Elk Hoof Disease

Background

Treponeme-associated hoof disease (TAHD), or more simply elk hoof disease, is a relatively new, poorly understood, and generally untreatable disease affecting elk in western North America.  Elk hoof disease was first suspected in Roosevelt elk in southwest Washington state in the 1990s; by 2008, prevalence and distribution of TAHD in Washington had increased substantially (Han and Mansfield 2014). Since then TAHD has been detected in Roosevelt and Rocky Mountain elk in Oregon (2014), Idaho (2018), and California (April 2020). The first documented cases of TAHD in California were confirmed in hooves of two Roosevelt elk harvested by hunters in December 2019. As of July 2020, elk hoof disease is not known to occur in tule elk.

TAHD gets its name from the treponeme bacteria associated with this disease, however, it is unknown if treponemes are the causative agent.  Researchers think that development of elk hoof disease involves several species of bacteria and may be influenced by environmental conditions (such as moist soils, local animal densities, overlap with contaminated pasture, nutritional condition of animals, and mineral deficiencies; Han et al. 2018), but additional work is needed to understand and manage TAHD in elk. Clinically, TAHD is characterized by degenerative hoof wounds in the form of lesions or ulcers and deformed, overgrown, sloughed (shed), or otherwise damaged hooves. Hoof wounds associated with TAHD are painful and can lead to limping or lameness.

There is no cure or treatment for TAHD in free-ranging elk. Preliminary, albeit limited, research suggests that TAHD progresses rapidly, most individuals will have advanced disease within a year of initial infection, TAHD can spread to multiple hooves, and TAHD generally does not resolve or improve on its own (Hoenes et al. 2018).

Potential impacts to elk populations

To date, few studies have been completed on elk hoof disease and research efforts have focused largely on describing hoof lesions or identifying causative agents (Han and Mansfield 2014; Han et al. 2018; Clegg et al. 2015). How TAHD may affect elk populations remains unclear and CDFW will continue to work with other wildlife agencies and researchers to better understand potential effects to elk populations.

One population of elk in Washington (Mount St. Helen’s elk herd) declined by almost 35% between 2009 and 2013, coinciding with an increase in the prevalence and distribution of TAHD in that herd (McCorquodale et al. 2014). During that time, however, efforts were undertaken to decrease the population size of the Mount St. Helen's elk herd, which was substantially above carrying capacity and animals were in poor nutritional condition (McCorquodale et al. 2014). Severe winter weather also contributed to population declines of the Mount St. Helen's elk herd (McCorquodale et al. 2014). Further, less than 15% of female elk followed in this study were thought to have TAHD (McCorquodale et al. 2014). Thus, TAHD alone did not account for the total observed population decline and its overall contribution to population dynamics remains unclear.

What to look for in live elk

  • Severe lameness or limping
  • Hoof abnormalities such as hooves that are:
    • Broken
    • Missing
    • Deformed
    • Overgrown
    • Ulcerated or have lesions

What to look for in harvested elk

TAHD is a progressive disease and lesions may be small and difficult to discern in early stages (Grade 1, below) and entire hooves may be missing in late stages (Grade 4). Beginning in 2020, CDFW requests all elk hunters voluntary submit all four hooves from harvested elk for TAHD surveillance. Information on sample collection will be mailed to hunters with information on tooth and DNA collection. If you have questions about sample collection, please contact the local unit biologist listed for the hunt zone, CDFW's Elk and Pronghorn Coordinator, or CDFW's Wildlife Investigations Lab.

Elk Hoof Disease Grades

Definitions

Coronary band
where the hair meets the hoof
Claw
one of two digits/toes on each hoof
Hoof capsule
the entire structure, made of horn, that covers the digit/toe/claw

Illustration of grades 1 through 4 of TAHD in elk
link opens in new windowFind more information at the wdfw.wa.gov website.

What to do if you see elk with signs of TAHD

If you observe an elk with signs of TAHD, such as limping or hoof abnormalities, please report your observation to CDFW as soon as possible by email (WILAB@wildlife.ca.gov), phone (916-358-2790), or by using the wildlife mortality report form.

Food safety precautions

While TAHD alone is unlikely to pose a risk to human health, elk with TAHD may develop secondary infections that cause systemic or body-wide disease. Evidence of systemic disease may include abscesses or animals that appeared emaciated or sickly. CDFW recommends abstaining from consumption of meat from animals with evidence of systemic disease.

Help stop the spread of TAHD

Humans may unknowingly spread TAHD when contaminated soil is transferred to new areas on vehicle tires or shoes. Vehicle tires and shoes should be cleaned of all soil before leaving a contaminated area to help minimize the spread of TAHD.

