Objective:To describe the use and determine the feasibility and user reliability of a commercially available digital palpation device, a myotonometer, on the canine patellar tendon (PT). Methods:In this prospective clinical feasibility study, client-owned dogs with no history of pelvic limb lameness were eligible for study enrollment from September through December of 2025 and included if their stifles were considered normal based upon physical examination and radiographic findings. Dogs were sedated, and a myotonometer was used to measure tone, stiffness, elasticity, relaxation, and creep of the PT. For each PT, a single user obtained 2 measurement series consisting of 5 individual measurements. Results:20 dogs were enrolled, and 400 total tendotonometric measurements were collected. No adverse events were observed. There were no statistically significant differences for any of the 5 biomechanical parameters between series within each side nor between left and right groups. There was good to excellent intraobserver repeatability between series and moderate to poor repeatability between sides. Conclusions:This clinical study demonstrated feasible myotonometer use as a novel method to obtain biomechanical data for the canine PT in a cohort of sedated dogs with normal stifles. Clinical Relevance:This study introduces tendotonometry into the clinical setting as a novel modality for in vivo evaluation of orthopedic soft tissues using the PT as a test case. Beyond the canine PT, future tendotonometry studies may allow for the generation of noninvasive, rapid, and objective biomechanical data in tendon repair and healing, soft tissue reconstruction for orthopedic conditions, and treatment response in neuromuscular disorders.

Abstract Osteosarcoma (OS) is a bone tumor that affects human and canine patients. Standard of care is neoadjuvant chemotherapy and surgery resulting in a 5 year survival rate for patients with localized disease of ∼70%. However, patients with metastatic disease and relapsed disease have a 5 year overall survival of less than 30%. Therefore, there is a critical need for improved therapies and a better understanding of the biological underpinnings of high risk disease. A subset of patients with particularly poor outcomes are known to have copy number amplification of MYC. However, it is not known if MYC contributes to the high risk phenotype by driving metastatic progression or drug resistance. Importantly, 20 compounds have been described as MYC inhibitors and perturb different steps of MYC driven transcription. In this report, we found that MYC drives cell migration and outgrowth but does not appear to contribute to drug resistance in OS cells. More precisely, MYC silencing reversed the metastatic phenotypes of migration and outgrowth of OS cells. Further, MYC downstream targets play an important role in metastatic progression. Silencing of MYC in 5 different cell lines revealed 45 common induced targets, many of which are known to modulate different steps in the metastatic cascade. We screened all 20 compounds previously shown to interfere with MYC transcription using an approach designed to capture the compound that modulates both MYC activity and the metastatic phenotype. Fourteen compounds modulated expression of MYC and/or downstream targets in 4 different OS models. Of those,10 compounds had a profound impact in cell viability in both 2D and 3D assays. Five of these showed selective toxicity in 3D relative to 2D; a phenotype linked to metastatic progression. Importantly, not all compounds that modulated MYC showed therapeutically favorable effects on migration or metastatic organization and outgrowth with at least 2 compounds driving a dramatic increase in migration despite suppressing expression of MYC. Nevertheless, 2 compounds, samuraciclib and THZ531, blocked MYC expression, downstream target expression, cell migration, metastatic organization and outgrowth. We confirmed these results and showed reversal of metastatic competence and complete reversal of metastatic outgrowth using the in vivo/ex vivo pulmonary metastasis assay (PuMA). We are now working to integrate CUT&Tag with BRUseq, an assay of nascent transcription, to determine if modulation of different steps in MYC transcription drives diverse cellular phenotypes as we hypothesized. Nevertheless, the top hit of the screen, samuraciclib, convincingly reverses MYC activity and the associated metastatic phenotype and is undergoing additional testing in metastatic OS mouse models and a canine clinical trial is under development. Correlative biology such as spatial transcriptomics will be used to guide the translation of samuraciclib to patients with high risk osteosarcoma. Citation Format: Emily Seiden, Scott Sauer, Emma Hiscock, Nha Nhu Le, Ainsley Hellens, Monica Inda, Andrew Fuller, Sridhar M. Veluvolu, Rachael Hinshaw, Zachary P. Tolstyka, Elissa Levine, Rashmi Chugh, Theodore W. Laetsch, Nouri Neamati, Heather Wilson-Robles, Chand Khanna, David Warshawsky, Patrick J. Grohar. Targeting high risk osteosarcoma: MYC modulation alters metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1151.

