Open heart surgery applications in dogs suffering from natural infection of Dirofilaria immitis

Abstract

This study includes 6 dogs naturally infected with Dirofflaria immitis of different ages and sexes. Clinical, radiographical, blood gas and blood biochemical evaluations were examined in the preoperative period. Microfilariae were determined in 6 cases with a modified Knott test. Cardiopulmonary bypass (CPB) and open-heart surgery were carried out. Animals were prepared for cannulation under general anesthesia. The heart was approached by right lateral thoracotomy. The femoral artery and vena cavas were cannulated before CPB. During the operation, arterial blood pressure and the heart rate were monitored and blood gas values were continuously observed. Before and 1 hour after the operation cardiac output was monitored. Mean operation time was 155 +/- 35 minutes, and cross-clamp time was 34 +/- 9 minutes. A total of 12 +/- 5 mature Dirofilaria immitis were collected from the right heart and the pulmonary artery. Radiographical evaluation showed that the heart was hypertrophic in all cases and right heart dilatation was seen in one case. In blood gas analysis, an increase in pCO(2) and decreases in pO(2), HCO3 and pH were observed. One dog was extubated for 1 hour, while the remaining 5 dogs were extubated for 3 hours after the operation. One dog was followed for 1.5 years whereas the others were followed for 6 months after surgery. No complications occurred during the operation, but premature ventricular contractions were observed in all cases. Arterial blood pressure and cardiac output decreased significantly when compared to preoperative values 1 hour after the operation. The heart rate increased significantly. In two cases, a postoperative superficial infection was identified. Two dogs were still infected with microfilariae two weeks after the operation. Ivermectin was administered and the microfilariae were destroyed two months after this medication. All dogs tolerated the CPB and open-heart surgery procedures well.