Journal of Veterinary Science最新文献

Importance: Tracheal collapse is a common respiratory disorder in small-breed dogs. Endoluminal stenting has become an important minimally invasive treatment option, particularly when medical management fails. Nevertheless, stent fracture remains a major postoperative complication, prompting the development of stents with alternative braided structures to improve durability and mechanical performance.

Objective: This study compared the mechanical properties of two self-expanding nitinol tracheal stents with different braided patterns-a conventional cross-braided design and a cross-and-hook braided design-to assess their mechanical characteristics and potential suitability for use in dogs.

Methods: Mechanical testing was performed on two commercial veterinary tracheal stents: a cross-braided stent and a cross-and-hook braided stent (Fauna stent; M.I.TECH. Co. Ltd, Korea). The flexural stiffness was assessed using a three-point bending test, while the radial and axial mechanical strengths were evaluated using compression and tensile tests, respectively.

Results: The cross-and-hook braided stent showed greater bending flexibility and slightly higher radial stiffness than the cross-braided stent. Both stents showed comparable tensile resistance within the physiological deformation ranges. The cross-and-hook structure also retained its cell geometry under compression and resisted permanent deformation more effectively.

Conclusions and relevance: The cross-and-hook braided stent showed trends toward improved mechanical properties relevant to the clinical performance in dogs, with possible benefits in reducing stent fatigue and rupture. These findings highlight its potential suitability for managing tracheal collapse in dogs and may help guide future development of veterinary and human stents.

Importance: Cutaneous epitheliotropic lymphoma (CEL) is a rare neoplastic disease in dogs, for which cases of atypical immunophenotypes or anaplastic morphological features have rarely been documented. Herein, we describe a rare case of CEL exhibiting marked cellular pleomorphism, complicating the cytological diagnoses, which included amelanotic melanoma.

Case presentation: A 12-year-old spayed female Golden Retriever presented with a rapidly growing oral mass, with an additional cutaneous lesion on the dorsum. Hematologic and biochemical analyses were unremarkable. Computed tomography revealed heterogeneously enhanced lymph nodes in the head and thorax. Fine needle aspirates from both lesions revealed individualized round cells, some of which exhibited multinucleation and giant cell morphology. Cytologic findings were suggestive of malignant round cell tumors, including lymphoma and amelanotic melanoma. Histopathologic examination confirmed the diagnosis of CEL. Flow cytometry revealed a CD45⁺CD21⁻CD3⁻CD5⁺CD4⁻CD8⁻CD25⁻ immunophenotype. Polymerase chain reaction for antigen receptor rearrangement revealed clonality in the T-cell receptor γδ region. The dog did not respond to lomustine and eventually showed rapid clinical deterioration shortly before euthanasia.

Conclusions and relevance: Here, we report atypical clinicopathological features observed in the case of CEL. These findings have potential biological, diagnostic, and prognostic relevance, emphasizing the need for further studies to elucidate their clinical significance and to expand the understanding of this disease.

Importance: Ultrasonographic reference values for evaluating the gastrointestinal (GI) tract in Korean raccoon dogs (Nyctereutes procyonoides koreensis) have not yet been established.

Objective: This 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.

Methods: A 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.

Results: All 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 relevance: These findings provide essential reference values for GI ultrasonographic evaluation in Korean raccoon dogs, with implications for diagnostic accuracy.

Importance: The developmental stage begins with implantation of a fertilized egg, followed by continuous cell division and differentiation to produce a complete organism. Developmental toxicity involves adverse effects that may be irreversible or undetectable until significant damage occurs, especially during early development, and must be assessed for drug and chemical safety. Animal tests face limitations such as cost, ethics, and species differences, prompting demand for alternatives. This review examines current alternative methods, institutional efforts, and future directions.

Observations: Recent advances have led to the use of various new approach methodologies to replace or complement animal testing. The embryoid body test now allows for faster and more reproducible assessment of early developmental toxicity, while organoids are being applied to evaluate organ-specific toxicities, such as neurodevelopmental and cardiac effects. Zebrafish offer validated endpoints for morphological and behavioral evaluation, enhancing their regulatory relevance. Predictive models, including those based on machine learning, are being integrated with in vitro data to strengthen mechanism-based analysis. These observations reflect a shift toward more human-relevant and efficient approaches in toxicity testing, which aligns with the central focus of this review. Regulatory bodies such as the Organisation for Economic Co-operation and Development are also actively promoting the acceptance and implementation of these methods.

Conclusions and relevance: Alternative methods provide ethical and rational approaches to developmental toxicity assessment. When integrated into regulatory science, they can contribute to early safety decisions in clinical development and public health. Coordinated efforts by stakeholders in technology advancement, implementation support, and guideline revision are essential for broader adoption.

Importance: Gentamicin 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.

