Dog obesity: how to tell if your dog is overweight and what to do

If your dog has put on weight gradually, over months or years of normal life, it is very easy not to notice. There is no single moment where a dog crosses from "a bit cuddly" to "overweight" — it happens slowly, one extra biscuit and one shorter walk at a time. You are not alone in this, and it is not a sign of neglect. It is simply the most common health problem seen in UK dogs, and it is one of the most fixable.

The good news is that you do not need scales, apps or guesswork to work out whether your dog needs to lose weight. A simple hands-on check, done regularly, tells you almost everything you need to know. And once you know, a safe, steady weight-loss plan — built around diet more than exercise — can add real, healthy years to your dog's life.

This guide walks through how to assess your dog's body condition, what actually causes dogs to gain weight, which breeds are most at risk, the health problems extra weight causes, and how to put together a weight-loss plan that works without starving or over-exercising your dog.

How to tell if your dog is overweight

Bathroom scales are not much use here — a dog's healthy weight varies hugely by breed, frame and build, so there is no single "correct" number in kilograms. What vets actually use is body condition scoring (BCS): a simple, hands-on check of shape rather than weight.

According to PDSA, you should be able to do the following on a dog at a healthy weight:

• Feel the ribs with only a light touch — the skin should move freely over them, not be buried under a padded layer.
• Feel the spine and hip bones under the skin, without being able to see them poking through.
• See a waist when you look down at your dog from above, with no obvious bulge behind the ribs.
• Check the tummy tucks up, rather than hanging or bulging, when you look at your dog from the side.
• Find no fat pad at the base of the tail.

If you have to press firmly to find the ribs, if the waist has disappeared into a straight or barrel-shaped body, or if the tummy sags rather than tucks, your dog is very likely carrying excess weight. This is worth doing every few weeks, not just once — it is the easiest way to catch weight gain early, before it becomes a bigger job to reverse.

The 9-point body condition scale, in plain terms

Vets often score dogs on a 1–9 scale rather than a simple yes/no. You do not need to memorise it in detail, but it helps to understand the shape of it:

• 1–3 (underweight): ribs, spine and hip bones are all easily visible, with an obvious loss of muscle.
• 4–5 (ideal): ribs easily felt with a light covering of fat, a visible waist from above, and a tucked abdomen from the side. This is the target for the vast majority of adult dogs.
• 6–7 (overweight): ribs are harder to feel under a moderate fat covering, the waist is barely visible or absent, and there may be a slight fat pad over the tail base.
• 8–9 (obese): ribs cannot be felt at all under a thick fat layer, there is no waist, the abdomen bulges, and fat deposits are obvious over the back, tail base and limbs.

Most overweight dogs sit somewhere in the 6–7 range without their owners realising, simply because the change happened gradually and everyone in the house got used to how the dog looks. If you are unsure where your dog falls, your vet or a veterinary nurse can score your dog in a couple of minutes at your next visit, usually free of charge as part of a weight clinic.

If you have to search for your dog's waist, or press hard to find their ribs, it is time for an honest weight check — not next month, this week.

Just how common is this?

This is not a minor issue affecting a handful of dogs. PDSA's ongoing work on pet obesity puts the figure at nearly half of all dogs in the UK carrying excess weight. Separately, research from the Royal Veterinary College's VetCompass programme, which tracks health records from vet practices across the country, found that around 1 in 14 dogs is formally recorded as overweight by their vet every year — and the researchers themselves noted this is likely only the visible tip of the problem, since many overweight dogs are never flagged at a check-up at all.

In other words: if your dog is a little heavier than they should be, they have a great deal of company. That does not make it harmless, but it does mean there is no shame in it, and no shortage of good, well-tested advice on fixing it.

