Pneumonia and bighorn sheep

Pneumonia outbreaks can devastate local herds and spread rapidly within and among bighorn sheep populations.

  • Pneumonia and bighorn sheep

Attention hunters

If you see sick or dead bighorn sheep contact your local Government of Alberta biologist. For contact information, see:

Fish and Wildlife Area Office – Contacts

Bighorn sheep in Alberta

Bighorn sheep are an iconic mountain species. In Alberta, they are the designated Provincial Mammal. Bighorn sheep are highly valued by Indigenous Peoples, Albertans and non-residents for hunting and wildlife viewing.

Rocky Mountain bighorn sheep are one of the rarest hoofed mammals in North America. Alberta, British Columbia and 13 US western states have approximately 40,000 bighorn sheep, less than 10% of their population size in the 1850s.

Alberta has approximately 9,000 bighorn sheep:

  • 3,000 in National Parks.
  • 6,000 on provincial lands.

Some of these sheep also spend time in British Columbia.

Bighorn sheep in Alberta are an important source of disease-free animals to support recovery of wild herds throughout the west.

Bighorn respiratory disease

Bronchopneumonia is a serious respiratory disease associated with large-scale catastrophic die-offs of bighorn sheep throughout North America. Pneumonia occurs when the air sacs (alveoli) in the lungs fill with fluid or pus.

The Western Association of Wildlife Agencies (WAFWA) considers pneumonia the single greatest threat to sustaining wild sheep herds. If a pneumonia outbreak in bighorn sheep occurred in Alberta or BC, the effects could be catastrophic.

Update March 2023

An outbreak of infectious bacterial pneumonia was identified in a small band of bighorn sheep west of Diamond Valley, with several sheep succumbing to the disease. Test results from the dead sheep indicated infectious bacterial pneumonia and confirmed the presence of Mycoplasma ovipneumoniae. On March 14, the 6 remaining bighorns in the group were humanely euthanized and submitted for full post-mortem. To date, additional sick or dead bighorn sheep have not been seen elsewhere in the Sheep River valley. Environment and Protected Areas, in conjunction with Alberta Parks, has undertaken additional monitoring on other bighorn sheep herds in Alberta.



  • Since 1937, Alberta recorded 7 bighorn pneumonia outbreaks, with mortality from 10-75%. Male and female sheep of all ages were affected.
  • Risk evaluations indicate high potential for another pneumonia outbreak in Alberta unless we mitigate and minimize the risks.
  • Population recovery after an outbreak often takes 5 to 10 or more years, depending on:
    • Number and age of infected bighorns.
    • Number of chronic carriers in the population (sheep that survive infection and continue to infect others).
    • Rate of lamb recruitment. Several years of poor lamb survival can occur after a die-off, particularly if ewes are chronic carriers.

Timeline: History of known die-offs in southwestern Alberta

  • 1937- 1949
    • Outbreak location: Southern Alberta
    • Population before event (rounded to nearest 5): 8500
    • Population after die-off (rounded to nearest 5): 2550
  • 1945-1946
    • Outbreak location: Highwood Pass
    • Population before event (rounded to nearest 5): Unknown
    • Population after die-off (rounded to nearest 5): “Significantly less”
  • 1978
    • Outbreak location: Sheep River
    • Population before event (rounded to nearest 5): 130
    • Population after die-off (rounded to nearest 5): 120
  • 1982-1983
    • Outbreak location: Yarrow-West Castle
    • Population before event (rounded to nearest 5): 400
    • Population after die-off (rounded to nearest 5): 100
  • 1985-1986
    • Outbreak location: Sheep River
    • Population before event (rounded to nearest 5): 175
    • Population after die-off (rounded to nearest 5): 105
  • 2000
    • Outbreak location: Sheep River
    • Population before event (rounded to nearest 5): 105
    • Population after die-off (rounded to nearest 5): 80
  • 2023
    • Outbreak location: Sheep River
    • Population before event (rounded to nearest 5): 110
    • Population after die-off (rounded to nearest 5): 95

Causes and transmission

  • There are many types of bacteria associated with pneumonia in wild sheep, but the most serious one is a bacterium called Mycoplasma ovipneumoniae (M. ovi).
  • M. ovi transfers from infected to healthy sheep or goats by:
    • Direct physical contact.
    • Airborne particles up to 30-100m from the source.
  • M. ovi cannot survive in the environment.
  • M. ovi does not infect humans.

