Identifying multidrug-resistant (MDR) bacteria in veterinary hospitals is crucial for treatment and public health risk mitigation. This study assessed the hospital prevalence of MDR isolates from canine bacterial skin infections, compared prevalence across services and infection types, and identified the most common MDR organisms. Data from hospital records and aerobic skin cultures from August 2021 to November 2024 were reviewed and analyzed. The dataset included 438 cultures from 416 patients and 647 bacterial isolates, and 196 MDR bacteria yielded from 182 samples. The hospital multidrug resistance prevalence was 42% among cultures and 30% among bacterial isolates. The highest multidrug resistance prevalence by service included Primary Care with 68%, Neurology with 62%, Dermatology with 49%, and Surgery with 44%. The MDR bacteria prevalence for superficial surgical site infections was 34%, pyodermas 33%, wounds 30%, masses 28%, and abscesses 13%. Dermatology cultured 72 of 196 (37%) MDR bacteria, Surgery 48 (24%), Emergency and Critical Care 27 (14%), Urgent Care 18 (9%), Primary Care 14 (7%), Neurology eight (4%), Internal Medicine six (3%), and Oncology three (2%). Staphylococcus pseudintermedius was the most common MDR bacteria. These results underscore the need for ongoing surveillance, antimicrobial stewardship, and targeted infection control strategies specific to each veterinary setting.

OBJECTIVE:To characterize clot waveform analysis (CWA) parameters (delta and derivative values), alongside standard coagulation parameters (prothrombin time [PT], activated partial thromboplastin time [aPTT], and fibrinogen) in dogs diagnosed with immune-mediated hemolytic anemia (IMHA) using a turbidimetric optical clot detection-based analyzer. DESIGN:Retrospective study from January 2018 to October 2022. SETTING:University teaching hospital. ANIMALS:Thirty-five client-owned dogs diagnosed with IMHA. MEASUREMENTS AND MAIN RESULTS:CWA parameters were characterized by an increased PT delta in 35 of 35 dogs with IMHA (100%) and an increased PT first derivative, aPTT delta, and aPTT second derivative in 34 of 35 (97.1%). Compared with healthy controls, the PT was prolonged and the fibrinogen concentration was increased in most of the IMHA cohort, while the aPTT fell within the reference interval. Of the 18 patients that had D-dimers performed, 17 (94.4%) measured above the reference interval. CONCLUSIONS:CWA of patients with IMHA revealed increased parameters compared with the reference intervals, consistent with a hypercoagulable state. This measurement may be helpful in identifying patients that may benefit from antithrombotic therapy.

BACKGROUND:Defining the reliability of oscillometry (NIBP) for measuring mean arterial pressure (MAP) during normotension and hypovolaemic hypotension could help with cardiovascular monitoring and management in horses anaesthetised in dorsal recumbency. OBJECTIVES:To assess agreement between NIBP and invasive MAP during normotension and hypovolaemic hypotension in dorsally-recumbent, anaesthetised horses. STUDY DESIGN:Prospective experimental study using 11 horses. METHODS:Under isoflurane anaesthesia, blood was removed at 5 mL/kg bwt increments up to 25 mL/kg bwt and returned in a similar fashion. Paired NIBP (from the tail base with a cuff width-to-tail circumference ratio of 0.25) and invasive MAP measurements (metatarsal, facial, and transverse facial arteries; MT, FA, TFA) were obtained before and during blood removal/return and analysed using a Bland-Altman analysis for repeated measurements. Sensitivity and specificity of NIBP to detect hypotension (MAP <70 mmHg) were calculated, and an optimum NIBP MAP cut-off for hypotension was estimated. RESULTS:A total of 280 paired NIBP and invasive MAP were compared. The ACVIM validation criteria were met for bias, precision, and limits of agreement (LoA) for all peripheral arterial locations. Correlations between paired measurements, which just fell short of the 0.9 required, were 0.888, 0.887, and 0.856 for the MT, FA, and TFA, respectively. Oscillometric technique underestimated invasive mean arterial pressure by an average of -2.5 mmHg (LoA -23 to 19), -1.3 mmHg (LoA -22 to 19), and -4.7 mmHg (LoA -27 to 18) when compared to the MT, FA, and TFA, respectively. MAIN LIMITATIONS:Only adult horses in dorsal recumbency were studied. CONCLUSIONS:NIBP, as studied here, was deemed acceptable compared to invasive MAP in the MT, FA, and TFA under normotension and hypovolaemic hypotension but not a replacement for invasive blood pressure monitoring in horses.

