Catheter-guided percutaneous heartworm removal using a nitinol basket in dogs with caval syndrome.

Carval syndrome is a severe heartworm infection where the worms have migrated to the right atrium and vena cava; this condition is associated with a myriad of clinical signs. Several non-surgical and interventional methods are currently used for mechanical worm removal. However, the success rate and complications related to these methods are heavily dependent on methodology and retrieval devices used. In this study, we developed a catheter-guided heartworm removal method using a retrieval basket that can easily access pulmonary arteries and increase the number of worms removed per procedure. With this technique, we successfully treated four dogs with caval syndrome.

Catheter-guided percutaneous heartworm removal using a nitinol basket in dogs with caval syndrome

Carval syndrome is a severe heartworm infection where the worms have migrated to the right atrium and vena cava; this condition is associated with a myriad of clinical signs. Several non-surgical and interventional methods are currently used for mechanical worm removal. However, the success rate and complications related to these methods are heavily dependent on methodology and retrieval devices used. In this study, we developed a catheter-guided heartworm removal method using a retrieval basket that can easily access pulmonary arteries and increase the number of worms removed per procedure. With this technique, we successfully treated four dogs with caval syndrome.

Crassicaudosis: a parasitic disease threatening the health and population recovery of large baleen whales.

This communication briefly reviews knowledge of the systemic disease caused by Crassicauda boopis in blue whales (Balaenoptera musculus), fin whales (B. physalus) and humpback whales (Megaptera novaeangliae). Infections with this giant nematode characteristically incite a chronic inflammatory reaction of the blood vessels which drain the kidneys. In this critical location, the parasite-induced lesion can cause complete vascular occlusion and kidney failure. Whale calves and juveniles typically suffer the heaviest parasite burdens following transplacental infection of the developing whale foetus. There is also probable whale-to-whale transmission post-partum, involving urinary contamination of the environment with C. boopis eggs and larvae. The frequency of the infection can exceed 95%. Haematological findings suggest that systemic pathological effects are typical at the population level. Gradual development of occlusive lesions in the renal veins appears to correlate with a major peak in natural mortality at about one year of age. To date, all findings support the conclusion that premature death caused by C. boopis infection is potentially a major impediment to population recovery of affected whale species. This suggests the interesting possibility of actively encouraging the population recovery of three species of large baleen whales. Such a restoration effort would entail remotely-deployed anthelminthic therapy administered, at sea, to infected whale cows and calves.

Caval syndrome in a Dirofilaria immitis-infected dog treated with dichlorvos.

In the dog of this report, lesions found were compatible with death attributable to acute circulatory collapse induced by caval syndrome and compounded by microfilarial death. Hepatic centrilobular hemorrhage and necrosis were suggestive of circulatory collapse, renal hemosiderosis was suggestive of disseminated intravascular coagulopathy, and multifocal subacute hepatic inflammation associated with microfilariae was similar to lesions attributed to microfilarial death. Treatment with dichlorvos may have precipitated these events. Previous descriptions of dichlorvos toxicity in microfilaremic dogs have suggested that death is attributable to shock, but pathogenic mechanisms have not been established. Although generalizations from a single case must be made with caution, lesions in this dog suggest that toxic effects may be mediated through effects on adult and larval heartworms.

Investigation of caval syndrome in dogs experimentally infected with Dirofilaria immitis.

Nine of 16 dogs inoculated with 200 infective heartworm larvae developed caval syndrome (CS) of heartworm disease (HWD). There was no difference between dogs that did and did not develop CS with regard to total heartworm burden, burden relative to body weight, or female heartworm burden, indicating that factors other than worm mass are involved in the pathogenesis of CS. Male dogs were twice as frequently affected as females, although this finding was not statistically significant. Dogs afflicted with CS exhibited radiographic, pathologic, and hemodynamic evidence of chronic HWD. In a model of single heartworm exposure, these findings strongly support the theory that CS develops due to retrograde migration of adult worms from the pulmonary arteries and right ventricle to the right atrium and venae cavae. Pulmonary artery pressures were dramatically and significantly greater in dogs with CS (60 +/- 18 torr) as compared to non-CS (30 +/- 4 torr) dogs with equal worm burdens.