Skip to main content

U.S. flag An official website of the United States government

Animal and Plant Health Inspection Service
U.S. Department of Agriculture

Mycoplasma ovipneumoniae

photo of 2 sheepMycoplasma ovipneumoniae is a respiratory bacterium associated with economically impactful pneumonia in domestic sheep and goats since 1972, when it was first described.

Although M. ovipneumoniae was previously reported to affect species of Caprinae (sheep, goats, and muskoxen), recent studies have identified the bacterium in animals outside Caprinae, highlighting the knowledge gaps in the basic epidemiology of this bacterium. To date, M. ovipneumoniae has been reported in Beira antelope, bighorn sheep, caribou, Dall sheep, moose, mountain goats, mule deer, caribou, muskoxen, white-tailed deer, and domestic cattle, sheep, and goats via a variety of diagnostic methods. The prevalence and epidemiology of M. ovipneumoniae is unknown for most of these species. In addition, it is unknown which species are susceptible to disease, which carry M. ovipneumoniae as a commensal organism, and what role susceptible species play in transmission. M. ovipneumoniae has been associated with polymicrobial pneumonia in both domestic sheep and bighorn sheep in the western United States. Although epizootics and high death losses of bighorn sheep associated with M. ovipneumoniae was first described in 2008, the epidemiology of this bacterium in bighorn sheep remains unclear. Other pathogens commonly detected in bighorn sheep pneumonia include lungworms (Protostrongylus species), Fusobacterium necophorum, Trueperella pyogenes, and members of the Pasteurellaceae bacterial family. M. ovipneumoniae was recently detected for the first time in Dall sheep, moose, and caribou in Alaska; however, the epidemiology of the bacterium in these species is not known.

In 2011, a USDA National Animal Health Monitoring System (NAHMS) study detected M. ovipneumoniae by PCR test in one or more domestic sheep on 88.5% (401/453) of sheep premises and 29.4% (1,199/4,073 ) of individual sheep tested. An unpublished Alaskan study detected M. ovipneumoniae in 57% (4/7) of Alaskan domestic sheep premises and 7.6% (13/171) of domestic sheep, which suggests that the prevalence in Alaska may be lower than in the conterminous 48 states.

Prevalence in domestic goats is less understood and studies differ. An unpublished Alaskan study detected M. ovipneumoniae in 4/32 domestic goat premises (12%), and in 12/485 domestic goats (2.5%), while a Washington study sampled 84 goats from 16 premises and detected M. ovipneumoniae in 7/16 (44%) premises (individual animal results not reported). An unpublished study, sampling goats on pack goat premises in 12 states, found M. ovipneumoniae in 14/83 premises (17%) and 46/571 of all goats sampled (8%), with significantly higher prevalence in those less than 1 year of age. An ongoing USDA NAHMS national study will report M. ovipneumoniae prevalence in U.S. domestic goats.

Infection with M. ovipneumoniae in domestic sheep may be subclinical, and generally causes low mortality with variable morbidity. Clinical signs vary from mild respiratory disease to severe pneumonia and sudden death; this variation is believed to be related to differences in strain virulence, host immune response, and secondary pathogens. Clinical signs include lethargy, fever, decreased appetite, coughing, nasal discharge, and decreased milk production in ewes. A coughing syndrome with rectal prolapse and decreased rate of gain occurs in domestic lambs infected with M. ovipneumoniae. M. ovipneumoniae can be pathogenic but also predisposes animals to other respiratory infections, resulting in polymicrobial pneumonia. Outbreaks of severe M. ovipneumoniae-related pneumonia have been reported when domestic sheep were moved into higher density housing conditions or commingled.

Reports of M. ovipneumoniae infections in bighorn sheep describe a range of clinical signs from coughing, nasal discharge, ear paresis and headshaking, to fever, lethargy, and sudden death.