Cardiac point-of-care ultrasound (cPOCUS) is used to obtain key information about the heart’s structure and function when an echocardiogram is not available. This prospective, cross-sectional study aimed to compare fractional shortening (FS%) and left-atrium-to-aorta ratio (LA:Ao) obtained by cPOCUS in different body positions to echocardiography. Thirty-nine dogs had cPOCUS performed in three different body positions: left lateral recumbency (RT), right lateral recumbency (LT), and standing or sternal recumbency (RST). The cPOCUS values from each body position for FS% and LA:Ao were tested for agreement with the echocardiogram by Bland-Altman plots, correct clinical assessment by generalized estimated equation models, and quality score of the cPOCUS images as a percentage. Bland-Altman analysis showed a positive bias for FS% (0.9% to 9.8%) and both positive and negative bias for LA:Ao (within 0.2) for the cPOCUS values. The correct clinical assessment was made in the majority of cases for FS% in RST (67%) and RT (67%), and for LA:Ao in RST (55%). The clinical assessment was more often correct when the image quality score was higher. Intraclass correlation showed good agreement (≥0.61) between investigators for FS% in all body positions and LA:Ao in RT and RST. This study showed that cPOCUS performed from the right hemithorax can provide estimates and correct clinical assessment of FS% and LA:Ao. Obtaining measurements in the LT position is not recommended.

Porcine reproductive and respiratory syndrome virus (PRRSV) infections in growing pigs are common and costly. We evaluated risk factors related to production practices and herd characteristics associated to wild-type PRRSV (WT-PRRSV) introduction into 63 wean-to-finish (WTF) herds through the implementation of surveys, active recording of activities and monthly oral fluid sampling during the growing phase. Herds were located in the Midwest region of the USA and observed prospectively. Logistic regression analysis of risk factors indicated that WTF herds that outsourced trucks for mortality removal (OR 7.08, p = 0.03) and herds with external maintenance crews (OR 7.14, p = 0.03) had higher risk of WT-PRRSV infections. These findings highlight the importance of mechanical transmission of PRRSV and the need to develop stricter biosecurity protocols in growing pigs. Overall, this study describes most common production management practices and characteristics of WTF sites, and potential risk factors that if addressed, can help improve biosecurity, control and elimination of PRRSV in growing pigs.

OBJECTIVE:To evaluate the utility of the dynamic indices, systolic pressure variation (SPV%), pulse pressure variation (PPV%) and plethysmographic variability index (PVI%) during induced hypovolemia, and to determine their correlation with cardiac output (CO) in anesthetized horses. STUDY DESIGN:Prospective experimental study. ANIMALS:A group of eight healthy adult research horses. METHODS:After sedation with intravenous (IV) xylazine, anesthesia was induced with IV ketamine and diazepam and maintained with constant-dose isoflurane delivered in 100% oxygen. Horses were positioned in dorsal recumbency, paralyzed with IV atracurium infusion, mechanically ventilated to normocapnia and instrumented with two 7 Fr Swan-Ganz catheters for measurement of thermodilution CO and a facial artery catheter to measure arterial blood pressure. Dobutamine was used to maintain normotension. All three dynamic indices of hypovolemia were recorded before (baseline), and 10 minutes after graded hemorrhage (5 mL kg-1 increments) up to 25 mL kg-1 and subsequent autotransfusion (5 mL kg-1 increments). A cut-off value that best distinguished nonbaseline time points while optimizing sensitivity and specificity was determined for each dynamic index. Relationships between dynamic preload indices and CO were determined using Spearman's correlation. RESULTS:Baseline median (range) for SPV%, PPV% and PVI% were 9% (5-15%), 14% (8-37%) and 12% (7-22%), respectively. Maximal accuracies for SPV%, PPV% and PVI%, respectively, were obtained at 25 mL kg-1 hemorrhage with cut-off values of 16.1% (96% accuracy), 28.5% (90% accuracy) and 15.4% (72% accuracy). Accuracy of cut-off values increased proportionally with blood volume removed for all three dynamic indices. Inverse associations were observed between CO and PPV% [-0.49; 95% confidence interval (CI): -0.74 to -0.15; p < 0.007], SPV% [-0.34; 95% CI: -0.69 to 0.10; p = 0.131] and PVI% [-0.20; 95% CI: -0.57 to 0.13; p = 0.253]. CONCLUSIONS AND CLINICAL RELEVANCE:SPV% followed by PPV%, but not PVI%, are useful dynamic preload indices with negative correlation to CO in anesthetized horses.

