Randolph L. Winter

Aortic thrombosis in dogs: presentation, therapy, and outcome in 26 cases.

OBJECTIVES The pathogenesis and presentation of aortic thrombosis (AT) in dogs is not well characterized and an effective antithrombotic therapy for AT in dogs has not been identified. Our goal is to report the clinical presentation and results of therapies in dogs with AT. ANIMALS Twenty-six client-owned dogs. METHODS Retrospective review of medical records of dogs diagnosed with AT between 2003 and 2010. RESULTS Twenty-six dogs had an apparent primary mural aortic thrombus. None had structural heart disease at diagnosis. Twenty dogs were ambulatory with varying degrees of pelvic limb dysfunction. Duration of ambulatory dysfunction was 7.8 weeks (range 1 day-52 weeks). A majority of dogs (58%) had no concurrent conditions at diagnosis. Fourteen dogs were treated with a standard warfarin protocol for a median period of 22.9 months (range 0.5-53 months). Ambulatory function improved in all dogs treated with warfarin. Time until clinical improvement was 13.9 days (range 2-49 days). Dogs treated with warfarin did not become non-ambulatory, die or undergo euthanasia related to AT, or have a known serious hemorrhagic event. CONCLUSIONS The pathogenesis of AT in dogs is distinct from that of aortic thromboembolism (ATE) in cats. Aortic thrombosis in dogs is more likely to involve local thrombosis in the distal aorta with embolization to the arteries of the pelvic limb resulting in chronic progressive ambulatory dysfunction. Chronic warfarin administration is well-tolerated and appears to be an effective short-term and long-term therapy for dogs with AT.

Effect of oral administration of pimobendan in cats with heart failure

OBJECTIVE To determine the effect of PO administration of pimobendan on clinical and echocardiographic variables and survival time in cats with heart failure characterized by ventricular systolic dysfunction. DESIGN Retrospective cohort study. ANIMALS 27 client-owned cats (16 male and 11 female) with heart failure, treated with pimobendan (mean ± SD dosage, 0.26 ± 0.08 mg/kg [0.118 ± 0.036 mg/lb], PO, q 12 h). PROCEDURES Information on medical history, laboratory results, diagnostic imaging findings, treatments received, and survival time were obtained from medical records of cats that received pimobendan because of cardiac disease. When possible, additional follow-up information was obtained through telephone interviews with referring veterinarians and owners. RESULTS The mean ± SD age of all 27 cats was 8.9 ± 5.2 years. All cats had received several cardiac medications. Types of heart disease represented included unclassified cardiomyopathy (CM; n = 11 [41%]), dilated CM (8 [30%]), arrhythmogenic right ventricular CM (4 [15%]), congenital heart disease (3 [11 %]), and hypertrophic CM with regional hypokinesis (1 [4%]). All cats had ventricular systolic dysfunction. One cat with systolic anterior motion of the mitral valve became severely hypotensive after initial administration of pimobendan and was excluded from the survival analysis. Median survival time was 167 days (95% confidence interval, 32 to 339 days). CONCLUSIONS AND CLINICAL RELEVANCE Pimobendan appeared to be well tolerated in cats with heart failure characterized by ventricular systolic dysfunction of various etiologies. Cats with systolic anterior motion of the mitral valve may develop systemic hypotension when treated with pimobendan. Additional studies are needed to establish dosages for pimobendan and its effects before it can be recommended for treatment of cats with CHF.

Surgical management of an aberrant left subclavian artery originating from a left patent ductus arteriosus in a dog with a right aortic arch and abnormal branching.

An increase in the availability of advanced imaging modalities has led to improved recognition of cardiovascular anomalies. Computed tomography angiography (CTA) provides a non-invasive means of acquiring 3D images with a relatively short acquisition time thereby providing essential information in regards to patient anatomy and procedure planning. The dog in this report had a right aortic arch and abnormal branching with an aberrant left subclavian artery originating from the ampulla of a left patent ductus arteriosus (PDA) that was detected with CTA. The PDA was creating a volume overload to the left side of the heart as well as contributing to the vascular ring and compression of the esophagus. Therefore, ligation and transection instead of a minimally invasive catheter-based procedure was required. This aortic arch anomaly and surgical management have not been previously reported in dogs.

