Medicine and Pharmacology

Abstract: Adhesive tape strip cytology at 1,000× magnification is the recommended method for the presumptive diagnosis of canine Malassezia overgrowth and/or dermatitis. This study aimed to determine the minimum number of microscopic fields required to achieve optimal intraobserver repeatability and interobserver reproducibility. Two groups of cytology slides were evaluated: 12 slides paired with photographs of pruritic dogs, in which a presumptive diagnosis of Malassezia dermatitis was defined by the detection of at least one yeast organism, and eight slides paired with photographs of non-pruritic dogs, in which a presumptive diagnosis of Malassezia overgrowth and dermatitis was defined by the detection of an average of at least one yeast organism per microscopic field. Twelve investigators examined each slide twice, and results from the first 10, 20, 30, 40, and 50 oil immersion fields were recorded and used for statistical analysis. Regardless of the number of microscopic fields examined, overall intraobserver repeatability and interobserver reproducibility were poor for both slide groups. Consequently, negative adhesive tape strip cytology results do not exclude Malassezia overgrowth and/or dermatitis in dogs with compatible clinical signs.

Abstract: Quality of life (QoL) assessment in companion animals has received increasing attention in veterinary medicine; however, companion rabbits have been systematically excluded from validated instrument development despite being the third most common companion species in several countries. The objective of this study was to develop and preliminarily validate a QoL questionnaire specifically designed for domestic rabbits (Oryctolagus cuniculus). Twenty-eight items were generated across three theoretical domains (behavioral, physical, and nutritional) through literature review and expert panel evaluation, and administered online to 192 owners of rabbits considered healthy. Exploratory factor analysis (EFA) identified a three-factor solution partially congruent with the proposed domains. Confirmatory factor analysis of the full 28-item model showed insufficient fit (CFI = 0.613; RMSEA = 0.056). Behavioral block sub-analysis revealed that the reactivity-to-owner subfactor achieved acceptable internal consistency (α = 0.709), the only domain to surpass the conventional 0.70 threshold. Significant overestimation of QoL by owners was observed relative to structured questionnaire scores (global: +0.62 points, p < .001; physical health: +0.57 points, p < .001). These results establish a preliminary psychometric profile for the first QoL instrument developed for companion rabbits, identifying a clinically viable reactivity subscale and delineating the modifications required for future validation cycles.

Abstract: Chronic synovial inflammation is a hallmark of osteoarthritis progression and is tightly regulated by synovial macrophages. Voltage-gated sodium channels (NaV) have emerged as modulators of macrophages-driven inflammation, positioning them as novel therapeutic targets. Neosaxitoxin, a highly selective NaV channel blocker, has anesthetic and immunomodulatory properties; however, its intra-articular effects on joint inflammation remain unexplored. Using a bilateral equine carpal osteoarthritis model, this study evaluated the immunomodulatory and tissue-preserving effects of intra-articular neosaxitoxin. Sixteen horses were randomized into two experimental groups (n=8/each): Neosaxitoxin in one joint and triamcinolone (+control) in the contralateral joint; or neosaxitoxin in one joint and saline (-control) in the contralateral joint. Clinical parameters, synovial fluid cytology and cytokine profiles, and histological changes in synovium and cartilage were assessed over 30 days. Neosaxitoxin reduced synovial inflammation, evidenced by decreased synovial effusion and surface temperature, along with improved joint flexion. Further, synovial fluid from neosaxitoxin-treated joints exhibited lower counts of erythrocytes, neutrophils, mononuclear cells, total protein, and key pro-inflammatory mediators (IL-1β, IL-6 and TNF-α). Histologically, neosaxitoxin-treated joints exhibited few synovium inflammatory infiltrate and cartilage integrity preservation. In contrast, control joints exhibited synovial hyperplasia, fibrovascular proliferation, and cartilage degeneration. Intra-articular neosaxitoxin better conserved joint homeostasis by limiting synovial inflammation and preserving cartilage integrity. These results warrant further investigation on NaV channel blockage as a novel disease-modifying strategy for osteoarthritis.

