May 17, 2012 - Horse owners and veterinarians alike were caught by surprise last year when pigeon fever (also called dryland distemoter) was reported in Texas horses. It isn't a disease that is normally seen in Texas, although it is common on the West Coast.
"It was everywhere," said Dr. Valerie Bixler D.V.M equine specialist. "Traditionally, it has always been a disease in California and in the west, because it is drier and it is sandy and the wind comes in and picks it up and they are exposed to it. But, we where so dry last year, I guess it has decided to move into our area. It was everywhere, it was just bizarre. I have to tell you, I have seen a case here or there in the past, but I just had the most bizarre cases I have ever seen of this stuff."
The Texas Veterinary Diagnostic Laboratory recorded over 350 positive cultures for the bacteria associated with pigeon fever in 2011, compared to less than 100 cases each year from 2005-2010.
There is no vaccine for the disease. The bacteria that cause the disease gets under the skin and forms an abscess. It can be anywhere on the horse's body, but is most often located in the pectoral region, hence its name, as it makes the chest appear to be swollen, like that of a pigeon.
"There has to be some kind of abrasion, it doesn't even have to be big, it can be a micro-abrasion and that is how this stuff gets in there," Bixler explained. "It gets into their system, under the skin."
The bacteria can also be airborne and travel from one horse to another. Even though this can be an airborne disease, Bixler said travel restriction is not necessarily a way to keep an animal from contracting the disease-causing bacteria.
If a horse does develop the disease, it is not an easy one to treat, and in some cases it is best to let it run its course. A veterinarian should be consulted, as further treatment might be necessary.
"I had a client that we battled this for five months," Bixler said. "It had small abscesses all along the ventral midline underneath the belly, then it had one up on the sheath and then it had one on the chest. We did not give this horse antibiotics because we just wanted this stuff to come out. Actually, we put it on an herb to help its immune system and that is it. There is nothing you can do."
With these abscesses, some of the controversy that comes into play is an argument both for and against lancing the abscess. Bixler said she personally has done both to her very own horses. Bixler saw three cases in her own horses in 2011.
"The first one that had it, it was on her hip and it looked like a hoof mark," Bixler explained. "It was on her hip, so I thought she had been kicked so I watched it, put stuff on it and it just kept getting bigger and she got to the point where she could hardly walk on it.
" I got to messing with it and I was like 'well that is an abscess,'" she continued. "So, I drained it. It didn't even occur to me that it could be pigeon fever. Of course, once I popped it open I was like, 'ah oh.' Then, I flushed it out and cleaned it out. Luckily. when I popped these things out, I collected them in a bucket and then threw everything, the gloves and other stuff I had, in the bucket put the top on the bucket and disposed of it."
According to the National Center for Foreign Animal and Zoonotic Disease Defense (FAZD), a horse suspected of having Pigeon Fever, also known as Dryland Heaves or Dryland Strangles, should be isolated, their stall and equipment disinfected, and if the horse is lanced, the pus should be collected and disposed as bio-hazardous material. After handling infected animals, wash hands, clean and disinfect boots, and change clothes immediately.
When a second horse contracted it, Bixler was still not certain that is was pigeon fever, given its rarity. She cautioned that she does not give antibiotics until she knows that all the pus is drained when dealing with this sort of situation. But, when one of her horses appeared to come up lame, she again did not suspect pigeon fever.
"I started him on antibiotics and he got better and then the next week he was really, really, really sore and he had this little lump on his flank, on both of them, I went. 'oh no.' I had just given him the antibiotics," she said. "So, what I did had just prolonged the procedure. If hadn't given him the antibiotics, it would have come up faster. Those things got to be the size of volleyballs. Once they got soft, I lanced them because he was so miserable and in pain, I had to. When I lanced those things, I could stick my whole arm in there that is how big they were."
Traditionally, a horse with pigeon fever gets it on their chest area, so when her third case came up on one of her own horses she was ready.
"The third horse that got it, I noticed on his front legs, that was the traditional on the chest," she said. "That is why it is called pigeon fever. He is a rescue, he is an older horse, I said, 'well it is going to take care of its self,' and it did."
So, with about four times more cases of pigeon fever in Texas in 2011 as there where in 2010, it is hard to say whether the disease will continue to infect Texas horses this summer again. Horse owners should be prepared for the risk and be sure to consult their veterinarian if any suspicious lameness or abscesses occur.