Airborne bacteria contribute to environmental hygiene challenges and may increase infection risk in veterinary hospitals. To evaluate the efficacy of a high-pressure spray disinfection system using neutral electrolyzed water to reduce airborne bacterial concentrations in veterinary hospitals and to characterize clinically relevant airborne pathogens and antimicrobial resistance. Active air sampling was performed before and after disinfection in multiple room types across five small animal hospitals in South Korea. Total airborne bacterial concentrations were quantified as colony-forming units per cubic meter. Representative colonies were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, with confirmatory sequencing for selected isolates. Susceptibility testing was performed for Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species using disk diffusion. Mean airborne bacterial concentrations decreased from 358.2 to 150.6 colony-forming units per cubic meter (58% reduction; p < 0.05). Waiting rooms showed the highest pre-disinfection concentrations, and operating rooms the lowest. Among 848 isolates, Micrococcus luteus, staphylococci, and Bacillus species were most frequent. Eight isolates were clinically important pathogens; two met multidrug resistance criteria. No targeted pathogens were detected after disinfection. High-pressure neutral electrolyzed water spraying significantly reduced airborne bacterial loads in veterinary clinical environments, supporting routine air disinfection and microbial surveillance as components of infection prevention programs.

With a growing companion animal population and their extended lifespans in South Korea, the need for health examinations tailored to specific life stages is increasing. However, an objective standard for defining these life stages is currently lacking. To classify life stages for companion dogs and cats by identifying clusters in age-specific disease proportions derived from medical records, providing a data-driven foundation for health examination programs. We collected 505,667 medical records from 82 veterinary facilities in South Korea between 2020 and 2023. Diagnoses were standardized using GPT-4o and S-BioBERT. Following preprocessing, data from 27 facilities yielded 222,706 canine and 39,910 feline records for the final analysis. Principal component analysis and K-means clustering (K = 4) were applied to age-specific disease proportions to identify life stages. The 10 most highest-proportion diagnoses diseases were determined for each cluster. Canine life stages were classified as ≤ 1 year, 2-5 years, 6-10 years, and 11-15+ years. Feline life stages were 1-2 years, 3-8 years, 9-12 years, and 13-15+ years. In dogs, developmental diseases were common in the youngest age group, while chronic diseases were more prevalent in older groups. In cats, oral and urinary diseases were high-ranking, conjunctivitis was most common in the early stage, and chronic diseases increased with age. Age-specific diagnosis patterns support four practical life stages for dogs and cats in South Korea. These boundaries can inform evidence-based preventive examination schedules, animal health policy, and pet insurance product design.

Canine distemper virus (CDV) has a broad host range, spanning mammals of the order Carnivora and other orders, often proving fatal. The detection of CDV in a Malayan tiger (Panthera tigris jacksoni) in Malaysia in 2019 marks the first such case diagnosed in Malayan tigers, suggesting possible exposure from domestic animals or wildlife reservoirs. This study aims to describe histological manifestations and characterise the CDV strain in the tiger to determine its molecular epidemiology and postulate viral pathogenicity. Histopathology characterisation of the infected tissues were performed through haematoxylin and eosin and immunohistochemistry staining, respectively. We conducted virus isolation and titration in Chinese hamster ovarian expressing the dog signalling lymphocytic activation molecule (CHO-SLAM) cells. Reverse transcription polymerase chain reaction was performed to confirm the presence of CDV RNA, nucleotide and amino acid sequence analyses for comprehensive characterisation of the CDV strain. Notable histopathological changes were observed primarily in the brain, lung, liver, kidney, spleen, and stomach, with viral antigens localised in the lung, liver, kidney, and stomach tissues. CDV-induced cell cytopathic effects yielding 4.27 × 10⁶ TCID₅₀/mL were observed at 48 h post-inoculation in CHO-SLAM cells. Phylogenetic analysis suggested that the virus originated from the Asia-1 clade. Notably, 549H and 519I mutations in the hemagglutinin protein were observed, indicating adaptation to a non-canid wildlife species. Overall, this study enhances our understanding of the molecular characterisation and evolutionary dynamics of the CDV strain present in the Malayan tiger and serves as a benchmark for developing effective preventative measures to protect Malayan tigers and mitigate their risk of extinction.

Fulvic acid can protect liver tissue against amoxicillin-clavulanate-induced hepatotoxicity through antioxidant and antiapoptotic effects. To evaluate the protective effects of fulvic acid against amoxicillin-clavulanate-induced hepatotoxicity using biochemical, histopathological, immunohistochemical, functional, and bioinformatic analyses. Twenty-eight male Wistar rats were randomly assigned to 4 groups (n = 7/group): sham (saline), amoxicillin-clavulanate (10 mg/kg/day), fulvic acid (100 mg/kg/day), and combined treatment. Treatments were administered orally for 21 days. Liver injury and oxidative stress were assessed by serum alanine aminotransferase, aspartate aminotransferase, malondialdehyde, total antioxidant status, and total oxidant status; tissue injury was assessed histologically. Apoptosis was evaluated by immunohistochemistry for BAX and BCL2. Hepatic detoxification capacity was assessed by a caffeine clearance test. In silico analyses predicted molecular targets of fulvic acid and enriched pathways. Amoxicillin-clavulanate increased transaminases, oxidative stress markers, and proapoptotic signaling and induced vascular congestion and sinusoidal dilatation. Co-treatment with fulvic acid improved serum biomarkers, reduced histological injury, downregulated BAX, and restored BCL2 staining intensity. In silico analysis identified predicted fulvic-acid targets enriched in metabolic and proliferation-related pathways. Fulvic acid attenuated amoxicillin-clavulanate-induced hepatotoxicity, consistent with antioxidant and antiapoptotic mechanisms. Further studies are warranted to define dose-response relationships and translational potential.