Objective: This 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.

Methods: Nine 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.

Results: The 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 relevance: The 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.

Importance: Radiation therapy (RT) is a vital modality for tumor control and palliative care in veterinary oncology. Despite increasing interest in Korea, no systematic study has analyzed the trends of RT in companion animals.

Objective: The purpose of this study was to retrospectively analyze the trends in RT among dogs and cats treated at the S Animal Cancer Center in Korea from 2020 to 2023.

Methods: A retrospective analysis was conducted on 376 animals (308 dogs and 68 cats) receiving RT for various tumors. Data collected included species, breed, sex, age, weight, tumor location, tumor type, RT protocols, and concurrent treatments.

Results: The number of patients receiving RT increased from 59 in 2020 to 120 in 2023, reflecting a 103.4% increase over the study period. Sinonasal, intracranial, oral, genitourinary, and skin tumors were the most common, with stereotactic RT being most commonly used for sinonasal and intracranial tumors. Of the patients, 175 (46.5%) received RT alone, 96 (25.5%) with chemotherapy, 64 (17%) with surgery, and 41 (10.9%) with both surgery and chemotherapy. Thirty-one patients (8.2%) underwent multiple RT sessions, primarily for sinonasal tumors (11 cases).

Conclusions and relevance: This study provides the first systematic analysis of RT use in companion animals in Korea and establishes a foundational dataset for future work in veterinary radiation oncology. The findings highlight the growing clinical use of RT and underscore the need for further research to optimize treatment protocols and evaluate patient outcomes in Korean veterinary oncology.

Importance: The Y439 lineage 01310 E20 H9N2 vaccine strain currently used in South Korea has undergone extensive egg adaptation, resulting in substantial changes, including an 18-amino acid neuraminidase (NA) stalk deletion. Additionally, both early and late 01310 passages inherently harbor an N-glycan at hemagglutinin (HA) residue 158-160 (HA158) that may interfere with virus-specific antibodies.

Objective: We aimed to develop a high-yield vaccine strain without egg passaging and to overcome the limitations of the conventional vaccine strain that may compromise immunogenicity.

Methods: We introduced a genetically modified 01310 PB2 gene (310-MVV: I66M, I109V, I133V) to increase replication in embryonated eggs and removed the N-glycan at HA158 and restored the NA stalk to improve immunogenicity. The resulting strain was assessed for egg replication and immunogenicity in chickens.

Results: The resulting vaccine strain (310-SNS-193D-MVV) grew efficiently in embryonated eggs without repeated passaging. As restoring the NA stalk alone was insufficient to enhance NA-specific immunity, simultaneously removing the N-glycan at HA158 markedly increased NA-specific antibody responses and neutralizing antibody titers across multiple H9N2 lineages. Additionally, incorporating 310-SNS-193D-MVV into a bivalent formulation with a Y280 lineage strain conferred broader coverage without evidence of immune interference.

Conclusions and relevance: These findings underscore how PB2, HA, and NA targeted genetic modifications can improve H9N2 vaccine productivity and immunogenicity. These strategies are not limited to our H9N2 strain and can be applied to other low propagating or NA stalk-deleted virus strains.

Importance: Since the early 2000s, companion animals emerged as unexpected players in influenza A virus ecology. Canine influenza viruses and the increasing detection of highly pathogenic avian influenza viruses in cats have raised concerns about their potential role as intermediate hosts for pandemic emergence. Their unique position at human-animal interface creates unprecedented opportunities for viral evolution and bidirectional transmission between humans and animals.

Observations: This review examined the transmission pathways and molecular adaptations of influenza A virus in companion animals. Cats primarily acquire infections through alimentary routes, including consumption of raw poultry and unpasteurized milk, as well as environmental exposure through hunting. Dogs transmit influenza viruses via respiratory droplets in high-density settings such as shelters and kennels. Canine influenza viruses demonstrate successful mammalian adaptation through accumulated mutations across multiple viral proteins, particularly in polymerase and hemagglutinin genes, enabling sustained dog-to-dog transmission. Feline isolates consistently exhibit mammalian adaptive mutations across geographically disparate outbreaks. Several molecular changes appear convergently in both species, suggesting shared evolutionary pressures at companion animal-human interface.

Conclusions and relevance: Despite molecular evidence of active viral evolution, companion animals currently pose a limited pandemic risk owing to no sustained zoonotic transmission chains. Critical knowledge gaps remain regarding subclinical infection frequency, natural transmission efficiency, and host genetic factors that influence susceptibility. Surveillance should prioritize high-risk interfaces, including raw pet food supply chains and veterinary facilities, while maintaining the perspective of actual versus theoretical risks. Understanding companion animal influenza virus dynamics is essential for comprehensive pandemic preparedness strategies.

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.