Risk factors

Domestic sheep and goats

  • Most domestic sheep and goats have a tolerance or immunity to M. ovi and infections go undetected.
  • Some domestic sheep and goats exhibit mild signs of pneumonia, ranging from coughing to reduced growth rates.
  • Recent testing of domestics finds high occurrence of M. ovi in some flocks in Canada and the US.
  • In Alberta, M. ovi testing in domestic sheep and goats is limited and infection rates are unknown.
  • Strong scientific evidence indicates increased risk of pneumonia in bighorn sheep following contact with domestic sheep or goats, including a single encounter with an infected domestic sheep or goat.
  • The Wildlife Society and the Association of Wildlife Veterinarians believe disease transmission from domestic sheep and goats poses a significant risk to the conservation and restoration of wild sheep populations. Visit the Wildlife Society website at:
  • Grazing, weed control and/or vegetation management, and backcountry packing can bring domestic sheep or goats in close proximity to bighorn sheep range in Alberta.
  • The Alberta Government generally does not allow domestic goat grazing near bighorn sheep ranges. Domestic goats may be used for back-packing; however, their use for recreation and commercial purposes is not recommended near bighorn range.

Llamas and alpacas

  • Llamas and alpacas can carry agents that potentially cause disease in wildlife, although there is no direct evidence that they have been a source of significant disease in wild sheep or goats.
  • However, current risk assessments are limited by insufficient data. More research is needed before the risks can be fully understood.
  • The Alberta Government encourages actions to minimize potential risk to bighorn sheep from llamas and alpacas:
    • Llamas, alpacas and domestic goats can be used as pack animals on most public lands but are prohibited, or require special permission, in some provincial parks (example: wilderness areas, ecological reserves).
    • A permit is required for all commercial businesses (example: tours, guided hunting) on public lands, but generally not for recreational activities.
    • Near bighorn sheep ranges, the Alberta Government recommends recreation users refrain from using llamas and alpacas.

Other livestock and wildlife

  • Although documented die-offs are rare, mountain goats may be at risk of infection from wild sheep, domestic sheep and domestic goats.
  • Other domestic species (example: cattle, bison, pigs, horses) do not appear to transmit M. ovi to wild sheep or goats, or vice versa.


  • Environmental stressors may increase susceptibility of wild sheep to disease agents. These stressors include:
    • High density of wild sheep.
    • Unhealthy rangeland (example: overgrazing, weeds).
    • Mineral deficiencies (example: selenium).
    • Harsh weather (example: severe winters, drought).
    • Human activities (example: disturbance, habitat loss).
    • Predators.
  • Stress may partially explain the variation in pneumonia die-off rates among wild sheep herds and the absence or delayed onset of disease following some contacts between domestic and wild sheep.
  • The Alberta Government works with wild sheep organizations and industry to reduce stress and disturbance to wildlife. Examples include:
  • Standards and guidelines for industrial operators:

Bighorn sheep behaviour

Bighorn sheep have several characteristics that may increase disease risk. These include:

  • Complex social systems, including:
    • large social groups that change composition throughout the year.
    • individual males that move among nursery bands, bachelor groups, and breeding units.
    • natural attraction to domestic sheep and goats, especially during the breeding season.
  • Long distance migrations from low to high elevations between winter and summer.
  • Exploratory movements by males and females beyond their traditional home ranges.
  • Exploration and dispersal of young males (2-4 years old).
  • Wandering of older, mature males up to 80 kilometres before and during the rut in search of breeding opportunities.

High-risk areas

  • Alberta has mapped bighorn sheep ranges at a landscape scale using data from aerial and ground surveys, habitat models, radio-telemetry, and hunter harvest data, as well as local and expert knowledge. To view the range data, see:
  • High-risk areas consider bighorn sheep behaviour, landscape features, and proximity to risk factors, as well as potential impacts to stakeholders.
  • High-risk areas in Alberta are mapped and include lands within 50 km from wild sheep ranges.

Disease management


Physical separation of wild sheep from domestic sheep and goats is critical to minimize risk of disease transmission. Options to prevent further spread if infection occurs in wild sheep are limited:

  • Cull the entire local herd to eliminate the disease agent.
  • Test wild sheep repeatedly and kill chronic carriers of M. ovi.

Transplanting sheep from healthy herds may help recover or restore populations in some areas. But only if the original risk factors are eliminated and there are healthy sheep available to transplant.

Alberta is an important source of transplants to the U.S. Maintaining heathy disease-free bighorn sheep in Alberta is vital to both the province and to conservation of herds elsewhere.

Early detection

Testing procedures are the same for domestic and wild animals. They typically involve nasal and/or tonsil swabs.

Testing Bighorn Sheep

Testing Domestic Sheep and Goats

  • Early detection of M. ovi is key to maintaining healthy domestic herds.
  • Alberta Environment and Protected Areas works closely with Alberta Agriculture and Irrigation, domestic sheep and goat organizations, and other partners to reinforce disease prevention measures and to improve understanding of prevalence of M. ovi in domestic and wild flocks.
  • It is important to ensure M. ovi-free domestic sheep and goats in high-risk areas for wild sheep.
  • The Alberta government has a voluntary testing program for domestic sheep and goats in high-risk areas. Testing and related veterinarian costs may be paid by the government on a case-by-case basis.