M. ovipneumoniae has been found in respiratory tracts of healthy animals and in animals with respiratory disease. Transmission occurs via respiratory droplets or secretions when animals are in close contact. Pathogen, environment, and host factors contribute to the manifestation of respiratory disease in domestic and wild ruminants. These factors include exposure to multiple viruses and bacteria (including M. ovipneumoniae and others), harsh climate and weather, nutritional status and deficiencies, genetics, immune system status, concurrent disease conditions, forage quality, population/stocking density, population distribution, handling/shipping stress, habitat fragmentation and destruction, and predation. Relative contributions of factors may shift temporally and seasonally and vary between geographic populations of a species, resulting in different disease outcomes between different animal populations. Recent detections of M. ovipneumoniae in wildlife species highlight knowledge gaps in the epidemiology of M. ovipneumoniae, such as the number of species that are susceptible or commensal carriers, M. ovipneumoniae prevalence among different species, and what role individual animals, including non-diseased carriers, may play in transmission.

Factors that influence M. ovipneumoniae virulence and pathogenicity in susceptible species are unknown. Studies indicate that strains of M. ovipneumoniae differ genetically and in protein expression. More than one M. ovipneumoniae strain type has been identified from single domestic sheep farms, bighorn sheep herds, and even in individual domestic sheep. Causes for this variability are unknown but may be related to strain virulence, host immune responses, and other factors. Knowledge gaps remain regarding the relationship of different strain types to the development of disease in different hosts.

Impacts of M. ovipneumoniae on bighorn sheep populations differ among studies. Studies in Hells Canyon (Washington, Idaho, and Oregon) describe population-limiting pneumonia epizootics, where M. ovipneumoniae is reported to be an important factor. Other states where M. ovipneumoniae-associated bighorn sheep pneumonia epizootics occur include California, Nevada, Nebraska, Arizona, Utah, Colorado, Montana, North and South Dakota, and Wyoming, though some herds with M. ovipneumoniae in Montana and Wyoming also have stable to increasing populations. This contrast suggests that other factors, aside from M. ovipneumoniae presence, also influence the onset of pneumonia epizootics in bighorn sheep. These factors are not fully understood and may be related to strain virulence, host, environment, and other unidentified risk factors.

Impacts of M. ovipneumoniae on other U.S. wildlife populations are unclear. Evidence suggests M. ovipneumoniae has been present in Dall sheep in Alaska since at least 2004, and it has been detected in caribou and moose populations, but reports of pneumonia deaths in Alaskan wildlife are sporadic. It is unknown if the M. ovipneumoniae strain(s) detected in Alaskan wildlife are part of the normal respiratory commensal flora, if the animals have adapted to the strain(s), and/or if the strain(s) are virulent.

Various diagnostic tests for M. ovipneumoniae identification have been developed, including bacterial culture, antibody-based tests including indirect hemagglutination (IH) and competitive enzyme-linked immunosorbent assay (cELISA), and DNA based tests like polymerase chain reaction (PCR). Sensitivity and specificity vary with test type and protocol. Protocols between laboratories may be different and change over time, which can result in variability in test results between laboratories.

An official antemortem diagnostic test for M. ovipneumoniae does not exist, and currently available tests have demonstrated some variability between laboratories. Regulatory tests must be standardized and validated and the definition of disease freedom must be clearly stated regarding test results and interpretation. The World Organization for Animal Health (OIE) criteria for assay development and validation include defining the assay purpose, assay optimization, assay standardization, repeatability, analytical sensitivity, analytical specificity, assay thresholds, diagnostic sensitivity, diagnostic specificity, reproducibility, and assay fitness for intended purpose. See The Manual for Diagnostic Tests and Vaccines for Terrestrial Animals for a detailed description

Recommended biosecurity measures to reduce likelihood of transmission of M. ovipneumoniae in domestic sheep and goat herds include avoiding overcrowding, improving ventilation in confinement, and using management strategies that reduce risk factors for respiratory tract disease.

1. Carmichael LE, St George TD, Sullivan ND, et al. Isolation, propagation, and characterization studies of an ovine Mycoplasma responsible for proliferative interstitial pneumonia. Cornell Vet 1972;62:654-679.

