Mycoplasma hyorhinis (Mhr): A THREAT TO THE HERD

Could Mhr be impacting your pigs’ performance? Help protect against it with INGELVAC MYCOMAX®—the first and only clinically proven vaccine for Mhr.

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An increasing challenge for swine veterinarians

Mycoplasma hyorhinis (Mhr) is a common commensal bacteria of the respiratory tract of pigs. While Mhr appears to be largely benign when limited to the airways, the organism can cause serious systemic disease. The mechanism by which this change happens is not well understood.1 Pigs of nursery age are the most susceptible to clinical disease caused by Mhr infection, exhibiting clinical signs including elevation in temperature, lameness, inappetence, difficulty in moving, swollen joints, otitis media and ocular discharge.1-7 Mhr can also cause outbreaks of polyserositis and arthritis in pigs. In fact, in a study conducted in 2010 at the University of Minnesota Veterinary Diagnostic Laboratory, approximately 55% of polyserositis cases tested positive for Mhr by polymerase chain reaction.1

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An underdiagnosed risk

Mhr is known to be a cause of arthritis, pericarditis, lameness and peritonitis in nursery and early finishing pigs.9 The recent increase in diagnostic testing and coding accuracy has improved detection rates, but often clinical signs are attributed to Haemophilus parasuis or other pathogens, allowing Mhr to be underdiagnosed and to continue causing significant impact on performance.1,6,7,10,11 This, along with increased pig variability, mortality and culling can result in economic losses, all attributable to Mhr.10,12

Coinfection with Mhr can lead to more severe disease12-15

The clinical signs of Mhr can be exacerbated when coinfected with porcine circovirus type 2 or porcine reproductive and respiratory syndrome.12-15 Compared to a PCV2 infection alone, a dual infection of PCV2 and Mhr results in more severe macroscopic and microscopic lung lesions, as well as a wider distribution of PCV2 DNA.14 Though Mhr is frequently detected in pigs with respiratory symptoms, its role in clinical cases remains unknown.

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A need for understanding through diagnostics

Between 2013 and 2017, Mhr was found in more than 50% of systemic samples and approximately 12% of arthritis samples submitted to the Iowa State University Veterinary Diagnostic Laboratory.16 Therefore, establishing a clear case definition and confirming Mhr-associated disease through diagnostic investigation are vital to identifying and preventing Mhr infection.1

Ingelvac Mycomax is the first and only clinically proven vaccine for Mhr

Current Mhr control strategies include vaccination with autogenous vaccines and/or treatment of clinical cases with antibiotics. However, efficacy for these vaccines has not been evaluated by the USDA. Before the introduction of Ingelvac Mycomax, there were no commercially available vaccines with demonstrated efficacy against Mhr.

Ingelvac Mycomax has been shown to be effective for the vaccination of healthy pigs 3 weeks of age or older — when they are most susceptible to an Mhr infection resulting in clinical disease.2-5,12,16 With duration of immunity lasting at least seven weeks following vaccination, Ingelvac Mycomax is proven to protect against arthritis, pericarditis, lameness and peritonitis associated with Mhr.

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Proven protection against arthritis, pericarditis, lameness and peritonitis associated with Mhr.9

For more information about determining the Mhr status of your herd and implementing control strategies using Ingelvac Mycomax, talk to your Boehringer Ingelheim representative, or visit

References: 1. Rovira A, Clavijo MJ, Oliveira S. Mycoplasma hyorhinis infection of pigs. Acta Sci Vet. 2010;38:S9-S15. 2. Straw BE, Zimmermann JJ, D’Allaire S, Taylor DJ. Diseases of Swine. 9th ed. Ames, IA: Blackwell Publishing; 2006. 3. Morita T, Ohiwa S, Shimada A, Kazama S, Yagihashi T, Umemura T. Intranasally inoculated Mycoplasma hyorhinis causes eustachitis in pigs. Vet Pathol. 1999;36:174-178. 4. Lin JH, Chen SP, Yeh KS, Weng CN. Mycoplasma hyorhinis in Taiwan: diagnosis and isolation of swine pneumonia pathogen. Vet Microbiol. 2006;115:111-116. 5. Martinson B, Minion FC, Jordan D. Development and optimization of a cell-associated challenge model for Mycoplasma hyorhinis in 7-week-old caesarean-derived, colostrum-deprived pigs. Can J Vet Res. 2018;82:12-23. 6. Kobisch M, Friis NF. Swine mycoplasmoses. Rev Sci Tech. 1996;15(4):1569-1605. 7. Morita T, Muraki Y, Awakura T, Shimada A, Umemura T. Detection of Mycoplasma hyorhinis in porcine eustachitis. J Vet Med Sci. 1993;55(3):475-477. 8. Swine Disease Reporting System. Report 7. September 4, 2018. 9. Boehringer Ingelheim Animal Health studies 2014245, 2015095, 2016077, published on 10. Murray D. Mycoplasma hyorhinis: not just an incidental finding. 2012 American Association of Swine Veterinarians; March 10-13, 2012; Denver, CO: 457–460. 11. Gomes Neto JC, Gauger PC, Strait EL, Boyes N, Madson DM, Schwartz KJ. Mycoplasma-associated arthritis: critical points for diagnosis. J Swine Health Prod. 2012;20(2):82-86. 12. Clavijo MJ, Murray D, Oliveira S, Rovira A. Infection dynamics of Mycoplasma hyorhinis in three commercial pig populations. Vet Rec. 2017;181(3):68. doi:10.1136/vr.104064. 13. Palzer A, Haedke K, Heinritzi K, Zoels S, Ladinig A, Ritzmann M. Associations among Haemophilus parasuis, Mycoplasma hyorhinis and porcine reproductive and respiratory syndrome virus infections in pigs with polyserositis. Can Vet J. 2015;56:285-287. 14. Chen D, Wei Y, Huang L, et al. Synergistic pathogenicity in sequential coinfection with Mycoplasma hyorhinis and porcine circovirus type 2. Vet Microbiol. 2016;182:123-130. 15. Lee JA, Oh YR, Hwang MA, et al. Mycoplasma hyorhinis is a potential pathogen of porcine respiratory disease complex that aggravates pneumonia caused by porcine reproductive and respiratory syndrome virus. Vet Immunol Immunopathol. 2016;177:48-51. 16. Data on file. Boehringer Ingelheim.

INGELVAC MYCOMAX® is a registered trademark of Boehringer Ingelheim Vetmedica GmbH, used under license.

© 2019 Boehringer Ingelheim Animal Health USA Inc., Duluth, GA. 
All rights reserved. US-POR-0029-2019 30279

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