Clostridium haemolyticum causes bacillary hemoglobinuria (BH), an infectious and usually fatal disease that occurs mostly in cattle, which is clinically characterized by jaundice, hemoglobinuria, and anemia. The trematode Fasciola hepatica has been commonly reported as the main predisposing factor that triggers this condition. The authors evaluated 20 naturally occurring cases of bovine BH to characterize the pathology and pathogenesis of the disease. Grossly, the most consistent finding was a large, frequently single focus of necrosis surrounded by a red to purple halo, observed most frequently on the parietal surface of the right and left hepatic lobes. Other findings were jaundice, dark-brown discoloration of kidneys, and red urine in the urinary bladder. Microscopically, characteristic lesions were locally extensive, necrotizing hepatitis with thrombosis and numerous intralesional Gram-positive rod-shaped bacteria, and acute renal tubular necrosis. By immunohistochemistry, many hepatocytes outside the necrotic focus in the liver were positive for activated caspase 3, suggesting that those cells were undergoing apoptosis. Ultrastructural evaluation revealed hepatocyte necrosis, hemolysis, and clumps of vegetative and sporulating bacilli within the liver. Polymerase chain reaction for the C. haemolyticum beta toxin gene was positive in randomly selected liver samples. No gross or microscopic lesions indicative of fascioliasis were detected in the liver of any animal, suggesting that other yet undetermined predisposing factors were associated with these cases of BH.

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Detection of bovine viral diarrhea virus (BVDV) in aborted fetus samples is often difficult due to tissue autolysis and inappropriate sampling. Studies assessing different methods for BVDV identification in fetal specimens are scarce. The present study evaluated the agreement between different diagnostic techniques to detect BVDV infections in specimens from a large number of bovine aborted fetuses and neonatal deaths over a period of 22 years. Additionally, genetic, serological, and pathological analyses were conducted in order to characterize BVDV strains of fetal origin. Samples from 95 selected cases from 1997 to 2018 were analyzed by antigen-capture ELISA (AgELISA), nested RT-PCR (RT-nPCR), and real-time RT-PCR (RT-qPCR). In addition, amplification and sequencing of the 5′UTR region were performed for phylogenetic purposes. Virus neutralization tests against the BVDV-1a, BVDV-1b, and BVDV-2b subtypes were conducted on 60 fetal fluids of the selected cases. Furthermore, the frequency and severity of histopathological lesions were evaluated in BVDV-positive cases. This study demonstrated that RT-nPCR and RT-qPCR were more suitable than AgELISA for BVDV detection in fetal specimens. However, the agreement between the two RT-PCR methods was moderate. The BVDV-1b subtype was more frequently detected than the BVDV-1a and BVDV-2b subtypes. Neutralizing antibodies to any of the three subtypes evaluated were present in 94% of the fetal fluids. Microscopically, half of the BVDV-positive cases showed a mild non-suppurative inflammatory response. These results emphasize the need to consider different methods for a diagnostic approach of BVDV associated to reproductive losses.

White muscle disease (WMD), nutritional myodegeneration or enzootic muscular dystrophy, is a nutritional condition associated with selenium and/or vitamin E deficiency in ruminants. These elements are constituents of the major body antioxidant systems. Depletion of selenium results in oxidative damage to cardiac and skeletal muscle cells, resulting in myodegeneration and myonecrosis, typical lesions of WMD. Selenium deficiency is common in South America, but WMD is underreported. This research describes clinical, biochemical and pathological findings in two episodes of WMD associated with selenium deficiency in beef and dairy calves in Argentina and Uruguay with concurrent copper deficiency in one of them, which resulted in spontaneous calf mortality. Further studies are necessary to estimate the true incidence and economic impact of clinical and subclinical mineral deficiencies in livestock production systems in the southern cone of South America.