Chlamydia is one of a number of common bacterial infections that can occur in pigs without any visible clinical signs. Chlamydiae are Gram-negative, intracellular eubacteria that live inside or on the surface of a host cell which, like viruses, are obligatory parasites. In most cases, the bacteria can be commensal parasites in pigs, meaning they do not cause noticeable damage to the pig, but in other cases they can be associated with respiratory disease, heart sac infection, anaemia, jaundice and poor growth. Chlamydia may also be responsible for some instances of infertility and abortion. Chlamydia suis and other chlamydia are primarily isolated in cases of reproductive disorders.

This particular study (Rypula et al., 2018) was performed to estimate the impact of Chlamydia suis infection on reproduction in sows by analysing reproduction rates and breeding parameters.

The study

• Conducted on first generation (F1) pigs from Polish Landrace (PL) × Polish Large White (PLW).
• Sixty-four herds were investigated.
• 500 vaginal swabs were collected and isolation of DNA was carried out directly from the swabs.
• All samples were analysed for Chlamydia suis by real-time PCR with a locked nucleic acid (LNA)-containing probe.
• Evaluation questionnaires were used to determine breeding parameters and reproduction rates of each individual sow.

The results

• Reproductive problems were found in 77.3% of the farms tested.
• In the farms with 10 up to 120 sows, there were higher reproductive problems with chlamydia infection than in farms with <10 and >120 sows.
• 57.81% of the surveyed farms reported oestrus repetition in their sows.
• 31.25% of the surveyed farms reported the birth of dead piglets.
• 28.12% of the surveyed farms reported abortions.

The conclusion

• The small- and medium-scale farms with 10 to 120 sows were most at risk of developing reproductive problems associated with chlamydia.
• Oestrus repetition was the most common clinical sign of chlamydia in sow herds and abortions were the least common of reproductive disorders associated with Chlamydia suis.
• Chlamydia can cause a number of reproductive disorders so should be tested for and treated accordingly to maximise sow and piglet health, welfare and productivity.

^{_{Rypuła, K, Kumala, A, Płoneczka‐Janeczko, K, Lis, P, Karuga‐Ku𓍅aniewska, E, Dudek, K, Całkosiński, I, Ku𓍅anik, P and Chorbiński, P (2018). Occurrence of reproductive disorders in pig herds with and without Chlamydia suis infection – statistical analysis of breeding parameters. Animal Science Journal, 89(5):817-824.}}