Which nematode is commonly recognized for its presence in puppies and associated with vomiting?

Toxocara canis is the correct choice as it is a well-known nematode, commonly found in puppies and frequently associated with gastrointestinal issues including vomiting. This parasite is transmitted via fecal-oral contamination; puppies can acquire Toxocara canis through ingesting eggs from contaminated environments or through their mother’s milk if she herself is infected.

Infection with Toxocara canis can lead to a range of clinical signs, and vomiting is a notable symptom due to the parasite's impact on the digestive system and overall gastrointestinal health. Treatment typically involves the administration of anthelmintics to eliminate the infection and help restore the puppy's health.

Other nematodes listed, while associated with various hosts and differing clinical issues, do not share this specific relationship with puppies or are not known for causing vomiting in this specific demographic. Toxocara cati primarily affects cats, Trichuris vulpis is more commonly encountered in adult dogs causing different intestinal problems, and Ascaris suum is a significant parasite in pigs, not in canines. Thus, Toxocara canis stands out as the nematode recognized for impacting puppies and being linked with vomiting.