Abstract: Distal radial and ulnar fractures in miniature and toy-breed dogs are associated with high rates of delayed union, non-union, and refracture. This retrospective observational study evaluated the outcomes of simple distal radial and ulnar fractures treated by open reduction and internal fixation using a locking plate in a non-rigid configuration. Ten fractures in eight dogs weighing less than 5 kg were included. Cases were selected according to predefined biomechanical construct criteria, including a plate bridge ratio > 0.7, plate span ratio > 10, plate working length > 40% of plate length, and screw density < 0.6. Median radiographic follow-up was 224 days (range, 46–408 days). Radiographic bone healing was achieved in all cases, with a mean time to union of 53 days (range, 28–113 days) and healing occurred faster in skeletally immature dogs. Indirect bone healing with callus formation was observed in 7 of 10 fractures. Minor postoperative complications occurred in three cases and resolved with local treatment. No implant failures or refractures associated with previous screw holes were observed. A reduction in ulnar thickness was identified in evaluable cases, although this finding remained stable during follow-up and did not appear clinically relevant. These findings suggest that locking plate fixation in a non-rigid configuration provides reliable bone healing with a low complication rate in simple distal radial and ulnar fractures of miniature- and toy-breed dogs.

Abstract: Levetiracetam, a second-generation antiepileptic drug, is effective in therapy of various types of seizures. Its pharmacological properties are increasingly used in diversified clinical conditions such as anxiety and neuropathic pain. Levetiracetam has unique mechanism of action - it selectively binds to the synaptic vesicle protein 2A (SV2A), which stabilizes synaptic function and reduces neurotransmitter release, distinguishing it from traditional antiepileptics. The aim of the present paper was to investigate whether levetiracetam (31.25; 62.5 mg/kg, ip) may also be effective drug in reducing of symptoms in morphine dependence in mice. It was studied in three paradigms: 1) morphine tolerance to antinociceptive effect measured in the hot plate test; 2) naloxone-induced (2 mg/kg, ip) morphine withdrawal signs (manifested as jumpings); 3) morphine-induced behavioral sensitization to the locomotor activity of mice. Levetiracetam, at least in one of the doses used, was effective drug in reduction of all measured parameters. The study highlights the need for further research on levetiracetam properties, because it seems to be an innovative target in morphine dependence.

Abstract: Primary hepatic masses in dogs represent a heterogeneous group of lesions with variable biological behavior and challenging preoperative characterization. The objective of this retrospective study was to describe the clinical presentation, diagnostic findings, surgical management, and outcome of dogs with primary hepatic masses treated surgically. Ten dogs with resectable hepatic lesions and no evidence of extrahepatic metastasis were included. Clinical records, imaging findings, histopathological diagnoses, treatment, and follow-up data were reviewed. Histopathological diagnoses included hepatocellular carcinoma (n=3), nodular hyperplasia (n=2), lobular hyperplasia (n=1), hepatocellular adenoma (n=1), undifferentiated sarcoma (n=1), osteosarcoma (n=1), and one case without definitive histological diagnosis. Tumor size ranged from 3.3 to 18 cm and was not associated with biological behavior. Preoperative cytology showed poor concordance with final histopathological diagnosis in all sampled cases. Abdominal ultrasound identified solitary lesions in all evaluated dogs, although surgery revealed previously undetected multifocal disease in two cases. Most lesions were located in the right hepatic lobes, differing from the predominance of left-sided lesions commonly reported in the literature. All dogs underwent surgical resection. Two perioperative deaths occurred secondary to postoperative renal failure. In the remaining dogs, surgery resulted in complete remission of clinical signs and prolonged survival, including dogs with malignant tumors. Four dogs remained alive and disease-free at the end of the follow-up period (>730 days). These findings highlight the limitations of preoperative diagnostic techniques for predicting the biological behavior and extent of canine hepatic masses. Surgical resection provided substantial clinical benefit and prolonged survival in most cases, supporting its consideration whenever complete excision is technically feasible.

