26 The Trusted Source for Canada’s Pork Producers Better Pork | December 2023 Mycoplasma is a group of bacteria that includes many species. Mycoplasmas are smaller and structurally different than most bacteria as they do not have a cell wall. In pigs, Mycoplasma are probably best known for causing respiratory disease and arthritis. Arthritis can be caused by two different species of Mycoplasma: M. hyosynoviae and M. hyorhinis. Mycoplasma hyorhinis and hyosynoviae are both ubiquitous and commonly live in the upper respiratory tract of healthy pigs. Sows often pass the organisms onto their piglets shortly after birth, which makes it extremely difficult to eradicate these pathogens from a farm. Infected pigs can shed the bacteria in their feces and infect other pigs. Both Mycoplasma hyorhinis and hyosynoviae are able to enter the bloodstream of pigs. From there, they distribute throughout the body and set up infection in different locations. Typically, M. hyosynoviae only affects the joints, causing inflammation of the lining of the joint (synovitis). M. hyorhinis has a larger potential for widespread disease as it has been known to infect the surfaces of the heart, lungs, abdominal organs and joints. Symptoms Mycoplasma can cause inflammation in multiple joints at the same time, including the shoulders, elbows, stifles (knees) and hocks. The lameness may be short-lived, or it may become chronic. Pigs affected by M. hyosynoviae often have a stiff gait, especially in the hind end, and may have a hunched or rounded back. They may be reluctant to stand or walk. Affected pigs often adopt a “dog sitting” posture to avoid putting weight on their affected limbs. They may demonstrate shivers or tremors from muscle tension. The lameness can range from mild and barely noticeable to very severe. Pigs with M. hyosynoviae often go off feed, but typically do not have a fever (or if they do, it is generally mild). M. hyorhinis may present differently, with more systemic signs of illness such as fever, respiratory signs such as cough and laboured breathing, depression and hairiness. M. hyorhinis classically presents earlier in life, with prevalence peaking at or just after weaning, up to 10 weeks of age. M. hyosynoviae usually does not affect pigs until later in the grow-finish period after three months of age. M. hyosynoviae usually does not cause the development of pus within affected joints. However, M. hyorhinis can cause deposition of fibrin (pus-like material) in the joint as well as infecHERD HEALTH MYCOPLASMA ARTHRITIS These tiny bacteria can cause big problems with lameness. By Hayley Bowling Mycoplasma hyosynoviae can cause swelling and bleeding in the joints. In this severe case, the pig would not bear weight on this limb. Dr. Jessica Law photo Dr. Jessica Law photo Pigs with Mycoplasma arthritis may walk with a stiff gait rather than showing lameness on one specific limb. Note the rounded back on the affected pig.
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