Background:Diarrhea is one of the most common reasons for visiting canine veterinary clinics or emergency centers. Common treatment approaches include dietary modification, antibiotics, and/or probiotics, which are frequently initiated empirically. Antibiotics can have detrimental long-term effects on the gut microbiome and contribute to antimicrobial resistance, prompting a need for alternative therapies. Probiotics are a promising option; however, their strain-specific effects on the canine gut microbiome have been insufficiently characterized in vivo, particularly in dogs with diarrhea. Hypothesis/objectives:This study aimed to evaluate tolerability and changes in fecal microbiota in dogs with diarrhea during the administration of a novel, advanced microbiome-derived probiotic (AMP) consisting of live Peptacetobacter hiranonis, Megamonas funiformis, and Enterococcus faecium, strains of which were all originally isolated from the feces of a healthy dog. Animals:This single-arm, prospective observational pilot study consisted of 11 client-owned adult dogs of various breeds presenting for chronic diarrhea (>5 days) with a Purina Fecal Score (PFS) between 4 and 7. Methods:Tolerability of the AMP was assessed through serial clinical examinations and comparison of PFS to baseline. Dogs were classified as responders if their PFS improved to <4 by day 7, and as non-responders otherwise. Fecal samples collected at baseline, day 7, and day 56 of AMP administration underwent Illumina amplicon next-generation sequencing (NGS) of 16S rRNA gene fragments (V4 region) to assess the fecal microbiome composition and diversity in each patient. Results:No adverse events were noted in any dogs receiving the AMP. Clinical improvement in diarrhea was noted in eight of 11 dogs after administration of the AMP. Increases in fecal microbiome alpha-diversity were observed after 1 week of AMP administration for six out of seven long-term participants. Conclusion and clinical importance:This pilot study indicates that the AMP was well tolerated in dogs with diarrhea, with dogs maintaining or improving clinical appearance during administration. These preliminary findings justify larger controlled studies to evaluate AMP efficacy and to explore associations between treatment, fecal microbiome changes, and clinical response. Clinical trial registration:Identifier: VCT23005615.

OBJECTIVE To assess gene expression profiles in canine whole blood with and without septic peritonitis to assess workflow fea- sibility and identify potential blood biomarkers that could be further investigated in future studies. METHODS This study enrolled 6 dogs with cytologically confirmed septic peritonitis of any cause and 6 healthy dogs. All dogs had a CBC and biochemistry performed. The dogs with septic peritonitis also had point-of-care lactate and blood oxygen saturation measured for acute patient physiologic and laboratory evaluation score calculation. All dogs then had 2.5 mL of whole blood collected and placed into an RNA stabilization tube, which was processed using a commercial assay based on the hybridization of fluorescent probes for transcript quantification. Quality control, normaliza- tion, and data visualization were performed. Raw counts were exported, and differential expression was performed. RESULTS The evaluation of canine whole blood expression profiles was confirmed to be feasible. Differential expression analy- sis of septic and nonseptic dogs demonstrated distinct gene expression profile signatures. Five genes of interest were upregulated in septic whole blood including matrix metallopeptidase 9, IL-1 receptor type 2, proliferating cell nuclear antigen, phosphatidylinositol 3-kinase catalytic-gamma, and cluster of differentiation 55. CONCLUSIONS The study and associated workflow were feasible and can be scaled in confirmatory studies. CLINICAL RELEVANCE Future studies are now proposed to further validate the increased expression of putative biomarkers in a larger cohort of canine septic peritonitis patients with more relevant comparator control cohorts.