Abstract: This prospective case series evaluated the short-term outcomes following percutaneous cementoplasty as the sole palliative treatment for appendicular osteosarcoma in 10 dogs. Synthetic self-hardening calcium-phosphate bone substitute was injected into the osseous defect under fluoroscopic guidance after curettage of the bone tumor. Clinician assessment included a numerical rating score for lameness, offloading, and ease of lifting the contra-lateral limb as well as the 4A-VET post-operative pain scale. Owner assessment was obtained using three descriptive questionnaires, the Helsinki Chronic Pain Index (HCPI), the Canine Brief Pain Inventory (CBPI) and the Canine Symptom Assessment Scale (CSAS). Measures were recorded preoperatively and at 2-, 4-, 8-, and 12-weeks following surgery. Early improvement in the 4A-Vet score was noted at the 2-, 4-, 8-, and 12-week time points for all major pain and function metrics. Similarly, the CBPI pain severity and interference scores demonstrated early postoperative improvement during the 2- and 4-week time points with partial attenuation by 8- and 12-weeks. Panting, difficulty sleeping, whining/moaning, and lack of appetite were significantly reduced when assessed via the CSAS. Cementoplasty as a monotherapy, affording early pain relief and improved structural integrity, supports its role as a limb-sparing option for dogs unable to undergo amputation.

Abstract: This study characterized the cultivable oral microbiota of domestic dogs and evaluated antimicrobial susceptibility patterns and resistance accumulation in a veterinary context. A cross-sectional analytical design was conducted including 100 domestic dogs attended in urban veterinary clinics in southern Ecuador, from which 139 bacterial isolates were obtained through oral swabbing and conventional microbiological identification. Antimicrobial susceptibility was assessed using the disk diffusion method according to CLSI guidelines. Resistance accumulation was defined as the number of antimicrobial classes to which each isolate exhibited resistance, and multidrug resistance as resistance to three or more classes. A predominance of Gram-negative bacteria was observed (65.5%), with Pseudomonas (27.3%), Klebsiella (20.9%), and Enterobacter (7.9%) as the most frequent genera, while Staphylococcus aureus represented 34.5% of isolates. Resistance to at least one antimicrobial was detected in 71.2% of isolates, and multidrug resistance in 9.4% of the total dataset, exclusively among Gram-negative bacteria, corresponding to 14.3% within this group. Resistance to two or more antimicrobial classes was observed in 42.9% of Gram-negative isolates. Multivariable logistic regression showed that bacterial genus was the only factor significantly associated with resistance accumulation, with Enterobacter presenting a higher odds ratio compared to Pseudomonas (adjusted OR = 16.30; 95% CI: 1.69–157.14; p = 0.016), while host-related variables were not significant (p > 0.05). These results indicate that antimicrobial resistance in the canine oral microbiota is primarily structured by bacterial identity rather than host factors, highlighting the role of the oral cavity as a reservoir of resistant bacteria with implications for veterinary clinical practice and epidemiological surveillance.

Abstract: Feline gingivostomatitis is an inflammatory syndrome of the oral mucosa characterized by chronic pain. Its multifactorial etiology and debilitating consequences are associated with difficult clinical management and high relapse rates even after invasive interventions, potentially severely compromising the animals’ quality of life. Cannabidiol (CBD) has been investigated for its anti-inflammatory, antioxidant, analgesic, and immunomodulatory effects and is considered a potential therapeutic alternative for chronic inflammatory diseases. The present report aims to describe a significant clinical improvement in a 5-year-old mixed-breed male cat affected by feline gingivostomatitis, presenting with hyporexia and sialorrhea. A broad-spectrum Cannabis oil rich in CBD was prescribed at doses ranging from 0.5 to 1.0 mg/kg, administered twice daily for two months. Early clinical improvement was observed from the first day of administration, with a dose-dependent response, ultimately resulting in an overall satisfactory clinical outcome. Therefore, it can be concluded that the clinical application of a broad-spectrum Cannabis oil rich in CBD may represent a promising therapeutic alternative for cats affected by feline gingivostomatitis, especially in refractory cases or those with limitations to conventional therapies.

