Malignant catarrhal fever (MCF), caused by ovine herpesvirus 2 (OvHV2; Orthoherpesviridae, Macavirus ovinegamma2), has sheep as natural hosts. OvHV2 is an important macavirus globally that induces fatal disease in dead-end hosts. Goats, which can be infected subclinically with OvHV2, rarely develop MCF. A 28-wk-old female goat was presented with fever and multifocal crusty skin lesions. Histologic examination of a skin biopsy suggested erythema multiforme (EM), with pyoderma and dermal vasculitis. The doe was euthanized and subjected to postmortem and histologic examination. MCF was suspected and PCR assays for macaviruses were performed, followed by immunohistochemistry (IHC) for OvHV2 latency-associated nuclear antigen (oLANA), RNA in situ hybridization for Ov2.5 mRNA, and IHC to characterize infiltrating leukocytes. The main postmortem finding was severe multifocal ulcerative dermatitis with macrophage- and T cell–mediated arteritis. The latter was also detected in kidney, spleen, heart, and intestinal wall. The PCR assay detected high loads of OvHV2 in tissues. OvHV2 oLANA and Ov2.5 mRNA were expressed within the lesions in leukocytes, endothelial cells, fibroblasts, and/or keratinocytes. Our case confirms that MCF can initially manifest clinically as a skin disease in goats and as EM with confirmed viral etiology.

Porcine circovirus 3 (PCV-3) has emerged as a significant pathogen affecting global swine populations, yet its epidemiology and clinical implications remain incompletely understood. This retrospective study aimed to investigate the prevalence and histopathological features of PCV-3 infection in pigs from Switzerland, focusing on archival cases of suckling and weaner piglets presenting with suggestive lesions. An in-house qPCR assay was developed for detecting PCV-3 in frozen and formalin-fixed paraffin-embedded tissues, enhancing the national diagnostic capabilities. Histopathological reassessment identified PCV-3 systemic disease (PCV-3-SD) compatible lesions in 19 (6%) of archival cases, with 47% testing positive by qPCR across various organs. Notably, vascular lesions predominated, particularly in mesenteric arteries, heart, and kidneys. The study confirms the presence of PCV-3 in Switzerland since at least 2020, marking the first documented cases within the Swiss swine population. Despite challenges in in situ hybridization validation due to prolonged formalin fixation, the findings indicate viral systemic dissemination. These results contribute to the understanding of PCV-3 epidemiology in Swiss pigs, emphasizing the need for continued surveillance and further research on its clinical implications and interaction with host factors. Our study underscores the utility and limitations of molecular techniques in confirming PCV-3 infections.

Porcine circovirus 3 (PCV-3) is associated with various pathological conditions, including systemic disease and reproductive disorders; however, its role in skeletal abnormalities has never been elucidated. This study included 36 cases displaying spinal malformations, rib swelling, head edema, gait abnormalities, and/or increased late-term abortions. Investigated animals consisted of 9 aborted fetuses, 9 piglets, 12 weaners, and 6 finishers. Histologically, PCV-3 associated lesions were identified in 23/36 cases (64%), including (peri-)arteritis and rib fractures with prominent callus formation. Central nervous system (CNS) lesions, in addition to vascular changes, comprised meningoencephalitis and gliosis. Thirteen animals (36%) did not display histological lesions. PCV-3 DNA was detected by real-time PCR (qPCR) in 25/36 animals (69%), with high viral loads in the bone and CNS. Three aborted fetuses tested positive for PCV-3 despite lacking macroscopic and histologic lesions. In situ hybridization (ISH) revealed the presence of PCV-3 RNA in multiple organs, including arteries, the heart, CNS, and bone. Signals were detected in periosteal arteries and osteoblasts, within calluses, and in arteries within the surrounding skeletal muscles. This study strengthens the association between PCV-3 and multisystemic inflammatory diseases, expanding its known pathogenicity to include skeletal lesions and spinal deformities. It is the first documentation of PCV-3 genome in histologically altered bone. This finding could suggest a possible etiological role in musculoskeletal abnormalities. In addition, this study is the first to report PCV-3-associated lesions in slaughter-ready finisher pigs. The integration of histological investigations, PCR, and ISH techniques is essential for the diagnosis of PCV-3-associated diseases and related lesions.