HIGH PREVALENCE OF MYCOPLASMA SUIS IN A SOW FARM: HEMATOLOGICAL FINDINGS AND ABSENCE OF ARTHROPOD-ASSOCIATED TRANSMISSION

Introduction and Objectives A sow farm in northern Italy recurrently experienced pale mucous membranes, lethargy, vulval and mammary edema. Hypogalactia was suspected due to the recurrent premature transfer of undernourished piglets (1.94 ± 0.92 per litter) to nurseries during mid-lactation. Additionally, a pre-weaning mortality rate of 26.84 ± 4.21% was observed. Previous diagnostic investigations for PRRSV, PCV2 and Leptospira spp. yielded negative results. An investigation was conducted to detect Mycoplasma suis and assess its effects on sow hematological parameters. Furthermore, entomological surveillance was conducted to explore the potential role of arthropods as vectors. Materials and Methods A total of 237 sows (parity 1 - 8) were enrolled during the summer period, and blood samples were collected at day 110 of gestation. Hemoglobin concentration (HGB) and serum fructosamine were determined. Entomological surveillance consisted of a total of 10 samples using CDC-like traps (Italian Mosquito Trap IMT®; PeP, Italy), allocated in the gestation rooms and outside the herd. A real-time SYBR-green PCR targeting M. suis was performed on arthropod pools and on a subsample of 50 sows. Results and Discussion M. suis was detected in 100% of the sows, a prevalence markedly higher than that reported in comparable European studies. Mean HGB was 11.48 ± 1.04 g/dL (min: 7.80; max: 14.10 g/dL), slightly below literature references (11.6 - 12.6 g/dL). However, only 16,8% sows were below the threshold for severe anemia (10.5 g/dL), suggesting a predominantly chronic infection pattern. Mean fructosamine concentration was 282.4 ± 19.4 μmol/L (min: 233; max: 392 μmol/L), supporting the absence of subclinical hypoglycemia. All arthropod samples tested negative, suggesting no pathogen detection within the sampled insect population and indicating that transmission dynamics in this herd may be largely independent of seasonal arthropod vectors. Conclusion The high prevalence of M. suis highlights the need to investigate management-related factors potentially contributing to the persistence and spread of infection within the herd, particularly iatrogenic transmission routes. Herd health strategies should include the strengthening of internal biosecurity protocols to limit within-herd transmission.