Look at the whole outline
Small stature, long limbs, a fine head, deep chest and short coat together make a familiar outline. One feature alone does not identify a breed. Mixed-breed dogs and other sighthounds can look similar from a distance.
Ask the person, not the internet
If you want to meet the dog, ask the owner whether you may approach and what breed it is. Do not pet without an invitation or argue from a picture on your phone. An encounter with one real Italian Greyhound teaches more than a hurried guess.
Clothing needs different questions
Even with the breed identified, a garment size cannot be guessed from the silhouette. Measure the dog and check the particular cut. Two Italian Greyhounds of the same height can differ in chest and back length.
A better question than “are you sure?”
On a walk, asking the owner about breed and age is easier than arguing from a photograph. A young larger sighthound and an adult Italian Greyhound can appear similar in size. An overhead angle changes proportions further, while a wide-angle lens enlarges the nose.
If you are buying a puppy, move from visual resemblance to information you can check: the puppy’s documents, details about the parents, the agreement and opportunities to question the breeder. Appearance cannot replace those checks. A claim that a dog is purebred but has no papers does not establish ancestry from a photograph.
With a found dog, the priority is different: find the owner and have identification checked by an appropriate professional. Helping the animal need not wait for a final breed debate. Clothing should still be selected using measurements, even when the breed is known with certainty.
Useful? Save it for your next walk.