2. Nicholas R, Ayling, R., McAuliffe, L. Mycoplasma Diseases of Ruminants. Oxfordshire, UK: CABI International, 2008.

3. Cassirer EF, Manlove, K.R., Plowright, R.K., Besser, T.E. Evidence for strain-specific immunity to pneumonia in bighorn sheep. The Journal of Wildlife Management 2016;81:133-143.

4. Rovani ER, Beckmen KB, Highland MA. Mycoplasma ovipneumoniae Associated with Polymicrobial Pneumonia in a Free-Ranging Yearling Barren Ground Caribou (Rangifer tarandus granti) from Alaska, USA. Journal of Wildlife Diseases 2019;55:733-736.

5. Highland MA, Herndon, D.R., Bender, S.C., Hansen, L., Gerlach, R.F., Beckman, K.B. Mycoplasma ovipneumoniae in wildlife species beyone subfamily Caprinae. Emerging Infectious Diseases 2018;24:2384-2386.

6. Black SR, Barker IK, Mehren KG, et al. AN EPIZOOTIC OF MYCOPLASMA OVIPNEUMONIAE INFECTION IN CAPTIVE DALL'S SHEEP (OVIS DALLI DALLI). Journal of Wildlife Diseases 1988;24:627-635.

7. Wolff PL, Blanchong JA, Nelson DD, et al. Detection of Mycoplasma ovipneumoniae in Pneumonic Mountain Goat (Oreamnos americanus) Kids. J Wildl Dis 2019;55:206-212.

8. Handeland K, Tengs T, Kokotovic B, et al. Mycoplasma ovipneumoniae--a primary cause of severe pneumonia epizootics in the Norwegian Muskox (Ovibos moschatus) population. PloS one 2014;9:e106116-e106116.

9. Spraker TR, Hibler CP, Schoonveld GG, et al. PATHOLOGIC CHANGES AND MICROORGANISMS FOUND IN BIGHORN SHEEP DURING A STRESS-RELATED DIE-OFF. Journal of Wildlife Diseases 1984;20:319-327.

10, Wolfe, L.L., Diamond, B., Spraker, T. et al. A Bighorn Sheep Die-off in Southern Colorado Involving a

Pasteurellaceae Strain that May Have Originated from Syntopic Cattle. J. Wildl Dis 2010; 46(4) : 1262-1268.

11. Alley MR, Quinlan, J.R., Clarke, J.K. The prevalence of Mycoplasma ovipneumoniae and Mycoplasma arginini in the respiratory tract of sheep. New Zealand Veterinary Journal 1975;23:137-141.

12. Cottew GS, Yeats FR. Occurrence of mycoplasmas in clinically normal goats. Aust Vet J 1981;57:52-53.

13. Goncalves R, Mariano I, Nunez A, et al. Atypical non-progressive pneumonia in goats. Vet J 2010;183:219-221.

14. Besser TE, Highland MA, Baker K, et al. Causes of pneumonia epizootics among bighorn sheep, Western United States, 2008-2010. Emerg Infect Dis 2012;18:406-414.

15. Besser TE, Cassirer EF, Potter KA, et al. Association of Mycoplasma ovipneumoniae infection with population-limiting respiratory disease in free-ranging Rocky Mountain bighorn sheep (Ovis canadensis canadensis). J Clin Microbiol 2008;46:423-430.

16. Gerlach RF. Personal communication, 2019.

17. Mycoplasma ovipneumoniae on U.S. sheep operations. 2015; Accessed 1/17/20, 2020.

18. Highland, M. Personal communication, 2019.

19. Heinse, L.M., Hardestly, L.H., Harris, R.B. Risk of pathogen spillover to bighorn sheep from domestic sheep and goat flocks on private land. Wildlife Society Bulletin 2016; 40(4):625-633.

