Re-migration of fifth-stage juvenile Dirofilaria immitis into pulmonary arteries after subcutaneous transplantation in dogs, cats, and rabbits

An assessment was made of the capacity for re-migration of the 5th-stage juvenile canine heartworm, Dirofilaria immitis. Live, 5th-stage juvenile worms recovered from the pulmonary arteries of infected dogs were transplanted into the subcutaneous tissue of uninfected dogs, cats, and rabbits. A mean of 45%, 61%, and 18% of the transplanted worms were recovered from the pulmonary arteries of dogs, cats, and rabbits, respectively, 1 and 3 mo later. The 5th-stage juvenile worms thus have the ability to re-migrate through tissue into the pulmonary arteries of the host.