Journal of Veterinary Science最新文献

Importance: Assisted 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.

Objective: To 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.

Methods: This 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 (PGF_2α) 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.

Results: Three 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 relevance: Thirteen-day CIDR insertion combined with gonadotropins and PGF_2α 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.

Importance: Cerebral ischemia arises from insufficient blood flow to the brain, resulting in substantial metabolic disturbances. Baicalin, a flavonoid compound derived from Scutellaria baicalensis, has anti-inflammatory, antioxidant, and neuroprotective properties.

Objective: To identify proteins regulated by baicalin in a rat model of ischemic stroke.

Methods: Adult male Sprague Dawley rats underwent middle cerebral artery occlusion (MCAO) or sham surgery and received intraperitoneal baicalin (100 mg/kg) or vehicle 1 h before surgery. Neurobehavioral assessments were performed 24 h after MCAO, and cerebral cortex tissues were collected. Cortical damage was evaluated using 2,3,5-triphenyltetrazolium chloride staining and hematoxylin-eosin staining. Protein expression changes between groups were assessed by liquid chromatography-tandem mass spectrometry, and selected targets were validated by reverse transcription-polymerase chain reaction.

Results: MCAO induced marked neurological deficits, infarction, and histopathological damage, all of which were significantly attenuated by baicalin treatment. MCAO decreased adenylate cyclase type 1 and solute carrier family 25 member 12 levels, and baicalin mitigated these reductions. Baicalin also reduced MCAO-induced increases in C-reactive protein and apolipoprotein C-II, as well as alpha-1 microglobulin, murinoglobulin, and hemoglobin subunit B, proteins associated with inflammation, lipid metabolism, mitochondrial function, and cellular injury.

Conclusions and relevance: Baicalin exerts neuroprotective effects in cerebral ischemia by modulating proteins involved in energy metabolism, myelination, and neuroinflammation. These findings support baicalin as a promising therapeutic candidate in experimental stroke models.

In October 2024, the Asian Association of Veterinary Schools hosted "VetEd Asia 2024," a symposium to promote veterinary education and collaborations in Asia, held in Daejeon, Republic of Korea. The event was co-organized with the Federation of Asian Veterinary Associations and the American Association of Veterinary Medical Colleges' Council on International Veterinary Medical Education and with the support of the World Organisation for Animal Health Regional Representation for Asia and the Pacific. The symposium brought together diverse stakeholders in veterinary education, facilitated networking, and highlighted emergent topics such as education research aimed at improving the quality of education in the region. These collaborative efforts are expected to strengthen veterinary education standards and outcomes, resulting in the development of a stronger veterinary workforce.

Importance: Canine heartworm disease remains a major global health issue. Despite the wide availability of ivermectin (IVM) formulations, pharmacokinetic and bioequivalence data are limited.

Objective: This study evaluated the pharmacokinetics and bioequivalence of eight oral IVM formulations (B-I) compared with the innovator product (A) in dogs.

Methods: Forty-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 (C_max) and area under the plasma concentration-time curve (AUC_72h), with acceptance limits of 80-125%.

Results: Absorption (Ka = 0.09-0.16 h⁻¹), elimination half-life (T1/2 = 4.89-14.97 h), and systemic exposure (C_max = 6.07-7.59 ng/mL) varied among formulations. Formulation C showed prolonged elimination (14.97 h) and higher exposure (AUC_72h = 214.16 ng·h/mL), whereas formulation H exhibited faster absorption but lower exposure (AUC_72h = 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 relevance: All 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.

Importance: The 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.

Objective: To evaluate the immune function of epitope peptides interacting with porcine PD-1 or PD-L1.

Methods: We 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.

Results: The 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 relevance: PD-L14QN-GF and PD-L14QN-AF induced stronger immune responses than PD-L14. PD-L14QN-GF has potential as an immune-enhancing adjuvant.

Importance: Kluyvera intermedia (K. intermedia) is an emerging pathogen associated with respiratory disease in pigs. Its multidrug resistance poses a significant threat to livestock health.

Objective: This 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.

Methods: 16S 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.

Results: L-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 relevance: K. 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.

