Aorto-left atrial fistula secondary to infective aortic endocarditis and endarteritis in a cat with valvular aortic stenosis.

A cat previously diagnosed with valvular aortic stenosis developed acute respiratory distress. A new continuous heart murmur was noted on physical exam. Echocardiographic examination revealed vegetative lesions on the aortic valve and continuously shunting blood flow from the aorta into the left atrium. Despite initial treatment for left-sided congestive heart failure, the cat died suddenly. In addition to confirming aortic valve endocarditis and an acquired aorto-left atrial shunt, pathological examination identified vegetative lesions on the luminal surface of the ascending aorta. Although antemortem aerobic blood culture, 16s bacterial ribosomal DNA PCR, and Bartonella PCR failed to identify causative organisms, Escherichia coli was identified on postmortem tissue culture of the aortic lesion. This represented a unique case of primary valvular aortic stenosis with secondary infective aortic endocarditis, infective aortic endarteritis, and aorto-left atrial fistula in a cat. It highlighted potential adverse outcomes of aortic stenosis that are more commonly recognized in humans and dogs.

Persistence of pulmonary endarteritis in canine heartworm infection 10 months after the eradication of adult parasites of Dirofilaria immitis.

Pulmonary endarteritis caused by Dirofilaria immitis and pulmonary hypertension (PH) are closely linked and the determination of PH could be validated to assess the severity and chronicity of the vascular damage, i.e. by the use of the Right Pulmonary Artery Distensibility (RPAD) Index. The aim was to evaluate the RPAD Index in dogs 10 months after the last dose of adulticide. The study included 23 client-owned dogs with heartworm brought for adulticide treatment. Echocardiographic exam was carried out to estimate worm burden, RPAD Index as well as other routine echocardiographic values on day 0 (diagnosis), day 120 (discharge), and 10 months after the last dose of adulticide. No significant differences were observed in the RPAD Index over time, neither when microfilaremic status and parasite burden were evaluated. An RPAD Index <29% was found in 52.2% of the dogs on day 0, day 120, and 10 months after the last dose of adulticide. Regarding other echocardiographic parameters, only significant differences were observed on tricuspid annular plane systolic excursion (TAPSE) values between day 0:day 120 (p = 0.008), and day 0:end of the study (p = 0.037). There was not significant improvement in pulmonary damage 10 months after the elimination of the parasites (p = 0.296), suggesting that, once the endarteritis has developed, the vascular changes are chronic and may not be reversible. The modifications of the TAPSE value suggest an improvement in the systolic function of the right ventricle after the disappearance of the worms, independently of the presence of PH. The endarteritis causes a decrease in the elasticity in the pulmonary vasculature and an increase in the resistance that, chronically, and depending on the severity, will cause the development of PH and later right heart failure. This complication of the disease is one of the most damaging and frequent, so it is necessary to adequately monitor PH in dogs undergoing adulticide treatment. Furthermore, knowing the pulmonary status could provide valuable information to help provide an objective prognosis and help assess the need to add additional treatments, once the worms have been eliminated.

Evaluation of pulmonary hypertension and clinical status in dogs with heartworm by Right Pulmonary Artery Distensibility Index and other echocardiographic parameters.

BACKGROUND: Pulmonary hypertension (PH) is a frequent and severe phenomenon in heartworm disease caused by Dirofilaria immitis, mainly caused by intimal proliferation of the arteries and pulmonary thromboembolisms. Transthoracic echocardiography is the method of choice for diagnosing PH in dogs although the diagnosis is often based on indirect and subjective parameters. The Right Pulmonary Artery Distensibility Index (RPAD Index) is a method that has been recently validated to estimate the presence and severity of PH in heartworm-infected dogs. This study compared some echocardiographic parameters commonly used to estimate PH in 93 dogs infected by D. immitis and evaluated the impact of the parasite burden, microfilaremia, sex or origin of the dog (client-owned/shelter). RESULTS: None of the studied echocardiographic variables seemed useful in the estimation of the evaluated clinical aspects, except for the PA/Ao ratio for parasite burden. The RPAD Index was determined in 88 of the dogs; of these, 70.4% had PH (mild: 37.5%, moderate: 19.3%, severe: 13.6%). This Index showed non-significant differences according to microfilaremia, sex, origin or parasite burden. Symptomatic dogs showed PH more often and displayed more severe PH, in addition the presence of symptoms was greater among dogs with high burden; on the other hand 64.4% of asymptomatic dogs had some degree of PH according to the RPAD Index. Apart from the PA/Ao ratio, the other evaluated echocardiographic variables were not useful in evaluating of the hypertensive status of the heartworm-infected dog compared to the RPAD Index. CONCLUSIONS: The estimation of most common indirect parameters is not useful in predicting PH in heartworm-infected dogs. The results confirm the RPAD Index as an objective and supportive test in the monitoring and evaluation of PH in the heartworm-infected dog, and show a potential diagnostic value for the detection of PH in asymptomatic animals.