20. Besser, T.E., Cassirer, E.F., Potter, K.A., Foreyt, W.J. Exposure of bighorn sheep to domestic goats colonized with Mycoplasma ovipneumoniae induces sub-lethal pneumonia. PLoS One 2017; 12(6) e0178707.

21. Besser, T.E., Cassirer. E.F., Potter, K.P., Lahmers, K., Oaks, J.L., Shanthalingam, S., Srikumaran, S., Foreyt, W.J., Epizootic pneumonia of bighorn sheep following experimental exposure to Mycoplasma ovipneumoniae. PLos One 2014; 9(10) e110039.

Thomas E. Besser1,2*, E. Frances Cassirer3, Kathleen A. Potter1,2, Kevin Lahmers1, J. Lindsay Oaks1,2,

Sudarvili Shanthalingam1, Subramaniam Srikumaran1, William J. Foreyt

22. Niang M, Rosenbusch RF, Andrews JJ, et al. Occurrence of autoantibodies to cilia in lambs with a 'coughing syndrome'. Vet Immunol Immunopathol 1998;64:191-205.

23. Jones GE, Buxton, D., Harker, D.B. Respiratory infections in housed sheep, with particular reference to mycoplasmas. Veterinary Microbiology 1979;4:47-59.

24. Alley MR, Ionas G, Clarke JK. Chronic non-progressive pneumonia of sheep in New Zealand - a review of the role of Mycoplasma ovipneumoniae. N Z Vet J 1999;47:155-160.

25. Goncalves R, Mariano I, Nunez A, et al. Atypical non-progressive pneumonia in goats. Vet J 2010;183:219-221.

26. Besser TE, Highland MA, Baker K, et al. Causes of pneumonia epizootics among bighorn sheep, Western United States, 2008-2010. Emerg Infect Dis 2012;18:406-414

27. Woolums AR. Lower Respiratory Tract Diseases In: Smith BP, ed. Large Animal Internal Medicine. 5th ed. St. Louis, MO: Elsevier, 2015.

28. Grissett GP, White BJ, Larson RL. Structured literature review of responses of cattle to viral and bacterial pathogens causing bovine respiratory disease complex. J Vet Intern Med 2015;29:770-780.

29. Rhyan JC, Spraker TR. Emergence of Diseases From Wildlife Reservoirs. Veterinary Pathology 2010;47:34-39.

30. Jenkins, E.J., Veitch, A.M., Kutz, S.J., et al. Protostrongylid parasites and pneumonia in captive and wild thinhorn sheep (Ovis dalli). Journal of Wildlife Diseases 2007; 43(2):189-205.

31. Aich, P. Potter, A.A., Griebel, P.J. Modern approaches to understanding stress and disease susceptibility: A review with special emphasis on respiratory disease International Journal of General Medicine 2009; 2:19-32.

32. Bengis, R.G. Kock, R.A., Fischer, J. Infectious animal diseases: the wildlife/livestock interface. Rev scie tec. Off. Int. Epiz. 2002; 21(1):53-65.

33. Besser TE, Cassirer EF, Yamada C, et al. Survival of bighorn sheep (Ovis canadensis) commingled with domestic sheep (Ovis aries) in the absence of Mycoplasma ovipneumoniae. J Wildl Dis 2012;48:168-172.

34. Ionas, G. and Mew, A. Colonisation of the respiratory tracts of lambs by strains of  Mycoplasma ovipneumoniae. Veterinary Microbiology 1985; 10:533-539.

35. Ionas, G., Norman, N.G., Clarke, J.K., Marshall, R.B. A study of the heterogeneity of isolates of Mycoplasma ovipneumoniae from sheep in New Zealand. Veterinary Microbiology 1991; 29(3-4) 339-347.

36. Harvey, M.E., Morrical, D.G., Rosenbusch, R.F. Sheep flock infections with Mycoplasma ovipneumoniae involve multiple strains. Small Ruminant Research 2007; 73:287-290.

37. Parham K, Churchward CP, McAuliffe L, et al. A high level of strain variation within the Mycoplasma ovipneumoniae population of the UK has implications for disease diagnosis and management. Vet Microbiol 2006;118:83-90.

