Yes, he was supposed to resemble a cat. Even the movie makers confirmed: "Then we had to make 'the dragon'. So, we thought more in something feline, instead of a reptile."

yes most of his caracteristices are bast on cats. and did you know that his "voice" was made by different types of animal noices such as lepord, house cat, dog, pig, and elephant.

He's always reminded me of a cat by the way he acts. I also agree with BaltoTrain though because it seems that the concept of "a boy and his dog" fits perfectly.

yeah the scene were toothless jumps into the areana to sace hiccup the way he jumps is sorta like hes pounceing

I always thought Toothless looked like a cat myself. It may just be a coincidence.

With his personality he's more likely supposed to resemble a dog. The whole "boy and his dog" feeling is probably the dead giveaway!

im not taking any credit im just gonna translate what sora said just incase you dont speak french heres what sora said: I would say rather Stitch ^ ^ but I saw in an extra film, designers have used Crocmou of a panther on the body and the eyes, the eyes of cats

je dirai plutôt à Stitch ^^ mais j'ai vu dans les bonus du film, les dessinateurs de Crocmou se sont servis d'une panthère pour le corps et pour les yeux, des yeux de chats

most likely not he could just be based on a cats movement