ImportanceGentamicin is an aminoglycoside antibiotic used to treat infections in dairy cows. Because of its potential toxicity and milk residue risk, an evidence-based withdrawal period is essential to ensure consumer safety.ObjectiveThis study aimed to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify gentamicin residues in milk and to establish a withdrawal period for an intramuscular gentamicin product in dairy cows.MethodsNine Holstein cows received a gentamicin product (50 mg gentamicin sulfate/mL) at 0.1 mL/kg twice daily at 12 h intervals via intramuscular injection. Milk samples were collected before dosing and at 12 h intervals up to 168 h after the final administration and analysed with a validated LC-MS/MS method using heptafluorobutyric acid as an ion-pairing reagent.ResultsThe method showed recovery rates of 86%–104%, coefficients of variation of 3%–11%, and limits of detection and quantitation of 23 and 70 ng/mL, respectively. Mean gentamicin concentrations exceeded the maximum residue limit (MRL; 0.2 mg/kg) at 12 h during treatment and 12 h after the final administration, and were < MRL in all cows from 36 h after the last dose. Based on residue depletion data and a national non-statistical guideline, a withdrawal period of 40–48 h was derived, and the regulatory withdrawal period for this product was established as 3 days.Conclusions and RelevanceThe validated LC-MS/MS method enables rapid quantitation of gentamicin residues in bovine milk. A 3-day regulatory withdrawal period for this product supports milk safety, regulatory compliance, and practical use in dairy herds.

ImportanceCanine heartworm disease remains a major global health issue. Despite the wide availability of ivermectin (IVM) formulations, pharmacokinetic and bioequivalence data are limited.ObjectiveThis study evaluated the pharmacokinetics and bioequivalence of eight oral IVM formulations (B–I) compared with the innovator product (A) in dogs.MethodsForty-five healthy dogs (mean body weight: 14.3 kg) were divided into nine groups (n = 5). Each received 6.2 µg/kg of IVM orally. Blood samples were collected up to 72 h post-dosing, and plasma IVM concentrations were quantified by liquid chromatography–mass spectrometry. Pharmacokinetic parameters were analyzed using a one-compartment model. Bioequivalence was assessed non-compartmentally using 90% confidence intervals for maximum concentration (Cmax) and area under the plasma concentration–time curve (AUC72h), with acceptance limits of 80–125%.ResultsAbsorption (Ka = 0.09–0.16 h−1), elimination half-life (T1/2 = 4.89–14.97 h), and systemic exposure (Cmax = 6.07–7.59 ng/mL) varied among formulations. Formulation C showed prolonged elimination (14.97 h) and higher exposure (AUC72h = 214.16 ng·h/mL), whereas formulation H exhibited faster absorption but lower exposure (AUC72h = 114.36 ng·h/mL). Simulated dosing indicated that most formulations maintained plasma levels above the minimum effective concentration (0.2 ng/mL), except formulation E. Only formulation G met full bioequivalence with the reference product.Conclusions and RelevanceAll formulations achieved plasma concentrations sufficient for prophylaxis, but only B, C, and G satisfied bioequivalence criteria. Larger sample sizes and standardized evaluation guidelines are recommended for multi-formulation bioequivalence studies.

ImportanceThe programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) pathway transmits negative immunoregulatory signals. Blocking this pathway using peptides or antibodies can restore immunity.ObjectiveTo evaluate the immune function of epitope peptides interacting with porcine PD-1 or PD-L1.MethodsWe optimized and synthesized peptides (PD-L14QN-GF and PD-L14QN-AF) using the solid-phase method and assessed their effects on peripheral blood mononuclear cell (PBMC) proliferation and PD-1 and cytokine expression after porcine reproductive and respiratory syndrome virus (PRRSV) infection in vitro and on antibody responses to a porcine circovirus type 2 (PCV2) vaccine in vivo.ResultsThe optimized peptides PD-L14QN-GF and PD-L14QN-AF exhibited lower binding free energy and higher stability when interacting with the PD-1 target protein. Under both PRRSV-infected and non-infected conditions in vitro, both peptides enhanced the proliferation of PBMCs, inhibited PRRSV RNA replication, and downregulated PD-1 transcription levels. Additionally, PD-L14QN-GF and PD-L14QN-AF upregulated the mRNA transcription and protein secretion of interleukin (IL)-2, IL-10, and interferon-γ to varying degrees. In vivo experiments demonstrated that PD-L14QN-GF significantly increased the antibody titer and seroconversion rate of the PCV2 vaccine.Conclusions and RelevancePD-L14QN-GF and PD-L14QN-AF induced stronger immune responses than PD-L14. PD-L14QN-GF has potential as an immune-enhancing adjuvant.

