Frontiers in Veterinary Science最新文献

Introduction: Antimicrobial resistance (AMR) represents a growing One Health challenge at the human-animal-environment interface. Wildlife rescue centres may represent potential, underrecognized settings where resistant bacteria could emerge and disseminate due to close human-animal contact and antimicrobial use. We investigated AMR profiles and genomic features of Escherichia coli isolated from European and northern white-breasted hedgehogs (Erinaceus europaeus, Erinaceus roumanicus) admitted to a Czech wildlife rescue facility.

Materials and methods: Faeces from 23 hedgehogs were collected during routine pen cleaning. E. coli isolates were obtained on MacConkey agar (MCA) and MCA with cefotaxime and confirmed by MALDI-TOF MS. Antimicrobial susceptibility to 13 antibiotics was assessed using the disc diffusion test. A subset of 26 isolates representing diverse resistance profiles was further characterised by whole-genome sequencing (WGS). Genomic analyses focused on sequence types, phylogroups, resistance genes, plasmid replicons, and virulence-associated genes.

Results and discussion: More than half of the isolates (37/69; 54%) were multidrug-resistant, with resistance most frequently observed to ampicillin and nalidixic acid. No cefotaxime-resistant isolates or genes encoding extended-spectrum beta-lactamases or carbapenemases were detected. Whole-genome sequencing revealed substantial genetic diversity, including several sequence types that are commonly associated with human and animal infections, such as ST457, ST162, and ST624. Isolates carried a wide range of resistance determinants, including bla _TEM-1 and qnrB2 genes, plasmid replicons, and virulence-associated genes, with phylogroup F showing the highest virulence gene content. Despite the modest sample size, our findings indicate that hedgehogs in rehabilitation settings can act as reservoirs of multidrug-resistant E. coli with diverse genomic backgrounds, contributing to the environmental dissemination of AMR. The presence of sequence types and resistance genes commonly associated with human and veterinary infections further supports the relevance of rehabilitated wildlife to the broader epidemiology of AMR. Enhancing biosafety practices and antimicrobial stewardship in wildlife rescue operations is therefore essential to mitigate zoonotic risks within a One Health framework.

Ticks, recognized as the second most significant vector of pathogens after mosquitoes, are of considerable interest in medical research. Although mitochondrial genomes are commonly employed in the phylogenetic studies of insects and arthropods, investigations into tick mitochondrial genomes are relatively scarce. The evolutionary and phylogenetic relationships at the family and genus levels remain unresolved. In this study, the mitochondrial genomes of Haemaphysalis warburtoni, Ixodes crenulatus, Rhipicephalus bursa, and Rhipicephalus pumilio were first sequenced and annotated based on the Illumina NovaSeq 6,000 platform, and compared with the mitochondrial genes of 150 other hard ticks. All examined tick mitochondrial genomes exhibit a notable AT bias, with A+T content ranging significantly from 72.28% to 81.06%. They also exhibit distinct codon usage patterns, with most codons ending in either A or U. A phylogenetic analysis, based on 13 protein-coding genes (PCGs), confirms that the Ixodidae family forms a monophyletic group. Based on the phylogenetic analysis of 13 protein-coding genes, the relationships of Ixodidae family as follows: Ixodes + (Robertsicus + ((Bothriocroton + Archaeocroton + Cryptocroton + Haemaphysalis) + (Amblyomma + (Dermacentor + (Rhipicentor + (Hyalomma + Rhipicephalus)))))). This study provides in-depth insights into tick mitochondrial genomes, offering important references for research on their systematics, evolution, and species identification, while also laying the groundwork for tick-borne disease control and public health risk assessment.

Multiple Myeloma (MM) in dogs is typically treated with a combination of alkylating agents and corticosteroids. However, treatment failure or intolerance, often due to cumulative toxicities, can limit the long-term efficacy of these protocols. Thalidomide, an immunomodulatory and anti-angiogenic drug widely used in human MM, remains largely unexplored in veterinary oncology. This study retrospectively evaluated the clinical efficacy and safety of thalidomide as a rescue therapy in dogs with MM that were refractory to or intolerant of standard treatments. Medical records from three referral centers were reviewed, identifying dogs that met the inclusion criteria. All seven selected dogs received melphalan, and four were also treated with cyclophosphamide prior to thalidomide. Thalidomide was administered once daily in all dogs, with one case requiring dose escalation. The median duration of thalidomide administration was 440 days (range: 146-580 days). A complete response was achieved or maintained in five dogs (71%). Adverse events (AEs) were limited to grade II lethargy in two cases, with no hematologic, gastrointestinal, or urinary AEs reported. The median PFS during thalidomide treatment was 490 days (95% CI: 408.7-571.4), while it was 180 days (95% CI: 54.8-305.2) during melphalan therapy. Median overall survival (OS), calculated from diagnosis to last follow-up, was 680 days (95% CI: 542.8-817.2). These findings suggest that thalidomide is a well-tolerated and potentially effective rescue therapy for canine MM, particularly in patients unresponsive to or unable to tolerate conventional chemotherapy. Further prospective studies are warranted to evaluate its efficacy as part of first-line or combined protocols.

