Prenatal and lactational transmission of Toxocara canis and Ancylostoma caninum: experimental infection of the bitch before pregnancy

Breeding of five parasite-free and five experimentally infected (6000 Toxocara canis eggs orally and 2500 Ancylostoma caninum larvae subcutaneously) beagle bitches was done so that pairs of bitches (1 uninfected, 1 infected) whelped simultaneously. Pups born to an infected bitch were removed at birth and nursed by the paired uninfected bitch until 4 weeks of age when pups were necropsied to determine the number of parasites they had acquired prenatally from their infected mother. Pups born to the parasite-free bitch were nursed by the infected bitch until necropsied at 4 weeks of age to determine the number of parasites passed via the lactational route. Of 680 ascarids transmitted to pups by either route, 98.5% were transmitted prenatally and 1.5% lactationally. Transmission of 2746 hookworms to 22 pups occurred solely by the lactational route; prenatal transmission of this parasite did not occur in any of the 25 pups born to infected bitches.