To All Horse Farms and Horse Owners: Links at Bottom! As of 6:00 p.m. Monday June 6, 2011: Update and Vaccination Considerations Now we are nearly at the four-week mark since the beginning of this equine herpes outbreak. There have been no new neurological cases diagnosed in Colorado since May 20th. Horses are traveling again, now with increased health awareness. Horse shows are requiring special health certificates and horseman are taking their horses temperatures regularly. There have though, been additional EHM cases and two newly quarantined horse farms in the United States. Some of the new neurological horses contracted the disease from non-symptomatic carriers on quarantined facilities. A few new neurological cases have now turned up without having any obvious exposure to the cutting horses that came from Utah show. Because EHV-1 neurological cases are occasionally seen anyway, it appears that some of the newly reported cases may be unrelated incidences that are now reported more frequently do to the country’s increased awareness. Most veterinarians rarely but occasionally do see the neurological EHM anyway, unrelated to outbreaks. It has now been proven that the equine herpes vaccines have not prevented the EHM neurological clinical disease. Of course, none of the vaccine companies have ever claimed that their vaccines would prevent the EHM anyway. The herpes vaccines, (EHV-1 and EHV-4) have been given by veterinarians for years to decrease the incidence of herpes respiratory disease and to help prevent herpes abortions. Because of the vast clinical epidemiological evidence newly at hand, more may be learned about the various vaccine types in the next few months. The EHV-1 vaccine has been given to prevent equine herpes abortions for some time but has not been perfect. Herpes vaccines are difficult to make and some protection is considered better than no protection. The EHV-1 vaccines used to prevent abortions, must be given at 5, 7, and 9 months of pregnancy. Even after vaccinating pregnant mares, herpes EHV-1 can produce “abortion storms” that are known to abort as many as one out of every five vaccinated mares. In the early 80’s, the EHM, (neurological disease) was seen occasionally on isolated stud farms around the country. Soon after the EHV-1 “three times vaccine protocol for pregnant mares” was started, the EHM neurological disease was rarely reported again on those stud farms. Because the EHV-1 seems to be seen more in the late fall through spring and not in the summer, new vaccine protocols may include extra herpes vaccinations for show horses during those important months. Interestingly, the “pregnant mare” vaccines may be used more in the future for non-pregnant show horses. Further research into this outbreak will enhance our understanding and improve vaccination proticols. Herpes vaccines vary in their quantity of antigen and in their quality of adjuvant. It appears that the "pregnant mare" vaccines may be better to prevent the EHV-1 disease because of their antigen specificity and FDA approval to prevent the EHV-1 abortion. Though no herpes vaccine can yet claim that it can prevent the EHM neurological disease, it does appear that higher immune responses may decrease the viral shedding from infected EHV-1 horses. There are many EHV-1 herpes vaccines that should be considered and several drug companies believe their vaccine is the best! Though it is not recommended for quarantined farms to be revaccinated at this point, authorities believe that particularly traveling horses, show horses and stabled horses should be revaccinated for the EHV-1 herpes disease soon after this outbreak diminishes. There is also an obvious new regulatory problem that horses who are exposed to respiratory EHV-1 at horses shows may cause their stables to be quarantined if they positive test for EHV-1. So in the interest of decreasing viral spread and the risk of stable quarantine, EHV-1 boosters will soon be considered. As of 6:00 p.m. Monday May 23, 2011 The Colorado State EHV-1 Outbreak statistics now show 9 confirmed cases, 22 suspect cases, and 12 quarantined farms in 8 different counties. It is believed that the "outbreak" disease, Equine Viral Myeloencephalomalasia will soon finish running its course. The problem is that nobody exactly knows "how soon" it will be over for sure! However, we do know that there are still no secondary farms in the United States that have shown the neurological disease in horses. We do know that with each wave of exposed horses, there is less virulence to the EHV-1 virus. This means that fewer horses get sick each time that the "outbreak" virus is spread and the horses that do get sick show fewer symptoms! It is believed that soon the "outbreak" disease will finish running its course and go away!! The big question haunting horse show committees and horse owners alike is, "What if our show is the first equine event to have a secondary outbreak"? In New