Staphylococcus spp. are one of the most predominant isolates in milk samples of dairy cows with mastitis worldwide. The aims of this study were to investigate the prevalence of bacterial pathogens in bovine mastitis milk samples in South Korea and the antimicrobial resistance profiles of staphylococcal isolates. In total, 1,245 strains were isolated from 1,260 mastitis quarter milk samples (with somatic cell counts ≥ 200,000 cells/mL) from 66 dairy farms between 2018 and 2022. The bacterial genus with the highest prevalence in bovine mastitis milk samples was Staphylococcus spp. (33.9%), followed by Streptococcus spp. (11.5%). S. aureus and non-aureus staphylococci (NAS) accounted for 11.0% and 89.0% of staphylococcal isolates, respectively. S. chromogenes was the most prevalent species among the 22 NAS species detected. S. aureus showed the highest resistance rates to penicillin (25.0%) and ampicillin (20.8%), whereas NAS showed the highest resistance rates to penicillin (18.3%), tetracycline (11.4%) and erythromycin (10.1%). Sixteen multidrug-resistant (MDR) isolates were only isolated from NAS, and the most commonly detected antimicrobial resistance gene in the 16 MDR isolates was mecA (75.0%), followed by tetK (62.5%), blaZ (50.0%), ermC (50.0%), and lnuA (43.8%). In conclusion, NAS were the most common isolates from mastitis milk in South Korea and MDR isolates carried a variety of antibiotic resistance genes. Our study suggests that continuous monitoring of the distribution and antimicrobial resistance in Staphylococcus spp., particularly NAS, is needed to improve the effectiveness of management and treatment strategies in dairy farms.

In recent years, reported cases of salmonellosis in cattle and horses in Hokkaido, Japan, have increased. To optimize antimicrobial therapy, we assessed the antimicrobial susceptibility of Salmonella isolates from these animals. Among 112 bovine isolates, high resistance rates were observed for streptomycin (92.0%), ampicillin (88.4%), and tetracycline (79.5%), while resistance rates for kanamycin (8.9%), ciprofloxacin (1.8%), gentamicin (0.0%), and colistin (0.0%) were low. Additionally, 18.8% of the bovine isolates were resistant to cefotaxime, and all of these cefotaxime-resistant isolates carried bla_CMY-2. Among 16 equine isolates, no resistance was observed to cefazolin, cefotaxime, gentamicin, nalidixic acid, ciprofloxacin, colistin, or chloramphenicol. Gentamicin and kanamycin are recommended as the first-line treatment for salmonellosis in cattle, with fluoroquinolones as the second choice.

A 14-year-old spayed female mixed-breed cat weighing 3.4 kg was admitted to the Tokyo University of Agriculture and Technology Animal Medical Center for syncope after vomiting. Echocardiography, electrocardiography, and thoracic radiography revealed no abnormalities. Holter electrocardiography showed a paroxysmal high-grade atrioventricular block coinciding with the vomiting. Based on these findings, the cat was diagnosed as having situational syncope with paroxysmal high-grade atrioventricular block triggered by vomiting, which improved with antiemetic treatment alone. The cat subsequently died of chronic kidney disease approximately 3 years and 4 months after the initial diagnosis. This is the first reported case of situational syncope triggered by vomiting in a cat.

Herein, we investigated the positional relationship between the cervical esophagus and trachea using computed tomography (CT) images in dogs with tracheal flattening. From these CT images, the ratio of the tracheal diameters in the short (vertical) and long (horizontal) axes of the tracheal ring (S/L ratio) and the vertebra–trachea–esophagus (VTE) angle were measured at the point from the 3rd cervical (C3) to the 3rd thoracic vertebra (T3) levels. The VTE angle in dogs with tracheal flattening with an S/L ratio under 0.24 tended to be smaller than the angles at the level from C4 to T2 in dogs with an S/L ratio over 0.25. The positional relationship between the esophagus and trachea seems to be possibly related to tracheal cross-sectional shape.

