Eggs of all other strongyles and trichostrongyles are similar and usually cannot be differentiated to specific genera. The presence of this type egg in dog or cat feces is usually indicative of a hookworm infection. This egg is from a horse parasite in the small intestine and only parasitic females are known to exist. This is a dog parasite which is sometimes called S. stercoralis . It is passed in feces as a larval stage.
Positive diagnosis is made from larval cultures of feces from suspect animals.
The presence of a third stage larva with a long esophagus is indicative of infection. Both nematodes are parasites of dogs and both may produce respiratiory complications that may be lethal to neonatal pups. Both also transmit larvae in mother's milk. There is some public health concern that these parasites might be transmissible to humans, however, direct evidence of regular or normal transmission is difficult to find. A relationship between human and dog infection is based on the similarities between adult females and infective larvae.