A possible port of entry into the eye of dog during erratic canine heartworm (Dirofilaria immitis) parasitism.

A dog was suspected of suffering from ectopic Dirofilaria immitis infection, because a large white nematode worm was detected in the anterior chamber of the left eye. A cylinder-shaped fibrin sac in the anterior chamber was found in the eye of the dog by slit lamp microscopy. After successful surgical removal of the worm, the corneal wound produced by the keratotomy healed in a short period. The worm was estimated to be extremely young, 5th-stage-immature male D. immitis, equivalent to a 90-120-day-old worm postinfection, by close morphological measurement and an experimental infection study. Thus, an immature worm can exhibit erratic parasitism in a host's eye. The fibrin sac was considered to be a trace of the invasion route, and the cornea may have been the port of entry into the anterior chamber of the eye in the erratic migration of D. immitis.