A 4-year 9-month-old Holstein-Friesian dairy cow presented with anorexia. On physical examination, swelling of superficial lymph nodes, pelvic masses, and prolonged urination posture after urinating a small amount were noted. Hematological examination revealed no lymphocytosis. The bovine leukemia virus proviral load was relatively high. At necropsy, enlarged lymph nodes, a large mass in the pelvic cavity, and mass lesions in several organs were observed. Histopathological examination revealed the proliferation of neoplastic lymphocytes, which were immune-positive for CD79α and negative for CD3. B-cell clonality test indicated the presence of monoclonality in the urine, masses, and lymph nodes and minor clonality in the peripheral blood. These findings led to a diagnosis of EBL with minor clonality of B-cell in the peripheral blood.

A 35-month-old Japanese Black cow was presented to a local veterinarian with a main complaint of premature labor. There was no swelling of lymph nodes on the body surface and no palpable mass on rectal examination. Although atypical lymphocytes were observed in the peripheral blood, no lymphocytosis was recorded. On Day 12, the cow developed hindlimb paresis and was euthanized. Necropsy revealed swelling of some lymph nodes, and white nodules in uterus and right atrial appendage. Histopathological examination revealed B-cell lymphoma. In clonality analysis of peripheral blood and tumor tissue, monoclonal proliferation was detected by PCR for immunoglobulin light chain (IgL) λ, suggesting neoplastic proliferation of B-cell. IgL-PCR is thought to be a possible tool for diagnosis of B-cell lymphoma.

The aim of this pragmatic approach to retrospective observational study was to identify the end-tidal concentration of sevoflurane which was associated with optimal surgical conditions (i.e., absence of any movement, coughing and straining) in 127 pregnant sheep. Optimal surgical conditions were observed in 90% of the ewes with an end-tidal concentration of sevoflurane of 2.4 Vol-% [95% CI: 2.2; 2.8] during minimal-mild nociceptive stimuli (placement of arterial catheter, bladder catheter, shaving), with 4.4 Vol-% [95% CI: 4.0; 5.2] during maternal laparotomy and hysterotomy and with 4.4 Vol-% [95% CI: 3.9; 5.8] during subsequent manipulation of the uterus and fetal surgery.

The study evaluated the larvicidal and reproductive effects of essential oils from Ocimum basilicum, Perilla frutescens, and Mentha spicata on engorged female Rhipicephalus sanguineus ticks. Adult immersion and larval packet assays were used to evaluate their larvicidal efficacy and impact on tick reproductive abilities. For tick larvae, Perilla frutescens essential oil had the highest 50% lethal dose of 1.89 mg/mL, followed by Ocimum basilicum at 1.58 mg/mL, and Mentha spicata at 1.07 mg/mL. Regarding adult ticks, although Mentha spicata essential oil had the lowest reduced oviposition value, it showed the highest product efficacy. Overall, all tested essential oils effectively killed tick larvae and influenced the reproductive capacity of engorged female ticks, with Mentha spicata essential oil being the most potent.

Dogs are the primary transmitters of the rabies virus in the Philippines; however, to the best of our knowledge, no published studies have examined its detailed neuropathology. The present study analyzed the neuropathology in the cerebrum, hippocampus, thalamus, and brainstem of 70 rabid dogs with confirmed rabies infection in the Philippines. Histopathologically, inclusion bodies (Negri bodies) were detected in the hippocampus (87.14%), cerebrum (70%), and thalamus (2.86%) of the dogs. The inclusion bodies in the cytoplasm of the hippocampal and cerebral cortical pyramidal cells were large and round to oval in shape. Whereas the inclusion bodies in the neurons of the thalamus and brainstem were small, fine, and granular. In contrast to the high prevalence of inclusion bodies in the hippocampus and cerebrum, perivascular cuffing and glial nodules were more prominent in the thalamus and brainstem. Immunohistochemically using the anti-phosphoprotein (anti-P), the sensitivity of viral antigen detection was 100% in the hippocampus, thalamus, and brainstem and 97.14% in the cerebrum. Our findings confirmed that observing the inclusion bodies in the hippocampus and cerebral cortex by histopathology could facilitate rabies diagnosis in the dogs in the Philippines, and furthermore, using immunohistochemistry on the brainstem could also be useful to detect rabies virus antigens with high sensitivity.

