© 2004-2012 Horse Tack Review
Extreme Weather Conditions Spark Potomac Horse Fever Epidemic Throughout U.S.
Horse Health - Press Release
Heavy rains, standing water and flooding
have led to increasing levels of Neoriketssia risticii (previously known as
Ehrlichia risticii) cases - more commonly known as Potomac Horse Fever -
across the United States. Outbreaks have been seen throughout the East Coast
and extremely wet weather has made conditions perfect for the disease in the
Midwest as well, affecting states such as Oklahoma. Equine media outlets are
currently tracking a severe outbreak in New York with fatalities already
Vaccination against Potomac Horse Fever (PHF) - including a fall booster
shot in this year's epidemic - is a critical component in the fight to save
horses from the deadly disease. PHF-Gard(TM), from Pfizer Animal Health, has
been shown in scientific studies to be 80% effective in preventing infection
by Neoriketssia risticii bacteria. Horses that have been vaccinated may
become infected, but they may also experience a less severe form of PHF, which
increases their chances for survival.
"I have no doubt that vaccination and a booster shot is absolutely needed
to save horses' lives," said Robert Holland, DVM, PhD, Senior Equine Technical
Services Veterinarian at Pfizer Animal Health. "Horse owners and veterinarians
are concerned about potentially fatal diseases like West Nile Virus, but the
truth is that as many, or even more horses in certain regions, may contract,
or even be killed, by Potomac Horse Fever this year."
Neoriketssia risticii is carried by fresh water snails, which can transmit
the disease to 17 different species of aquatic insects. The horse then
acquires the disease by ingesting these bugs, which can spread out onto
pastures and throughout water supplies. The disease often requires nine to
twelve days of incubation before symptoms appear.
"Owners need to understand that this is a very serious disease," said Dr.
Holland. "Horses are dying because the symptoms of infection aren't easily
recognized and the vaccine isn't being used widely enough. There also seems to
be the impression, perhaps because of the name Potomac Horse Fever, that the
disease is restricted to a particular area of the East Coast. This is simply
not true. Neoriketssia risticii is an extremely widespread organism and it's
seen virtually everywhere in this country."
Potomac Horse Fever is extremely difficult to diagnose as its clinical
symptoms mimic many other equine bacterial infections. Depression and a
transient high fever are among the first signs of infection. After seven to
ten days, owners may notice a loss of appetite, colic, toxemia, diarrhea and
even life-threatening laminitis.
In many cases, the animal's stool is loose and profuse and dehydration may
result. Edema of the legs, abdomen and head indicate poor circulation caused
by the disease, as well as a protein imbalance. Mares infected with Potomac
Horse Fever may abort pregnancies late in gestation.
PHF-Gard is supplied to veterinarians in convenient ten-dose vials. Each
dose is in a small, one-milliliter amount and is administered via an
intramuscular injection to healthy horses one year of age and older. The
vaccine uses an established antigen purification system to produce an
immunogenic response. Annual revaccination is recommended. The AAEP
Vaccination Guidelines suggest that horses in endemic areas be vaccinated more
frequently due to increased risk of exposure.
For more information on Pfizer Animal Health's complete line of equine
health care products, visit http://www.pfizer.com/equine.
Pfizer Inc discovers, develops, manufactures and markets leading
prescription medicines, for humans and animals, and many of the world's best-
known consumer products.