Obesity in Pets: How to Tell and How to Help

At a glance

What it is	Carrying enough excess body fat to affect health and wellbeing
Who's at risk	Any dog or cat, especially neutered, older, less active or indoor pets, and those given lots of treats
Main signs	Ribs hard to feel, no visible waist, a rounded or sagging tummy, slowing down and tiring easily
Contagious?	No
Can it be prevented?	Yes, in most cases, through measured feeding, regular weigh-ins and daily activity

What it is

Obesity means a pet is carrying so much body fat that it starts to affect their health. Being a little overweight is the step before this, and both are very common in dogs and cats.

It is easy to see why. Our pets rely completely on us for food, and many of us show love through treats and extra titbits. Modern pet foods are tasty and energy-dense, and many pets live calmer, less active lives than their ancestors. Over months and years, even a small daily surplus of food adds up.

Because weight tends to creep on slowly, it is easy to miss. Many owners are surprised to learn their pet is overweight, especially as we get used to how our own animals look. Please do not feel guilty if this is the case. Recognising it is the first and most helpful step.

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Too thin: ribs, spine and hip bones easy to see Ideal: ribs easy to feel, visible waist Overweight: ribs hard to feel, no waist

Very thin

Ideal

Overweight

Signs to watch for

Scales are useful, but the best way to judge your pet's weight is by looking and feeling. Vets use a system called body condition scoring, which looks at fat cover rather than weight alone. Our guide to healthy weight and body condition explains it step by step, but here are the basics.

Ribs

Run your hands gently along your pet's sides. At a healthy weight, you should be able to feel the ribs easily under a thin layer of fat, a bit like feeling the knuckles on the back of your hand. If you have to press firmly to find them, or cannot feel them at all, your pet is likely carrying extra weight.

Waist

Look down at your pet from above while they are standing. You should see a gentle inward curve behind the ribs, like an hourglass. If their sides are straight or bulge outwards, they may be overweight.

Tummy

Look from the side. In most dogs, the belly should tuck up from the chest towards the back legs. In cats, a small flap of skin on the lower tummy can be normal, but a large, swinging or fat-filled belly is a sign of extra weight.

Other clues

• Fat pads over the hips, the base of the tail or the neck
• Getting out of breath or tired more quickly
• Reluctance to walk, play, jump or use the stairs
• Struggling to groom properly, which is common in overweight cats and may show as a scruffy or matted lower back
• Collars or harnesses that need loosening

Some medical conditions can cause weight gain or a swollen tummy, so a sudden change in shape, especially alongside other signs, should always be checked by a vet.

When to see a vet

Book a check-up with your vet if you think your pet is overweight. They can confirm their body condition, suggest a realistic target weight and check for any medical conditions that might be contributing. Certain hormonal conditions, for example, can cause weight gain and need treating in their own right.

It is especially important to involve your vet before starting a weight-loss plan for a cat, or for any pet who is very overweight, older, or already has health problems.

Contact your vet promptly if your pet:

• Gains weight quickly without an obvious reason
• Has a swollen or tight tummy
• Is drinking or peeing much more than usual
• Becomes much less active, breathless or lethargic
• Is a cat who has stopped eating, even for a day or two

If you are unsure what a change in your pet means, our symptom checker can help you decide how soon to seek help.

How vets diagnose it

Your vet will weigh your pet and give them a body condition score by looking at and feeling their ribs, waist and tummy. They may also measure muscle condition, since some older pets lose muscle while gaining fat.

They will ask about your pet's diet, including treats, table scraps and food from other people in the household, along with their exercise and routine. Being honest here really helps, and your vet will not judge you.

If anything suggests an underlying medical cause, or before starting a weight-loss plan in an older pet, your vet may recommend blood tests or other checks.

Treatment and management

Why it matters

Extra weight is not just about appearance. It can affect your pet's health and happiness in many ways:

• Joints. Extra weight puts more strain on joints and is closely linked to arthritis. Even modest weight loss can make a noticeable difference to comfort and mobility. Our article on arthritis in dogs explains more.
• Diabetes. Being overweight increases the risk of diabetes, particularly in cats.
• Breathing and heat. Overweight pets can struggle more with exercise and hot weather.
• Other problems. Obesity is linked with skin problems, urinary issues in cats and higher risks during anaesthesia.
• Lifespan and quality of life. Pets kept at a healthy weight tend to live longer and more comfortable lives, with more energy for the things they enjoy.

Common causes

• Portion sizes. Guessing amounts, using a cup or scoop that is not measured accurately, or following feeding guides that do not suit your individual pet.
• Treats and extras. Treats, chews, table scraps and food from children or visitors can add up to a surprising amount.
• Low activity. Shorter walks, indoor lifestyles and less play.
• Neutering. Neutering is often recommended for good health reasons, but it lowers your pet's energy needs. Many pets need less food afterwards.
• Age. Older pets often become less active and need fewer calories.

Losing weight safely

Weight loss works best when it is planned with your vet or veterinary nurse. Many practices run weight clinics with regular weigh-ins and friendly support. Your vet can work out a target weight, recommend how much to feed and suggest whether a special weight-loss diet would help.

The aim is slow, steady progress. Losing weight gradually is safer, preserves muscle and is much more likely to last.

Cats must never be put on a crash diet. If a cat stops eating or eats far too little, their body can start breaking down fat too quickly, and this can overwhelm the liver and cause a serious condition. Always follow your vet's advice for cats, never cut their food dramatically, and contact your vet if your cat refuses food.

Practical steps that help

• Weigh your pet regularly. Every two to four weeks is a good rhythm. Many vet practices are happy for you to pop in and use their scales.
• Measure food accurately. Use kitchen scales to weigh each meal rather than relying on a scoop. Our pet calculators can help you estimate daily needs, and your vet can fine-tune them.
• Use part of the daily food as treats. Set aside some of your pet's measured daily allowance and use those pieces as rewards during the day.
• Keep treats small and few. If you do give extra treats, choose small, low-calorie options and reduce meals to allow for them. Check our toxic foods guide before sharing any human food.
• Get everyone on board. Make sure everyone in the household knows the plan, so your pet is not being fed twice.
• Make mealtimes last. Puzzle feeders, scatter feeding and slow-feed bowls make food more satisfying and add gentle activity.
• Increase play and exercise gradually. For dogs, add a little extra walking time or some fetch, building up slowly. For cats, short play sessions with wand toys a few times a day work well. Older or very overweight pets may need gentler options such as shorter, more frequent walks, so ask your vet what is suitable.

For dogs, our guide on how much to feed your dog has more practical tips.

Prevention

The best way to manage weight is to stop it creeping on in the first place:

• Check your pet's body condition every month or so, using the rib, waist and tummy checks above
• Weigh and measure food rather than guessing
• Review portions after neutering, as your pet grows older or if their activity level changes
• Keep treats to a small share of the daily diet
• Build daily play and exercise into your routine
• Ask your vet to check your pet's weight and body condition at every routine visit

Living with it

Helping a pet lose weight takes patience, and progress can feel slow at times. Try to focus on the small wins: a more comfortable walk, an easier jump onto the sofa, a cat who can groom properly again.

It is normal for pets to ask for food more at first. Extra attention, a game, a walk or a puzzle feeder can often satisfy what they are really asking for. Remember that you are doing something very kind for your pet, and with steady effort, most pets reach a healthier weight and enjoy a better quality of life as a result.