Images in the media of chubby cats and well-rounded dogs may be skewing pet-owners' ideas of what a healthy animal should look like - and this can cause ongoing problems for their health.
Sam Boston, pet advisor and technical specialist for Bombay Petfoods, manufacturers of the Jimbo's brand, says vets see obesity as a growing problem for pets, just as it is in the human population.
"It's definitely one of the most common diseases vets see today. Unfortunately, many owners don't see it as a disease - they can see their pet's body condition but don't realise it has serious consequences," says Boston. "We have this trend of big, cute, fluffy animals so when we see a pet which is a healthy weight, with a healthy, normal body, people tend to think its owners don't feed it enough."
While those "well-fed" animals might be cute, what owners don't see is the effect extra weight is having on their pet's heart, respiratory system, internal organs and joints.
"Obesity is a contributor to diabetes and heart disease in animals just as it is in humans," Boston says. "It also means a reduced quality of life - often overweight pets aren't able to be as active or to do the kinds of things an animal with a healthy body condition can."
Boston says a "healthy weight" is harder to define for cats and dogs than humans, with a variety of builds and breed types.
"However, you can take your pet to the vet for a body condition check, or just look online and there are some good diagrams and resources.
To do a basic check at home, Boston recommends running your hands down the sides of your pet's body.
"You should be able to feel their ribs under a thin layer of fat, and dogs should have a bit of a 'waist'," she says. "If you think your dog looks a bit circular and its tummy sticks out, it's probably overweight. Dogs should have a nice tuck in their tummy.
"While weighing your pet initially won't give you much of an idea if they are overweight, you can use that starting weight to track weight loss over time."
Just like humans, reducing food intake and increasing exercise are the keys to helping your pet lose weight - but can be easier said than done. Cats in particular can be their own worst enemy when it comes to weight loss.
"Any cat owner knows it's almost impossible to force a cat to exercise. You can play games with them and encourage them to move around but diet is a more significant factor," Boston says.
The other issue with outdoor cats is they tend to scavenge, finding food elsewhere if they think they're not getting enough at home.
"The key is to feed them food with a lower calorie count so they feel full, rather than feeding them less," Boston says. "Raw food is a good way to do that, so they are getting lots of protein and moisture but less carbohydrate and fat, so fewer calories.
"Cats and dogs aren't designed to digest carbohydrates anyway and it's a big contributor to weight gain."
The other big no-no is giving your pets human food, even if it's just the odd scrap: "It's very easy to feed little bits and pieces to cats and dogs but small animals put on weight so quickly. Even if you're just giving them the corner of your toast it can make them pile on the weight. People think 'oh, it's just a little bit' but it really adds up."