38. Cassirer, E.F., Sinclair, A.R.E. Dynamics of pneumonia in a bighorn sheep metapopulation. Journal of Wildlife Management 2007; 71(4):1080-1088.

39. Justice-Allen et al Investigation of Pneumonia Mortalities in a Mycoplasma positive desert bighorn sheep population and detection of a different strain of mycoplasma ovipneumoniae. Biennial Symposium of the Northern Wild Sheep and Goat Council 20:68-72.

40. Butler CJ, Edwards WH, Paterson JT, et al. Respiratory pathogens and their association with population performance in Montana and Wyoming bighorn sheep populations. PLOS ONE 2018;13:e0207780

41. Nicholas RAJ, Ayling, R.D., Loria, G.R. Ovine mycoplasmal infections. Small Ruminant Research 2008;76:92-98.

42. Niang M, Rosenbusch, R.F., DeBey, M.C., Niyo, Y., Andrews, J.M., Kaeberle, M.L. Field isolates of Mycoplasma ovipneumoniae exhibit distinct cytopathic effects in ovine tracheal organ cultures. Journal of Veterinary Medicine 1998;45:29-40.

43. Niang, M. Rosenbusch, R.F., Andrews, J.J., Kaeberle, M.L. Demonstration of a capsule of Mycoplasma ovipneumoniae Am. J. Vet. Res. 1998; 59:557-562.

44. Walsh, D.P., Cassirer, E.F., Bonds, M.D., et al. Concordance in diagnostic testing for respiratory pathogens in bighorn sheep. Wildlife Society Bulletin 2016; 40(4):634-642.

45. McAuliffe, L., Ellis, R.J., Ayling, R.D., Nicholas, R.A.J. Differentiation of Mycoplasma Species by 16S Ribosomal DNA PCR and Denaturing Gradient Gel Electrophoresis Fingerprinting. J. Clin. Micr. 2003; 41(10)4844-4847.

46.Ziegler, J.C., Lahmers, K.K., Barrington, G.M., et al. Safety and immunogenicity of a Mycoplasma ovipneumoniae bacterin for domestic sheep (Ovis aries). PLoS One 2014; 9(4):e95698.

47. Manual of Diagnostic Tests and Vaccines for Terrestrial Animals 2019, Accessed 12/12/20.

48. Besser, T.E., Cassirer, E.F., Highland, M.A., et al. Bighorn sheep pneumonia: Sorting out the cause of a polymicrobial disease. Preventive Veterinary Medicine 2013; 108(2-3): 85-93.

49. Cassirer, E.F., Manlove, K.R., Almberg, E.S., et al. Pneumonia in bighorn sheep: Risk and Resilience. J. Wild.Manage. 2018; 82(1):32-45.

50. Western Association of Fish and Wildlife Agencies Wild Sheep Working Group Feb 2019 meeting. North Dakota DMV Update. Accessed 9/10/20.

51. Western Association of Fish and Wildlife Agencies Wild Sheep Working Group July 2018 WSWG Meeting. Summer 2018 WSWG Meeting Notes rev 8 22 18. Accessed 9/10/20

52. Western Association of Fish and Wildlife Agencies Wild Sheep Working Group Feb 2019 WSWG Meeting WSWG Winter WAFWA Mtg NOTES 5-6 Feb 2019 corr 6 24 19.

53. National Park Service, Mojave National Preserve, Sweeney Granite Mountains Desert Research Center Science Newsletter. Updates on respiratory disease affecting desert bighorn sheep in and near Mojave National Preserve. April 2016. Accessed 9/21/20.

54. Kamath, P.L, Manlove, K., Cassirer, E.F., et al. Genetic structure of Mycoplasma ovipneumoniae informs pathogen spillover dynamics between domestic and wild Caprinae in the western United States. Sci Rep.2019; 9, 15318.

The Center for Epidemiology and Animal Health
(970) 494-7200

Complementary Content