moxidectin and Zoonoses

The history of an 18-month-old English bulldog with a painful lump in the skin on its thigh is described. After opening the nodule a few Dirofilaria repens nematodes were found. Oval-shaped transparent eggs with moving larvae were seen microscopically. The dog was treated with milbemycin and made a complete recovery. The dog had never been abroad, but 6 months earlier in early May had been on a campsite in the middle of the Netherlands where many mosquitoes were present. This is the first described case of an autochthonous D. repens infection of a dog in the Netherlands.

Topics: Animals; Antinematodal Agents; Culicidae; Dirofilaria; Dirofilariasis; Dog Diseases; Dogs; Female; Insect Vectors; Life Cycle Stages; Macrolides; Netherlands; Treatment Outcome; Zoonoses

The outcome of Toxocara canis infections in the canine host depends on the migratory pathway of parasite larvae (somatic or tracheal) which is considered to be related to the host's age and its immune status. However, field studies attest high prevalences of patent T. canis infections in adult animals. The controlled induction of patent infections with low doses of embryonated eggs was investigated in 18 beagles in a 7-month study until their 16th life month. The animals were assigned to three groups, each consisting of three vertically infected dogs (with a short patent infection as pups before anthelmintic treatment) and three helminth-free dogs. At study days 10 and 40, the animals of groups 1 and 3 were given each 100 embryonated T. canis eggs. In each case, group 1 was treated 10 days post-infection with Milbemax, while dogs of group 3 remained untreated. Control group 2 was not experimentally infected but treated as group 1. Two weeks after first egg administration, a sharp increase of specific antibody reactions in ELISA and increased eosinophilic counts indicated larval invasion in all infected dogs. 42-56 days following first infection, patent infections were detected coproscopically in all animals of group 3, but in none of the uninfected dogs (group 2) or the infected and treated dogs (group 1). Following a 3-month observation period, all animals of the three groups were treated with piperazine citrate to eliminate intestinal infections and all were administered 100 embryonated eggs. Subsequently, patent infections developed in animals of all groups: in one of the infected and treated animals of group 1, in five of the so far not infected control group 2 and in four of the dogs with previous patent infections (group 3). Susceptibility to patent infections was not significantly altered in T. canis-free dogs compared to dogs with previous patent infection (vertically acquired or experimentally induced). However, dogs of group 1 treated with Milbemax after repeated egg administration developed a significantly increased resistance to patent infections as compared to control dogs (group 2). Observed prepatency periods were between 40 and 56 days and did not differ in the three groups. Even in urban areas, facing high infection pressure with Toxocara eggs maintained by a high dog and fox population, dogs of all ages are at risk to develop patent T. canis infections.

Topics: Age Factors; Animals; Anthelmintics; Antibodies, Helminth; Disease Susceptibility; Dog Diseases; Dogs; Eosinophils; Feces; Female; Macrolides; Male; Parasite Egg Count; Random Allocation; Switzerland; Toxocara canis; Toxocariasis; Zoonoses