Importance: Cryptorchidism, defined as the failure of one or both testes to descend into the scrotum, is a pathological condition that adversely impacts testicular development and spermatogenic function. In livestock, particularly bulls, such impairment can lead to substantial economic losses due to compromised fertility. A comprehensive understanding of the morphological and molecular alterations associated with cryptorchidism is essential for efforts to develop effective diagnostic and therapeutic strategies.

Objective: This study aimed to examine morphological changes and changes in the extracellular signal-regulated kinase (ERK) and cyclic AMP response element-binding protein (CREB) activity in the testes of bulls with cryptorchidism.

Methods: Testes from the 18-month-old unilateral cryptorchid bulls, including the descended (normal) and undescended (cryptorchid) testes from each animal, were analyzed through gross examination, histology, immunohistochemistry (Ki-67, phosphorylated p-ERK, p-CREB), and Western blotting.

Results: Cryptorchid testes were smaller and exhibited reduced epithelial thickness, although seminiferous tubule area remained unchanged. Expression of Ki-67, p-ERK, and p-CREB was significantly decreased, indicating impaired cell proliferation and signaling. Total ERK and CREB protein levels were unchanged, but phosphorylation levels were notably reduced in cryptorchid samples.

Conclusions and relevance: Our findings demonstrate that cryptorchidism alters testicular morphology and disrupts key signaling pathways, particularly those involved in cell growth and function. Such alterations may contribute to infertility and highlight the importance of early diagnosis and intervention in the context of reproductive management in livestock.

Importance: Mesenchymal stem cells (MSCs) play a pivotal role in advancing veterinary regenerative medicine in dogs and cats and serve as valuable preclinical models for human therapies. Despite their widespread application, fundamental knowledge gaps and the absence of standardized criteria for canine and feline MSCs remain. This review focuses exclusively on direct comparative studies across species and tissue sources to support evidence-based practices in which clinical use often precedes full scientific validation.

Observations: This review consolidates available comparative studies of canine and feline MSCs, categorizing them by species, tissue origin, and donor factors. We systematically assessed fundamental biological properties of MSCs (yield, morphology, proliferation, differentiation) and functionalities (immunomodulation, angiogenesis, migration). Overall, MSCs from both species exhibit properties comparable to those of human MSCs. However, canine MSCs have been more extensively studied across diverse tissues, whereas feline MSC research remains primarily restricted to adipose tissue and bone marrow. Notable interspecies and tissue-specific differences include proliferation rate, chondrogenic potential, and surface marker variability. Donor factors such as age also influence MSC behavior. Nevertheless, inconsistencies in sampling sites, culture protocols, and surface marker panels across studies continue to pose challenges for achieving a comprehensive understanding through direct comparison.

Conclusions and relevance: Establishing consistent characteristics of MSCs in companion animals requires well-designed and controlled comparative studies. Standardization of MSC characterization, production, and application has been widely advocated. This review highlights ongoing efforts to address species- and tissue-specific knowledge gaps and emphasizes the need for additional comparative research to strengthen the preclinical and therapeutic utility of MSCs, thereby advancing evidence-based stem cell therapies in veterinary medicine.

Importance: The raccoon dog (Nyctereutes procyonoides), native to East Asia, is a key reservoir of zoonotic diseases, crucial for understanding tick-borne pathogen (TBP) transmission in ecosystems.

Objective: This study aimed to assess the prevalence of Rickettsiales pathogens including Anaplasma, Ehrlichia, and Rickettsia species in raccoon dogs across South Korea over a three-year period (2021-2023).

Methods: A total of 275 blood samples were collected from raccoon dogs across nine wildlife centers in South Korea. Molecular detection of pathogens was conducted using polymerase chain reaction to identify Anaplasma, Ehrlichia, and Rickettsia species.

Results: The study revealed an overall infection rate of 10.5% for Anaplasma phagocytophilum and 0.4% for Rickettsia conorii ssp. raoultii. Notably, this represents the first molecular detection of R. conorii ssp. raoultii in raccoon dogs. No samples tested positive for Ehrlichia spp. The central region of South Korea geographically had the highest prevalence of A. phagocytophilum, while all cases of R. conorii ssp. raoultii were detected in the northern region.

Conclusions and relevance: These findings highlight the raccoon dog as a reservoir for TBPs, especially A. phagocytophilum and R. conorii ssp. raoultii, and emphasize the need for further research on its role in public health and zoonotic disease ecology in South Korea.