Abstract: Feline Infectious Peritonitis (FIP) has been transformed from a fatal disease to a treatable condition following the introduction of GS-441524, a nucleoside analogue targeting feline coronavirus replication. However, the widespread use of unregulated compounded formulations and the absence of validated analytical tools for therapeutic drug monitoring (TDM) represent critical gaps in clinical FIP management. This study describes the development and full ICH M10-compliant validation of a high-throughput LC-MS/MS method for the quantification of GS-441524 in feline serum, incorporating an automated protein precipitation protocol and a PBS-BSA surrogate matrix in accordance with 3Rs principles. The method met all acceptance criteria across validated parameters, including linearity (0.1–50 µg/mL), accuracy (bias within ±12.5%), precision (CV ≤10.9%), selectivity, extraction recovery (87.5–107.9%), and stability under clinically relevant storage conditions. Matrix equivalence between PBS-BSA and authentic feline serum was confirmed, enabling routine calibration without animal-derived materials. The validated method was applied to clinical TDM in cats undergoing GS-441524 treatment for FIP, providing preliminary evidence of inter-individual pharmacokinetic variability. The compounded formulations administered to the TDM cohort were independently verified by LC-MS/MS, confirming drug content within ±15% of labelled claims and excluding pharmaceutical quality as a confounding factor in the interpretation of serum drug concentrations.

Abstract: Cranial cruciate ligament (CrCL) rupture in cats is less common than in dogs, and its optimal treatment remains a subject of debate. The aim of this study was to evaluate the application of cranial tibial wedge osteotomy technique (CTWO) as a dynamic stabilization technique in cats with CrCL rupture, describing the technical aspects and clinical outcomes obtained. Five cases with a confirmed diagnosis of CrCL rupture between 2020 and 2024 were included in this study. All patients were treated with CTWO using specific osteosynthesis locking plates for this technique in dogs and a complementary cerclage wire. Radiographic rechecks were performed at 8 and 12 weeks postoperatively and clinical evaluations were performed 24 hours, 8 weeks, 12 weeks and six months postoperatively in every patient. Successful and complete bone healing of the tibial osteotomy was observed in every case. No intraoperative or postoperative complications related to implants or soft tissues were recorded. All cats achieved a complete functional recovery without lameness at the last recheck six months after surgery. The technique was performed without significant technical difficulties, providing adequate stability and favorable clinical outcomes in all cases. Although the use of a cranial tibial wedge osteotomy in combination with a tibial plateau leveling osteotomy (TPLO) was reported by Hoot et al to treat a cruciate ligament rupture in a cat presenting a deformity of the proximal tibia (Hoot et al), to the authors´ knowledge the use of the cranial tibial wedge osteotomy as single technique to treat the CrCL rupture in cats has not been previously reported in the literature. These preliminary results support the use of CTWO as an effective surgical alternative for the treatment of CrCL rupture in cats. However, further studies with a larger number of cases and a longer follow-up are required to evaluate better its clinical application, outcomes and influence on osteoarthritis progression in the long term.

Abstract: Osteoarthritis (OA) in companion animals is a progressive and debilitating condition for which current treatments primarily provide symptomatic relief without modifying disease progression. Cell-free regenerative approaches have recently emerged as promising alternatives. This study evaluated the clinical effectiveness of membrane-free stem cell extract (MF-STEM) in canine and feline osteoarthritis in comparison with intra-articular hyaluronic acid in a real-world clinical setting. A total of 271 animals were enrolled, including an MF-STEM group (n = 210) and a control group (n = 61), with treatment allocation based on owner preference. Clinical outcomes were assessed using the Joint Evaluation Index (JEI), along with recovery and recurrence rates. MF-STEM treatment resulted in a marked reduction in JEI scores (12.3 → 2.2), compared with a more limited decrease in the control group (11.3 → 7.0). The recovery rate was significantly higher in the MF-STEM group (93.3% vs. 32.8%), while the recurrence rate within one year was substantially lower (2.4% vs. 60.6%). No treatment-related adverse events were observed (0%). Although the non-randomized design limits causal interpretation, key baseline characteristics were generally comparable between groups, and consistent improvements were observed across multiple outcome measures in a relatively large real-world cohort. In conclusion, MF-STEM demonstrated clinically meaningful improvements in canine and feline osteoarthritis and may suggest a potential to influence disease progression with sustained therapeutic benefits. Further randomized controlled and mechanistic studies are required to confirm these findings.

