Durango Equine Veterinary Clinic 
Veterinarian's Perspective on the Lost Foals Group Website
By Dr. Traci Hulse
Many of our clients have visited the website, "Lost Foals Group" and wondered about its validity. First, I would like our clients to know that there is absolutely no evidence anything claimed on this website is proven or accurate. Be wary of statements that are so obviously biased. The statements on this website are one-sided and skewed. According to this website, people are jumping on the bandwagon blaming the West Nile Vaccine (WNV) for everything from cryptoorchid colts (genetic), to wry noses (a rare congenital defect), to open mares, to abortions. What do we know about these cases? Have these mares been checked by ultrasound by a veterinarian to confirm pregnancy? Or, did the owner just assume the mare was pregnant? Were any other vaccines also given to these horses? Do they live in Kentucky (MRLS- Mare Reproductive Loss Syndrome)? Could these mares been exposed to the rhino virus or fescue grass (both correlated with reproductive problems).
I personally wrote a letter to this group in response to their website. I learned a few things: 1) They would not identify who they were. Be wary of advice from someone who won't identify themselves or their credentials 2) The “Lost Foals Group” responded with foul language and extremely poor written English with numerous grammatical and spelling errors. I would not take advice from someone with those traits 3) The comments made by Butch Amberg, whom they use as their prime example, are inaccurate and misconstrued. We learned from veterinarians near his farm that he never had any of his mares tested for pregnancy that he claimed "lost their foals due to the vaccine". Moreover, he states he shot his horse in the head- what kind of horse person is he anyway?! 4) They would not print my response on their website proving their bias.
For those of you who don't know me, my name is Dr. Traci Hill Hulse. I have been a veterinarian at Durango Equine Veterinary Clinic, a 3 doctor exclusive equine practice, for 8 years. Our clinic is a general equine practice which specializes in reproduction, with the owner, Dr. Lloyd Kloppe, being a board certified theriogenologist (animal reproduction). All three doctors are active members of the American Veterinary Medical Association (AVMA), American Association of Equine Practitioners (AAEP), Arizona Veterinary Medical Association (AZVMA), and Arizona Academy of Veterinary Medicine (greater than 40 hours of continuing education/ year). We stay on top of the latest news in the equine veterinary community.
First, I would like to send my condolences to those horse owners you who have lost foals & fetuses either by abortion, stillbirths, or reabsorption. It is always disappointing, both emotionally and economically, for owners to lose a foal. At this point in time, I think the jury is still out if there is any link between the West Nile Virus Vaccine and reproductive losses in horses. If you have lost a foal or fetus, I would encourage you to send it for an autopsy so there are facts, rather than unfounded accusations that this vaccine has caused these losses.
As with ANY vaccine, there is always an inherent risk when vaccinating that a horse will have a reaction to the vaccine. Due to the risk of fever or a reaction, our practice recommends that owners wait till the mare is at least 45 days pregnant before vaccinating with ANY vaccine. The endometrial cups, which form by 40-45 days, allow the mare's body to recognize the fetus as not being foreign. This is very important so that the mare's body does not reject the growing fetus. Also by 45 days of pregnancy, organogenesis is complete- which means all the fetus's organs are developed. Therefore, if you wait to vaccinate till at least 45 days of gestation, there is less risk of foal abnormalities. At 60 days of gestation, this is the time when the placenta attaches firmly to the uterus. Once this attachment occurs, risk of miscarriage or reabsorption is much less. Our practice has vaccinated hundreds of pregnant mares without any increase in deformed foals or reproductive problems- including many miniature mares. The veterinarians in Colorado, including Colorado State University’s field service team, equine reproductive laboratory, and other Colorado equine veterinarians have also not observed pregnancy loss or deformed foals attributed to the WNV vaccine. All of the problems listed on this website have been occurring for years, before the WNV vaccine ever came out. Reproductive losses, premature placental separation, dystocia, and the occasional congenital defect will occur. Pictures of congenital defects, as shown on this website, are used for shock value. Of course, they are upsetting. That is the goal of this website- to shock and upset horse owners. But, that does not prove that those defects were caused by this vaccine.
We have not seen any change in these numbers before or after the WNV vaccine came out. According to the veterinarians at University of Florida, they also have not seen any change this year in the number of reproductive losses or problems. If you have a broodmare farm and never had any of these problems before, you are one of the few lucky ones. Horses are very fertile animals with an overall pregnancy rate of 65% per cycle (as compared to humans who have only 15-20% pregnancy rate per cycle), 85% pregnancy rate, and 75% live foal rate. If you look at these statistics another way, 25% of mares either don't get pregnant, miscarry, or lose their foals at birth. Unfortunately, foal loss occurs regardless of vaccine history.
There was some question as to the effectiveness of the vaccine: According to the Colorado State University's study (not associated with Fort Dodge), the overall fatality rate of the West Nile Virus disease is 28.6%. Out of 500 horses who contracted the disease, only 13 of these horses were vaccinated according to the manufacturers recommendations (two vaccines separated by 3-6 weeks, followed by 4-6 weeks before exposure). That is a 2.6% failure rate. All of those horses survived. Of those horses who were vaccinated at least once before onset of signs, the fatality rate was 20.3%, while 36.6% of unvaccinated horses died or were euthanized.
Currently, the WNV vaccine is not labeled for use in pregnant mares.
Therefore, that is a decision the horse owner and their veterinarian should
make together as to whether or not to vaccinate. Until there is proof that
this vaccine is directly related to reproductive losses, our practice will
recommend vaccination in mares at least 45 days pregnant due to the high
fatality rate of the disease.
20908 West Durango Street * Buckeye, Arizona 85326 * Phone (623)386-2928 * Fax (623)386-7914