 |
Herpes-
not just cold sores.
In human medicine, we
think of Herpes as the bringer of cold sores, an embarrassment for those
afflicted, certainly not something to be mentioned in polite company. As
horse owners however, it is a subject that can NOT be ignored.
The Run-Down:
 | 5 types of herpes viruses affect domestic horses. |
| 3 are known to commonly cause disease:
 | equine herpesvirus-1 (EHV-1) |
| equine herpesvirus-3 (EHV-3) |
| and equine herpesvirus-4 (EHV-4) |
|
| Species-specific- if you have a cold sore, you can’t
give herpes virus to your horse or vice-versa. |
| Infection is life-long. Over 80% of horses carry the
herpes virus. The virus can remain latent (quiet, showing no symptoms) for
long periods of time. During times of stress, the virus becomes active and
can cause disease or be spread. |
| The most important viral cause of abortion |
| The second most important viral respiratory disease |
| The most contagious equine neurologic disease. |
The Culprits:
| Equine herpesvirus-1: abortions, respiratory
disease, neurologic disease, and death in newborn foals. It also causes a
newly recognized fatal disease of adult horses, peracute pulmonary
vasculitis. This affects the lungs of adult horses and kills them
practically overnight. |
| Equine herpesvirus-3: aka Equine coital
exanthema- venereal disease, It is a rare disease, and does not require
treatment, however, it can shut down breeding operations with devastating
financial consequences. The virus is shed when there are active lesions on
the genitals of affected horses. |
| Equine herpesvirus-4: aka Rhinopneumonitis-
upper respiratory disease in young horses (foals up through 3-year-olds in
training). Very rarely, it can cause abortions or neurologic disease. |
EHV-1 abortions usually occur in the last third of
pregnancy, and present with a fresh, dead fetus. The fetal fluids and
placenta contain high levels of the virus, which can spread the disease to
other horses. Outbreaks can be sporadic or occur as abortion storms in
previously unexposed herds. Sometimes, affected foals can be born alive, but
have extensive damage to their internal organs. These foals require very
intensive and expensive care and rarely survive despite the best treatment.
In recent years there has been an increase in the
number of EHV-1 neurologic cases reported world-wide. It is unclear whether
this is due to an increased incidence of the disease or an increased
awareness of the disease and therefore increased testing for it. EHV-1
neurologic disease usually first presents as a fever, followed by neurologic
abnormalities. Classic symptoms of the disease include hind-limb weakness,
incoordination, and bladder paralysis (leak urine). Horses may also show
signs of mild limb edema (swelling), weak tail tone, weak anal and/or vulva
tone, swelling of the penis and scrotum of stallions, and/or inability to
retract the penis into the sheath. These signs can develop gradually or very
rapidly, and progress to an inability to stand. If a horse recovers from the
initial disease process, it may have lasting neurologic damage- drooping
face, hind end weakness, bladder damage, etc.
Recent outbreaks:
| January 2003, an outbreak at the University of
Findlay affected 97 horses, of whom 42 developed neurologic signs and 19
died or were euthanized. This outbreak then spread to The Ohio State
University’s College of Veterinary Medicine, where more horses were
affected. |
| October 2006, EHV-1 outbreaks at Monmouth and the
Meadowlands racetracks in New Jersey prompted track-wide quarantines. |
| October 2006, an outbreak at Colorado State
University, despite very strong biosecurity protocols, forced 20
hospitalized horses into a quarantine. It remained in place until
mid-November. |
| December 2006, 9 cases of EHV-1 confirmed, with 5
deaths as of 12/27, in horses on a quarantined premises in Wellington, FL.
15 clinical cases and 3 deaths are attributed to this disease. The
outbreak is linked to horses traveling from the USDA animal import station
in NY. Another horse from this shipment died in CA, after being
quarantined.
Additional Outbreaks
| Late December
2006, a horse Golden Gate Fields in Northern California developed
neurological symptoms of EHV-1, prompting a quarantine at Golden Gate,
Bay Meadows, and Pleasanton that has since been lifted. |
|
December 24, 2006, Fairfield Equine Associates in Newton, Conn, is
quarantined until January 23rd 2007 after a horse tested
positive for EHV-1 after developing a high fever. |
| January 2007,
horses at the University of Connecticut go under quarantine after
twenty-one horses there showed signsof EHV-1. Five showed neurologic
signs, the others have had fevers and/or respiratory signs. |
| As of January
17, 2007, one barn at Los Alamitos, California remains under quarantine
for EHV positive horses. |
|
Vaccines- The Options:
| Rhinomune- Pfizer- modified-live
EHV-1, every 3 months- studies suggest may have best efficacy against
EHV-1 neurologic strains. |
| Calvenza-Boehringer Ingelheim- killed
virus EHV-1, EHV-4 and Influenza, intramuscularly or intranasal, not yet
widely used |
| Fluvac Innovator-Fort Dodge- killed
virus EHV-1, EHV-4 and Influenza |
| Pneumabort K-Fort Dodge- killed virus
EHV-1, given at 5,7, & 9 months of pregnancy |
| Prestige/Prodigy-Intervet- killed
virus EHV-1, EHV-4 |
TEC Recommendations:
| At Risk Horses- booster Flu & Rhino vaccines
quarterly |
| Low Risk Horses- booster Flu & Rhino vaccines every
6 months |
| Call The Equine Center to discuss and initiate the
ideal vaccination plan for your horse. |
|