Objective:To describe the tolerability and activity of IV allogeneic mesenchymal stromal cell (MSC) therapy in 13 Pugs with presumptive early necrotizing meningoencephalitis (NME). Methods:255 Pugs were screened from 2021 to 2024 for neurological examination (NE) abnormalities suggestive of early NME. All dogs received a minimum of 2 NEs spaced 2 to 4 weeks apart. An NE score (NES) was assigned at each visit. Magnetic resonance imaging, CSF analysis, and infectious disease testing was obtained in all affected Pugs. Pugs with consistent or progressive NES and MRI or CSF findings supportive of early NME were eligible for MSC therapy. Results:NE abnormalities prior to MSC therapy included spinal hyperesthesia (11 of 13 [85%]), paw placement deficit (11 of 13 [85%]), menace deficit (9 of 13 [69%]), obtundation (9 of 13 [69%]), seizures (7 of 13 [54%]), and ataxia (4 of 13 [31%]). The NES improved in all dogs within 24 hours of the first dose of MSC (mean improvement, 86%). Mild adverse events were noted after 3 of 30 MSC doses (10%). All 13 dogs are currently in remission (follow-up time, 5 to 43 months); 7 of 13 Pugs (54%) remained in remission after MSC therapy alone, and 6 of 13 (46%) required the addition of immunosuppressive therapy. Conclusions:IV allogeneic MSC administration was well tolerated and resulted in immediate clinical benefit in this small cohort of Pugs with presumptive early NME. Strategies to maintain the long-term benefits of MSC therapy require further study. Clinical Relevance:Immunomodulatory MSC therapy may be a potential treatment for neuroinflammatory disease in dogs. Further studies are needed to optimize long-term benefits.

Introduction:The purpose of this study is to describe the outcomes and prevalence of hemoperitoneum recurrence in dogs presumptively cured following splenectomy for spontaneously ruptured benign splenic lesions. Methods:A retrospective analysis of a cohort of 83 client-owned dogs with spontaneous hemoperitoneum due to a histologically benign, bleeding splenic lesion was performed. Medical records of dogs with ruptured benign splenic tumors presenting with hemoperitoneum were reviewed, in addition to owner follow-up, to determine if subsequent hemoperitoneum events occurred. Data were analyzed using statistical software(GraphPad Prism 10.1.2). Results:A total of 59 patients (71%) were alive at the end of the follow-up period (median follow-up duration of 375 days; range: 128-1,062),with no new concerns related to previous splenectomy or hemoperitoneum. Of the 59 dogs, 6 died and 18 dogs (28.9%) were euthanized during the follow up period. Recurrent hemoperitoneum was identified in three dogs at 40, 68,and 385 days postoperatively, associated with a new liver lesion, an abdominal lesion of unclear origin, or hepatic nodules as the reason for the rebleeding events. Additional sectioning of the initial lesions was not performed. Discussion:Second hemoperitoneum events occurred, but were uncommon, accounting for 3.6%of cases in this study. Reasons for recurrent spontaneous hemoperitoneum may include the development of a new lesion, the presence of a secondary non-splenic lesion that was unidentified during preoperative staging or abdominal exploratory, or histopathologic misdiagnosis of the original lesion.

