Something that often takes people by surprise when they bring home a new puppy is just how much they grow – it’s amazing to see! But not all puppies gain weight at the same speed. It’s quite a common experience to find yourself worrying about whether your puppy is too skinny, or why they don’t seem to be putting on weight although they’re eating plenty of food.
This article will share advice on how to care for your growing pup. It should also help reassure you that for healthy puppies, getting bigger is a slow and steady process. If you have concerns about your puppy’s growth, the first step is checking whether they actually are underweight for their age and breed, before seeking veterinary advice.
Key takeaways
- You can use the Body Condition Score scale to quickly and easily find out whether puppies are underweight, overweight or a healthy weight – ask a friend or a veterinary professional to help you get an unbiased perspective.
- It’s quite common for people to mistake a healthy, lean puppy for one that’s underweight, in part because people don’t always know what their dog’s ideal weight looks like. So before you increase your dog’s daily calories, it’s important to make sure they actually need it.
- Puppies might be underweight for a number of reasons: they might not be eating enough, or they might have a medical condition that needs attention.
- Puppies need a complete and balanced diet that’s appropriate for their age and size. In particular, large breed dogs need a diet that will help them put weight on slowly, to protect their growing bones and joints.
- 3-4 small meals a day is often ideal for puppies. If you do start giving them larger portions, increase the size of their meals gradually, so that you don’t overwhelm their digestive system.
- Check your puppy’s weight regularly. Your vet is very likely to either have a free set of scales in the reception area for patients to use, or offer drop-in puppy clinics or weight clinics with nurses who can give professional advice.
Table of contents
Is my puppy underweight? How to tell
Why isn’t my puppy gaining weight?
When to speak to your vet
How to help a puppy gain weight safely
What to feed an underweight puppy
How much should I feed my puppy to help them gain weight?
How to track healthy weight gain in puppies
Is my puppy underweight? How to tell
Here’s how to check if your puppy is underweight.
Body Condition Score (BCS) for puppies
The Body Condition Score is a very helpful tool that helps you find out whether a dog is underweight, healthy or overweight, based on what you can see and feel. Check to see if their ribs and spine are easy to feel, and review the shape of their body from the side and from above. To make sure that the result is objective, it can help to get someone else to work out your puppy’s Body Condition Score. This could be a veterinary nurse (they often don’t charge for puppy weight checks) or even a friend.
The Body Condition Score is a scale that goes from 1 to 9, with puppies with a score from 1-3 being classified as underweight. Underweight puppies will have very little muscle or fat on them, and will have a very tucked in waist when you look at them from the side. Their ribs, spine and hips will also be easy to see, even from a slight distance, and the bones will feel prominent when you touch them.
However, if you have a short coated puppy, don’t worry if you can see one or two ribs through their fur, especially when they’re stretching or running. Large breed puppies in particular should be lean and “ribby”, for reasons we’ll go into later. You can read more about Body Condition Scoring in our handy blog post – we go into more detail about how to carry out the test and what to look for when checking to see if your dog’s a healthy weight.
Why isn’t my puppy gaining weight?
Before we get into the reasons why puppies might be underweight, there’s something important to explain. Even if you’re feeling worried that your puppy’s not putting enough weight on, they might actually be growing at a normal, healthy rate.
The PDSA annual PAW report, one of the biggest surveys into pet welfare in the UK, has consistently found that people misjudge their dogs’ weight. The charity’s 2023 report had some particularly significant data. [1] In 2022, 81% of people said they perceived their dog to be a healthy weight (with 79% giving this answer in 2020 and 2019). But this doesn’t match up with what vets say, with the PDSA finding in 2023 that veterinary professionals estimate 46% of dogs to be overweight or obese.
A study from UK Pet Food also found that 50% of dogs are overweight in the UK. [2] With so many dogs at a higher than ideal weight, this can make it harder for people to know what a healthy dog looks like. So it’s quite common for people to worry that their puppy’s too skinny, when really they’re in perfect shape, just lean.
However, there are several reasons why your puppy might not be putting enough weight on. They might not be eating enough – this could be down to a few things. Your puppy might need more calories in order to grow. Your vet will be able to tell you how many calories your puppy needs – and here at Tails.com, we’re also able to help, sending you just the right amount of food for your growing pup based on their age, breed and size.
Your puppy might be a picky eater, meaning they’re not eating enough food to put on healthy weight. Have you noticed they’re happy to gobble up their treats, but leave a large portion of their meals? Alternatively, something might be making them feel stressed, affecting their appetite – keep an eye out for signs of stress and anxiety including yawning, lip licking and pacing. [3]
If your puppy is extremely active, for instance if they run a lot, they might have such a high energy output that they need more food. Lastly, if there are other dogs in your household, there’s a chance that they might be competing for food. You might need to separate them at feeding time for now.
Is your puppy younger than six months old? If so, they might be teething – when puppies’ adult teeth are coming through, it can cause them some pain and discomfort. It can put them off their food, especially if they eat a dry kibble diet. To make it easier for your teething puppy to eat, you can try putting a little water on the kibble to soften it up.
