Journal of Veterinary Medical Science最新文献

Neonicotinoid pesticides (NNs) are widely used for their selective toxicity to insects via an agonistic action on nicotinic acetylcholine receptors. However, growing evidence suggests that NNs may have adverse health effects in mammals. In parallel, recent studies have shown that trace environmental chemicals such as antibiotics, endocrine disruptors, and pesticide residues can alter the gut microbiota, a key regulator of host health. Thus, NNs may also disrupt gut microbial homeostasis and impact host physiology. In this study, we investigated the effect of the neonicotinoid pesticide clothianidin (CLO) on the rat gut microbiota. Male rats were orally administered CLO at 0, 30, and 300 mg/kg/day (designated as the CLO-0, 30, and 300 groups) for 28 days; doses were selected based on the no-observed-adverse-effect level (NOAEL; 27.9 mg/kg/day). Cecal contents were collected after euthanasia and subjected to 16S rRNA sequencing. Our results showed that even at approximately the NOAEL dose, CLO exposure altered gut microbiota composition and tended to reduce microbial diversity, especially in the CLO-300 group. Notably, several CLO-affected taxa are known producers of short-chain fatty acids, and changes were particularly prominent in two individuals from the high-dose group. Moreover, CLO exposure resulted in distinct alterations in butyrate-producing bacteria, with increases observed in the CLO-30 group and decreases in the CLO-300 group. These results suggest that CLO has various effects on the gut microbiota and that even exposure at the NOAEL may affect host health.

Classical swine fever (CSF) is a highly contagious disease in pigs, and vaccination with antibody monitoring is critical for its prevention. In this study, the effectiveness of two enzyme-linked immunosorbent assay (ELISA) kits for antibody detection against CSF virus (CSFV)-an indirect ELISA kit authorized in Japan in 2001 (N-kit) and a competitive ELISA kit additionally authorized in 2024 (I-kit)-was compared. For each ELISA kit, detection accuracy in terms of sensitivity, specificity and agreement rate, and quantitative accuracy were evaluated based on neutralizing antibody titers determined by serum neutralization tests. In addition, the impact of serum heat-inactivation at 56°C for 30 min on ELISA results was assessed. The results indicated that the I-kit showed the highest sensitivity and agreement rate in detection accuracy, whereas the N-kit showed the highest quantitative accuracy. Although blocking rates of the I-kit increased after heat-inactivation, high correlation rates between treated and untreated samples were confirmed for both kits, suggesting that heat-inactivation does not affect the final interpretation of the test results. These findings demonstrated that the I-kit is suitable for initial antibody screening in pigs due to its higher sensitivity, whereas the N-kit provides better quantitative accuracy, making it preferable for measuring antibody titers in sows. Therefore, the selection of an appropriate ELISA kit according to the purpose of antibody detection is necessary to ensure a more accurate evaluation of the effects of CSFV vaccination on preventing CSF in pig herds.

Working memory tests were performed on days 8-18 after 5-min cerebral ischemia in juvenile (2-month-old) and adult (6-month-old) gerbils, followed by observation of cell death in the hippocampus on postoperative day 19. Both 2- and 6-month-old ischemic gerbils made significantly more working memory errors than age-matched sham-operated ones. After repeated trials, the number of working memory errors in 2-month-old ischemic gerbils reached the level of sham-operated ones earlier than in 6-month-old gerbils. However, no significant differences were seen in the number of hippocampal cell deaths between 2- and 6-month-old ischemic gerbils. This study revealed that juvenile gerbils recovered from cognitive impairment more quickly than adults, although no difference in hippocampal damage was evident after transient forebrain ischemia.

Lactococcus is the causative agent of lactococcosis in fish; however, its genetic characteristics in yellowtail from Japan have not been fully elucidated. In this study, we used whole-genome sequencing (WGS) to investigate virulence genes, antimicrobial resistance genes, and genetic relationships among 40 Lactococcus isolates from diseased yellowtail in 2021. Serotype II accounted for 82.5% of the isolates, while the remaining 17.5% comprised serotype I. No novel serotype (serotype III) was identified. Compared with serotype III Lactococcus strains isolated from other fish species, virulence gene patterns varied among serotypes, and the nucleotide sequences were distinct from those of serotype III. The isolates showed resistance rates of 87.5% to lincomycin and 12.5% for erythromycin, and no resistance to tetracycline, ampicillin, or florfenicol was detected. All erythromycin-resistant isolates carried the erm(B) gene on a plasmid. The core-genome single-nucleotide polymorphism-based phylogenetic tree showed clear clustering by serotype. Although no novel serotype was found in the yellowtail, isolates from other fish species exhibited distinct gene sequences encoding surface proteins, suggesting caution regarding vaccine efficacy. Because high lincomycin resistance was observed, susceptibility testing is recommended to guide appropriate antimicrobial selection. Overall, the elucidation of the WGS-based characteristics of field isolates of Lactococcus provides useful information for vaccine use and antimicrobial therapy for the prevention and treatment of lactococcosis.

Canine oligodendrogliomas express platelet-derived growth factor receptor alpha (PDGFRA), an oligodendrocyte precursor cell (OPC) marker. In this study, tumor cells derived from 3 French bulldogs with oligodendroglioma were cultured in conventional medium with 10% fetal bovine serum (FBS) and an OPC-tailored medium containing platelet-derived growth factor (PDGF)-AA and basic fibroblast growth factor (bFGF). Immunocytochemically, cells cultured with 10% FBS were negative for PDGFRA, but tended to express 2',3'-cyclicnucleotide 3'-phosphodiesterase (CNPase) and β3-tubulin. In contrast, the cells cultured with PDGF-AA and bFGF tended to express PDGFRA. These results suggest that canine oligodendroglioma cells cultured with PDGF-AA and bFGF exhibit OPC-like immunophenotype. Cells cultured with OPC-tailored medium may be useful for further in vitro research on canine oligodendrogliomas.