Objective:To assess the feasibility of gene expression profiling of platelets in dogs with sepsis. Methods:This was a prospective observational feasibility study conducted at a university veterinary teaching hospital. All study dogs had CBCs and serum biochemistry profiles, and blood samples were collected for platelet isolation. Gene expression profiling of isolated platelets was performed using a commercial multiplex assay based on direct hybridization and detection of single RNA molecules bar coded with fluorescent probes. Quality control, normalization, and data visualization were performed using standardized workflows. Raw counts were exported, and differential expression between groups was assessed. Results:6 client-owned dogs with sepsis and 6 healthy dogs were enrolled from March through August 2023. Platelet isolation and transcript profiling were successful for all dogs. The septic dog group included 3 males and 3 females with peritonitis (n = 3), pyometra (n = 2), and pyothorax. Principal component analysis did not fully segregate septic from healthy dogs, but disease status accounted for 59% of the variance. Upregulated genes contributing substantially to principal component analysis variance included those for S100 calcium-binding proteins (S100s) and cytokines. Significantly upregulated genes based on log2 fold change included S100A8, S100A12, cathelicidin, lactoferrin, and innate immune response signaling proteins. Conclusions:Sample processing and data analysis workflows are scalable to larger, confirmatory studies to explore potential sepsis biomarkers. Clinical Relevance:Platelet gene expression profiles might offer insights into sepsis pathophysiology and potential diagnostic and prognostic biomarkers. Follow-up studies are warranted to characterize platelet expression profiles in larger populations of dogs with sepsis and noninfectious critical illnesses.

Paclitaxel is an antimitotic agent that targets elements of the cancer phenotype, including cell proliferation, DNA repair, and apoptosis, predicting its broad activity in a spectrum of cancers. An oral paclitaxel formulation has been developed to overcome challenges associated with parenteral administration of this drug, notably the development of Cremophor-induced acute hypersensitivity reactions, which are particularly problematic in dogs. The aim of this open-label, dose-escalating study was to evaluate the tolerability and determine the maximum tolerated dosage (MTD) and dose-limiting toxicity (DLT) of oral paclitaxel when co-administered with the P-glycoprotein pump inhibitor, encequidar, in dogs with cancer. Paclitaxel was administered as a 3-consecutive-day course starting at 90 mg/m2 with encequidar weekly for 3 weeks, using escalation of 30 mg/m2 increments. MTD was established using a rolling-six dose escalation study design, based on the number of dogs experiencing any DLT assessed after each dosing cycle and during a 28-day post-treatment monitoring period. Nineteen client-owned dogs were enrolled. MTD was established at 90 mg/m2 and the most frequent adverse events (AEs) were gastrointestinal, followed by hematologic, with the majority being self-resolving and low grade. VCOG Grades 3 and 4 gastrointestinal toxicity, Grade 4 neutropenia, and acute kidney injury were defined as DLTs at 120 mg/m2. Conclusions of this study define oral paclitaxel MTD in cancer-bearing dogs at 90 mg/m2 when given with encequidar for 3 consecutive days weekly for 3 weeks. Future Phase 2 trials evaluating the therapeutic activity of oral paclitaxel at its MTD co-administered with encequidar in defined tumour histologies are warranted.

Objective:To define the histopathologic diagnoses and clinical stage from a prospectively enrolled cohort of dogs with spontaneous hemoperitoneum (SH) of splenic origin undergoing splenectomy. Methods:This post hoc analysis of prospective data evaluated canine patients presenting with SH enrolled into a nationwide study of ruptured splenic tumors undergoing splenectomy from October 2020 to June 2024. Results:This study enrolled 345 dogs with SH secondary to a ruptured splenic tumor. Benign lesions accounted for 35.7% of all dogs (n = 123), and malignant tumors accounted for 64.3% of all dogs (222). Of the malignant tumors, hemangiosarcoma (HSA) represented 56.2% of all dogs (n = 194) and other malignant tumors represented 8.1% of dogs (28). The median weight in kilograms and age in years for all dogs enrolled were 27.9 kg (5.4 to 84.5 kg) and 10 years (3 to 15 years), respectively. Conclusions:While splenic HSA (spHSA) has remained the most common cause of SH in canines, benign lesions had a higher prevalence in this study at 35.7% (n = 123) than previously reported. There was no statistically significant difference identified when comparing body weight or age between the groups. Clinical Relevance:This study did not identify a statistically significant correlation between age or weight with the development of spHSA and reported an overall higher incidence of benign lesions, thus calling for an adjustment to the narrative claiming that old large-breed dogs have a higher prevalence of spHSA. The published data represent the largest prospective study on SH of splenic origin in canines and can be utilized by the practicing clinician to provide a comprehensive discussion when recommending surgical intervention.