There could also be a medical issue that needs attention. If your puppy isn’t teething, but seems to be experiencing mouth pain, it could be a case of dental disease or a fractured or broken tooth. Digestive problems are another possibility, as well as other conditions that affect how well your puppy absorbs the nutrients they need from their food.
Another reason why dogs might seem to be eating well but still losing weight might be a parasitic infection. Worms and other parasites can make puppies very poorly, so it’s very important to give them suitable worming treatments every 2 to 3 weeks until they are 16 weeks old, when you can slow down to a monthly treatment until they are 6 months old. [4]
When to speak to your vet
If you’re worried that your puppy’s underweight, speak to your vet as soon as you can – it’s very likely that they’ll be able to put your mind at ease and reassure you that your pup’s doing fine. However, there are several situations where it’s especially important to get your puppy checked over by the vet:
- Your puppy is eating well, but isn’t gaining weight.
- Your puppy has lost weight rather than growing.
- You’ve noticed symptoms like diarrhoea, vomiting or lethargy.
- Your puppy is overdue for a worming treatment or you believe they may have worms – intestinal parasites can be very dangerous for young puppies.
How to help a puppy gain weight safely
For growing puppies, slow and steady is the way to go when it comes to putting on weight. Here’s how to plan your puppy’s diet to support healthy growth and development.
Feed the right puppy food
Puppies need a complete and balanced diet, with all the nutrients they need. However, it isn’t enough for the food to be labelled ‘complete and balanced’ – it has to be complete and balanced for puppies specifically. Puppies have different nutritional requirements to adult dogs, and need significantly higher amounts of certain vitamins and minerals. [5]
Puppies also need enough protein, fat and energy to support all that growing they need to do! Food for adult dogs is designed for weight maintenance, not growth, and tends to contain less protein, less fat and fewer calories. It’s important to bear in mind that the size your pup will eventually grow to will also affect the type of food they need. For instance, if larger breed puppies grow too quickly or put on too much weight, it can put them at risk of bone and joint problems. This means they need food that’s formulated to prevent them growing too fast. [6] In contrast, small breed puppies can grow quickly, meaning they might need proportionally higher calories – as well as smaller pieces of kibble for their tiny mouths! We’ll go into more detail later about how different breed sizes require different diets.
Increase calories gradually
It’s best not to increase calories too suddenly. Overeating might affect your puppy’s digestion, giving them an upset stomach. Instead, we recommend a gradual increase in calories, only increasing the size of your puppy’s meal by about 10% at a time. Pay attention to how your puppy responds – are they eating all their food or do they leave some of it in their bowl?
If you subscribe to Tails.com, our clever Adaptive Nutrition system will work out how much food your puppy needs as they grow, and we’ll gradually send you bigger portions, making it easier for you to make sure your pup’s getting the right amount.
Feed little and often
3-4 small meals a day is often just right for puppies. Their little stomachs get full quickly, but they also expend a lot of energy playing (and growing!) meaning that soon enough, they’ll be ready for their next meal.
Small, frequent meals support healthy digestion, helping puppies process food and absorb nutrients without overwhelming their digestive systems or small stomachs. This way of feeding also works with their natural appetite – growing is hungry work! Lastly, some people find that frequent meals help them with toilet training their puppy, as having a meal can also encourage them to go to the toilet.
What to feed an underweight puppy
When trying to help your underweight puppy gain healthy weight, it’s not just about feeding them more food in general. What they need to grow is high-quality protein and healthy fats. Puppy food should be nutritious and easy to digest. So for this reason, it’s best to give your underweight puppy an appropriate amount of nutrient-dense food that’s been formulated for dogs their age, breed and size.
While puppies love treats, and these tasty snacks can help tempt those with a lower appetite to tuck in, they don’t have the right nutritional breakdown to take the place of proper meals. Likewise, human food (like scraps from your table) aren’t suitable either when it comes to helping your puppy put on weight. Food for people is usually much too high in salt and fat for dogs, and it can also often contain ingredients that are toxic for them, like onions and garlic.
How much should I feed my puppy to help them gain weight?
Your vet will be able to help you work out a meal plan for your puppy, and here at Tails.com, we can also adjust the portion sizes we send you based on any information you share with us about your dog.
Start off by giving your puppy the recommended amount, and gradually increase this over time based on your vet’s recommendations. As mentioned earlier, it’s best to increase the size of your puppy’s meal by about 10% at a time.
Make sure you weigh your puppy on a weekly basis – and here’s a handy tip that might help your pup develop positive associations with the vets. Many vet practices provide a set of scales in reception where you can weigh your dog for free, as well as offering free puppy drop in clinics or weight clinics where you can talk to a veterinary nurse.
As you continue gradually increasing your puppy’s meal sizes and calorie intake, adjust how much food you’re giving them based on how they’re growing, as well as their body condition. As well as their size, take into account their age and their breed. The Tails.com Adaptive Nutrition system uses all this information and more to work out their perfect meal plan.