INTRODUCTION/OBJECTIVES:Transvenous pacemakers are routinely used for pathologic bradyarrhythmias including third-degree atrioventricular block (3AVB), sick sinus syndrome (SSS), high-grade second-degree atrioventricular block (2AVB), and atrial standstill (AS). This study reports the multi-institutional complications and survival rates in a large cohort of dogs. ANIMALS, MATERIALS AND METHODS:A retrospective analysis of outcomes and complications in dogs that underwent transvenous pacemaker implantation between January 2000 and December 2016 at four academic institutions was conducted. RESULTS:In total, 595 dogs were identified (221 males and 374 females) with a median age of 10.1 years (range: 0.3-17.0 years). Presenting arrhythmias included 3AVB (54.5%), SSS (24.4%), high-grade 2AVB (16.1%), and AS (4.0%). Major complications occurred in 17.5% (104/595) of cases including lead dislodgement (n = 39), infection (n = 24), thrombus formation (n = 19), ventricular fibrillation (n = 8), cardiac arrest (n = 6), cardiac perforation (n = 5), and iatrogenic tricuspid stenosis (n = 3). Ventricular lead dislodgement in AS (20%) occurred more frequently than SSS (1.4%; P=0.002), and 80% of the ventricular leads that dislodged in dogs with AS were passive leads. Procedural mortality rate was 0.8% (5/595). Median survival time was 2.8 years (2AVB, 2.9 years; 3AVB, 2.9 years; AS, 3.3 years; SSS, 2.5 years). Cardiac mortality occurred in 60.0% of AS cases compared to 2AVB (25.0%), 3AVB (21.9%), and SSS (16.9%). STUDY LIMITATIONS:Limitations of this study included the retrospective nature of the project with some loss to follow-up. CONCLUSIONS:Pacemakers have a low procedural mortality rate, and overall, complications were minimal. Type of lead and underlying disease process may impact the risk of lead dislodgement. Dogs with AS are more likely to die from cardiac-related disease.

IntroductionDopamine signaling contributes to tumor progression in human lung adenocarcinoma. Isoforms of dopamine-and-cAMP-regulated phosphoprotein Mr. 32,000 (DARPP-32) are overexpressed in human lung adenocarcinoma and are associated with prognosis and development of treatment resistance. Despite similarities to human lung adenocarcinoma, dopamine signaling has not yet been evaluated in canine pulmonary adenocarcinoma. The objective of this study was to characterize immunohistochemical expression of DARPP-32 isoforms in canine pulmonary adenocarcinoma and assess associations with clinical variables, markers of proliferation and angiogenesis, and outcome.MethodsImmunohistochemistry for DARPP-32 isoforms DARPPN and DARPPC, EGFR, D2R, and VEGFR2 was used to assess 46 canine adenocarcinomas. The percentage of tumor cells positive for target protein expression and staining intensity of DARPPC, DARPPN, and EGFR were quantified using a modified immunohistochemical scoring scheme. Intratumoral vascular endothelial D2R and VEGFR2 expression were quantified based on the number of positive vessels.ResultsDARPPN or DARPPC was expressed in 40 (87%) adenocarcinomas; 54% of tumors expressed both isoforms. DARPPN was positively correlated with tumor volume, VEGFR2 expression and mitotic count. DARPPC was positively correlated with EGFR expression. VEGFR2 expression was positively correlated to EGFR expression and mitotic count. When stratified by the median, survival was shorter with increased tumor volume (p = 0.003) and greater intratumoral VEGFR2 expression (p = 0.042). Dogs with DARPPN (p = 0.059) or DARPPC (p = 0.120) expression greater than the median had shorter survival than those with lower expression.ConclusionCollectively, data support further investigation of DARPP-32 protein signaling in canine lung adenocarcinoma.

