Mycoplasma hyopneumoniae is the causative bacterium of porcine enzootic pneumonia and one of the primary etiologic agents of the porcine respiratory disease complex. Most Brazilian commercial pig farms are positive for this pathogen. However, the prevalence of the pathogen in backyard pig farms has not been described, to our knowledge. Therefore, we aimed to determine the prevalence of M. hyopneumoniae in backyard pig farms in the state of Paraná, Brazil. In January–March 2020, we collected 585 serum samples from pigs in 187 non-vaccinated herds. We tested the sera with an indirect ELISA for anti– M. hyopneumoniae antibodies and found that 182 of 585 (31.1%) samples were positive, and were found in 109 of 187 (58.3%) herds assessed.

Erysipelothrix ( E .) piscisicarius is an emerging pathogen previously described in fish and more recently isolated from a clinical outbreak in swine. This study aimed to evaluate the course of infection and pathological outcomes of E. piscisicarius in pigs using an experimental intradermal challenge model. Twenty‐six 70‐day‐old pigs were randomly allocated into three groups: high‐dose (HD group, n = 10) and low‐dose (LD group, n = 10) were challenged intradermally with 10 ¹⁰ colony forming units (CFUs) and 10 ⁸ CFU using a Brazilian field isolate obtained from a pig with erysipelas‐like lesions and confirmed by whole‐genome sequencing (WGS) and average nucleotide identity (ANI), respectively, while CONT (control, n = 6) served as a negative control. Clinical monitoring, hematological assessments, acute‐phase proteins (APPs) quantification, bacteriological culture, and quantitative PCR (qPCR) targeting the spaC gene were performed over 14 days. Challenged pigs developed mild clinical signs, including transient fever and characteristic rhomboid skin lesions resembling classical swine erysipelas. No mortality occurred. Hematological analysis revealed significant reductions in red blood cell (RBC) count, hemoglobin (HGB), and hematocrit (HCT), particularly in the LD group at 7 and 14 days post‐challenge (dpc) ( p < 0.05), suggestive of inflammatory anemia. APP analysis showed a significant increase in ceruloplasmin across all groups over time, whereas transferrin levels decreased only in the control group. Bacterial isolation was unsuccessful; however, qPCR detected E. piscisicarius deoxyribonucleic acid (DNA) in blood, skin, liver, and spleen samples, confirming systemic dissemination, particularly at 7 dpc. These findings demonstrate that E. piscisicarius can induce clinical and pathological alterations in swine, although with mild severity under experimental conditions. Moreover, the study highlights the importance of differentiating E. piscisicarius from E. rhusiopathiae in diagnostics, given the potential limitations of current vaccine strategies.

O presente relato de caso trata-se de um equino, fêmea, 6 anos, raça crioulo, 400 kg, que foi atendido no setor de Clínica e Cirurgia de Grandes Animais da Universidade Federal de Santa Catarina, apresentando lesão supurativa próximo à região temporomandibular. Na avaliação clínica observou-se edema unilateral moderado na região da articulação temporomandibular (ATM) direita, e um ponto de drenagem apresentando um exsudato purulento. O diagnóstico baseou-se na avaliação radiográfica, e ultrassonográfica da região, bem como pelos achados laboratoriais de cultura da amostra exsudativa. Como tratamento instituiu-se a utilização de antibioticoterapia sistêmica e local, a qual foi ajustada conforme os resultados laboratoriais de cultura bacteriana e o estado clínico do animal. Após 3 meses do início do tratamento instituído e drenagem do abscesso, o paciente apresentou boa evolução clínica. O objetivo é relatar um abscesso localizado na ATM causado pelo agente Streptococcus equi subsp. equi com provável origem de uma adenite anterior.