Summary A retrospective study of 10 horses with bacterial endocarditis was performed in order to describe the echocardiography findings in horses with bacterial endocarditis, in conjunction with clinical signs and post mortem findings, and to evaluate the usefulness of echocardiography in the diagnosis of bacterial endocarditis and the formulation of a prognosis. Echocardiographic and post mortem examinations were performed in 7 horses. Post mortem examination alone was performed in 2 horses and echocardiographic examination alone performed in one horse. No breed or sex predilection was obvious. Mean age ± s.d. was 2.12 ± 3.32 years. Predominant clinical signs and abnormal clinical pathology data were fever, cardiac murmur, tachycardia, tachypnoea, hyperfibrinogenaemia, anaemia and leucocytosis. Pasteurella/Actinobacillus spp. and Streptococcus spp. were most commonly cultured. Vegetative lesions were found most frequently on the mitral valve and secondarily on the aortic valve. The location and number of lesions identified with echocardiography in the horses accurately described the lesions found on post mortem examination. Medical treatment was attempted in 50% of the horses. Serial echocardiography was used to assess the response to treatment in 2 horses. All horses with vegetative lesions of the mitral and/or aortic valve died or were subjected to euthanasia due to the severity of their cardiac disease. Both horses with tricuspid valve endocarditis were cured of the infection; one horse returned to racing after antimicrobial therapy and the other was subjected to euthanasia due to severe laminitis.

This report describes the history, clinical, electrocardiographic and echocardiographic findings, treatment, outcome and post-mortem findings in seven horses with aorto-cardiac fistula. Affected horses included 5 stallions, one gelding and one mare; 2 each of the Thoroughbred, Arabian and Standardbred breeds and one Thoroughbred-cross with a mean +/- s.d. age of 12 +/- 4 years, range 6-18 years. The presenting signs were acute distress (four horses), exercise intolerance (two horses) and the lesion was detected during a routine examination in one horse. Five horses had monomorphic ventricular tachycardia on admission and one other had a history of this arrhythmia. Five horses had a characteristic continuous murmur loudest in the right fourth intercostal space. Echocardiography (six horses) and/or post-mortem examination (four horses) revealed the horses had aorto-cardiac fistulas arising from the right aortic sinus in all five horses in which the site was recorded. Two horses had ruptured aneurysmal dilatations of the aortic wall at this site. Fistulas extended into the right ventricle in four horses; the right atrium in two horses, the left ventricle in one horse, and five horses had dissecting tracts in the septal myocardium. Horses survived for periods ranging from 24 h to 4 years. Aorto-cardiac fistula should be considered in the differential diagnosis for horses presenting with acute distress, bounding arterial pulse, a right-sided continuous murmur and/or monomorphic ventricular tachycardia, particularly in middle-aged or older stallions. Echocardiography is the technique of choice for confirming the diagnosis and demonstrating accompanying cardiac changes.

A mare with hemorrhage caused by guttural pouch mycosis was treated by insertion of a balloon-tipped catheter into the left internal carotid artery. During recovery from general anesthesia, the mare had profuse epistaxis, and was anesthetized again to determine the site of hemorrhage. The affected guttural pouch was opened to confirm that hemorrhage was from the left internal carotid artery. The mare was euthanatized, and, at necropsy, the balloon catheter was found in an aberrant branch that arose from the internal carotid artery and joined the basilar artery. The mycotic plaque was on the left internal carotid artery, distal to the origin of the aberrant branch, so that the balloon did not obstruct retrograde flow through the infected segment. Additional dissection of the internal carotid artery before insertion of a balloon catheter is recommended to identify any aberrant branches. Ligation of aberrant branches at their bifurcation with the internal carotid artery is recommended to prevent both inadvertent catheterization and retrograde flow from the cerebral arterial circle.