Mexico today a new EHV-1 case was reported on a quarantined cutting farm. This is an interesting development because the sick horse contracted the neurological disease from cutting horses that had never shown symptoms of the disease. The asymptomatic carrier horses had returned from the Utah cutting event approximately 10 to 14 days before the new sick horse contracted the disease. Such carriers are possible on quarantine farms but are not expected to carry the "outbreak" virus for very long. The regular EHV-1 "Rhinopneumonitis" virus infected horses can cough and shed virus for several months. The National Cutting Horse Association believes that the EHV-1 virus has almost finished running it's course. The association plans to re-evaluate the information on Friday and to likely go back to work soon. This issue will be updated daily but the future already looks bright. It is quite unlikely that a horse from a non-quarantined farm will contract the "outbreak" virus since there have been no secondary outbreaks in the entire United States. The problem is that experts are obviously not in a position to make definitive claims on this date. On the other hand, the feeling of panic should now be curtailed. Tomorrow will bring further information. As of 2:40 p.m. Thursday May 19, 2011 Colorado now has a minimum of 22 suspected cases with 10 quarantined farms in six counties. There are 8 confirmed cases now in Colorado and it is rumored that 4 international countries may be involved. The process of confirming that a horse has contracted EHV-1 is somewhat difficult even with advanced DNA testing. The problem is that not all EHV-1 infected horses are sheading virus while they are being tested! There are also differences in the sensitivity of different DNA testing methods. The first horse to be diagnosed with the disease in Colorado and in the nation was initially negative to both nasal and lung tissue DNA samples. That horse was extremely positive to the EHV-1 virus in the spinal cord. Later, another lab did find the horse to be positive to the nasal DNA test. There are many horses that will remain suspects and will not be proven to be DNA positive to EHV-1 virus. Alternatively, since the EHV-1 disease is a herpes virus that horses commonly carry anyway, positive nasal DNA tests do not necessarily imply that a horse has the "outbreak" EHV-1 virus, (please read further below). DNA samples may have to be sent to multiple labs to receive complete testing information. A Dressage horse was confirmed positive to the EHV-1 "outbreak" virus after attending a dressage clinic in Wyoming. The Dressage horse had been in contact with a family member's cutting horse that had come from the Utah cutting event before the outbreak was diagnosed. The movement of the Dressage horse to the Wyoming dressage clinic was certainly an innocent event but did cause more farms to be quarantined. As of 8:00 a.m. Wednesday May 18, 2011 The movement of horses is still legal in most states. Many equine events have been cancelled or have changed their show dates to give this outbreak a little time to see what it does. So far there have been no secondary outbreaks in the entire United States, ("secondary outbreaks" are viral movements to farms other than the quarantined farms that care for a horse that was in the Utah cutting event as described below). This is good news! If there are any secondary outbreaks, equine events and travel will be more affected. At this point, it is up to each state's official state veterinarians to make specific rules for that specific state. It is important to know when hauling a horse to a different state that the receiving state's rules for entry may have changed. It is up to the veterinarian who issues your horse's health certificate to contact the receiving state and to consider contacting all states that you will be traveling through to request any change in the rules. Colorado now requires that all horse's entering the state should have an Official Colorado State Permit Number for future tracking. This is to make sure that horses entering the state do not come from quarantined farms and don't bring in the virus. This permit requirement is very logical. It is no more likely for a horse to contract the Herpes Virus in Colorado than in any other state. And in fact, Colorado was the first state to diagnose the viral outbreak and Colorado has been above reproach in their process to seek solutions. Colorado is by no means a more contagious state than any other part of the United States. Part of the reason that Colorado has been ahead of everyone else is because of the sacrifice of a loving cutting horse owner whose paralyzed horse was euthanized for humane reasons and the owner agreed to extensive diagnostics. As a result of her gift, other sick Colorado horses have been treated faster and more accurately. Many horses are now nearly well. Because of this person's sacrifice, horses all over the