Background: Bacterial biofilms, characterized by robust antibiotic resistance and involvement in chronic infections, present significant clinical challenges such as endometritis. While linalool as a natural extract exhibits potent antibiofilm properties, its precise mechanisms of action against Escherichia coli (E. coli) remain unclear.

Methods: The inhibitory effect of linalool on E. coli biofilm formation was evaluated using inhibitory curve analysis and scanning electron microscopy. The influence of linalool on flagella and fimbriae formation in E. coli biofilms was assessed through swarming and swimming motility assays, scanning electron microscopy, and qRT-PCR. Viable count assays and confocal laser scanning microscopy were employed to examine the suppression of E. coli adhesion to bovine endometrial epithelial cells by linalool. Furthermore, an in vivo rat intrauterine infection model with E. coli biofilms was established to investigate the anti-adhesion activity of linalool.

Results: In vitro assays demonstrated concentration-dependent biofilm inhibition by linalool, achieving 99% inhibition at 4 µL/mL, with structural disintegration confirmed through scanning electron microscopy. Mechanistically, linalool disrupted flagellar gene regulation, downregulating fliA and motA while upregulating fliG and fliM, and impaired both swarming and swimming motility. Simultaneously, it suppressed fimbriae-associated genes (csgA, csgD, and fimH), leading to 99% reduction in bacterial adhesion to bovine endometrial epithelial cells and the eradication of 95% of intrauterine biofilms in vivo.

Discussion: As a low-toxicity phytochemical, linalool exhibits a dual-action mechanism in inhibiting E. coli D5 biofilm formation by suppressing motility and blocking adhesion, representing a potent multitarget agent against biofilm-associated infections. Future studies should validate its pharmacodynamics and potential synergies with conventional antibiotics to facilitate clinical application.

Background: Canine visceral leishmaniasis (CVL) is a vector-borne zoonotic disease caused by Leishmania infantum. This parasite has been reported in humans and dogs from Costa Rica over the past four decades as sporadic reports. In this study, we analyzed eight cases of autochthonous infections in dogs presumably originating from Santa Cruz, Guanacaste, and Santa Ana, San José, Costa Rica, none of which had a history of travel abroad.

Methods: Eight dogs with suspected CVL were analyzed using serological assays (Speed Leish K® (VIRBAC Diagnostics, France) or Antigen Rapid CaniV-4 (Leish)® (BIONOTE, Mexico)), five dogs were detected in 2023, and three during 2025. Histopathological staining was applied in cases with spleen, dermal, and lymph node involvement to determine the presence of Leishmania amastigotes. Blood, lymph node aspirates, conjunctival swabs, or cutaneous lesion swabs were also analyzed for the presence of Leishmania spp. ITS1, hsp70, and kDNA fragments. Phylogenetic and haplotype network analyses were conducted for hsp70 and kDNA data.

Results: Four dogs showed various clinical manifestations that included persistent anemia, thrombocytopenia, splenomegaly, exfoliative dermatitis, and onychogryphosis, whereas the other four dogs remained subclinical or asymptomatic. Histopathological analysis revealed numerous intracellular amastigotes in lymph node aspirates, spleen sections, and ear skin biopsy. Moreover, seven out of eight dogs were positive in the serological analysis, and the other seven to the Leishmania ITS1 PCR. Phylogenetic analysis of kDNA fragments revealed that sequences derived from our country clustered with those of L. infantum from the Old World, rather than with ones from Brazil, indicating a likely introduction from outside the Americas. All infected dogs received allopurinol and, when available, also meglumine antimoniate.

Conclusion: Infection with L. infantum in Costa Rican dogs was confirmed by clinical and laboratory evidence and thus represents the first autochthonous cases of CVL in our country. This study highlights the urgent need for routine canine testing, sandfly surveillance, access to proper treatments, and increased awareness, emphasizing the importance of public health policies for controlling leishmaniasis in both animals and humans from a One Health perspective.

Infectious bursal disease (IBD) is an important immunosuppressive disease of chicken caused by infectious bursal disease virus (IBDV). At present, the newly emerging novel variant IBDV (varIBDV) and the persistently prevalent very virulent IBDV (vvIBDV) are two major threats, while the non-var/vvIBDV, such as classic IBDV (cIBDV) and attenuated IBDV (attIBDV), also increases the complexity of clinical detection. In this study, a multiplex real-time quantitative fluorescence RT-PCR (qRT-PCR) was developed. Based on sequence analysis of different pathogenic IBDV strains, three probes with different fluorescent signals (FAM, VIC, CY5) and two pairs of primers were designed. Specifically, varIBDV exhibits three fluorescent signals (FAM, VIC, CY5), vvIBDV shows two signals (FAM, VIC), and non-var/vvIBDV displays one signal (FAM). The method possesses excellent specificity: no cross-reactivity was observed between different pathogenic IBDV types, nor with other common avian pathogens. This method has good reproducibility and high sensitivity, with a minimum detection limit of about 10 copies. Furthermore, in the detection of laboratory or clinical samples, the consistency rate of this method with the conventional sequencing analysis method reached 100%. In conclusion, this study developed for the first time a multiplex qRT-PCR that can universally detect IBDV and simultaneously distinguish between vvIBDV and varIBDV, which is of great significance for high-throughput emergency detection and comprehensive prevention and control of new IBDV epidemics.

