important equine diseases like:

  • Eastern equine encephalomyelitis
  • Western equine encephalomyelitis
  • Rabies
  • Tetanus
  • Equine influenza
  • Equine herpesvirus

The site also provides information on Merck Animal Health’s new WNV vaccine portfolio:

  • PRESTIGE® V + WNV (EWT + EIV + EHV-1&4 + WNV)

This portfolio is a completely customizable lineup of WNV vaccines that can be tailored to the needs of each individual horse. The WNV fraction of the new PRESTIGE and ENCEVAC combination vaccines, as well as EQUI-NILE, demonstrated a statistically significant reduction in clinical signs of neurologic disease, encephalitis, viremia and rectal body temperatures in a severe WNV intrathecal challenge study.

To learn more, visit To learn more about Merck Animal Health’s entire product portfolio visit Veterinarians also can learn more by contacting their distributor or sales representative. Horse owners can learn more by contacting their veterinarian.

Use of PROTAZIL (diclazuril) 1.56% Antiprotozoal Pellets is contraindicated in horses with known hypersensitivity to diclazuril. For use in horses only. Do not use in horses intended for human consumption. Not for human use. Keep out of reach of children. The safe use of PROTAZIL (diclazuril) 1.56% Antiprotozoal Pellets in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. The safety of PROTAZIL (diclazuril) 1.56% Antiprotozoal Pellets with concomitant therapies in horses has not been evaluated.

Today’s Merck is a global healthcare leader working to help the world be well. Merck Animal Health, known as MSD Animal Health outside the United States and Canada, is the global animal health business unit of Merck. Merck Animal Health offers veterinarians, farmers, pet owners and governments one of the widest ranges of veterinary pharmaceuticals, vaccines and health management solutions and services. Merck Animal Health is dedicated to preserving and improving the health, well-being and performance of animals. It invests extensively in dynamic and comprehensive R&D resources and a modern, global supply chain. Merck Animal Health is present in more than 50 countries, while its products are available in some 150 markets. For more information, visit






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