OBJECTIVE To evaluate the reliability of preoperative abdominal ultrasonography as a staging tool for dogs with hemoperitoneum due to presumed splenic tumor rupture, focusing on the detection of metastatic lesions in the liver. ANIMALS 99 dogs from 20 emergency and specialty hospitals across the US. METHODS Dogs with nontraumatic hemoperitoneum secondary to splenic tumor rupture were included. A post hoc analysis was conducted on data from a nationwide prospective trial investigating novel treatments for canine hemangiosarcoma. The accuracy of preoperative staging was assessed by comparing ultrasonographic findings with intraoperative observations and histologic findings. RESULTS On preoperative ultrasonography, there was a 20% incidence of liver lesions identified, with no association to liver lesions seen during operation. Notably, 22% of liver lesions observed during operation were missed on preoperative ultrasonography. The presence of liver lesions on preoperative ultrasonography was associated with a higher likelihood of a benign splenic tumor diagnosis. There was no association between the identification of liver lesions on preoperative ultrasonography and the presence of metastatic disease on liver biopsy, with a sensitivity and specificity of 19% and 82%, respectively. Additionally, ultrasound had low sensitivity in detecting intra-abdominal lesions beyond the liver and spleen, with 82% of these lesions missed preoperatively. CLINICAL RELEVANCE This study challenges conventional perceptions around the approach to staging in dogs with hemoperitoneum. These findings advocate for a reevaluation of the staging approach, with more comprehensive modalities like whole-body CT or MRI potentially being more warranted.

CCL9 promotes tumor cell survival and colonization.

Supplementary Table 1 contains the inclusion and exclusion criteria for pet dogs considered for enrollment into the SOC and SOC + S clinical trial arms.

Objective To investigate the statistical association of severe intraoperative hypoxemia in thoracic surgery with mortality, postoperative hospitalization times and cost of care.Study design Retrospective study.Animals Dogs that underwent thoracic surgery in three veterinary hospitals between October 1, 2018 and October 1, 2020.Methods Anesthesia and hospitalization records from 112 dogs were reviewed and 94 cases met inclusion criteria. Recorded data included signalment, disease etiology, pulmonary or extrapulmonary nature of disease, surgical procedure performed, episodes of severe intraoperative hypoxemia defined as a pulse oximetry reading (SpO2) <90% of 5 minutes or longer duration, survival to discharge, time from extubation to hospital discharge and total invoice cost for clinical visit. Dogs were divided into two groups, those that experienced severe hypoxemia (group A) and those in which SpO2 reading <90% was not observed throughout the procedure (group B). Results Group A had a greater risk of mortality (odds ratio 10.6, 95% confidence interval 1.9-106.7; p = 0.002), prolonged hospitalization (median 62 hours versus 46 hours; p = 0.035) and more expensive cost of care (median US$10,287 versus $8506; p = 0.056) than group B. No significant difference was found for the type of surgical procedure or pulmonary versus extrapulmonary nature of disease. Conclusions and clinical relevance Severe intraoperative hypoxemia was statistically associated with an increased risk of mortality and longer postoperative hospitalization times. Although not achieving statistical significance, there was a trend toward increased costs to the client for animals with intraoperative hypoxemia.

Relationship of variables to metastasis at diagnosis in the discovery set.

Supplementary Materials and Methods

Supplementary Table S9 from Cancers as Wounds that Do Not Heal: Differences and Similarities between Renal Regeneration/Repair and Renal Cell Carcinoma

Legend for Supplementary Figures S1-S6.

Supplementary Figure S4 from Cancers as Wounds that Do Not Heal: Differences and Similarities between Renal Regeneration/Repair and Renal Cell Carcinoma

Supplementary Table S5B from Cancers as Wounds that Do Not Heal: Differences and Similarities between Renal Regeneration/Repair and Renal Cell Carcinoma