country are actually safer. Because of the diligence of the Colorado farm with the first diagnosed clinical case in the United States and as a result of the farm's persistence to follow exact medical protocol, many horses have been saved and the outbreak is seemingly under control. The Colorado State University Veterinary Teaching Hospital has taken a huge role in the diagnostics, treatment protocols and in making their hospital available for sick horses. Dr Keith Roehr who is the Official State Veterinarian of Colorado has been instrumental in communicating the outbreak to the entire nation! All horses that were exposed to the sick horse at the Utah cutting event have been traced and their farms are quarantined. Horses on non-quarantined farms appear to be very safe! This process will be over soon and will not interrupt equine events for very long. Please see links and continue reading below. As of 5:00 p.m. Monday May 16, 2011 We are currently experiencing the first national outbreak of Equine Herpes Myeloencephalopathy. This is a national outbreak that started at the recent, (last week's) Utah Cutting Show. The virus may have originated in Canada. All horse stables have horses that carry this virus latently similar to cold sores in people. The Equine Herpes Virus Type 1 is released when carrier horses are stressed and it normally causes only a mild upper respiratory disease. Young horses usually get immunity and also become carriers early in life. This "outbreak" virus is the same Equine Herpes Virus Type 1 that causes respiratory disease. The difference is that either this outbreak virus has changed it's DNA to become a more virulent mutant strain or a particular horse has shed excessive numbers of virus to contact horses. The result is that the virus enters the spinal cord and local vasculature in such large numbers that the horse's immunity is overwhelmed and the horse develops symptoms of SEVERE SPINAL CORD DISEASE. There are many variations in the symptoms. All horse stables that have horses that were in the Western States Cutting Horse Finals in Utah are now quarantined around the country as well as Internationally. Many horses have died and many are in slings. Some horses have returned to normal. Because of this EHV-1 outbreak, horses are not allowed to move from farms that stable horses that were in the Utah cutting show. Horses from all other farms that are not quarantined (per the state veterinarian) are still allowed to move nationally and to attend all equine events. Colorado State University advises that moving horses should be carefully calculated, as all horses need to avoid exposure to infected horses. Historically, outbreaks of EHV-1, (EHM) have occurred in local areas and have been much less spread around the country. What has been learned from other outbreaks is that the sick horses come in waves and each wave has fewer and less sick horses until the outbreak just dies out. Vaccines are not proven to prevent this disease. Vaccinating during an outbreak could help but could also make the disease worse. At this point, there have been no secondary outbreaks in the US. However this outbreak was first diagnosed five days ago. Incubation is approximately five to ten days. Quarantines are for thirty days past the last sick horse. The state veterinarians have agreed to have the USDA be the monitoring agency for this outbreak. This is considered to be a biosecurity issue even though it was not caused by terrorism. This is classified as an emerging disease because of the degree of the upgrade of severity seen in the symptoms. Because of economic considerations and because of the probability that this outbreak will slowly die out, the state veterinarians around the United States have decided to allow all horses to travel and to attend equine sporting events as long as they do not come in contact with cutting horses that participated in the Utah cutting show or horses from quarantined stables. The Oklahoma Show and the Mile High Quarter Horse Show have been appropriately cancelled to wait further development. The Colorado State University Veterinary Teaching Hospital has graciously changed the status of their facility to make available intensive care space for Herpes Virus Equine Cases. CSU will also be continuing colic surgeries and all other equine emergency services. This is a day-by-day changing outbreak. More information will be provided as it becomes available! LINKS: CSU EHV-1 Information APHIS: Equine Herpes Virus Brochure ((Lengthy upload time) USDA: EHV-1 Resources American Association of Equine Practitioners Fact Sheet Colorado Department of Agriculture and State Veterinarian, Dr. Keith Roehr Kenny Platt Interview on Channel 9 News in Denver Sievers Equine Sports Medicine Brochure
CSU, (Dr. Dean Hendrickson) EHV-1 Interview Channel 5 News CSU Veterinary Hospital Now Fully Open for All Equine Cases!! Awakening The Dormant Dragon, (University of California, Davis) |