The distribution of anesthetic solutions, sensory blockade (SB), and motor blockade (MB) following coccygeal epidural anesthesia in dogs were evaluated. Six dogs received three different doses (0.1, 0.2, and 0.3 mL/kg) of a mixture containing equal volumes of ropivacaine and iohexol, administered via the first and second coccygeal intervertebral spaces. Drug spread was assessed using computed tomography, whereas SB and MB were evaluated using standardized scoring methods. The cranial extent of contrast medium spread reached L5, the L4-5 interspace, and L4 in the 0.1, 0.2, and 0.3 mL/kg groups, respectively, with no significant differences among groups. SB extended from the tail to the cranial femoral region in the 0.1 mL/kg group, to the caudal femoral-pubic region in the 0.2 mL/kg group, and to the cranial femoral-pubic region in the 0.3 mL/kg group. The 0.2 and 0.3 mL/kg groups showed significantly higher SB than the 0.1 mL/kg group did (P=0.039 and P=0.019, respectively). MB extended to the femoral nerve territory in dogs receiving 0.2 or 0.3 mL/kg, while dogs in the 0.1 mL/kg group maintained motor function. The 0.3 mL/kg group showed significantly higher MB than the 0.1 mL/kg group did (P=0.019). Despite the increased volume at 0.3 mL/kg, greater leakage through the neural foramina resulted in a net epidural dosage comparable to 0.2 mL/kg. These findings indicate that coccygeal anesthesia at 0.1 mL/kg provides SB from the tail to the perineal region while maintaining hindlimb motor function in dogs.

Bovine leukemia virus (BLV) is a retrovirus that infects bovine B lymphocytes and causes enzootic bovine leukosis in approximately 1-5% of infected cattle. Although recent studies have shown that older Holstein cattle with a high proviral load (PVL) exhibit significantly reduced carcass weight, the impact of BLV infection on young fattening cattle remains unclear. In this study, we investigated the relationship between BLV infection and carcass weight in fattening Japanese Black cattle, a breed of high economic importance in beef production, worldwide. A total of 474 blood samples were collected from slaughterhouses in Kyushu, Japan. Cattle were classified into enzyme-linked immunosorbent assay (ELISA)-negative and ELISA-positive groups to assess the effect of BLV infection, and PVL was quantified. No significant differences in carcass weight were observed between ELISA groups, and no significant correlation was found between carcass weight and PVL. These findings suggest that subclinical BLV infection does not directly affect carcass weight in fattening Japanese Black cattle. Although BLV may not cause immediate economic losses in beef production, potential long-term effects and breed-specific responses warrant further investigation. To minimize economic losses while maintaining practical disease control, strategic herd management approaches are essential. We propose that BLV-infected cattle, particularly high-risk animals with elevated PVL, be separated from uninfected cattle during fattening and subsequently shipped for processing. This strategy may offer a realistic, economically viable, and low-burden approach to controlling BLV transmission in beef herds.

Cutaneous plasmacytosis (CP) is a rare condition characterized by multiple cutaneous plasmacytomas without multiple myeloma. While no pruritus or spontaneous regression occurs in typical CP, the clinical behavior is limitedly understood due to its low incidence. This case report describes atypical cases of CP. Case 1 had skin nodules on the face and limbs and pruritus, whose pruritus kept progressing. After the diagnosis of CP, the dog died on Day 170 despite the treatment with prednisolone and melphalan since Day 157. Case 2 had multiple skin nodules on the back and abdomen. After the skin biopsy, the nodules regressed without treatment on Day 28. These cases suggest the variation of CP's clinical behavior, which helps further understand the disease.

White Heifer Disease (WHD) is a congenital reproductive abnormality, especially in white female offspring in certain breeds of cattle like Belgian Blue. The roan locus was reported to affect coat color and fertility. It was suggested that a missense mutation (Ala218Asp) in the transmembrane domain of Kit ligand (KITL) gene was responsible for WHD. Here we generated two types of knock-in (KI) mice to reproduce the missense KITL mutation using pigmented agouti ICR mice. KI mice carrying compound mutations mimicking bovine transmembrane domain showed moderate coat color change, but single missense mutation KI did not. None of them exhibited uterine abnormalities, suggesting that localized gene modification may not fully affect murine KITL function.

A 6-month-old female toy poodle, weighing 2.15 kg, presented with acute vomiting and lethargy after ingesting ibuprofen. Hemoperfusion was performed using an extracorporeal blood purification cartridge, comprising polystyrene-divinylbenzene copolymer beads, connected to a hemodialysis platform as a pre-dialyzer. Serum ibuprofen concentration, measured using high-performance liquid chromatography, was 61.9 mg/L before therapy. The ibuprofen concentrations gradually decreased, reaching 20.5 mg/L after 2 hr (66.8% reduction; half-life of 1.4 hr). The dog showed significant improvement in vitality and recovered fully without further extracorporeal treatment. This case is the first documented instance of successfully treating ibuprofen intoxication in a small dog using hemoperfusion with a blood purification cartridge specifically designed for small animals.