Canine hemangiosarcoma is a common and aggressive vascular malignancy predominantly affecting dogs over six years of age. Despite surgical resection followed by adjuvant chemotherapy, median survival remains around 4–6 months. Propranolol, a beta-adrenergic receptor (β-AR) antagonist, has shown efficacy in human angiosarcoma, a tumor with similar clinical and morphological characteristics, when combined with chemotherapy. To determine if propranolol could be repurposed as an effective adjunct to chemotherapy, we conducted a phase I clinical study evaluating the safety and efficacy of propranolol combined with doxorubicin (PRO-DOX) in 20 dogs with stage 1 or stage 2 splenic hemangiosarcoma.Plasma from 19 dogs was analyzed for propranolol pharmacokinetics and RNA was extracted from tumors from 13 of the dogs for transcriptional profiling. Although propranolol did not appear to influence treatment outcomes, our results revealed long-term survival in young adult dogs (less than 6 years of age), suggesting the possibility of a better response to doxorubicin. Faster clearance of 4-OH propranolol also correlated with long-term survival in younger dogs, but this appeared to be associated with drug metabolism due to age rather than effects of the drug on survival outcomes. Gene expression analysis identified distinct age-associated tumor signatures, with young dogs exhibiting increased immune-related gene expression and older dogs showing elevated expression of genes associated with the cell cycle and the DNA damage response and repair. These findings highlight several hallmarks of cellular aging in hemangiosarcoma that may influence treatment responses and long-term survival. Our findings suggest that young adult dogs with splenic hemangiosarcoma treated with doxorubicin have a better prognosis and underscore the need for further research into age-related molecular mechanisms of disease. These insights could refine therapeutic strategies and clinical decision-making in hemangiosarcoma management.

Objective:To assess the effectiveness of cleaning protocols and support infection prevention efforts, we instituted ATP bioluminometer monitoring at the University of Minnesota Veterinary Medical Center. Our objective with this serial cross-sectional study was to summarize our ATP bioluminescence reading from animal and human contact areas and the impact of seasonality. Methods:From April 2020 through November 2023, swabs were collected from common contact surfaces at the hospital. Using the 3M Clean-Trace ATP Luminometer, relative light units (RLUs) served as a surrogate for an assessment of hygiene. Relative light unit values were compared by location, season, and "animal contact" or "human contact" surfaces. A mixed model compared RLU levels across different locations and dates. Results:ATP readings varied across locations, ranging from 5 to 301,158 RLUs, with a mean of 1,441.14 (± 8,951.79), a median of 494, and an IQR of 1,138. Most readings were below 1,000 RLUs (67%), and 37% were below 300 RLUs. Animal contact areas had lower RLU readings compared to human contact areas. The mixed model identified statistically significant variable RLU values by location but not by season. Conclusions:We observed a wide variation in median RLU values across the sampled locations. This is to be expected since hospital environments are dynamic, with varied animal and human interactions throughout the day as well as changing staffing patterns and patient volumes across different seasons. Clinical Relevance:Maintaining high hygiene standards is crucial for patient well-being and reducing the risk of healthcare-associated, zoonotic, and antimicrobial-resistant infections. The use of the ATP bioluminometer is one tool to reduce healthcare-associated infections and support better patient outcomes.

Guide dog organizations have strict criteria to breed, raise, and select dogs to assist people with visual impairments. In collaboration with Dr. James Serpell, several guide dog training organizations developed a scoring tool called the Behavior Checklist (BCL) to evaluate candidate guide dogs. The tool's use has expanded to the entire assistance dog industry and is rapidly emerging as the standard behavior assessment. Since 2003, Guiding Eyes for the Blind (GEB) has used the BCL to measure individual dogs' behaviors up to 8 times between puppyhood and final placement. Here, we evaluate the consistency of the BCL over multiple evaluations in a population of 3,969 Labrador Retrievers raised by Guiding Eyes. We grouped BCL evaluations by two methods, factor analysis, and trainer-defined groups, and summarized groupings of behavior in two ways, using mean and lowest scores. We then determined the agreement between pairs of evaluations using kappa statistics and the predictive capacity of early BCL scores to predict later scores using positive and negative predictive values. Evaluations that are similar in nature and those that are scored within 3 to 6 months of one another agree the most. When a dog scores well early in life, they are likely to consistently score well and the dog's behavior is unlikely to regress over time. We also found that dogs who score poorly early in life either improve their scores on later evaluations with training intervention or are removed from training. One limitation of this data is that dogs who score poorly at early time points are often removed from training and the data from later BCL evaluations is biased toward higher-scoring dogs. Regardless, these data show that the BCL is an effective way to evaluate assistance dog behavior and has some predictive capacity.