Report lame, limping elk or elk with abnormal hooves

TAHD surveillance in California

In response to initial detections of TAHD in elk in Del Norte County, CA, CDFW veterinarians and scientists developed a link opens in new windowStrategic Surveillance Plan for Treponeme-Associated Hoof Disease. The surveillance plan outlines strategies for statewide surveillance of TAHD in elk. Information collected during surveillance will better inform CDFW's long-term response to and management of TAHD in California.

Surveillance goals

The two primary goals identified in CDFW's TAHD surveillance plan are to:

  1. Determine the geographic distribution of TAHD in California (and estimate prevalence, where feasible)
  2. Collect information to inform research and management actions.

Meeting these goals will allow CDFW to better understand and mitigate risks of TAHD to California's elk populations.

Surveillance results

Surveillance efforts largely focus on collecting samples from hunter-harvested elk and opportunistically from other mortalities. As of July 2020, hooves from 6 elk in the North Coast Elk Management Unit have been tested for TAHD. Of these, 3 individuals were positive for TAHD, 1 was negative for TAHD, and results for 2 other samples are pending. The following map shows where TAHD has been detected in elk in California, Oregon, Washington, and Idaho. These results will be updated periodically as new results become available.

Primary literature available on TAHD in elk

Collaborators

Frequently Asked Questions

What is TAHD?

Treponeme-associated hoof disease (TAHD) is an infectious disease that affects hooves of elk.

What causes TAHD?

Although TAHD is associated with spiral-shaped bacteria in the genus Treponema, it is believed that multiple species of bacteria contribute to development of TAHD in elk. Other contributing factors likely include the environment, nutritional condition of individuals, and population density. Animal age and sex do not appear to be factors in disease transmission.

How can I tell if an elk has TAHD?

Lameness or limping and hoof abnormalities are common symptoms of TAHD in elk. Abnormal hooves may be elongated, deformed, broken, or missing altogether. These symptoms, however, are not definitive and can be symptoms of other diseases or injuries, which is why CDFW is instituting a program for statewide surveillance of TAHD. When the disease is severe, elk may become too weak to graze, fight off other infections, or escape predators.

Where does TAHD occur?

Lameness and hoof abnormalities believed to be caused by TAHD began being reported sporadically in populations of free-ranging elk in Washington state in the mid-1990s, but TAHD cases have been on the rise in Washington since ~2008. Oregon confirmed its first cased of TAHD in 2014, Idaho in 2018, and California most recently confirmed its first cases of TAHD in free-ranging Roosevelt elk in Del Norte County in April 2020.

Where did TAHD originate?

The origin of TAHD is unknown, but Treponema bacteria also cause similar hoof diseases in domestic cattle (bovine digital dermatitis) and sheep (contagious ovine digital dermatitis).

How is TAHD spread? Can it be transmitted to humans or other animals?

Treponema bacteria may persist in moist soils and may be spread when contaminated soils or infected animals move associated bacterial pathogens to new areas. 

TAHD is not transmissible to humans, although humans may unknowingly spread TAHD when contaminated soil is transferred to new areas on vehicle tires or shoes. Vehicle tires and shoes should be cleaned of all soil before leaving a contaminated area to help minimize the spread of TAHD.

Currently, it is not known if domestic cattle and sheep or other wild ungulates (e.g., deer) are susceptible to TAHD, however, there are no reports of increased prevalence of hoof disease in areas with greater levels of TAHD prevalence than in California.

Is there a cure or treatment?

Although hoof diseases in livestock can be treated using repeated doses of antibiotics and regular foot baths, these options are not practical or feasible for treating hoof disease in free-ranging populations of elk. TAHD generally does not resolve on its own.

How will TAHD affect elk in California? How is CDFW responding?

The potential effects of TAHD on populations of elk in California are unknown, but CDFW has initiated statewide surveillance and is collaborating with researchers at Washington State University (WSU) who specialize in TAHD.

CDFW’s statewide surveillance plan for TAHD focuses on collecting hoof samples from hunter-harvested elk throughout the state, as well as other samples that become available opportunistically.  Because early stages of TAHD can be difficult to discern, CDFW will be collecting samples of apparently “normal” hooves, in addition to visibly abnormal hooves, as part of the surveillance program.  All hoof samples collected by CDFW, with assistance from the public, will be inspected for signs of TAHD and submitted for testing.

What should I do if I see an elk with signs of TAHD (e.g., limping, abnormal hooves)?

If you observe an elk with signs of TAHD, such as limping or hoof abnormalities, please report your observation to CDFW as soon as possible by email (WILAB@wildlife.ca.gov), phone (916-358-2790), or by using the wildlife mortality report form.