Mycoplasma (M.) hyopneumoniae is the key pathogen of the porcine respiratory disease complex (PRDC) and contributes to pleurisy in pigs. Due to its limited metabolism and laborious cultivation, molecular tools are useful for diagnosis. This study investigated the genetic diversity of M. hyopneumoniae in slaughter pigs with pneumonia and pleurisy, and it assessed co-infections by Pasteurella multocida type A (PM), Actinobacillus pleuropneumoniae (APP), and swine influenza virus A (sIVA). Lungs (n = 70) with different pleurisy scores and lesions compatible with M. hyopneumoniae infection were collected for convenience. Macroscopic and microscopic evaluations were performed. M. hyopneumoniae was detected using qPCR, and MLST was used for genetic characterization. Co-infections with PM and APP were also evaluated by qPCR, while the immunohistochemistry assessed sIVA infection. All lungs were positive for M. hyopneumoniae. Histopathology confirmed M. hyopneumoniae-associated lesions. MLST characterization was possible in 25 lungs and revealed 10 distinct allelic profiles, with none matching known sequence types in the public database. Co-infections were detected in 40% of the samples with APP and 32% with PM, with 12% showing both pathogens and 52% of the samples presenting microscopic lesions compatible with sIVA infection. The diverse genetic profiles found underscore the need for research on isolation and potential pathogenic variations.

Heavy metal poisoning poses a challenge in diagnostic practices and environmental safety. This study describes the epidemiological, clinical, and pathological aspects of a chromium (Cr) poisoning outbreak in growing/finishing pigs housed in pens with bedding of pine wood shavings containing Cr. A visit to the affected farm was conducted. Epidemiological data were collected, and necropsy and histopathological examinations and heavy metal quantifications were performed. Up to 30% of the animals from the affected pens displayed clinical signs 48 h after housing, characterized by apathy, rigid gait, distended abdomen, pain to abdominal palpation, fever, vomiting, and skin cyanosis. The lethality rate reached 76.6%. Main postmortem findings consisted of ulcerative gastritis with perforation of the glandular stomach in all necropsied swine. Heavy metal analysis revealed a higher concentration of Cr in the bedding of the affected pens, along with elevated levels of Cr in the livers of the affected swine. Given that Cr is a known cause of poisoning in humans (with acute oral exposure resulting in corrosive lesions in the gastrointestinal tract), this study marks the first diagnosis of acute oral natural Cr poisoning in animals. This diagnosis was established through the association of epidemiological, pathological, and heavy metal quantification data.

Nerium oleander, also known as “espirradeira” in Brazil, is a shrub or small tree widely used as an ornamental plant in temperate and subtropical regions of the world. Ingestion of N. oleander can cause intoxication due to the presence of cardioactive glycosides, in both humans and animals. This study aims to report the epidemiological, clinical, postmortem, and immunohistochemical features of an outbreak of natural intoxication by N. oleander in cattle and the use of immunohistochemistry (IHC) for troponin C, for the first time, in this intoxication in the species. Twenty-eight cattle had access to pruned branches of N. oleander and 20 animals started presenting clinical signs of apathy, anorexia, ataxia, tachypnea, tremors, and recumbency ten hours after the consumption. Eight cattle progressed to death 48 hours after the clinical progression and one was submitted for necropsy. Macroscopic findings included petechiae and ecchymosis on the epicardium and endocardium. Histologically, there were multifocal areas of necrosis of individual or multiple cardiomyocytes, mainly in the left ventricular papillary muscle. Immunohistochemistry for troponin C revealed decrease or absence of cytoplasmic immunolabeling in necrotic cardiomyocytes. Although intoxication by N. oleander is uncommon in cattle, it should be considered as a differential diagnosis for other conditions that cause sudden or acute death in livestock and IHC for troponin C is an auxiliary tool in the identification of peracute and acute cardiac lesions.

We describe an unusual outbreak of mortality in suckling piglets following the misadministration of an oral vaccine against Salmonella Typhimurium and Salmonella Choleraesuis. Within 3–48 h of vaccination of a batch of ~700 piglets, ~300 developed marked swelling in the dorsal neck region, respiratory distress, fever, recumbency, and apathy. In total, ~100 died, and 4 were submitted for autopsy. Gross and microscopic lesions consisted of focally extensive areas of purple discoloration in the skin of the cervical region, associated with edema and hemorrhage in the subcutis and muscles. Additionally, there was interstitial pneumonia with marked interlobular edema and mild fibrinous pleuritis. Aerobic bacterial culture identified Salmonella Typhimurium (3 cases) and Salmonella Choleraesuis (1 case) in samples of skeletal muscle and lung and from pleural swab samples. Marked immunostaining against Salmonella spp. was observed in the skeletal muscle of the cervical region, as well as in blood vessels and macrophages from the lung, liver, spleen, and kidney. We concluded that inappropriate intramuscular administration of an oral vaccine against Salmonella resulted in septicemia and death in a batch of piglets.

Necropsies can reveal herd problems or comorbidities that can lead to management corrections, improvements in animal performance, and better decision making. Furthermore, the pattern and causes of mortality might differ when different systems are evaluated. The present study was conducted to establish the main causes of death in nursery pigs from different systems in Brazil, as well as the clinical, microbiological, and pathological aspects of these mortalities. Eighteen nurseries were analyzed (a total of 120,243 housed piglets), and 557 necropsies were performed. Streptococcus suis infection was the most prevalent cause of death (21.2%), followed by bacterial polyserositis (16.7%), chronic atrophic enteritis (13.5%), salmonellosis (8.8%), pneumonia (8.6%), and colibacillosis (6.1%). The increase in mortality rate in individual nurseries and, consequently, in the diagnoses was commonly associated with disease outbreaks. Infectious diseases constituted the largest portion of the diagnoses, making a great opportunity for improving production rates in herds. Moreover, the extensive range of observed diagnoses highlights the importance of conducting preliminary diagnostic investigations based on necropsy to determine the causes of death. This approach allows for the direction of complementary tests, which can diagnose agents with greater specificity. As a result, this allows for the implementation of more effective prevention and control strategies.

Encephalomyocarditis virus (EMCV) is a zoonotic disease caused by a highly pathogenic virus that affects wild and domestic animal species, with rodents as its reservoir. Most recently, in South America, this virus was detected in an outbreak affecting humans in Peru. In Brazil, EMCV infection was described in some wild species, in horses, and once in farrowing pigs. The aim of this study is to report the reemergence of EMCV in commercial growing–finishing pigs from two different farms that experienced sudden pig death in midwest Brazil. This aim was achieved through gross pathology, histologic examination, RT‒PCR analysis, and genetic characterization of the virus. Clinical signs, such as trembling, dyspnea, and squealing sounds shortly before death, were only occasionally observed and were nonspecific. On gross examination, cardiomegaly was observed, along with multifocal pale tan foci in the epicardium extending to the myocardium on the cut surface. Microscopically, there was severe myocardial necrosis, dystrophic mineralization, fibrosis, and lymphoplasmacytic and histiocytic myocarditis. Gross and microscopic examinations of the rats were unremarkable. The RT‒PCR analyses of the pig and rat organs were positive for EMCV, and the phylogenetic analysis of the VP1 gene showed that the samples from pigs and rats contained similar strains that had their closest relatives identified in humans in Peru. This is the first genetic characterization of EMCV in Brazil, and the other findings confirm the reemergence of the disease that was transmitted from rats to pigs.