OBJECTIVE:To compare survival between cats diagnosed with a nonketotic hyperosmolar hyperglycemic state (HHS) and cats diagnosed with diabetic ketoacidosis (DKA), and to determine whether clinical parameters, clinicopathologic data, and insulin type are associated with survival. Secondary objectives were to evaluate whether these parameters were associated with survival in cats undergoing a generalized hyperglycemic diabetic crisis. DESIGN:Retrospective evaluation of medical records of cats diagnosed with DKA and HHS between 2000 and 2020. SETTING:University teaching hospital. ANIMALS:The HHS group consisted of 29 cats (blood glucose concentration [BG] ≥31.08 mmol/L [≥560 mg/dL]; calculated serum osmolality ≥350 mOsm/kg; ketone negative). The DKA group consisted of 71 cats (BG ≥7.77 mmol/L [≥140 mg/dL]; pH <7.35; ketone positive). INTERVENTIONS:None. MEASUREMENTS AND MAIN RESULTS:No clinicopathologic parameters or previous use of glargine U-100 were significantly associated with survival in the HHS group. There was no difference in survival of the HHS group versus the DKA group (65.5% vs. 68.6%; p = 0.85). In all cats, higher serum BUN (p = 0.014), creatinine (p = 0.0098), or BG (p = 0.015) and lower serum sodium concentration (p = 0.03) or body temperature (p = 0.0098) were associated with decreased odds of survival. Calculated total and effective osmolalities were not associated with survival in either group. CONCLUSIONS:Cats with HHS had a survival of 65.5% in this study. No serum biochemical parameters predicted prognosis for the HHS group, and insulin type was not found to be associated with survival. Azotemia, hyponatremia, hyperglycemia, and hypothermia were associated with decreased survival when combining all cats. Hyperosmolality was not associated with survival; therefore, distinguishing HHS and DKA into separate syndromes may be arbitrary.

BACKGROUND:Diagnosis of porcine reproductive and respiratory syndrome virus (PRRSV) infections can be accomplished using various sample types and testing methods.  The objective of this study was to evaluate the feasibility of using air emission samples to detect the onset of PRRSV type 2 infections in growing pigs. METHODS:Air emissions and oral fluid samples were collected from three grow-finish barns, stocked with PRRSV-negative pigs every 2 weeks for 14-20 weeks. All samples were assayed for PRRSV using RT-PCR. RESULTS:In all barns, PRRSV was initially detected in both air emissions and oral fluid samples at the same sampling event. Compared with oral fluids, air emissions collected subsequently yielded higher cycle threshold values and showed a lower likelihood of being RT-PCR positive. LIMITATION:Sampling was limited to three grow-finish barns. CONCLUSION:Air emission samples from pig barns are a biosecure and non-invasive sample type that is comparable to oral fluids for detection of the onset of PRRSV infection.

Humanized (h) DRAGA mice are a promising in vivo model for investigating immunotherapies for treating HIV infections. These mice are not only susceptible to HIV infection, but they also develop functional human immune cells, including T cells and B cells, as well as follicular-like structures that mimic lymphoid B-cell follicles, where HIV-producing cells concentrate during infection in a manner similar to that found in humans. This study evaluated HIV-infected hDRAGA mice as a model for testing the safety, tissue targeting, and efficacy of HIV-specific CAR/CXCR5 T cells. We also evaluated whether HIV infection in hDRAGA mice can be suppressed by antiretroviral therapy. We produced functional HIV-specific CAR/CXCR5 T cells from disaggregated hDRAGA splenocytes and infused cell products into HIV-infected hDRAGA mice. CAR/CXCR5 T cells persisted in hDRAGA mice for the duration of the study, peaking 6 d postinfusion. Treatment with CAR/CXCR5 T cells appeared to be safe, with 100% survival rate and no noticeable changes in pathology. Six days after infusion, CAR/CXCR5 T cells had accumulated in the follicle-like structures in the spleen, with many in direct contact with HIV-producing cells. However, CAR/CXCR5 T-cell treatment did not reduce viral loads compared to controls, likely because CD4 T cells in the infused product became infected with and spread HIV infection. Despite this, all mice treated with antiretroviral therapy showed complete suppression of viral replication, indicating that HIV infection was treatment responsive in the DRAGA mice. These studies indicate that hDRAGA mice are a valuable model to study cellular immunotherapies for HIV.