The danger of “over-bulking” (large breed warning)
Large breed puppies (like German Shepherds and Great Danes) have different dietary and health requirements than other breeds. For example, large breed puppies require a different ratio of calcium to phosphorus than smaller breeds, to prevent excessive bone growth that can lead to orthopaedic issues. All our blends at Tails.com are tailored for different dog breeds’ needs. If you’re buying dog food in the supermarket rather than on a subscription with us, you’ll notice that food available on the shelves for larger breed puppies will be labelled as such.
As briefly mentioned earlier in this blog, it’s dangerous if these puppies put on weight too quickly. Our Head Vet Sean says:
“If large breed puppies put on weight too fast, it puts pressure on their joints, bones and growth plates (the soft areas of cartilage where more bone develops). This can increase the risk of conditions like elbow or hip dysplasia, as giant and large breed puppies can be prone to skeletal problems. They might also develop conditions affecting their limbs or the strength of their bones. To give your large breed puppy the best start in life, they need to grow at a steady, sustainable rate.”
Most giant breed puppies reach their adult size in 18-24 months, and although this is slower than smaller breed dogs, it’s still not that long. So it’s important to make sure they’re being fed just the right amount, so that they can gradually put on healthy weight, and grow strong and healthy bones.
How to track healthy weight gain in puppies
Slow and steady is the way to go, as your puppy grows. Whether you’re doing weekly weigh-ins at home or at the vets, keep a log of how much weight your puppy puts on. And don’t forget about their Body Condition Score, too – how they look as well as how their ribs feel to the touch.
It’s normal for puppies to sometimes experience a growth spurt, but overall, steady growth is ideal rather than rapid bulking. If you’re concerned, your vet will be able to advise you whether a sudden increase in your puppy’s weight is down to a growth spurt, or whether it means you may need to cut back slightly on their portion sizes.
Conclusion: supporting healthy growth in puppies
So if you’re worried that your pup might be underweight, the first thing you can do is check with your vet. They’ll be able to tell you whether your puppy is a good weight for their age and breed. They’ll also be able to show you how to complete a Body Condition Score check, as it can be a little daunting if you’ve never done this before.
If it’s confirmed that your puppy is underweight, the next step is to rule out any health issues that could be slowing their growth. Medical reasons like worms, digestive problems or a sore mouth due to teething or other problems can all affect puppies’ ability to put on healthy weight.
Make sure that you’re feeding your puppy the right amount of the right food to support their growth and development, and remember that every puppy will have different needs. Keep checking their progress as they grow up, and make sure you enjoy every moment of their puppyhood because it will go by faster than you think!
With the right support and nutrition, most underweight puppies can reach a healthy weight. We’re here to help at Tails.com – if you have an account with us, make sure you keep your dog’s profile updated with their weight and Body Condition Score. If your puppy is underweight, our clever system will respond by changing their tailored blend and increasing the calorie count to suit their needs. You can always contact the experts in our nutrition team for advice as well.
FAQs
How long does it take for a puppy to gain weight?
It depends, based on the puppy’s age, breed and size. Small breeds are likely to have reached their full size within a year but giant breeds might reach their adult size in two years. Your puppy should grow fairly steadily, but growth spurts are normal.
Why is my puppy eating but not gaining weight?
Puppies might not put on weight despite eating healthily because of medical reasons, which could include intestinal parasites or digestive problems. If you think this might be the case with your pup, contact your vet to rule out any issues and put your mind at ease.
How many meals should an underweight puppy eat?
Puppies should eat 3-4 small meals a day. Pups that have been confirmed to be underweight may need these meals to contain more calories, protein and healthy fats.
Can worms cause puppies not to gain weight?
Yes, if a puppy has worms it can prevent them gaining weight healthily. This might be due to parasites affecting the health of your dog’s intestinal lining, or making it harder for them to absorb essential nutrients from their food. Worms are a serious risk for puppies, so it’s important to make sure they’re up to date with worming treatments.
Is it safe to give treats to help a puppy gain weight?
You shouldn’t feed your puppy too many treats even if they’re underweight. Instead, give them nutritious meals full of all the proteins, healthy fats, vitamins and minerals they need to support them as they grow. A balanced diet is much more important than just upping the calories.
When do puppies start to fill out?
“Filling out” is a term usually used to refer to the weight and muscle puppies put on as they reach their adult size, when they begin to lose that gangly look. Small breed puppies will reach this stage sooner, as large and giant breed puppies take longer to reach their full height. For the smallest breeds, they might fill out before they turn a year old, but giant breed dogs can be nearly two years old and yet to be done filling out.
Sources
[1] ‘PDSA Animal Wellbeing Report 2023’, PDSA
[2] ‘Obesity report released to tackle rising pet obesity’, UK Pet Food, 16 October 2024
[3] ‘Dealing with separation anxiety in dogs’, Battersea Dogs & Cats Home, 26 May 2023
[4] ‘Worms in dogs’, PDSA
[5] ‘Puppy nutrition’, UK Pet Food
[6] ‘Puppy nutrition’, UK Pet Food