Perioperative changes in cardiac biomarkers in juvenile cats during neutering.

Perioperative myocardial injury (PMI) is commonly caused by myocardial ischemia that develops during or after non-cardiac surgery. It occurs in 17.9% of human patients after non-cardiac surgery due to elevated high-sensitive perioperation cardiac troponin. However, PMI has not been demonstrated in cats. To investigate its occurrence, this study aimed to analyze the perioperative changes in cardiac biomarkers and clinical data, including measurement of vital signs, echocardiography, blood pressure, electrocardiogram, X-ray, and anesthetic profile, in 30 juvenile cats under neutering surgery. All cats had increased high-sensitive cardiac troponin I (hs-cTnI) postsurgery compared with presurgery. In particular, 48% of cats (14/29) showed elevated hs-cTnI over a reference range after surgery. In all groups, hs-cTnI and systolic arterial blood pressure (SAP) were significantly higher at 0 h and 18 h postoperation than at preoperation. A significant positive correlation was found between hs-cTnI and SAP at 18 h postoperation. Atrial natriuretic peptides, heart rate, and left ventricular wall thickness were markedly higher at 0 h postoperation than at preoperation; however, respiratory rate and body temperature were significantly lower at 0 h postoperation than at preoperation. Anesthetic time and hs-cTnI were significantly higher at 18 h postoperation in females than in males. Significant positive correlations were observed between hs-cTnI and anesthetic time at 18 h postoperation in females. These results indicate that postoperative hs-cTnI level can greatly increase in juvenile cats and hs-cTnI measurement at perioperation is potentially beneficial for early detection and evaluation of the presence of PMI.

A swine model of acute thrombocytopenia with prolonged bleeding time produced by busulfan.

Animal models of thrombocytopenia are indispensable for evaluating the in vivo efficacy of hemostatic agents, cryopreserved platelets, and artificial platelets, but no large animal models are available. In this study, we generated a swine model of acute thrombocytopenia with prolonged bleeding times by administering the chemotherapeutic drug busulfan. First, we tested multiple doses of busulfan (4, 6, and 8 mg/kg) in pigs, and found that 6 mg/kg of busulfan is an optimal dose for producing a safe and moderate thrombocytopenia, with a platelet count of less than 30,000/µl. The pigs administered 6 mg/kg of busulfan (n=8) reached half their initial counts at day 7, counts below 30,000/µl at day 12, and their nadirs at day 15 (on average). The minimal platelet count was 14,000/µl. With this dose of busulfan (6 mg/kg), bleeding times were significantly prolonged in addition to the decrease in platelet counts (r=-0.63, P<0.01), while there were no cases of apparent hemorrhage. White blood cell counts were maintained at over 5,000/µl, and there were no infections or other adverse events including anemia or appetite or body weight loss. All pigs were sacrificed on day 16, with subsequent examination showing a significant reduction in cellularity and colony-forming units in the bone marrow, indicating that thrombocytopenia was the result of myelosuppression. In summary, administration with 6 mg/kg of busulfan induces safe and moderate thrombocytopenia with a prolonged bleeding time in swine.

Phenotypic and functional properties of feline dedifferentiated fat cells and adipose-derived stem cells.