What actually causes dogs to gain weight

For the overwhelming majority of dogs, the cause is straightforward: more calories go in than get burned off. This is rarely one dramatic thing — it is usually a combination of small, everyday habits that add up:

• Feeding by eye or by "a scoop" rather than weighing food, which is easy to get wrong by a surprising margin.
• Treats, table scraps and training rewards that are never counted as part of the day's food.
• A walk that has gradually shortened as life gets busier, without the food bowl shrinking to match.
• Multi-dog households where a faster or greedier dog eats more than their share.
• Neutering, which lowers a dog's calorie needs — PDSA notes that neutering itself doesn't directly cause weight gain, but many owners keep feeding the same amount afterwards, and the dog's requirements have quietly dropped.

A smaller number of cases have a medical cause. PDSA lists hypothyroidism (an underactive thyroid) and Cushing's disease (excess cortisol production) as conditions that can cause weight gain, along with certain medications such as long-term steroids. These are far less common than simple calorie imbalance, but they are worth ruling out with your vet, especially if your dog has gained weight despite no real change in food or exercise, or shows other signs like lethargy, a dull coat, or increased thirst.

Which dogs are most at risk

Any dog of any breed can become overweight, but some are more genetically predisposed than others. The RVC VetCompass study looked at breed risk compared with crossbred dogs and found eight breeds with a significantly higher chance of being recorded as overweight:

• Pugs — over three times more likely to be overweight than the average dog, with the study noting close to one in five Pugs formally diagnosed with obesity each year.
• Beagles
• Golden Retrievers
• English Springer Spaniels
• Border Terriers
• Labrador Retrievers
• Cavalier King Charles Spaniels
• Cocker Spaniels

PDSA's own clinical experience lists a similar cluster of breeds prone to weight gain, including Labradors, Golden Retrievers, Pugs, Cocker Spaniels and Cavalier King Charles Spaniels. If your dog is one of these breeds, it is worth being a little more vigilant with portion control and regular body condition checks than you might otherwise be, simply because the odds are stacked against them from the start. This is especially true for Pugs and other flat-faced breeds, where extra weight makes existing breathing difficulties considerably worse.

The health risks of carrying extra weight

It is tempting to think of a few extra pounds as cosmetic — a dog who is a bit rounder, a bit slower on stairs. The evidence says otherwise. PDSA and the RVC both link canine obesity to a long list of serious health problems, including:

• Osteoarthritis and joint pain, made worse by the additional load on hips, knees and spine.
• Cruciate ligament damage, a common and painful knee injury that is more frequent in overweight dogs.
• Diabetes mellitus.
• Breathing difficulties, particularly in flat-faced breeds already prone to restricted airways.
• Heatstroke risk, since excess fat makes it harder for a dog to regulate body temperature.
• Urinary incontinence and back problems.
• Certain cancers.
• Complications under anaesthesia, which matters for any dental work, surgery or investigation your dog may need in future.
• A shorter lifespan and a lower quality of life overall — the RVC's research specifically found that overweight dogs live adversely affected, shorter lives compared with dogs at a healthy weight.

Put together, this is why vets treat weight management as a genuine medical priority rather than a lifestyle preference. Helping your dog reach a healthy weight is one of the single most effective things you can do for their long-term wellbeing — arguably more impactful than any supplement or treatment you could buy.

Building a safe weight-loss plan

The most important first step is a trip to the vet, not a new bag of food. A vet check does two things: it rules out a medical cause for the weight gain, and it gives you an accurate starting weight and a realistic target weight to work towards, tailored to your individual dog rather than a breed average.

From there, both the AKC and VCA Animal Hospitals describe weight loss in dogs as roughly 60–70% diet and 30–40% exercise — diet does most of the work, and exercise supports it rather than replacing it. A few principles make the biggest difference:

• Weigh food on a gram scale, not by cup or scoop. Cup measurements are notoriously inaccurate and vary by how tightly the food is packed.
• Count everything — treats, training rewards and any table scraps all count towards the daily calorie total, not just the main meals.
• Keep treats to no more than 10% of daily calories, with the other 90% coming from a properly balanced main diet.
• Feed dogs separately in multi-dog households, so a faster eater cannot finish another dog's portion.
• Aim for gradual loss — PDSA recommends around 1–2% of starting bodyweight per week as a safe, sustainable target (nearer the lower end for dogs who are very overweight). Rapid weight loss is not healthier; it is simply harder to maintain and can be counterproductive.

