In addition to its possible role as an enteropathogen in dogs, C. difficile isolates from dogs have a high genetic similarity with those recovered from infected humans, raising the possibility of a zoonotic disease with animals playing a role in increasing cases of community acquired CDI in humans (^{RODRIGUEZ et al. 2016}; ^{WEESE et al. 2020}).

Vibrio vulnificus is an opportunistic pathogen in humans and exhibits pathogenic behavior in several aquaculture fish species. To date, in Brazil, there are no reports of V. vulnificus outbreaks in farmed fish. However, in 2019, sorubim (Pseudoplatystoma sp.) in the grow-out phase with clinical signs and cumulative mortality of 40% was registered. We aimed to identify and characterize the etiological agents of this outbreak. Seven moribund fish were sampled for bacteriological studies, and isolates were obtained from the brain and kidneys. Bacterial identification using matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF/MS) revealed V. vulnificus. One isolate, RP4, was used for identification via dnaJ and 16S rRNA gene sequencing and antimicrobial susceptibility evaluation. Sorubim juveniles were experimentally challenged with RP4 isolate via intracelomic injection (IC, 10⁷ colony-forming units [CFU] fish⁻¹) and immersion bath (IB, 10⁶ CFU mL⁻¹ for 30 min). Identities to V. vulnificus of dnaJ and 16S rRNA genes by BLAST analysis were higher than 92% and 98%, respectively. Susceptibility to oxytetracycline, florfenicol, and other antimicrobial molecules was also observed. In the IC-challenged group, the mortality rate was 100% with V. vulnificus recovered from fish organs (brain, liver, spleen, and kidney). Additionally, splenic endothelium alterations were observed in the IC group. On the contrary, the control and IB groups did not develop any clinical signs, mortality, or bacterial recovery after 7 days of challenge. To the best of our knowledge, this is the first report of pathogenic V. vulnificus in farmed Pseudoplatystoma sp.

Fowl aviadenovirus (FAdV) is an important pathogen in the global poultry industry and the etiology of inclusion body hepatitis-hydropericardium syndrome (HHS) in chickens. Since the 1990s, several outbreaks of HHS have occurred in poultry producing areas, including South America. The coinfection of FAdV and chicken anemia virus (CAV) may markedly impact the incidence of HHS. This study describes an outbreak of HHS in coinfection with CAV in industrial broiler breeders and characterizes the FAdV isolate. The three-week-old male broiler breeders had pale bone marrow, enlarged and yellowish liver, splenomegaly, and atrophied thymus; one chicken was also found with hydropericardium. Virus isolation was performed in SPF chicken embryos of liver and thymus. Tissues of the naturally infected chickens and the inoculated embryos were evaluated by PCR and histopathology. All affected chickens and inoculated embryos were positive for FAdV and CAV. The inoculated embryos had enlarged, greenish and hemorrhagic livers, and 30% died within 7 days of inoculation. Phylogenetic analysis of the FAdV isolate hexon gene partial sequence enabled grouping with E species. The E species has recently become a relevant species in several countries. The association of FAdV with CAV in breeders is of further concern due to both being capable of vertical transmission. Within the last decade, a worldwide upsurge of HHS in broiler breeders owing to failed biosecurity has occurred. In this episode, the failure on biosecurity may have enabled challenge with both FAdV and CAV, with pathological synergism. The CAV-impaired adaptive immunity may have benefited the FAdV infection.

This study evaluated the susceptibility of three Amazonian fish species, Arapaima gigas, Brycon amazonicus and Colossoma macroporum to Lactococcus spp., through experimental infection, and performed a detailed examination of the pathological damage. While lactococcosis-causing bacteria have already been isolated from these fish species, their pathogenic role remains unconfirmed. Lactococcus formosensis, L. garvieae and L. petauri strains were used to intracoelomically infect juvenile Amazonian fish. Following infection, the fish were monitored for 15 days to evaluate clinical signs and mortality. Fish that died or survived until the end of the experiment underwent bacteriological and histopathological examinations. Clinical signs were observed in the L. garvieae-challenged A. gigas, with one fish dying at five days post-infection. The remaining experimental animals, regardless of fish species, did not die. Bacteriological examination confirmed re-isolation of asymptomatic animals in the L. garvieae-challenged A. gigas and L. formosensis-challenged C. macropomum groups. No bacterial growth or histological alterations were observed in the control groups nor in the groups infected with L. petauri. Microscopic examination revealed L. garvieae-induced fibrinoid-necrotic hepatitis, lymphohistiocytic myocarditis and myositis in A. gigas, while L. formosensis caused lymphohistiocytic pericarditis in C. macropomum. These findings demonstrate that A. gigas and C. macropomum are susceptible to L. garvieae and L. formosensis, respectively, and that they can become bacterial carriers. The distinct histopathological profiles—particularly myositis (L. garvieae) and pericarditis (L. formosensis)—highlight species-specific manifestations of piscine lactococcosis in Amazonian fish species.

In forensic toxicology, the detection of toxic chemicals from human bone marrow is often used in cases with an extended post mortem interval; however, in veterinary medicine, this practice is not used. Therefore, this study was performed to investigate the suitability of bone marrow for toxicological analysis in dogs and cats. Six animals with suspected poisoning were selected; the carcasses were sent for necropsy, and the organs were collected and preserved in buffered formalin and processed routinely for histological examination. In addition, bone marrow samples from the femur, humerus, and tibia were collected for toxicological analysis by liquid chromatography coupled to mass spectrometry detection (LC-MS). This analysis confirmed the presence of aldicarb, aldicarb sulfone, asulam, carbendazim, chlorpyrifos, dichlorvos, thifensulfuron methyl and trifloxysulfuron-sodium and associated with clinical symptoms and anatomo-histopathological alterations it was recognized the poisonings. It is expected that this study will promote the toxicological investigation of bone marrow and open avenues for the use of this tissue as an option for the detection of toxic chemicals in cases of forensic pathology.