Abstract: The present study evaluated the effects of three β‑adrenergic agonists, salbutamol, clenbuterol, and terbutaline on growth performance and the kinetics of residue depletion in broiler chickens. A total of 100 Ross 308 chicks were randomly allocated to six treatment groups and one untreated control group. Each β‑agonist was administered via drinking water at two concentration levels (2.5 mg/L and 5 mg/L) starting on Day 19 of age. Body weight was monitored from Day 20 to Day 40 to assess growth performance. Additionally, residue depletion was investigated in breast muscle, liver, kidney, and feathers at predefined time points after treatment cessation. All β‑agonist‑treated groups exhibited significantly reduced body‑weight gain compared with the control group, regardless of compound or dose, indicating that none of the tested β‑agonists conferred growth‑promoting effects in broiler chickens under the conditions of this study. Residue analysis revealed rapid absorption and widespread tissue distribution of all three compounds, with the highest residue concentrations detected during the early post‑exposure period, particularly in kidney and liver tissues. Residue levels declined progressively during withdrawal and fell below the corresponding decision limits (CCα) in all edible tissues at later sampling points. Quantitative residue determination was performed using a validated liquid chromatography–tandem mass spectrometry (LC–MS/MS) method compliant with Commission Decision 2002/657/EC. The findings confirm that salbutamol, clenbuterol, and terbutaline do not improve growth performance in broiler chickens and are efficiently eliminated from edible tissues when appropriate withdrawal periods are observed. These results support existing regulatory restrictions on the use of β‑agonists in poultry production and provide additional evidence relevant to food‑safety risk management.

Abstract: A 7-year-old, 38.3 kg, male neutered Labrador retriever presented to the Teaching Hospital for a consultation of Comprehensive Oral Health Assessment and Treatment. Nine months prior to the consultation, the patient presented to the ER service due to acute right facial swelling. To further evaluate the swelling, the patient was sedated by IV administration of dexmedetomidine and fentanyl, and ventricular premature contractions (VPCs) were confirmed. The facial swelling subsided afterward, but it recurred. Therefore, a dental procedure under general anesthesia was scheduled. Although norepinephrine CRI was initiated to treat the hypotension perioperatively, VPCs were noticed a few minutes after norepinephrine CRI. After the dental procedure, a prolonged recovery was observed, and naloxone (0.01 mg/kg) was administered IV to reverse the effects of fentanyl. Before administration of naloxone, the HR was 80 bpm. Within one minute of administering naloxone, the patient was extubated. However, the HR surged to 240 bpm, and sinus tachycardia was observed. Ninety minutes after naloxone IV, the HR was 105 bpm with normal sinus rhythm, gradually approaching the pre-anesthesia HR level (110 bpm). Veterinarians should recognize that administration of naloxone could induce arrhythmias. Therefore, continuous monitoring of ECG, pulse, and blood pressure is imperative when administering naloxone.

Abstract: Hypospadias is a congenital malformation of the male external genitalia resulting from incomplete fusion of the urethral folds during embryonic development. The perineal form represents the most severe phenotype and is frequently associated with abnormalities such as cryptorchidism and penile hypoplasia. Although surgical correction is generally recommended in young dogs, the long-term clinical course of severe hypospadias under conservative management remains poorly documented. In this study, we describe an un-usual canine case of severe perineal hypospadias that survived to geriatric age under conservative management and subsequently developed bilateral testicular tumors arising from cryptorchid testes. Despite recurrent urinary tract infections during early life, the pa-tient maintained an acceptable quality of life with long-term supportive care, providing a rare clinical example of extended survival without surgical correction. Because no molec-ular material was available from the patient, publicly available mouse transcriptomic da-tasets related to genital tubercle development and Leydig cell differentiation were con-sulted only as contextual reference. These datasets illustrate established developmental regulators and steroidogenic pathways relevant to genital formation and testicular func-tion but do not represent direct molecular findings from the reported case. This report primarily highlights the clinical course and management of severe hypospadias in a dog, while using existing transcriptomic knowledge solely to provide biological context. The findings should therefore be interpreted as descriptive and hypothesis-generating rather than as evidence of a direct mechanistic link between developmental abnormalities and endocrine tumorigenesis.