ImportanceKluyvera intermedia (K. intermedia) is an emerging pathogen associated with respiratory disease in pigs. Its multidrug resistance poses a significant threat to livestock health.ObjectiveThis study characterized the resistance phenotype and genotype of K. intermedia L-40-1, isolated from a pig in Jilin Province, China, and investigated the genomic determinants of its antibiotic resistance.Methods16S rRNA sequencing was performed to identify the strain. The resistance phenotype was assessed by determining minimum inhibitory concentrations (MICs), and resistance determinants were characterized by whole-genome sequencing. Comparative genomic analysis against the national center for biotechnology information (NCBI) database of K. intermedia strains was conducted to determine phylogenetic relationships and resistance gene profiles.ResultsL-40-1 exhibited high resistance to β-lactams, cephalosporins, macrolides, aminoglycosides, and sulfonamides. Comparative analysis identified 19 high-frequency resistance genes (e.g., arnT, rsmA, emrR, and acrA). A 159,618 bp plasmid (PYL-8) harbored multiple resistance genes (e.g., sul1, dfrA27, qnrB6, and tet(D)) and transposons (e.g., IS6, IS1, and Tn3), contributing to its multidrug resistance. Chromosomal and plasmid-borne resistance mechanisms were identified.Conclusions and RelevanceK. intermedia L-40-1 uses a combination of chromosomal and plasmid-mediated resistance genes, facilitated by transposons, to confer multidrug resistance. This highlights the need for surveillance of K. intermedia in livestock to mitigate the spread of antibiotic resistance.

ImportanceUltrasonographic reference values for evaluating the gastrointestinal (GI) tract in Korean raccoon dogs (Nyctereutes procyonoides koreensis) have not yet been established.ObjectiveThis study aimed to establish baseline ultrasonographic parameters for GI wall thickness and assess differences based on sex, gastric distension, body weight, and the presence of GI symptoms.MethodsA retrospective analysis was conducted on 42 Korean raccoon dogs (35 healthy, seven symptomatic). Total and individual layer thicknesses (mucosa, submucosa, muscularis, and serosa) were measured for the stomach, duodenum, jejunum, ileum (folded and interfolded regions), and colon. Statistical analyses were performed to assess the effects of sex, body weight, gastric distension, and GI symptoms on wall thickness.ResultsAll Korean raccoon dogs exhibited a five-layer GI wall and echogenicity similar to that of domestic dogs. Mean total wall thickness values were: stomach (2.77 ± 0.74 mm), duodenum (2.19 ± 0.31 mm), jejunum (2.06 ± 0.35 mm), ileum (folded, 1.75 ± 0.35 mm, interfolded, 2.31 ± 0.24 mm), and colon (1.06 ± 0.37 mm). Stomach wall thickness was greater in collapsed (3.31 ± 0.37 mm) than in distended (2.15 ± 0.52 mm) states. No statistically significant differences in GI wall thickness were observed based on sex or body weight. Symptomatic Korean raccoon dogs exhibited significant thickening of the duodenum, jejunum, and colon, along with increased mucosal echogenicity, loss of normal wall layering, and intestinal corrugation.Conclusions and RelevanceThese findings provide essential reference values for GI ultrasonographic evaluation in Korean raccoon dogs, with implications for diagnostic accuracy.

ImportanceAssisted reproductive technologies have not been widely applied to Himalayan tahrs (Hemitragus jemlahicus), a Near Threatened species, despite increasing concerns over population management and conservation. Developing effective estrus synchronization and artificial insemination protocols is critical for their reproductive management.ObjectiveTo evaluate the effectiveness of transcervical insemination using extended-fresh (EF) and extended-chilled (EC) semen following estrus synchronization using controlled internal drug release (CIDR) and hormonal treatments in female Himalayan tahrs.MethodsThis study involved eight female Himalayan tahrs, which were divided into two treatment groups of 13-day and 15-day according to duration of CIDR insertion. Hormonal treatments including pregnant mare serum gonadotropin, human chorionic gonadotropin, and prostaglandin F2 alpha (PGF2α) were administered. Semen was collected from two males by electroejaculation, extended, and used either fresh, frozen-thawed, or chilled. Transcervical insemination was performed at fixed times after CIDR removal, and pregnancy was diagnosed 64 days post-insemination using Doppler ultrasonography.ResultsThree of four females in the 13-day group and one of four in the 15-day group were confirmed pregnant. Vaginal and cervical changes were more favorable for insemination in the 13-day group. Hormonal data supported that a sharp drop in progesterone after CIDR removal was associated with successful conception.Conclusions and RelevanceThirteen-day CIDR insertion combined with gonadotropins and PGF2α is effective for estrus synchronization in Himalayan tahrs. Transcervical insemination using EF and EC semen resulted in successful pregnancy, offering a practical and reproducible protocol for ex situ conservation breeding in this species.