Biologic variability of cardiac troponin I in healthy dogs and dogs with different stages of myxomatous mitral valve disease using standard and high-sensitivity immunoassays

BACKGROUND Biologic variability (BV) is one aspect of interpreting changes in biomarker concentrations known to be clinically important in people with cardiac disease, but it has not been adequately addressed in dogs so far. OBJECTIVES The purpose of the study was to determine BV of cardiac troponin I (cTnI) in healthy dogs and dogs with 3 stages of myxomatous mitral valve disease (MMVD). METHODS Healthy dogs and dogs with 3 stages of MMVD were prospectively assigned to groups based on comprehensive clinical evaluation using current guidelines. Concentrations of cTnI were measured hourly, daily, and weekly using standard and high-sensitivity immunoassays. Within- (CVI ) and between-subject (CVG ) coefficients of variability, percent reference change value (RCV), and index of individuality (IoI) were calculated. RESULTS All 10 healthy dogs and 76/112 (68%) of samples from 28 MMVD dogs had cTnI concentrations below the limit of detection (LOD) using a standard sensitivity immunoassay. Only 49/160 (31%) of healthy dog samples and no MMVD samples had cTnI below the high-sensitivity immunoassay LOD. Data analysis for the high-sensitivity immunoassay revealed CVI of 48.1%, CVG of 60.1%, RCV of 134.0%, and IoI of 0.804 in healthy dogs. In MMVD dogs, CVI was 39.6%, CVG was 80.7%, RCV was 110%, and IoI was 0.494. Of all MMVD dogs, those with Stage B2 had the lowest RCV of 91%. CONCLUSIONS Biologic variability affects cTnI concentrations in healthy dogs and dogs with MMVD. Consideration of BV may be clinically relevant when monitoring individual changes in cTnI values, using high-sensitivity immunoassays.

Echocardiographic and radiographic findings in a cohort of healthy adult green iguanas (Iguana iguana)

OBJECTIVES To describe characteristics of echocardiography and cranial coelomic radiography in a cohort of iguanas. ANIMALS Twenty apparently healthy adult green iguanas (Iguana iguana) from a reptile sanctuary. METHODS Physical examination, radiography, two-dimensional and color Doppler echocardiography were performed to assess cardiac structures and function, and any related normal or abnormal findings were recorded. RESULTS Echocardiographic examination was possible without sedation and allowed visualization of the great vessels, atria, and ventricle. Some structures could not be evaluated in a minority of the iguanas due to individual differences in bony conformation and imaging quality. Suspected abnormal echocardiographic findings in 3 iguanas included pericardial effusion (n = 1) and enlarged caudal vena cava and/or sinus venosus (n = 2). Objective measurements were repeatable as assessed by within-subject coefficient of variation, and reliable as assessed by intra-observer intraclass correlation coefficient. Left atrial and ventricular measurements were significantly correlated with body weight. Valve regurgitation was common, with atrioventricular valve regurgitation present in 53% (9/17) and aortic or pulmonic valve regurgitation in 71% (12/17) of otherwise normal iguanas. A heart murmur was not appreciated during examination of any of the iguanas. Heart size cannot be measured radiographically due to superimposition and silhouetting of other coelomic structures. Echocardiographic or radiographic findings consistent with mineralization of the great vessels were present in 76% of iguanas (13/17). CONCLUSIONS Echocardiography in iguanas is well tolerated without sedation and allowed both subjective evaluation and structural measurements. Valve regurgitation and great vessel mineralization were commonly observed in this cohort of apparently healthy adult iguanas.

Subcutaneous infection of a cat by Colletotrichum species

A 13-year-old, domestic shorthair cat was presented for evaluation of a right tarsal mass. Physical examination revealed a 5 cm×5 cm×5 cm, soft, fluctuant, subcutaneous tarsal mass. Thoracic radiographs revealed several discrete lung parenchymal lesions. Abdominal ultrasound revealed abnormal architecture to both kidneys. Fungal culture and sensitivity from the subcutaneous mass revealed a uniform growth of Colletotrichum species that was susceptible to itraconazole. Colletotrichum species infection was confirmed in the subcutis and suspected to be disseminated. Colletotrichum species fungal infections in cats have not been previously documented.

Multicenter evaluation of signalment and comorbid conditions associated with aortic thrombotic disease in dogs

OBJECTIVE To assess signalment and concurrent disease processes in dogs with aortic thrombotic disease (ATD). DESIGN Retrospective case-control study. ANIMALS Dogs examined at North American veterinary teaching hospitals from 1985 through 2011 with medical records submitted to the Veterinary Medical Database. PROCEDURES Medical records were reviewed to identify dogs with a diagnosis of ATD (case dogs). Five control dogs without a diagnosis of ATD were then identified for every case dog. Data were collected regarding dog age, sex, breed, body weight, and concurrent disease processes. RESULTS ATD was diagnosed in 291 of the 984,973 (0.03%) dogs included in the database. The odds of a dog having ATD did not differ significantly by sex, age, or body weight. Compared with mixed-breed dogs, Shetland Sheepdogs had a significantly higher odds of ATD (OR, 2.59). Protein-losing nephropathy (64/291 [22%]) was the most commonly recorded concurrent disease in dogs with ATD. CONCLUSIONS AND CLINICAL RELEVANCE Dogs with ATD did not differ significantly from dogs without ATD in most signalment variables. Contrary to previous reports, cardiac disease was not a common concurrent diagnosis in dogs with ATD.