Abstract: Neurochemical imbalances in the striatum are thought to contribute to the patho-physiology of DYT1 dystonia (TOR1A), a severe movement disorder. Parvalbumin- positive GABAergic fast-spiking interneurons (PV+ FSI) exert a powerful inhibition within the striatal microcircuitry. To elucidate the impact of PV+ FSI on striatal neu-rotransmitter dynamics in a DYT1 knock-in (KI) mouse model, we combined optoge-netic inhibition of PV+ FSI with in vivo microdialysis (optodialysis) and LC-MS/MS analysis. Dialysates were collected across baseline (light off), stimulation (light on, 595 nm) and post-stimulation (light off) periods. Basal extracellular concentrations of sev-eral analytes, including GABA, dopamine and adenosine, showed no significant dif-ferences between wildtype (WT) and DYT1 KI mice. In WT mice, PV+ FSI inhibition decreased GABA and adenosine levels. In contrast, DYT1 KI mice showed no change in GABA and only a delayed reduction in adenosine post-stimulation. Dopamine, choline or 5-HIAA were largely unaffected by optogenetic inhibition, with the exception of a genotype-specific reduction of 5-HIAA in the post-stimulation period. These findings suggest impaired inhibitory and neuromodulatory control in the DYT1 KI mice, po-tentially reflecting compensatory circuit adaptations. The results provide novel insights into striatal microcircuit function in DYT1 dystonia, establish a basis for exploring circuit-level alterations in other movement disorders, and may inform future thera-peutic strategies.

Abstract: Combination of antiparasitic drugs with different mechanisms of action has been suggested as an effective strategy to delay the development of parasite resistance. Upon the need to understand the pharmacological basis of drug combinations, the current study evaluated the potential pharmacokinetic (PK) interactions and the clinical efficacy (pharmacodynamic response) occurring after the subcutaneous administration of ivermectin (IVM) and levamisole (LEV) given both separately and co-administered to parasitized calves on three commercial farms (A, B and C). Sixty (60) male calves naturally infected with gastrointestinal nematodes were randomly allocated into three groups (n= 15): IVM: treated with IVM by subcutaneous injection (0.2 mg/kg); LEV: treated subcutaneously with LEV (8 mg/kg); IVM+LEV: simultaneously treated with IVM and LEV (2 subcutaneous injections at the same dose rates). Seven (7) animals from each treated group (farm C) were randomly selected to perform the PK study. Drug concentrations were measured by HPLC. The therapeutic response (efficacy) was determined at 14 days after treatment by the fecal eggs reduction test (FECRT). The mean IVM area under the concentration vs time curve (AUC) obtained after administration of IVM alone (274 ng.d/mL) was similar to that obtained when IVM was co-administered with LEV (295 ng.d/mL). Likewise, mean LEV AUC values were similar after LEV administration alone (8.90 µg.h/mL) or combined with IVM (9.11 µg.h/mL). No adverse PK interactions were observed after the combined treatment, with similar PK parameters (P>0.05) obtained between the single-drug and the combination-based strategies. On farm A, the overall therapeutic responses (clinical efficacy) were 38% (IVM), 99% (LEV) and 100% (IVM+LEV). While the gastrointestinal nematode species Cooperia spp. and Haemonchus spp. survived the IVM treatment, Haemonchus spp. survived the LEV treatment. Similarly, total efficacies were 42% (IVM), 99% (LEV) and 100% (IVM+LEV) on farm B, and 54% (IVM), 99% (LEV) and 100% (IVM+LEV) on farm C. On those farms, IVM was ineffective against Cooperia spp. and/or Haemonchus spp., while LEV failed to control Ostertagia spp. Remarkably, the combination of both molecules was the only treatment that achieved 100% efficacy against all nematode genera (Cooperia, Ostertagia, Haemonchus and Oesophagostomum spp.). Based on the described PK-pharmacodynamic (PK-PD) assessment, the IVM+LEV combination appears to be a promising pharmacological option for controlling resistant gastrointestinal nematodes in cattle, with the additional potential to delay the progression of nematode anthelmintic resistance. Overall, the work described here contributes with sound and original pharmacology data useful to optimize parasite control in livestock. This drug combination strategy may enhance treatment efficacy while promoting more sustainable parasite management practices in cattle production systems.

