Small pets like Chihuahuas need to be walked on a dog collar and lead just as any other dog, the Blue Cross has said.
The charity has said that small dogs need huge amounts of care to keep them happy and healthy and said no one should get a dog because of a trend.
Its announcement follows the programme Super Tiny Animals that was on ITV recently.
Julie Bedford, head of behaviour at The Blue Cross said: "We hope that anyone watching the programme will realise you should never get an animal to follow a trend, or for the way it looks.
"Dogs such as Chihuahuas and Pomeranians are great pets but they need to be given the stimulation and exercise they need to keep them happy and healthy."
She added that small dogs have big personalities and people should get them for this reason, not because they are a fashion accessory.
Before getting a dog, the Blue Cross advises people to think if they have the time to walk and play the animal, as well as training and socialising it.
It is also advisable to work out if you can afford a dog, as there are a number of costs that need to be considered such as insurance and dog food.