Infecção patente em cães adultos com larvas de Toxocara canis (Werner, 1782) recuperadas de camundongos experimentalmente infectados

Abstract

The objective of the present study was to establish trial infections in adult dogs by administering T. canis larvae recovered from tissues of experimentally infected mice and to evaluate patent infection by determining the pre-patent period (PPP) and the number of recovered nematodes in relation to the different infective larvae doses. T. canis females were collected from naturally infected dogs. These were dissected and the eggs were obtained from their uteri followed by posterior incubation at 27±1° C under 75 ±10% RH. After 60 days, mice were orally infected by the embryonated eggs gathered from the culture. The mice were killed 26 days post-infection (dpi) and then submitted to necropsy. Its organs and carcasses were processed by the Acid-Isolation Technique for the recovery of larvae, which were quantified and subdivided in aliquots for the dogs infection. Twelve adult male Beagle dogs from the Kennel of the Laboratory of Experimental Chemotherapy in Veterinary Parasitology, Department of Animal Parasitology, Veterinary Institute, Universidade Federal Rural do Rio de Janeiro were used in our study. They were considered free from parasitism, however with previous history of exposition. The animals were divided in two groups of six animals each. The dogs from Group I were infected with 60 larvae, and the ones from Group II with 300 larvae, which were recovered from the brains and carcasses of the paratenic hosts. To evaluate the PPP we used the coproparasitological techniques of Centrifugal flotation, Sedimentation and Sedimentation centrifugal flotation on days +8, + 12 and, consecutively between days +16 e + 56. For the recovery of nematodes from feces, the dogs were treated on days +57, +58 e +59 with piperazine. The animals from Group I reached the PPP on 48±5.37 dpi, and Group II on 41.5±5.09 dpi, presenting statistically significant difference between the periods (p<0.05). Ten nematodes were collected from Group I, with the mean intensity of 1.66±1.63, resulting in 2.78±2.73% of recovery. The 85 nematodes collected from Group II, presented mean intensity of 14.17±28.12, resulting in 4.72±9.39% of recovery from the total of administered larvae. Non-statistical difference was noted regarding the total recovered nematodes. It is possible to establish patent T. canis infection in adult dogs by administering larvae recovered from tissues of experimentally infected mice.