Abstract: Severe nasal vestibular stenosis in brachycephalic cats involves species-specific anatomi-cal structures distinct from those in dogs, often leading to a high recurrence rate even after standard surgical correction. This case report introduces an innovative surgical strategy for a refractory Exotic Shorthair cat presenting with obligate open-mouth breathing and complete nasal obstruction despite three previous surgical interventions. To remove the recurrent scar tissue and maximize the nasal vestibular lumen, a combined surgical ap-proach was performed, incorporating a modified Trader's technique, bilateral wedge re-section, and bilateral single pedicle advancement flaps. To maintain the acquired airway and prevent restenosis, a steroid-eluting bioabsorbable implant (PROPEL Contour) was placed within the resected nasal vestibule, marking its first application in veterinary medicine. Postoperatively, open-mouth breathing resolved immediately. At the three-month follow-up, normal nasal breathing was maintained without restenosis or nasal discharge, and no implant-related adverse effects or infections were observed. The concurrent application of radical structural resection and a PROPEL Contour implant ef-fectively suppresses tissue regrowth and maintains stable nasal patency, offering a highly promising therapeutic protocol for refractory feline nasal vestibular stenosis.

Abstract: Potassium homeostasis is essential for maintaining membrane potential and normal neuromuscular function. Although potassium disturbances are clinically relevant in several species, their prevalence and prognostic significance in pet rabbits remain poorly characterized. This retrospective study evaluated plasma potassium concentrations at admission in 1,773 venous samples from 1,312 pet rabbits and assessed associations with mortality, glycemia, and renal markers (BUN and creatinine) using i-Stat portable analyzer. Normokalemia (3.4–5.7mmol/L) was observed in 78.1% of samples, while hypokalemia and hyperkalemia occurred in 13.9% and 8.0%, respectively. Overall, 7-day mortality was 21.3%, with most deaths (68.7%) occurring within 48 hours. Both hypo- and hyperkalemia were associated with increased mortality, with hyperkalemia conferring the greatest risk (relative risk up to 5.4 at 24 h; P< 0.0001). Potassium concentrations were higher in non-survivors at all time points. Hyperkalemia was also associated with hypoglycemia and azotemia (P< 0.0001), suggesting impaired renal potassium excretion and possible alterations in insulinmediated cellular potassi-um uptake. No consistent association was observed between hyperglycemia and hyperkalemia. These findings indicate that plasma potassium disturbances are common in pet rabbits and are associated with short-term mortality and metabolic derangements. Early identification and correction of potassium imbalances and their causes may improve outcomes in critically ill rabbits.

Abstract: Yellow fever (YF) remains a significant vector-borne zoonotic disease in tropical regions of the Americas, despite the availability of an effective vaccine for more than eight decades. In South America, the virus is maintained primarily through a jungle transmission cycle involving mosquitoes of the genera Haemagogus and Sabethes and several species of non-human primates (NHPs), which serve as amplifying hosts and important epidemiological sentinels. This narrative review revisits the current status of YF epizootics in South America and examines their implications for surveillance, ecological dynamics, and the risk of spillover to human populations. The review synthesizes recent evidence on the role of NHPs in the maintenance and detection of YF virus circulation, highlighting the high susceptibility of certain neotropical primates, particularly species of the genus Alouatta, which often experience high mortality during outbreaks. Reports of epizootics across Brazil, Colombia, Peru, Bolivia, and Venezuela illustrate the virus's ongoing circulation and geographic expansion in tropical ecosystems. Ecological factors such as deforestation, habitat fragmentation, environmental change, and increased human activity in forested areas modify transmission dynamics and increase opportunities for spillover to humans. The integration of wildlife monitoring, entomological surveillance, genomic analysis, and epidemiological data is essential to improve early detection and response. In this context, the One Health framework provides a comprehensive approach to understanding the complex interactions among humans, animals, and ecosystems that drive YF transmission. Strengthening regional surveillance systems, improving laboratory capacities, and promoting coordinated public health interventions are critical to preventing human outbreaks and mitigating the ecological and public health impact of YF in South America.