Today, we are sharing an original research article published by the MycoLab and Dr. Maria Pieters in PLOS One regarding detection patterns for 2 species of mycoplasmas in sows and piglets.
The objectives of this study were to:
- describe when Mycoplasma hyorhinis and Mycoplasma hyosynoviae can be detected in piglets and is sows,
- assess if there was a correlation between detection of the mycoplasmas in the sow and in the piglet, and
- assess if there was a correlation between lameness and mycoplasma detection.
Under the conditions of this investigation, dams appeared to be consistently positive for both M. hyorhinis and M. hyosynoviae prior to weaning.
In contrast, higher detection was observed in piglets at week 3, in comparison to week 1 post-farrowing, with M. hyorhinis, while detection of M. hyosynoviae was remarkably minimal.
The relative risk of developing lameness in postweaning piglets was highly associated with the detection of M. hyorhinis at 3 weeks of age
This research article is available in open-access on the PlOS One website.
To answer their questions, researchers selected a 2,000 farrow-to-wean farm located in the Midwest with an unknown prevalence of the 2 mycoplasmas. 128 piglets were randomly selected from 30 sows, representative of the parity structure of the farm.
Swabs of the piglets and sows tonsils were taken 1 and 3 weeks post-farrowing. Starting at 5 weeks of age, piglets were evaluated for lameness every 2 weeks until they reached 22 weeks.
Tonsillar swabs were sent to the UMN VDL and were tested by PCR for Mycoplasma hyorhinis and Mycoplasma hyosynoviae.
Lameness scores were determined as follows: Score of 0) pig gets up immediately from a lying position and moves freely in the pen with balanced weight on all four limbs. Score of 1) pig rises immediately but a reluctant movement is observed, with short steps and uneven distribution of body weight. Score of 2) pig moves slowly in the pen with short steps and reduced weight in the sore limb, or pig rises slowly and the affected limb was not weight bearing. Score of 3) pig is reluctant to rise, with muscle shivering when standing and lifts the sore limb from the floor, or pig refuses to walk or walks on three limbs only and Score of 4) pig only rises when forced and when standing has marked signs of pain (e.g. reluctance to move, limping and vocalization).
Dams appeared to be consistently positive for both M. hyorhinis (72% positive) and M. hyosynoviae (72% and 55% of positive sows respectively at week one; 65% and 48.3% positive at week 3). On the other hand, M. hyorhinis and M. hyosynoviae were detected in a small proportion of piglets in week one (8.3% and 0% of piglets positive respectively). However, M. hyorhinis was detected in half of the sampled piglet population just prior to weaning whereas only 0.9% of them were positive for M. hyosynoviae.
M. hyorhinis was detected in a higher proportion of first parity dams than in multiple parity dams in both weeks of sampling, although this difference was only significant on week 3 of sampling. Detection of M. hyosynoviae, however, was higher in multiple parity dams in the first week of sampling, yet an increase in PCR detection was observed in first parity dams in week 3. The pattern of increasing detection between weeks one and three post-farrowing observed for both microorganisms in first parity dams may reflect a more recent transmission event and consequent colonization.
The risk of developing lameness at least once during post-weaning was higher if the piglets were detected positive for M. hyorhinis at week three. Additionally, there was a significant association between positive detection of M. hyorhinis at week 3 and a positive lameness score during its post-weaning age.
However, the association between positive detection of M. hyosynoviae and lameness score in post-weaning was not established due to fewer numbers of positive cases in week three.
Mycoplasma hyorhinis and M. hyosynoviae are agents associated with arthritis in pigs. This study investigated the tonsillar detection patterns of M. hyorhinis and M. hyosynoviae in a swine population with a history of lameness. The plausibility of dual PCR detection of these agents in dams at one and three weeks post-farrowing and their offspring at the same time was determined. The association between M. hyorhinis and M. hyosynoviae detection in piglets and potential development of lameness in wean-to-finish stages was evaluated by correlating individual piglet lameness scores and PCR detection in tonsils. Approximately 40% of dams were detected positive for M. hyorhinis and M. hyosynoviae at both one and three weeks post-farrowing. In first parity dams, M. hyorhinis was detected in higher proportions (57.1% and 73.7%) at both weeks of sampling compared to multi-parity dams. A lower proportion of first parity dams (37.5%) were detected positive at week one with M. hyosynoviae and an increase in this proportion to 50% was identified in week three. Only 8.3% of piglets were detected positive for M. hyorhinis in week one compared to week three (50%; p<0.05). The detection of M. hyosynoviae was minimal in piglets at both weeks of sampling (0% and 0.9%). Lameness was scored in pigs 5–22 weeks of age, with the highest score observed at week 5. The correlation between PCR detection and lameness scores revealed that the relative risk of developing lameness post-weaning was significantly associated with detection of M. hyorhinis in piglets at three weeks of age (r = 0.44; p<0.05).The detection pattern of M. hyorhinis and M. hyosynoviae in dams did not reflect the detection pattern in piglets. Results of this study suggest that positive detection of M. hyorhinis in piglets preweaning could act as a predictor for lameness development at later production stages.