Technical Abstract: Neosporosis was diagnosed ante-mortem in a litter of neonatally-infected dogs. Three pups developed weakness of limbs 7-9 weeks after birth. One of the dogs developed megaesophagus. Treatment with clindamycin improved clinical signs but did not eradicate the parasite. All 3 dogs were euthanized and viable N. caninum was isolated from the brains of all 3 dogs. Tissue cysts were found in the brain and muscles of dogs. The dam was bred again. Seven apparently healthy pups were born in the second litter. Six of the 7 pups from the second litter had no demonstrable N. caninum antibodies at 32 day of age. The seventh pup had high (1:1,280) titer in the Neospora agglutination test and the titer remained stable at day 227 when the study was discontinued. The results suggest that the rate of congenital transmission of N. caninum decreased in the subsequent pregnancy.