Our Pet Calorie Calculator is a useful starting point for working out a rough daily calorie target, though your vet's figure — based on your dog's actual body condition and any health conditions — should always take priority.

Getting the diet right

Vets will often recommend a specific weight-management diet rather than simply feeding less of the usual food. These diets are formulated to be lower in energy density but still nutritionally complete, so your dog gets a satisfying volume of food, adequate protein to protect muscle mass, and enough fibre to help them feel full — without the same calorie load. VCA Animal Hospitals recommends introducing any new food gradually over two to three weeks, mixing increasing proportions of the new diet with the old, to avoid digestive upset.

If you would rather not switch foods entirely, simply weighing out an accurate, reduced portion of your dog's current diet under vet guidance can also work, provided the reduction does not compromise essential nutrients. Puzzle feeders and slow-feed bowls are a genuinely useful addition here too — they stretch mealtimes out, add mental stimulation, and stop a hungry dog from feeling like their portion has been cut too sharply.

Exercise: how much, and what kind

Exercise supports weight loss and, just as importantly, helps prevent it creeping back afterwards. The AKC suggests building towards at least 20 minutes of purposeful activity twice a day, working up gradually rather than all at once — a sudden jump in exercise can risk injury in a dog whose joints are already carrying extra load. VCA similarly points to a brisk 30-minute daily walk alongside a couple of shorter play sessions as a reasonable target for many dogs, once your vet has confirmed it is safe to increase activity.

For dogs who are very overweight, or who have joint pain, swimming and hydrotherapy are worth asking your vet about, since they let a dog work muscles without the same impact on hips and knees. Our Dog Walking Calculator can help you plan a realistic weekly walking routine that suits your dog's age, breed and current fitness level, and can be built up steadily as their weight comes down.

Common mistakes to avoid

A few habits quietly undermine even a well-intentioned weight-loss plan:

• Guessing portions instead of weighing them. Even experienced owners are often surprised by how much a "normal" scoop actually weighs.
• Forgetting treats count. A handful of training treats through the day can add up to a meaningful chunk of daily calories.
• Expecting fast results. Steady, modest loss is safer and far more likely to stick than a crash diet.
• Increasing exercise too quickly. Ramping up walks or runs before your dog's joints and fitness can cope risks injury, particularly in older or very overweight dogs.
• Stopping too soon. Reaching an ideal body condition score is only half the job — the diet and exercise habits that got your dog there need to continue afterwards to keep the weight off.
• Not re-weighing regularly. Regular check-ins, whether at home with a body condition check or at the vet with a set of scales, are what catch small regains before they become a bigger problem again.

When to see your vet

See your vet before starting any weight-loss plan, not just if things go wrong — they need to rule out medical causes and set a safe target weight and calorie plan for your individual dog. You should also contact your vet if your dog has gained weight rapidly or without any change in diet or exercise, if weight loss stalls completely despite sticking to the plan, or if your dog shows other symptoms alongside the weight gain, such as increased thirst, lethargy, hair loss or a change in coat condition. These can point to an underlying condition like hypothyroidism or Cushing's disease that needs its own treatment before weight loss will succeed.

*This is general guidance, not a substitute for advice from your vet, who can assess your individual pet.*

Sources

• PDSA — obesity in dogs, causes and health risks (pdsa.org.uk).
• PDSA — your dog's body condition score (pdsa.org.uk).
• Royal Veterinary College VetCompass — RVC study reveals extent of dog obesity crisis in the UK (rvc.ac.uk).
• VCA Animal Hospitals — creating a weight reduction plan for dogs (vcahospitals.com).
• American Kennel Club — how to help your dog lose weight safely (akc.org).