Researchers explored senior/clinical year veterinary trainees' perceptions of the Goal Oriented Learner Driven-Entrustment (GOLD-E) scale. Researchers recruited trainees from on-campus clinical service rotations to explore the following questions: 1) How do trainees regard the feedback the GOLD-E tool provides? 2) How do trainees enter into the clinical feedback relationship? 3) How does the GOLD-E tool create opportunities for trainees to engage authentically with themselves and with clinical coaches (i.e., clinicians, technicians, interns, and house officers)? Clinical year trainees completed the GOLD-E form with clinical coaches during the 2018–2019 academic year. Data collection included both quantitative and qualitative methods using bi-weekly surveys and focus groups. Findings point to the need for: Thoughtful integration of feedback and coaching when assessing practice using EPAs; better understanding of the role coaches play in the everyday expectations and practices of learning to become a practicing veterinarian; and realization of trainees’ uncertainty concerning their role in the coaching relationship, the learning process, and when asking for feedback. These findings connect with the first paper in this series and further emphasize that culture change requires significant time and effort. Moreover, there needs to be careful consideration of organizational structures to effectively implement change.

Background: Hypertriglyceridemia (HTG) is prevalent in Miniature Schnauzers, predisposing them to life-threatening diseases. Varied responses to management strategies suggest the possibility of multiple subtypes. Hypothesis/Objective: To identify and characterize HTG subtypes in Miniature Schnauzers through cluster analysis of lipoprotein profiles. We hypothesize that multiple phenotypes of primary HTG exist in this breed. Animals: Twenty Miniature Schnauzers with normal serum triglyceride concentration (NTG), 25 with primary HTG, and 5 with secondary HTG. Methods: Cross-sectional study using archived samples. Lipoprotein profiles, generated using continuous lipoprotein density profiling, were clustered with hierarchical cluster analysis. Clinical data (age, sex, body condition score, and dietary fat content) was compared between clusters. Results: Six clusters were identified. Dogs with primary HTG were dispersed among 4 clusters. One cluster showed the highest intensities for triglyceride-rich lipoprotein (TRL) and low-density lipoprotein (LDL) fractions and also included 4 dogs with secondary HTG. Two clusters had moderately high TRL fraction intensities and low-to-intermediate LDL intensities. The fourth cluster had high LDL but variable TRL fraction intensities with equal numbers of NTG and mild HTG dogs. The final 2 clusters comprised only NTG dogs with low TRL intensities and low-to-intermediate LDL intensities. The clusters did not appear to be driven by differences in the clinical data. Conclusions and Clinical Importance: The results of this study support a spectrum of lipoprotein phenotypes within Miniature Schnauzers that cannot be predicted by triglyceride concentration alone. Lipoprotein profiling might be useful to determine if subtypes have different origins, clinical consequences, and response to treatment.

Abstract Background: Osteosarcoma a common cancer in dogs that can serve as a translational model for certain aspects of human osteosarcoma. We previously developed a serum exosome gene signature in dogs with osteosarcoma capable of detecting minimal residual disease and predicting prognosis after therapy. Our goal is to continue expanding our understanding of exosomes for liquid biopsy applications in dogs with cancer, and to leverage this information in the design of liquid biopsy tests to address risk, early detection, and management of human cancer patients. For this study, we hypothesized that dogs with cancer would have higher plasma exosome concentrations compared with healthy control dogs. Methods: Plasma exosomes were enriched from 29 dogs with cancer, including 8 dogs with osteosarcoma, and 26 healthy control dogs. Exosome size and concentration in the plasma samples were characterized with nanoparticle tracking analysis. Wilcoxon rank sum tests were performed to assess differences between groups. Results: Dogs with cancer had a higher mean exosome concentration at 1.4 x 1012 (+/- 1.1 x 1012) particles/ml, compared with 5.0 x 1011 (+/- 2.7 x 1011) particles/ml in healthy control dogs (p = 0.0046). There was no difference in exosome size between dogs with cancer (mean diameter = 99.9 nm) and healthy control dogs (107.8 nm; p = 0.16) when all cancer types were included. However, exosomes enriched from healthy control samples were found to be significantly larger when compared to the exosomes enriched from the subset of cancer dogs that had osteosarcoma (mean exosome diameter = 83.9 nm; p = 0.0065). Similarly, when comparing exosome size between dogs with osteosarcoma and dogs with other cancers, plasma exosomes were larger in the dogs with other cancers (107.4 nm; p = 0.023). Conclusions: In this population, dogs with cancer have higher plasma exosome concentrations compared with healthy control dogs. Interestingly, we also found that dogs with osteosarcoma had significantly smaller exosome size than dogs with other cancers and healthy control dogs. Though the size of exosomes from dogs with osteosarcoma was found to be smaller, it is possible that the larger exosome concentration in dogs with osteosarcoma results in a similar total exosomal mass. Ongoing work includes analysis of exosomal cargo to develop a liquid biopsy test capable of assessing risk of osteosarcoma development in dogs, and applying similar methodology to determine exosomal genes associated with prognosis in pediatric osteosarcoma. The higher exosome concentrations in dogs with cancer suggests that this feature, combined with analysis of exosomal cargo, may have utility in development of a liquid biopsy cancer test in dogs. Citation Format: Kelly M. Makielski, Jaron M. Magstadt, Courtney H. Labe, Ali Khammanivong, Meagan Wojtysiak, Kyle Duval, Mitzi Lewellen, Amber Winter, Kelly Reid, Andrea Chehadeh, Michelle Buettner, Caitlin Feiock, Aaron K. Rendahl, Gary R. Cutter, Logan G. Spector, Brenda J. Weigel, Jaime F. Modiano. Dogs with cancer have higher plasma exosome concentrations compared with healthy dogs in the COED (canine osteosarcoma early detection) study [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B003.