It has been reported that mature adipocyte-derived dedifferentiated fat (DFAT) cells show multilineage differentiation potential similar to that observed in mesenchymal stem cells. Since DFAT cells can be prepared from a small quantity of adipose tissue, they could facilitate cell-based therapies in small companion animals such as cats. The present study examined whether multipotent DFAT cells can be generated from feline adipose tissue, and the properties of DFAT cells were compared with those of adipose-derived stem cells (ASCs). DFAT cells and ASCs were prepared from the floating mature adipocyte fraction and the stromal vascular fraction, respectively, of collagenase-digested feline omental adipose tissue. Both cell types were evaluated for growth kinetics, colony-forming unit fibroblast (CFU-F) frequency, immunophenotypic properties, and multilineage differentiation potential. DFAT cells and ASCs could be generated from approximately 1g of adipose tissue and were grown and subcultured on laminin-coated dishes. The frequency of CFU-Fs in DFAT cells (35.8%) was significantly higher than that in ASCs (20.8%) at passage 1 (P1). DFAT cells and ASCs displayed similar immunophenotypes (CD44(+), CD90(+), CD105(+), CD14(-), CD34(-) and CD45(-)). Alpha-smooth muscle actin-positive cells were readily detected in ASCs (15.2±7.2%) but were rare in DFAT cells (2.2±3.2%) at P1. Both cell types exhibited adipogenic, osteogenic, chondrogenic, and smooth muscle cell differentiation potential in vitro. In conclusion, feline DFAT cells exhibited similar properties to ASCs but displayed higher CFU-F frequency and greater homogeneity. DFAT cells, like ASCs, may be an attractive source for cell-based therapies in cats.

Mitral valve repair under cardiopulmonary bypass in small-breed dogs: 48 cases (2006-2009).

OBJECTIVE: To determine whether mitral valve repair (MVR) under cardiopulmonary bypass would be an effective treatment for mitral regurgitation in small-breed dogs. DESIGN: Retrospective case series. ANIMALS: 48 small-breed dogs (body weight, 1.88 to 4.65 kg [4.11 to 10.25 lb]; age, 5 to 15 years) with mitral regurgitation that underwent surgery between August 2006 and August 2009. PROCEDURES: Cardiopulmonary bypass was performed with a cardiopulmonary bypass circuit. After induction of cardiac arrest, a mitral annuloplasty was performed, and the chordae tendineae were replaced with expanded polytetrafluoroethylene chordal prostheses. After closure of the left atrium and declamping to restart the heart, the thorax was closed. RESULTS: Preoperatively, cardiac murmur was grade 3 of 6 to 6 of 6, thoracic radiography showed cardiac enlargement (median vertebral heart size, 12.0 vertebrae; range, 9.5 to 14.5 vertebrae), and echocardiography showed severe mitral regurgitation and left atrial enlargement (median left atrium-to-aortic root ratio, 2.6; range, 1.7 to 4.0). 45 of 48 dogs survived to discharge. Three months after surgery, cardiac murmur grade was reduced to 0/6 to 3/6, and the heart shadow was reduced (median vertebral heart size, 11.1 vertebrae, range, 9.2 to 13.0 vertebrae) on thoracic radiographs. Echocardiography confirmed a marked reduction in mitral regurgitation and left atrium-to-aortic root ratio (median, 1.7; range, 1.0 to 3.0). CONCLUSIONS AND CLINICAL RELEVANCE: We successfully performed MVR under cardiopulmonary bypass in small-breed dogs, suggesting this may be an effective surgical treatment for dogs with mitral regurgitation. Mitral valve repair with cardiopulmonary bypass can be beneficial for the treatment of mitral regurgitation in small-breed dogs.

Estimating glomerular filtration rate in healthy dogs using inulin without urine collection.

The goals of this study were to determine if the glomerular filtration rate (GFR) in dogs could be estimated by plasma inulin clearance and/or infusion inulin clearance analyses without urine collection, and to compare these results with GFR values obtained by urinary inulin clearance analysis. The dogs included in this study were healthy 20 beagles. Inulin clearance values were obtained by urinary inulin clearance, infusion inulin clearance, and plasma inulin clearance techniques. Urinary inulin clearance was 4.09±0.52 ml min(-1) kg(-1) (body weight); infusion inulin clearance, 4.01±0.49 ml min(-1) kg(-1); and plasma inulin clearance, 4.14±0.66 ml min(-1) kg(-1). The urinary inulin clearance was strongly correlated with infusion inulin clearance and weakly correlated with plasma inulin clearance. The GFR for dogs can be estimated by infusion and plasma inulin clearance analyses by blood sampling alone, without urine collection.