Allergic dermatitis (AD) is a skin disease characterized by a chronic inflammation caused by immune dysregulation. In the histopathology of patients with AD, there are several features, such as accumulation of eosinophils and mast cells, hyperkeratosis, and dermal fibrosis which are related to the exacerbation of AD. Mast cells and eosinophils are thought to be involved in fibrosis, but the details are unknown. Yama mouse is an inbred mouse showing genetically eosinophilia. If eosinophils have significant effect on fibrosis, it may be possible to establish a new AD model with severe fibrosis. In this study, AD was induced by applying dinitrofluorobenzene to mice auricle. Yama mice showed AD lesion with more severe dermal fibrosis with severe eosinophil infiltration than Balb/c and Nc/nga mice. The expression of transforming growth factor-β (TGF-β), a cytokine important for fibrosis, was not significantly different among Yama, Balb/c, and Nc/nga mice, while the expression of interleukin-4 (IL-4), which is also mediator of tissue fibrosis, was increased only in Yama mice. The results of this study showed that AD with more severe fibrosis could be induced in Yama mice than in Balb/c and Nc/nga mice. In Yama mice, it can be concluded that the severe fibrosis is TGF-β independent, and IL-4 would be the main mediator of severe fibrosis. This mouse model may be useful for elucidating the mechanism of fibrosis in chronic AD, and for conducting research leading to the development of new therapies.

An 8-year-old castrated male mixed-breed cat presented with an abdominal mass of unknown origin, accompanied by eosinophilia. Autopsy revealed mild-to-severe enlargement of lymph nodes throughout the body and multiple nodules in the lungs. Histopathologically, the lymph nodes showed severe fibroplasia and infiltration by a large number of eosinophils and fewer tumor cells, exhibiting large-sized lymphoid cell morphology. Metastatic lesions of tumor cells with eosinophilic infiltration and fibrosis were observed in the lungs, liver, kidneys, stomach, and intestines. Immunohistochemistry revealed that the tumor cells were positive for CD3 and negative for B cell and mast cell markers. Thus, T-cell lymphoma with eosinophilic infiltration and sclerosing fibroplasia was diagnosed.

Feline mammary tumors (FMT) are the third most common form of neoplasm in cats. The prognosis of FMT is poor due to its high malignancy and metastatic potential. The outcomes of treatment using the common anticancer drug doxorubicin (DOX) are unsatisfactory, with resistance inevitably leading to treatment failure and disease recurrence. Salinomycin (SAL), an antibiotic, has been reported to exert anticancer effects on both human and canine mammary tumors. To recapitulate the genetic and molecular imprints of the original tumor sample, we generated four strains of patient-derived FMT 2.5D organoids (FMTO) to examine the anti-tumor potential of SAL. Our results revealed that SAL decreased cell viability in a dose-dependent manner. Treatment of FMTO with SAL-induced cell apoptosis, represented by an upregulation of P21, Caspase-8, and Caspase-9, and increased activity of Caspase-3/7. The combination of low-dose SAL with DOX (SD) potentiated the cytotoxicity of the latter in both DOX-resistant and DOX-sensitive strains, promoting cell apoptosis and cell-cycle arrest. In vivo, experiments using FMTO-derived xenografts engrafted into mice revealed decreased tumor growth following SAL administration. In conclusion, SAL showed anticancer activity against FMTO and potentiated the anticancer effect of DOX by inhibiting cell proliferation and inducing apoptosis and cell cycle arrest. These results suggest that SAL may represent a new adjuvant treatment option for patients with FMT.