OBJECTIVE To compare how often owners identified concerns about their pets’ behavior during routine examinations in 2 test conditions (voluntarily or when completing a questionnaire), and to test the efficacy of a simple behavior screening questionnaire to be used by practicing veterinarians. ANIMALS Privately owned dogs and cats presenting for routine examinations to 1 of 2 primary care clinics. METHODS The study was conducted in 2 sequential phases. In Phase 1, veterinary staff recorded whether pet owners or veterinarians inquired about behavior during routine examinations. In Phase 2, a different set of pet owners completed a short behavioral screening questionnaire as they waited for the veterinarian. We compared the 2 phases for how often behavior concerns were identified, the types of concerns, the pets’ ages, and the owners’ levels of satisfaction and desire for help. RESULTS Dog and cat owners were more likely to identify behavior concerns when prompted than they were to volunteer this information, especially for older patients in which behavior changes may be the first sign of disease. Most owners were satisfied with their pets’ behavior, though owners were more likely to be unsatisfied with certain identified concerns. Owners who were dissatisfied were much more likely to want help. CLINICAL RELEVANCE A behavior screening questionnaire enhances detection of behavior problems that may have medical implications and impact the security of the pet in its home. A behavior screening questionnaire can elevate standard of care by enabling veterinarians to quickly assess behavior during every examination.

Limitations in diagnostic test performance are one of the major challenges hampering the eradication of bovine tuberculosis (bTB). Non-tuberculous mycobacteria (NTM) are considered one of the main causes of non-specific reactions in the intradermal tuberculin test, the most widely used bTB diagnostic test. To determine the role of NTMs in bTB misdiagnosis in Spain, an experimental study including the NTM species most commonly found in bTB-positive animals from bTB-free farms in the country (M. avium subsp. avium (Maa), "Mycobacterium avium subsp. hominissuis" (Mah), M. bourgelatii, M. intermedium, M. kansasii and M. nonchromogenicum) was carried out on guinea pigs and cattle. First, guinea pigs were sensitized with the selected NTMs, and six weeks postsensitization four antigen mixtures (bovine-PPD, avian-PPD, P22 and ESAT6-CFP10) were inoculated intradermally and their effect was measured 24- and 48-h post-inoculation. Larger erythematous reactions were observed in guinea pigs sensitized with Mah, M. kansasii, and Maa, with significant differences in the reactions measured at the bovine-PPD inoculation site for the two first bacteria compared with other NTMs. The sensitization process was repeated in cattle, and five months post-sensitization the same antigen mixtures were inoculated in the cervical region and responses were measured at 48- and 72-h post-inoculation. A significantly higher increase in the skinfold thickness measured at the bovine-PPD inoculation site was observed in calves sensitized with Mah, Maa, M. intermedium and M. kansasii. These results demonstrate that certain NTM species may play a more significant role in bTB diagnostic interferences and show that results obtained in guinea pig and bovine models do not always coincide.