Occurrence Angiostrongylus vasorum (Baillet, 1866) (Nematoda, Angiostrongylidae) in Cerdocyon thous Linnaeus, 1766 (Carnivora, Canidae) in Minas Gerais State Brazil

In Brazil, reports of domestic canids naturally infected by A. vasorum have been made by Gonçalves (1961) in Rio Grande do Sul, Langenegger et al. (1962) in Rio de Janeiro, Giovanonni et al. (1985) in Paraná and Lima et al. (1985) in Minas Gerais. In wild Brazilian canids, this nematode has been reported parasitizing the lungs of Dusicyon vetulus (Lund, 1842) in Minas Gerais (Lima et al., 1994) and the right ventricle and pulmonary arteries of Cerdocyon thous Linnaeus, 1766, in Rio de Janeiro (Travassos, 1927).

In Brazil, reports of domestic canids naturally infected by A. vasorum have been made by Gonçalves (1961) in Rio Grande do Sul, Langenegger et al. (1962) in Rio de Janeiro, Giovanonni et al. (1985) in Paraná and Lima et al. (1985) in Minas Gerais. In wild Brazilian canids, this nematode has been reported parasitizing the lungs of Dusicyon vetulus (Lund, 1842) in Minas Gerais (Lima et al., 1994) and the right ventricle and pulmonary arteries of Cerdocyon thous Linnaeus, 1766, in Rio de Janeiro (Travassos, 1927).
The objective of the present study is to report the occurrence of A. vasorum in C. thous in Minas Gerais State and also provides data on the ecology of A. vasorum in these hosts.
Necropsies were performed in six C. thous killed by cars in the municipality of Juiz de Fora, MG.
The specimens were colleted between 2000 and 2004. The hearts and lungs were weighed and, then, dissected on plastic trays containing 0.85% physiologic solution. Then, the nematodes were fixed in AFA (ethyl alcohol 70 o GL, 93 parts; formalin 37%, five parts; glacial acetic acid, two parts) for 48 hours and placed in 70% ethyl alcohol with 5% glycerin. For species identification, the specimens were clarified in Lactophenol and mounted according to Amato et al. (1991). They were identified according to Kinsella (1971), Ubelaker (1986) and Bessa et al. (2000). The ecological analyses were carried out according to Bush et al. (1997) and Zuben (1997).
In the present study, A. vasorum was found in the lungs and right atrium of C. thous, with a prevalence of 50%, mean abundance 4±4.47, mean intensity 8±3.00 and sex ratio (male/female) 1:1.19. The A. vasorum infrapopulations presented an aggregated spatial distribution pattern (ID=5.70 and K=0.355) and the population components were composed of 24 specimens.
The A. vasorum specimens found had a whitened coloration when recently collected. The cuticle was fine and transparent, beneath it the helicoidal shape of the genital organs could be seen wrapped around the digestive tube. The anterior extremity was rounded with a buccal aperture surrounded by three pairs of cephalic pupillae (Fig. 1B). They had a small buccal cavity (Fig.  1B) and the esophagus was claviform (Fig. 1A). The excretory pore was located near to esophagus-intestinal junction (Fig. 1A). The female was larger and more robust than the male and the vulva was near the tail, which was short and had a rounded posterior extremity, with a cuticular expansion in the form of a sheath that protruded (Fig. 1C). The males had a small but distinct copulatory bursa, with two symmetric lateral lobes (Fig. 1E). The ventral rays originated from a common trunk and diverged at the extremities. The ventro-ventral ray was slightly smaller than the ventro-lateral one. The lateral rays also originated from a common trunk; the anterior lateral ray diverged near the base and the medial and posterior lateral rays continued fused until the final third, where they diverged. The lateral dorsal rays originated separately from the medial dorsal, which was shorter and thicker and had two well-defined digits (Fig. 1D). The spicules (Fig. 1E) were long with transversal striations. These descriptions agreed with those of Kinsella (1971), Ubelaker (1986) and Bessa et al. (2000). This is the first report of the presence of A. vasorum in C. thous in Minas Gerais State, the first occurrence of this nematode in either domestic or wild animals in Juiz de Fora county.