That's where I looked...

"When neonatal pups die due to hookworm infection, subsequent litters from the bitch should be treated weekly for*A caninum*for ~12 wk beginning at 2 wk of age. In addition, fenbendazole (25 mg/kg, PO) given daily to pregnant bitches from day 40 of pregnancy to day 2 after whelping greatly reduces transmammary transmission to the pups (approved in the UK). Likewise, treatment of the bitch with ivermectin (0.5 mg/kg) on two occasions (4–9 days before whelping and 10 days later), or with moxidectin/imidacloprid spot-on on day 56 of pregnancy, has the same effect (extra-label use)"

Link: http://www.merckmanuals.com/vet/dige...0animal&alt=sh

Link: http://www.merckmanuals.com/vet/dige....html#v4720080