Campylobacter fetus is a zoonotic pathogen. Although the precise virulence mechanisms have not yet been fully elucidated, cytolethal distending toxin (CDT) is considered as one of the well-characterized virulence factors in Campylobacter. In silico analysis of the genome of C. fetus type strain ATCC27374^T indicates that there are three cdt gene clusters, Cfcdt-I, Cfcdt-II and Cfcdt-III. However, it is not clear whether these clusters are ubiquitously present in C. fetus and their association with diseases in humans and animals. In this study, we have analyzed the distribution and nucleotide sequences of these cdt gene clusters in 137 C. fetus strains isolated from human patients and healthy cattle. MLST and PFGE were also applied to determine clonal relationship between C. fetus strains isolated from patients and cattle. We found all C. fetus strains carry three Cfcdt gene clusters by colony hybridization assay and the strains belonged to 38 different pulsotypes. Whole genome sequencing of 38 C. fetus strains was carried out to determine the entire cdt gene cluster sequences and their sequence type (ST). Among 38 strains, six STs were identified, and each cdt gene cluster showed high similarity (>99%). Interestingly, some of these Cfcdt genes are more similar to the cdt genes of other Campylobacter species than other Cfcdt gene types. Altogether, the results suggest that three Cfcdt gene clusters are highly conserved in C. fetus and the strains belonging to ST-6 may be more pathogenic to human.

Porcine parvovirus (PPV) is an important trigger of reproductive issues in pigs. Infection of the porcine kidney-15 (PK-15) cells with PPV induces cell death and inflammation. To explore the impact of PPV infection on gene expression in PK-15 cells and to identify the associated signaling pathways, we performed weighted correlation network analysis (WGCNA) on both PPV-infected and uninfected cells. We identified the blue and brown modules, with the blue module demonstrating decreased gene expression and the brown module showing increased gene expression at 48 hr post-PPV induction. Gene Ontology (GO) analysis revealed that genes in the blue module were predominantly associated with cellular components, while those in the brown module were enriched in biological processes, including the immunological response to PPV infection. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the modules indicated that the “Cytokine-cytokine receptor interaction” was linked to PPV. Furthermore, we screened 124 target genes involved in more than 100 pathways that interact with C-X-C motif chemokine ligand 8 (CXCL8), which plays an essential role in regulating numerous biological processes. The signaling pathways we identified facilitate a comprehensive examination of the mechanisms of interactions initiated by PPV infection.

Equine herpesvirus type 1 (EHV-1) causes abortion, respiratory infection, and neurological diseases (equine herpesvirus myeloencephalopathy) in horses. A single nucleotide polymorphism (SNP) associated with a single amino acid in the DNA polymerase gene (ORF30, in which D752 is neuropathogenic and N752 is non-neuropathogenic) of EHV-1 has been associated with neuropathogenicity in horses. We constructed an EHV-1 Ab4p ORF30 N752 mutant and a repair virus to examine the effect of a D752N mutation on the neuropathogenicity of the virus in Syrian hamsters. The N752 mutation did not affect viral growth in cultured cells but it did attenuate the neuropathogenicity of Ab4p in the hamsters. The results suggest that D752N is involved in neuropathogenicity not only in horses but also in hamsters.

Prevalence of elephant endotheliotropic herpesvirus (EEHV) infections in Asian elephants in Japan was assessed by determination of EEHV gB specific antibody levels. Among 28 healthy Asian (sub) adult elephants from 11 zoos, 27 animals exhibited intermediate to high antibody levels. Like elsewhere worldwide, this suggested exposure of Asian elephants in Japan to at least one EEHV (sub) species. Longitudinal observations of two elephants monitored from birth to 30-month of age showed consistent high antibody levels. Another juvenile showed antibody levels that decreased to undetectable levels prior to death at 13 months of age. This fatal case supports earlier reports that low antibody levels are a risk factor for development of EEHV hemorrhagic disease.