Vaccines and treatment

  • There are no vaccines or treatment for pneumonia in wild sheep. Even if available, administering vaccines or treatments to wild sheep would be challenging.
  • There are no treatments to eliminate M. ovi in domestic sheep and goats. However, pneumonia in domestics can be treated with antibiotics.

Minimizing disease risk

Working together

Wild sheep enthusiasts and livestock owners share common goals:

  • Maintain healthy wild and domestic herds.
  • Sustain an economically viable domestic industry.
  • Maintain sustainable harvest and enjoyment of bighorn sheep.

Improved collaboration among government, livestock owners, industry, conservation organizations, hunters, researchers and Indigenous Peoples is key to minimizing the risks.

Sightings and strays

Please report the following to your local Government of Alberta biologist:

  • Any bighorn sheep near domestic sheep and goats.
  • Any sick bighorn sheep (for example, coughing, nasal discharge/runny nose).
  • Stray domestic sheep or goats in high risk areas.

For contact information, see:

Also report all stray livestock to:


Biosecurity measures minimize the spread of wildlife disease or disease-causing agents, and help ensure healthy and productive domestic herds. Visit the Canadian Food Inspection Agency website at:


In areas near bighorn sheep ranges, “no contact” fencing is recommended when other management strategies are not possible.

To minimize the risk of disease, fencing must:

  • Prevent nose-to-nose contact between wild sheep and domestics.
  • Minimize the likelihood of airborne transmission of disease agents.
  • Exclude bighorn sheep (they can jump over 2m high).
  • Have wire mesh size small enough to exclude lambs.

Livestock guardian dogs may increase the effectiveness of fencing.

Weed and vegetation management

Weeds and competitive vegetation is a concern in various situations in or near areas used by wild sheep. Several methods can effectively control weeds and manage vegetation:

  • Domestic sheep or goats
  • Fire
  • Herbicides and chemicals
  • Insect biological control
  • Mechanized or manual removal

The preferred method depends on:

  • budget
  • project objectives
  • site location
  • target species
  • timelines
  • work force

In specific situations, domestic sheep and goats may be more cost-effective, organic or ecologically friendly than other methods such as herbicide application.

For example, in riparian areas, strategies to prevent trampling, erosion and microbial contamination of waterways are important. Disease risks associated with domestic sheep and goats can outweigh the benefits for weed or vegetation management if there is increased probability of a pneumonia outbreak.

Attention weed control and vegetation managers

Do not use domestic sheep and goats for weed control or vegetation management in high-risk areas in Alberta.

Separation zones

Alberta considers separation zones a potential and effective tool to minimize the risk of pneumonia in bighorn sheep on public lands. Separation zones in a sheep context help maintain healthy wild and domestic herds, and sustain an economically viable domestic industry.

Maintaining physical separation between wild sheep and domestic sheep and goats is key to minimizing disease risk. Zoning on public lands can be effective in reducing this risk.

Many jurisdictions with wild sheep use separation zones in association with wild sheep ranges.

How you can help

Commercial and recreational pack animal users

  • Do not take domestic sheep or goats into high risk areas (stay at least 50 km from bighorn sheep and mountain goat range).

Domestic sheep and goat owners

Sheep hunters

  • Have your sheep tested for M. ovi
  • Look for sinus tumours

For further details, see:

Weed control and vegetation managers

  • Do not use domestic sheep and goats in high risk areas (~ 50 km from bighorn sheep and mountain goat range).

General public

  • Report sightings of coughing or sick bighorns, as well as any bighorn sheep near domestic sheep or goats to the local Government of Alberta biologist. For contact information, see Fisheries and Wildlife Management – Contacts.
  • Test for M. ovi.
  • Use good biosecurity measures and regularly monitor herd health.

It is prohibited to use domestic sheep or goats for any purpose in high risk areas by certain user groups (for example, industry).

Refer to the following to learn more:

Additional resources

Film and video


There are over 70 peer-reviewed scientific publications on M.ovi and pneumonia in wild sheep. Below are a few recent references.

Contributing factors (example: density, behaviour)

Exposure history, immunity and chronic carriers

Management strategies

Pneumonia research consortium

Transmission from domestic sheep and goats


Connect with a local Government of Alberta biologist or Provincial Disease Specialist (Edmonton) for more information about pneumonia in bighorn sheep:

Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Toll free: 310-0000 and ask to be connected to a government wildlife biologist or 780-427-3462 in Edmonton.

Also see: