Point-of-Care Cardiac Troponin I Assay Evaluation in New Zealand White Rabbits (Oryctolagus cuniculus).

Cardiac troponin I (cTnI) is a cardiac-specific biomarker, used for the detection of myocardial injury. While rabbits develop naturally occurring cardiovascular disease, they are also an animal model for human disease; thus, rapid detection of cTnI has implications for both veterinary and human medicine. The objective of this study was to validate and establish a reference interval for a point-of-care (POC) cTnI assay in New Zealand White rabbits. In the first portion of the study, rabbit cardiac and skeletal muscle tissues were used to create homogenates, serially diluted with saline or rabbit whole blood, and run by repeated analysis on the POC assay. In the second portion of the study, a reference interval of peripheral whole blood cTnI was determined by robust methods from 49 New Zealand White rabbits. The least diluted cardiac muscle homogenates produced detectable cTnI (mean 23.12 ± 3.557 ng/mL), while skeletal muscle homogenates produced low to undetectable cTnI. The CV ranged from 0.00% to 32.51% for cTnI of diluted cardiac muscle homogenates. Rabbit cardiac homogenate diluted in blood had a linear relationship to cTnI concentration (Y = 0.2254 × X + 0.5396, R² = 0.975). The reference interval for cTnI in this population was less than 0.04 ng/mL. This POC assay may be useful when rapid detection of cTnI is needed and differentiation between normal and elevated values is required. Given the high CV, this assay may not be appropriate for cases that require high sensitivity or detection of low concentrations of cTnI.

Case report: Severe hepatopathy following rivaroxaban administration in a dog.

Rivaroxaban, a specific factor Xa inhibitor and commonly utilized anticoagulant, has been known to cause hepatotoxicity and liver failure in humans. Although rivaroxaban is frequently used in veterinary medicine, hepatotoxicity has not been previously reported in dogs. The current case report describes a dog that developed severe hepatopathy following rivaroxaban administration for a large right pulmonary artery thrombus. An estimated 6-year-old spayed female mixed-breed dog developed anorexia and lethargy 9 days after rivaroxaban administration began. Subsequent labwork revealed severe hepatocellular hepatopathy, and rivaroxaban was discontinued. Additional diagnostics did not reveal an underlying etiology, although hepatic cytology could be consistent with a toxic injury. The hepatopathy and clinical signs improved after rivaroxaban was discontinued. The time to onset, type of hepatopathy, and time to resolution were all similar to those reported for human cases. This case provides precedence to advocate for improved and closer monitoring of dogs receiving factor Xa inhibitors. In cases of suspected hepatotoxicity with no other identifiable cause, a risk-benefit analysis should be performed, and discontinuation of rivaroxaban administration or alternative anticoagulant medications should be considered.

Cardiovascular disease in central bearded dragons (Pogona vitticeps): 54 cases (2007-2022).

OBJECTIVE: To describe the clinical features, histopathologic lesions, and outcome of cardiovascular disease in central bearded dragons. ANIMALS: 54 bearded dragons. METHODS: Retrospective evaluation of captive bearded dragons with antemortem imaging or postmortem diagnosis of cardiovascular disease from 2007 to 2022 from 6 hospitals. RESULTS: The total prevalence of cardiovascular disease was 3.3% (54/1,655). Physical examination findings were available in 46 cases with change in mentation being the most common finding (n = 28/46 [60.9%]), followed by dehydration (17/46 [37%]), palpable coelomic mass (13/46 [28.3%]), dyspnea (10/46 [21.7%]), and sunken eyes (10/46 [21.7%)]. Doppler auscultation revealed an arrhythmia in 5/34 (14.7%) animals. Diagnostic imaging was only performed on 21 animals, and 10 (47.6%) had cardiovascular abnormalities described. In total, 84 cardiovascular diagnoses were found in 54 animals. The most common diagnosis was myocarditis (n = 14) followed by aneurysms (11), pericardial effusion (9), atherosclerosis (7), epicarditis (7), and myocardial degeneration/necrosis (7). Overall, 62 causes of death were identified in 52 cases, with cardiovascular disease being the most common (n = 18/52 [34.5%]). Only 3/54 animals were diagnosed with congestive heart failure. Animals with aneurysms were more likely to die to due cardiovascular disease compared to other types of cardiovascular diagnoses (OR, 43.75; 95% CI, 4.88 to 392.65; P < .001). CLINICAL RELEVANCE: Diagnosis of cardiovascular disease in bearded dragons is challenging given the inconsistent clinical presentation; however, it should remain a differential in animals with nonspecific signs of illness. Antemortem diagnostics are recommended in suspected cases, including diagnostic imaging. Of the cardiovascular diseases described, aneurysms most often contributed to clinical demise.

Self-reported radiation safety behaviors among veterinary specialists and residents performing fluoroscopic procedures on small animals.

OBJECTIVE: To describe the radiation safety behaviors of veterinary specialists performing small animal fluoroscopic procedures and examine potential risk factors for these behaviors, including knowledge of radiation risk and training regarding machine operating parameters. SAMPLE: 197 veterinary specialists and residents in training. PROCEDURES: An electronic questionnaire was distributed to members of the American Colleges of Veterinary Internal Medicine (subspecialties of cardiology and small animal internal medicine), Veterinary Radiology, and Veterinary Surgery. RESULTS: The overall survey response rate was 6% (240/4,274 email recipients). Of the 240 respondents, 197 (82%) had operated an x-ray unit for a small animal fluoroscopic procedure in the preceding year and fully completed the questionnaire. More than 95% of respondents believed that radiation causes cancer, yet approximately 60% of respondents never wore hand or eye protection during fluoroscopic procedures, and 28% never adjusted the fluoroscopy machine operating parameters for the purpose of reducing their radiation dose. The most common reasons for not wearing eye shielding included no requirement to wear eyeglasses, poor fit, discomfort, and interference of eyeglasses with task performance. Respondents who had received training regarding machine operating parameters adjusted those parameters to reduce their radiation dose during procedures significantly more frequently than did respondents who had not received training. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of the self-reported suboptimal radiation safety practices among veterinary fluoroscopy users, we recommend formal incorporation of radiation safety education into residency training programs. All fluoroscopy machine operators should be trained regarding the machine operating parameters that can be adjusted to reduce occupational radiation exposure.

Acute Effects of Pimobendan on Cardiac Function in Dogs With Tachycardia Induced Dilated Cardiomyopathy: A Randomized, Placebo-Controlled, Crossover Study.

Background: Pimobendan provides a significant survival benefit in dogs with cardiac disease, including degenerative mitral valve disease and dilated cardiomyopathy (DCM). Its positive inotropic effect is well-known, however, it has complex effects and the mechanisms behind the survival benefit are not fully characterized. Secondary hemodynamic effects may decrease mitral regurgitation (MR) in DCM, and the benefits of pimobendan may extend to improved cardiac relaxation and improved atrial function. Hypothesis/Objectives: Our objective was to investigate the acute cardiac effects of pimobendan in dogs with a DCM phenotype. We hypothesized that pimobendan would increase left atrial (LA) contractility, reduce mitral regurgitation, improve diastolic function, and lower circulating NT-ProBNP levels. Animals: Seven purpose-bred Beagles were studied from a research colony with tachycardia induced DCM phenotype. Methods: The effects of pimobendan were studied under a placebo-controlled single-blinded cross-over design. In short, dogs underwent baseline and 3 h post-dose examinations 7 days apart with echocardiography and a blood draw. Dogs were randomized to receive oral placebo or 0.25 mg/kg pimobendan after their baseline exam. Investigators were blinded to treatments until all measurements were compiled. Results: When treated with pimobendan, the dogs had significant increases in systolic function and decreases in MR, compared to when treated with placebo. There were no detectable differences in left atrial measures, including LA size, LA emptying fraction, LA functional index or mitral A wave velocity. Heart rate decreased significantly with pimobendan compared to placebo. There was also a decrease in isovolumetric relaxation time normalized to heart rate. NT-proBNP levels had a high degree of variability. Conclusions: Improved mitral regurgitation severity and improved lusitropic function may contribute to the reported survival benefit for dogs with cardiac disease administered pimobendan. Pimobendan did not overtly improve LA function as assessed by echocardiography, and NT-proBNP was not significantly changed with a single dose of this medication. Further studies are needed to better characterize LA effects with other imaging modalities, to better quantify the total improvement of MR severity, and to assess chronic use of pimobendan on diastolic function in DCM.

Surgical repair for canine tricuspid valve dysplasia: Technique and case report.

Tricuspid valve dysplasia (TVD) is a congenital malformation of the right atrioventricular valve characterized by restricted leaflet motion, annular dilation, and tricuspid regurgitation (TR). Severe cases typically exhibit progressive right-sided congestive heart failure, affecting the quality of life and survival. This article describes a technique for surgical repair of TVD and a case report with long-term follow-up. A 1.5-year-old intact male Labrador retriever with severe TR underwent surgical repair for TVD. Valve repair was performed under cardiopulmonary bypass and consisted of neochord mobilization of the valve leaflets and partial band annuloplasty. Transthoracic echocardiogram performed 5 days after surgery showed mild TR, a 93% decrease in anatomic regurgitant orifice area, and decreased right chamber dimensions. Forty-eight months after repair, the patient was free of clinical signs, did not have a heart murmur, and was receiving no cardiac medications. Based on this case, surgical repair of TVD is feasible with long-term durability, and the outcome suggests that the described technique may be a viable treatment option for patients with severe TVD.