By Randall Bonner
Several elk harvested in Multnomah and Columbia counties have shown signs of a hoof disease that has been a problem in neighboring areas across the Columbia River in Washington. Processors in Washington familiar with the disease have reported receiving elk from Oregon that share the symptoms, but the presence of the bacteria is still unconfirmed.
The disease first appeared in southwest Washington’s elk herds in 2002 and has become widespread since 2007, affecting nearly 20 to 90 percent of herds. State wildlife managers in Washington are researching a possible link to treponeme bacteria. Four independent laboratories have found treponeme in hooves of diseased elk. (There is no evidence that the bacteria is harmful to humans. It is specific to the hooves and does not affect the animal’s organs or meat.)
The bacterial disease results in debilitating lameness caused by deformed, overgrown or broken hooves, abscesses and laminitis. Commonly appearing in livestock such as sheep and cattle, it is possible that the bacteria may have been transmitted through wet soil in Washington’s lowland areas. With known interchange of elk herds crossing the boundary of the Columbia River, Oregon Department of Fish and Wildlife (ODFW) has joined a working group of veterinary staff and biologists to track the spread of the disease. The disease has not transferred to other wildlife, nor has it been observed being commonly transferred from domestic livestock to elk and vice versa. This evidence indicates that neither population is suspect for infecting the other, although the possibility of that becoming an issue is being monitored.
The Columbian newspaper reports, during recent work group meetings on the issue, that some locals have questioned the possibility of a link from herbicides being used on private timber land. One of those locals, Krystal Davies, is a farrier who lived near recently logged Weyerhauser land. She had been out riding horses on the company’s property earlier in the year until she noticed her horses having a rapid increase in abscesses. However, without lab testing, it’s difficult to draw links to the abscesses, herbicides, and the bacteria.
Herbicide experts advising the WDFW claim there is no evidence that herbicides used on forest land have had adverse effects on elk or other animals. Regional wildlife manager Sandra Jonker said, “To date, we’re just not seeing that relationship,” pointing to the fact that lab samples are pointing to bacteria and not toxins. Mark Smith of Toutle mentioned that even if the herbicides do not harm the elk directly, they change the variety and quantity of forage foods for elk, leading to malnutrition and making them more susceptible to disease. Locals questioning the possible link also pointed out that WDFW’s invited experts that denied a connection to the use of herbicides were funded by the forest products industry. They also questioned the toxicology being conducted on infected elk that were killed for examination, and called for blood samples from elk living with the bacterial infection.
Timber companies treat clearcuts by spraying herbicides to prevent other emerging plants from competing with the newly planted saplings. Clearcut timber restorations were managed in the past by controlled burns until concerns for air quality prompted a switch in management methods in the 90s. Clark County Commissioner Ed Barnes called for a moratorium on the spraying of herbicides by timber companies, and legislation requiring the moratorium if they did not agree to it voluntarily. In spite of his petition to the governor, Washington state agencies haven’t shown an interest to set this particular idea into motion.
To better understand the game management plan south of the Columbia River, I spoke with Julia Burco, an ODFW veterinarian serving the elk hoof disease technical advisory committee. Her perspective highlights three main factors, “host, environment, and pathogen,” while tracking the spread of the disease. She pointed out that Roosevelt elk are more predisposed to abnormal wear due to chronic moisture in the environment, making them more likely to suffer from lesions and bacterial infections. A lack of forage food in the elk’s habitat (due to herbicides in some areas) resulting in poor nutrition could contribute to the susceptibility of disease as well.
“The bacteria itself is difficult to observe because it’s constantly changing,” said Burco. She suggested that replicating the disease in domestic animals may make it easier to study, but most of the treatments used with domestic animals like foot baths and cleaning pens are difficult to apply to free-roaming herds. Antibiotic injections common in domestic animals can’t be used on wild populations that hunters are harvesting for food either. The lack of field-treatment options makes it a difficult challenge to contain the range of its spread.
“It’s very frustrating managing illnesses in wild herds of any kind,” said Burco. “We’re simply trying to better understand the bacteria, how it’s spreading, and how to contain it.” She mentioned that minimizing the transfer of animals over the state line, both wild and domestic, is the best that can be done for now.
Still, the issue appears to be caused by multiple contributing factors perpetuated by the host’s lack of natural predators, population density, changes in habitat, and the persistent evolution of bacteria that is difficult to treat. Containing it seems to be the top priority of ODFW.
Hunters who harvest visibly infected elk are encouraged to report to ODFW and turn over the damaged hooves for examination. Hunters can fill out a form online or contact the wildlife health lab toll-free at 888-968-2600 or by email at WildlifeHealth@state.or.us to arrange for collection of the infected hooves.