Pulmonary hypertension in dogs with heartworm before and after the adulticide protocol recommended by the American Heartworm Society.

Pulmonary hypertension (pH) is a frequent and severe phenomenon in heartworm disease (Dirofilaria immitis). There is a lack of studies assessing the evolution of the proliferative endarteritis and pH caused by D. immitis after the death of the parasites, so this study evaluated the influence that the elimination of the worms exerts over the pulmonary pressure and therefore evolution of the endarteritis, through the evaluation of the Right Pulmonary Artery Distensibility (RPAD) Index and other echocardiographic measurements in 2D mode, M-mode and Doppler echocardiography in 34 dogs naturally infected by D. immitis on day 0, and one month after the last adulticide dose (day 120). pH, based on the determination of the RPAD Index, was present in 68% of the dogs (n=23) on day 0 and on day 120. No significant differences were observed between the RPAD Index between the two measurements, and only significant differences were found in pulmonary deceleration time, ejection time, and left ventricular internal diameter in telediastole when measurements from day 0 and day 120 were compared. There was not any worsening in the development of pH after the elimination of the parasites, independently of the parasite burden. During the adulticide treatment, the death of the worms causes thromboembolism and tends to worsen the vascular damage and presence of pH . It seems that following the adulticide protocol recommended by the American Heartworm Society with the previous elimination of Wolbachia and reduction of microfilariae followed by the stepped death of the worms did not cause a significant aggravation of the pulmonary damage of the treated dogs. Neither is present any significant improvement in the RPAD Index on day 120; probably, more time is needed before appreciating some positive changes after the elimination of the worms and Wolbachia from the vasculature and further studies are necessary.

Septic pericarditis, aortic endarteritis, and osteomyelitis in a dog.

A 7-year-old, female spayed rottweiler was referred with a history of an acute onset of collapse attributable to cardiac tamponade. Thoracic radiographs revealed an enlarged cardiac silhouette compatible with pericardial effusion, sternal osteomyelitis, and an unusual mineralized lesion determined later to be within the aortic wall. The pericardial effusion was a septic exudate secondary to infection with Staphylococcus species and hemorrhage into the pericardium through a mineralized aortic lesion. The case demonstrates the importance of complete evaluation of thoracic radiographs in a patient with cardiac disease and the potential value of cytopathological evaluation of pericardial fluid.

Endothelial MHC class II antigen expression and endarteritis associated with Marek's disease virus infection in chickens.

Experimental Marek's disease virus (MDV) infection in chickens was used to study the early pathogenesis of virus-induced atherosclerosis. Previous investigations using this model have reported the occurrence of atherosclerotic lesions after approximately 7 months postinfection. In this study, a total of 75 susceptible Cornell P-line chickens were inoculated intraperitoneally with the CU-2 strain of MDV at 3 days of age and subsequently perfused for histologic examination. At 2, 4, 8, 13, and 20 weeks postinoculation, the ascending aorta and the brachiocephalic and coronary arteries were evaluated for early changes. Expression of class II major histocompatibility complex (Ia) antigen by the vascular endothelium was demonstrated by indirect immunodetection as early as 2 weeks after virus inoculation. This change was followed by significant thickening of the intimal layer associated with mononuclear cell infiltration. All the arteries examined from the MDV-infected chickens were affected. Preliminary immunohistochemical staining showed the presence of CD3+ CD4+, and CD8+ cells among the infiltrating cells. The results suggest that an immunopathologic mechanism may be involved in the early pathogenesis of MDV-induced atherosclerosis in chickens.

Occlusion of the digital arteries -- A model for pathogenesis of navicular disease.

The digital arteries of 10 horses suffering from navicular disease, and 7 horses from a control group, were examined angiographically. The horses from the disease group showed complete or partial occlusion of the digital arteries in all cases. In the control group of 7 healthy horses, isolated vessel obstructions were also found but these were limited to narrowing of part of an artery only. Histological investigations showed that total occlusion of a vessel involved an organised thrombus but that partial occlusion generally involved changes to the vascular wall, similar to those caused by endarteritis obliterans. The vessel changes are discussed, with particular reference to their possible significance as a cause of navicular disease.

An epizootic among knots (Calidris canutus) in Florida. I. Disease syndrome, histology and transmission studies.

About 150 knots found sick or dead had distention of serosal blood vessels, and small, raised hemorrhagic foci on the serosal surface of the jejunum and ileum. The principal finding was endaortitis with large intimal multinucleated cysts that contained a protozoan parasite within a cytoplasmic vacuole. There was endarteritis of mesenteric arteries and muscular arteries of the external layers of the intestinal tract. Single or multiple schizont-like stages containing zoites were in the wall of the small intestine and close to affected muscular arteries. The more usual intestinal lesion was an aneurysm of the inflamed muscular artery. It was concluded that endarteritis led to colonic infarction. Schizonts in medullary renal tubular cells were smaller than stages in the intestine. There was necrosis of epithelial cells of themedullary collecting ducts and inflammatory and regenerative changes. Schizonts and zoites were free in collecting ducts and ureters.