Dichelobacter nodosus (D. nodosus) is the pathogen responsible for causing footrot in sheep and goats, which poses significant challenges to animal health and welfare. D. nodosus is classified into 10 different serogroups (A-I and M) based on the genetic variation of this fimbrial (fimA) gene. These fimbriae are immunogenic and play an important role in virulence, making serotyping of these fimbriae valuable for identification and vaccine development. In this study, three multiplex quantitative polymerase chain reaction (qPCR) assays, targeting the most commonly prevalent nine serogroups (ABC, DEF, and GHI), were studied for the detection of serogroups in foot swab samples collected from Dutch sheep farms. A total of 147 samples tested positive for D. nodosus using pnpA qPCR, and 144 (98%) samples exhibited a serogroup using qPCR. The multiplex qPCRs detected significantly more serogroups than conventional serogroup PCRs and detected more than one serogroup in a swab. In 46 samples (31%, 46/147), two to five different serogroups were identified from a single swab sample. In three samples, no serogroup was identified, likely due to sequence variation in the fimA gene in these samples. These direct multiplex qPCR tests provide faster, more sensitive, and accurate testing for the direct classification and quantification of D. nodosus serogroups for studying the epidemiology of footrot and for the formulation of serogroup-specific targeted vaccination strategies for prevention, control, and treatment of footrot.

Introduction: Antimicrobial resistance (AMR) is a global public health concern that requires a One Health approach. The role of veterinarians in promoting antimicrobial stewardship is essential for successful mitigation of AMR.

Objective: This study aimed to design a self-administered questionnaire and evaluate its reliability as a tool to assess veterinarians' knowledge, perceptions, and attitudes regarding AMR and antibiotic prescription and use in animals.

Methods: The questionnaire was developed based on a comprehensive review of relevant literature and by employing collective intelligence methodologies, including focus groups with veterinarians and pharmacists. For the pilot study, veterinarians working in the Northern region of Portugal were recruited. A test-retest was conducted with a 4-week interval. Reproducibility was determined with the intraclass correlation coefficient (ICC; 95% confidence interval) and internal consistency was calculated using Cronbach's alpha.

Results: In total, 31 (out of 34) veterinarians completed the retest phase of the study. Four sections with scale-items were assessed for reliability, with ICC values ranging from 0.10 (p = 0.285) in Section 2 (AMR) to 0.85 (p < 0.001) in Section 4 (prescription and antibiotic use). The questionnaire achieved Cronbach's alpha coefficient values of 0.81 and 0.78 in test and retest, respectively. Based on ICC values and veterinarians' comments, some items were deleted or reformulated.

Conclusion: The developed questionnaire is a reliable instrument capable of capturing veterinarians' knowledge, perceptions, and attitudes on AMR and antibiotic use.

A 6.08 kg female stray Arctic fox (Vulpes lagopus) of unknown age was presented with tail gland inflammation. Initial conventional therapy and subsequent tail amputation at a primary veterinary facility resulted in limited improvement. Subsequently, a topical medication red mercuric oxide (Hydrargyri Oxydum Rubrum) was applied for 4 weeks. Although the local infection showed signs of improvement, the fox subsequently developed progressive systemic signs, including anorexia, dark urine, and weight loss, prompting referral. Clinical examination revealed a large amount of cherry-red medication covering the wound. Hematological tests indicated elevated neutrophils and C-reactive protein (CRP), suggesting an inflammatory response. Serum biochemistry revealed elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bile acids (TBA), indicating hepatobiliary injury, alongside an elevated creatine kinase (CK) suggestive of abnormal muscle metabolism. The whole-blood mercury concentration was significantly elevated (4.7583 μg/L). Imaging findings included: ultrasound showing gallbladder sludge, abnormal liver parenchyma echogenicity, and indistinct kidney contours; X-ray revealed gastric gas, liver edge extending beyond the costal arch, blurred renal contours, and significantly increased density in the tail gland area. The Arctic fox was diagnosed with chronic topical mercury (II) oxide-induced mercury poisoning and secondary liver injury. The treatment regimen included: (1) removal of the topical medication and surgical debridement; (2) intravenous administration of reduced glutathione (hepatoprotection), ceftiofur sodium (anti-infective), and vitamin C (antioxidant); (3) oral administration of a mercury chelating agent (dimercaptosuccinic acid) and choleretics (ursodeoxycholic acid); and (4) intramuscular injection of appetite stimulants. After 4 weeks of systemic treatment, the fox's abnormal biochemical parameters returned to normal, and the prognosis was good. This case addresses a specific gap in the diagnosis and treatment of heavy metal poisoning in wildlife. It provides a valuable reference for the clinical management of poisoning cases associated with topical mercury-containing wound medications.