Vaccination time coming

I was just starting to think about mid/late summer vaccinations when Julie at the barn mentioned that the other local vet practice had already been out to the barn to do their clients' horses. The Potomac and the flu/rhino vaccinations were given. I'm never very consistent about getting Dude and Bestie scheduled for these two (I feel like in past years they've been given them anytime between August and September), so it was good she reminded me. They'll get scheduled soon with the handful of other horses that use the same vets we do.

Word on the streets is that Potomac may be bad this year in our area, although our vets do not yet have any words of warning on their website, and they're usually good about that. I can never remember the specifics of the disease, and had only a vague sense that snails were somehow involved. I visited the website for the American Association of Equine Practitioners to grab the following info:

"Equine monocytic ehrlichiosis (Potomac Horse Fever) is caused by Neorickettsia risticii (formerly Ehrlichia risticii). Originally described in 1979 as a sporadic disease affecting horses residing in the eastern United States near the Potomac River, the disease has since been identified in various other geographic locations in the United States and Canada. The disease is seasonal, occurring between late spring and early fall in temperate areas, with most cases in July, August, and September at the onset of hot weather.

Clinical signs are variable but may include: fever, mild to severe diarrhea, laminitis, mild colic, and decreased abdominal sounds. Uncommonly, pregnant mares infected with N. risticii (usually in the middle trimester between 90 and 120 days) can abort due to fetal infection at 7 months of gestation.

If Potomac Horse Fever has been confirmed on a farm or in a particular geographic area, it is likely that additional cases will occur in future years. Foals appear to have a low risk of contracting the disease. Vaccination against this disease has been questioned because field evidence of benefit is lacking. Proposed explanations for this include lack of seroconversion and multiple field strains whereas only one strain is present in available vaccines.

Vaccine
The currently available commercial vaccines are killed, adjuvanted products. Two of these are also available combined with a rabies vaccine. None of the current vaccines carry a label claim for the prevention of abortion.

Vaccination Schedules
Due to the seasonal incidence of disease, vaccination should be timed to precede the anticipated peak challenge during the summer months or fall.

Adult horses, previously vaccinated: Manufacturers recommend revaccination at 6- to 12-month intervals. However, veterinarians may consider an interval of 3 to 4 months for horses in endemic areas because protection following vaccination can be incomplete and short-lived."

(There's a bit more info on the vaccination protocol on the AAEP site at http://www.aaep.org/potomac_fever.htm)

It certainly doesn't sound as though the vaccination is a sure bet in terms of prevention, which is unfortunate. But still, it will give me some peace of mind once they've received the vaccination.