Copy Email-Outbreak of horse, goat disease causing concern
By: GIG CONAUGHTON - Staff Writer
RAMONA Ca.---- Horse owners and veterinarians in Ramona are buzzing with rumors that unusually large numbers of horses are coming down with "dryland distemper," also known as "pigeon fever," a disease that can cause horses and goats to develop large abscesses.
Unlike West Nile virus, dryland distemper is rarely fatal in horses if treated, is almost unheard of in people, and therefore not a "reportable disease" monitored by veterinary and public health officials.
There are no solid estimates of the total number of dryland distemper cases this year, but veterinarians say they have seen more cases this year than last.
Ramona veterinarian Jon Matthews said his office has treated about 110 cases this year, more than three times the approximately 35 cases he saw last year. Matthews said he thought the illness may be caused by a "mutant strain" of the bacterium that causes the disease, that it wasn't behaving normally and could even invade San Diego County's beef industry and the San Diego Zoo's Wild Animal Park.
But other veterinarians, locally and at the UC Davis School of Veterinary Medicine, said predictions of devastation were "exaggerations;" and that people should not be alarmed by the disease, which occurs routinely in Ramona and California communities yearly.
"We don't want to spread panic," according to veterinarian and UC Davis associate professor Dave Wilson.
Still, talk of the disease last week prompted UC Davis officials to meet with Ramona residents and to say they intended to collect samples from afflicted horses to see if the bacterium is different than seen before.
Local and UC Davis veterinarians said dryland distemper is caused by a bacterium indigenous to soils in many parts of California. The disease is often referred to as "pigeon fever" because the bacterium can cause huge pus-filled abscesses inside horses, puffing out their chests like a pigeon.
Veterinarian Corine Selders told a group of about 35 Ramona horse owners at the San Diego Country Estates International & Western Equestrian Center Wednesday night that the disease can take several forms.
Selders said horses can get abscesses either internally or externally, often on their legs, stomachs and pectorals. The disease can't be transmitted from horse to horse, and afflicted animals don't need to be quarantined. But it can be spread by flies that attack the abscesses and then fly into scratches or wounds on other horses. And large abscesses eventually rupture and spread the infection in the horses' environment, exposing other animals to it.
Selders said that if horses get large internal abscesses, the disease will kill them "100 percent of the time" if they are not treated ---- usually with expensive antibiotics that may have to be given for up to six months. But with treatment, she said, in general, 91 percent of horses recover.
Because there are no vaccines for dryland distemper, Selders recommended Wednesday that horse owners "use common sense" and try to keep horse stalls and their animals clean, and to use bleach and other devices to keep flies to a minimum and to prevent the spread of the disease.
Selders works with the East County Large Animal Practice, lives in Ramona and appeared at Wednesday's meeting for Davis veterinary school. Some horse owners who attended the meeting said their animals had been infected; others said they were afraid their animals could become sick.
Mutant strain?
Matthews, the veterinarian and owner of Matthews Equine Services in Ramona, said last week that he had been working in the semirural town for 16 years, and that he had never seen anything like the current outbreak.
"Usually we only see it every five to six years," Matthews said. "To see it two years in a row is really strange. Even months ago, we thought it had to be a new strain because it shows up differently in the horses."
Matthews said dryland distemper could affect sheep and goats, and that there was a possibility that it could infect cattle or spread to the San Diego Zoo's Wild Animal Park in San Pasqual, between Ramona and Escondido.
But most other veterinarians who could be reached for comment, locally and at UC Davis, downplayed those predictions. They also said, contrary to Matthews assertion, that it was not unusual to see the disease yearly.
Veterinarian Sharon Spier at Davis, who has been studying for some time to come up with a vaccine for horses for dryland distemper, said it was "possible" that the disease could work its way to the Wild Animal Park because flies were known to be able to range about 22 miles "depending upon the winds."
Officials from the park said Thursday that they don't consider the disease a threat to their zebras and other equine-related animals, because they don't think flies from the infected areas could reach them.
Spier, meanwhile, said that although there is a strain of dryland distemper that attacks goats and sheep, and that cattle have been known to become infected, it was not a threat to the cattle industry or the public health.
"Absolutely not," she said. "It's nothing like foot-and-mouth (disease) or mad cow. And pasteurization would kill it. ... It's a nuisance disease."
Numbers unknown
One thing that nearly everyone agreed upon was that the disease does seem to be occurring more often this year and last than it has in the past. And the disease, which was once considered a "California-only" illness, has shown up in horses in Colorado, Wyoming and Kentucky.
Veterinarian Linda Byer, who has had a practice in Lakeside for 20 years, said she saw 10 cases of the disease in one week in July, a trend that concerned her.
"That just doesn't happen," she said.
But Byer said the numbers have dropped since then.
Meanwhile, Ramona veterinarian Larry Martin, who attended Wednesday night's meeting, said the consensus among veterinarians is that the number of dryland distemper cases is definitely up.
But even in that agreement, there was controversy.
Asked by audience members Wednesday night just how many cases of the disease had turned up this year, Selders said it was impossible to tell.
The number of cases is not being tracked, she said.
In addition, several veterinarians were treating animals, and no one was collecting information from those doctors to compile lists.
One distraught woman at Wednesday's meeting in Ramona said that her sister's horse had died from the disease.
Wilson, the associate UC Davis professor, said he had contacted the state laboratories in San Bernardino, where most necropsies ---- animal autopsies ---- from San Diego County would occur. He said not all animal owners have necropsies done, but that the San Bernardino labs reported not having any dryland distemper deaths this year.
Spier and Wilson, meanwhile, said there was nothing in what they had heard so far to suggest that the Ramona outbreak was vastly different or suspected of being from a "mutant strain."
But Spier said she asked Selders and Martin to spread the word that she was interested in collecting swabs from infected animals to study in her laboratory to see if there really is something unusual going on.
"I don't want to downplay the disease," she said. "It is important. It's something that I've dedicated my life to. I do want the vaccine. We can certainly can type the organism and we want to follow up."
They had better hurry up and get samples for analysis to a medical school to confirm that it is a bacteria that they are dealing with. It could be the first Western Hemisphere occurance of Sichuan Sheet (CHINA) that is causing bleeding from the legs of the animals that contact it. (southern Vietnam, Russia, Mongolia, Tibet, India....)
