If your dog's collar feels tighter or their waist has disappeared, you're not alone. Weight gain is one of the most common health issues we see in New Zealand dogs, and it usually creeps on so slowly that owners don't notice until the vet mentions it. The good news is that most causes are easy to fix once you know what's behind them. This guide covers why dogs gain weight, how to tell if your dog is overweight, and a simple plan to get them back on track.
Is your dog actually overweight?
Scales help, but your hands and eyes are just as useful. Check these three things:
- Ribs. You should be able to feel them easily under a thin layer of fat, like the back of your hand. If you have to press to find them, your dog is carrying extra weight.
- Waist from above. Looking down, there should be a visible waist behind the ribs.
- Tummy from the side. The belly should tuck up behind the ribcage rather than hang level or sag.
Even a few extra kilos matter. Carrying excess weight puts strain on joints and is linked to arthritis, diabetes and a shorter life.
The most common reasons dogs gain weight
1. Portion creep. Most of us feed with a scoop or a "cup". A heaped scoop can easily hold 20% more than a level one, and that adds up. The feeding guide on the bag is also only a starting point, often written for active dogs.
2. Treats and table scraps. A crust of toast, a bit of cheese, a couple of chews a day. Treats should make up no more than 10% of your dog's daily calories. For a small dog, one pig's ear can be a big chunk of that.
3. Desexing. Desexed dogs need noticeably fewer calories than entire dogs, by as much as a quarter. If your dog's food wasn't adjusted after desexing, weight gain often follows within months.
4. Age and activity. As dogs get older they slow down and need less energy. Shorter walks over winter, an injury, or a change in your routine can all tip the balance too.
5. Adding extras without cutting back. Toppers, raw food and supplements all carry calories. If you add them without reducing your dog's main food, the extra adds up. Our guide to mixing dry and raw food explains how to adjust portions.
6. Breed. Labradors, beagles, cavaliers and some other breeds are prone to putting on weight and are often hungrier than other dogs.
When to see your vet
Sometimes weight gain has a medical cause. Underactive thyroid (hypothyroidism) and Cushing's disease are two of the more common ones, and some medications, such as steroids, can increase appetite. See your vet if your dog is gaining weight without eating more, or if you notice:
- tiredness, low energy or reluctance to exercise
- drinking or weeing much more than usual
- thinning coat or hair loss
- a swollen, pot-bellied tummy, which can be fluid rather than fat
A simple plan to help your dog lose weight
- Weigh the food. Use kitchen scales for a couple of weeks. It's the single biggest change most owners can make.
- Feed for the weight you want. Work out your dog's target weight, then use the feeding guide for that weight, not their current one.
- Count the treats. Take treats out of the daily food allowance, or swap to lower-calorie options.
- Aim for slow, steady loss. Around 1–2% of body weight per week is safe. For a 30kg dog that's about 300–600g a week.
- Weigh every two weeks. Adjust portions if progress stalls.
- Add a little more movement. An extra 10 minutes of walking, sniffing or play each day helps.
Weight management food we stock
Simply feeding less of your dog's usual food can leave them hungry and short on nutrients. A weight management food has fewer calories per bowl but keeps protein, vitamins and minerals where they need to be.
Black Hawk Healthy Benefits Weight Management, our go-to recommendation. High-fibre, hollow kibble helps your dog feel full, while added L-carnitine helps the body use fat for energy. Comes in 2kg and 10kg bags.
Purina Pro Plan Weight Management. Lower in fat than standard Pro Plan, with high protein to help protect muscle while your dog loses weight.
Hill's Science Diet Perfect Weight. A well-known weight-loss range from a vet-trusted brand, with Small & Mini and Large Breed versions. For heavier dogs with stiff joints, try Perfect Weight & Joint Support. Hill's is ordered in especially for you, so allow a few extra days.
Black Hawk Chicken & Rice. Not a weight-loss food, but slightly lower in fat and energy than many standard foods. A good choice for keeping weight off once your dog has reached their goal.
Maranui Wallaby, Heart & Tripe Medallions. For raw feeders, wallaby is a naturally lean protein. Use it as part of a measured diet, not on top of a full bowl. Available in-store only at our Oxford shop.
Switch to a new food gradually over 7 to 10 days, mixing a little more of the new food in each day.
Smarter treats
You don't have to give up treats. Break them into smaller pieces, set aside part of the daily kibble to use as rewards, or choose a single-ingredient treat like our Lamb Marshmallows, which come in bite-sized cubes that are easy to portion. Save richer chews like pig's ears for occasional treats.
Got an overweight cat?
The same rules apply. Indoor and desexed cats are especially prone to gaining weight. Hill's Science Diet Perfect Weight for cats and ACANA Indoor Entrée are both good options. Never put a cat on a crash diet, as losing weight too quickly can make cats seriously unwell. Talk to your vet before starting.
Find the right food for your dog
Browse our full range of dry dog food, with delivery across New Zealand and click and collect from Oxford, North Canterbury. Or get in touch and tell us about your dog. We're happy to help you choose.
This article is general information, not veterinary advice. If your dog is unwell, see your vet.