A performance horse, much like a sports car, is a fine-tuned machine that runs, stops and quickly turns on a dime. When that sleek machine turns sluggish and infirm, the owner calls in a mechanic like Patrick Young, DVM.
Young’s practice, in Washington, Okla., focuses on treating lameness and illness in performance horses. A 1998 graduate of the Mississippi State College of Veterinary Medicine, Young is an avid horseman and understands the importance of a healthy horse.
During the summer of 2011, the veterinarian saw a rapid increase in the number of cases of pigeon fever reflected in a growing concern across the nation. For the health of his equine clients, Young began to research, test and develop a vaccine for pigeon fever.
Quarter Horse News: What is pigeon fever?
Young: Pigeon fever is a disease caused by the bacteria Corynebacterium pseudotuberculosis. It has nothing to do with a pigeon, but when a horse contracts it through an abrasion or an insect vector, the horse will get an abscess in its chest and it causes the chest to swell up [like a pigeon]. Pigeon fever is also known as a bunch of other names [such as pigeon breast, dryland distempter and Colorado strangles].
There are several different forms of pigeon fever bacteria. The most common form causes the deep abscesses in the chest. There is an internal form that can involve the vital organs, like the lung and kidney. Or, there is a form called lymphanitis that causes swollen legs and sloughs skin. That is by far the worst scenario.
QHN: Why isn’t there a vaccine available on a national scale?
Young: I think initially there wasn’t a large enough market for a pharmaceutical or biologic company to pursue a vaccine. Typically, this has been a fairly regional disease in dry, arid environments like part of Oregon, California, Texas and southwestern Oklahoma. Recently, I don’t know if the bacteria has changed a bit or if the environment has changed, but this has spread throughout the United States. Initially, this was fairly localized, but now it’s reached Kentucky and the Southeastern states.
If we don’t get more significant rain soon, I think we will get more cases popping up. When it is dry and dusty, the bacteria becomes more prevalent. The bacteria lives in the ground and once it is there, it is hard to get rid of it.
QHN: What made you decide to focus on developing a vaccine for pigeon fever?
Young: The first case I ever saw in Oklahoma was in 2004 in a broodmare, and that was in April. But, in the fall and early winter of 2011, I was seeing a different case each day. During the summer of 2011 through 2012, when it was so dry, my cases increased rapidly.
Typically, the way we approach it is to make an incision and drain [the abscess]. If you give antibiotics, they will suppress the bacteria, but [the bacteria] comes back stronger. The majority of the horses I work on are performance horses. If the horse has a draining abscess for two to six months, it is prohibitive for them to perform to their ability. There is a high possibility that the horse will spread the disease.
That is the main reason I decided to do something about it: I honestly got tired of treating all of these horses. I want a horse treated, on the mend, and the owner back showing their horse. With a disease like this, you can’t do that. So, that was one of the main urges that I had for my clients, was to get some kind of disease prevention.
QHN: How did you develop the vaccine?
Young: This is the first time I’ve ever worked on a vaccine. I’ve worked on supplement production with companies, but I’ve never taken a vaccine all the way through. Like other veterinarians, we try to think outside the box and figure out the best way to approach a disease, from the standpoints of treatment and prevention. Prevention is the key. If you can prevent it, you won’t be called on to treat it at all.
The way that the vaccine is produced is the bacteria is inactivated, cultured and purified, then diluted and added to an adjunct. The vaccine is given in the muscle – specifically, in the neck – and two to four weeks later, the horse gets a second dose. That is enough for at least a year. It is too early for me to tell if the vaccine lasts longer.
Out of 100-some dosages, I haven’t had any significant [negative] reactions, like anaphylactic shock, localized swelling, or any side affects like stiffness or soreness. I’ve been pleased with the progress.
If a horse has had pigeon fever, I elect not to vaccinate it. Typically, after a horse has it, he has immunity to any similar strains for five to seven years. Strangles is about the closest disease I can compare pigeon fever to – 99 percent of the time this disease is not life-threatening, but it is extremely debilitating.
QHN: Whose horses do you treat with the vaccine?
Young: Right now, I can only use the vaccine on my [existing] clients’ horses.
QHN: Will your vaccine eventually be available to the public?
Young: I’ve applied for a provisional patent and, ideally, I’d like to license this to a biological company. If not, I’m going to apply for USDA [United States Department of Agriculture] accreditation and get it out there. Whoever is the first one to get the vaccine out there will get a provisional license, and that requires less testing to get it approved.
This has been a painful process to get to where I am, but at the same time, it is well worth it. Even if my vaccine doesn’t get approved, if it spurs the vaccine and biologic companies to get out there and get going for prevention and protection of all the horses in the U.S., then I’ll consider what I have done a huge success.