# Why Is My Puppy Not Gaining Weight? A puppy who is not gaining weight may simply be growing at their own pace, or something may be interfering with normal growth. Puppies should gain weight steadily every week, so a flat or falling scale is a signal worth checking. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Weigh your puppy weekly on the same scale and write down the numbers. A trend matters more than a single reading. - Very young puppies are fragile. Birth weight and weight changes in the first days of life are key predictors of survival, so early monitoring matters [1]. - Common reasons a puppy is not gaining weight include underfeeding, intestinal parasites, and gastrointestinal disease. - Never free-feed a puppy hoping they will catch up. Sudden overfeeding can cause serious digestive upset. - If your puppy is losing weight, vomiting, or acting weak, call your veterinarian right away. ## What "Puppy Not Gaining Weight" Really Means A puppy not gaining weight means the scale is staying flat or rising too slowly for the puppy's age and breed. Growth is not a straight line. Some puppies grow in small spurts, and littermates can differ in size without anything being wrong. The trouble is telling normal slow growth apart from a real problem. A runt puppy, for example, may be small but still gaining a little each week. A sick puppy often stops gaining or starts losing. That difference is why weekly weights matter more than how your puppy looks next to their siblings. Your veterinarian can score your puppy's body condition on a 1 to 9 scale, with 4 or 5 being ideal. At an ideal weight, you can feel the ribs but not see them, and there is a visible waist in published veterinary research and a tucked abdomen from the side [2]. That scoring system gives you a target to aim for as your puppy grows. ## Signs Owners Notice Weight is only one clue. Watch for these signs alongside the scale: - Ribs, spine, or hip bones that feel sharp under the skin - A potbellied look with a thin body, which can point to parasites - Dull coat, low energy, or sleeping more than littermates - Loose stools, vomiting, or eating less than usual - Poor muscle tone or trouble keeping up during play Some puppies show failure to thrive, which means they lag behind in weight, energy, and development at the same time. In one reported case, a 6-month-old puppy with failure to thrive, lethargy, muscle atrophy, and exercise intolerance was diagnosed with a form of muscular dystrophy [3]. That is uncommon, but it shows why a puppy who is not gaining weight and also seems weak needs a full veterinary workup. ## Why Is My Puppy Not Gaining Weight? Causes and Risk Factors ### Underfeeding or the Wrong Food The simplest cause is not enough calories. Puppies need more calories per pound than adult dogs, and they need food made for growth. If you are feeding an adult maintenance diet or measuring portions by eye, your puppy may be running a calorie deficit. ### Intestinal Parasites Roundworms, hookworms, and other parasites steal nutrients and can cause a potbelly, diarrhea, and poor growth. Puppies are commonly exposed before birth or through their mother's milk, which is why deworming schedules exist. ### Gastrointestinal Disease Chronic diarrhea, inflammatory bowel disease, and food intolerance all reduce how well a puppy absorbs food. If your puppy eats well but stays thin, absorption is a prime suspect. A puppy who is not eating at all is a different problem and needs prompt care. ### Genetics and Litter Size Small puppies in large litters often get less milk and less food at the bowl. Birth weight and early weight changes are important for prognosis and growth monitoring, and they help flag puppies who need special care [1]. Sex and maternal factors also influence birth weight and early growth, so littermates are not always comparable [1]. ### Rare Metabolic and Muscle Conditions A small number of puppies have inherited conditions that affect growth, muscle, or metabolism. These are uncommon but real, and they usually come with other signs like weakness or exercise intolerance [3]. ### A Note on the Other Direction Weight problems run both ways. If your puppy is gaining too fast, that carries its own risks, and you can read about the opposite pattern in [Why Is My Dog Gaining Weight?](/knowledge/veterinary-medicine/nutrition/why-is-my-dog-gaining-weight). If your puppy has stopped eating, see [Why Is My Dog Not Eating?](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-not-eating). And if the scale is going down instead of flat, [Why Is My Dog Losing Weight?](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-losing-weight) covers that pattern in detail. ## How Veterinarians Diagnose Poor Growth Your veterinarian starts with history and a physical exam. Bring your weight log, your feeding amounts, and a stool sample if you can. | Step | What it looks for | |---|---| | Weight and body condition score | Growth trend and ideal target [2] | | Fecal flotation or smear | Intestinal parasites | | Blood work | Anemia, organ problems, low protein | | Fecal PCR or giardia test | Specific infections | | Food trial or diet review | Calorie shortfall or intolerance | | Imaging or genetic testing | Rare structural or inherited disease [3] | A body condition score gives your veterinarian a baseline to compare against at each visit [2]. If the exam and fecal tests are normal, the next step is usually a careful calorie count. Many "failure to gain" cases turn out to be a feeding math problem, not a disease. ## How to Help a Puppy Gain Weight Safely ### Feed the Right Amount of the Right Food Choose a diet labeled for growth or all life stages. Puppy formulas are more calorie dense than adult maintenance foods. Feed measured meals three to four times a day for young puppies, and adjust the amount based on the weekly scale. If you are switching foods, do it slowly over about a week, mixing increasing amounts of the new food into the old. Sudden changes cause diarrhea, which works against weight gain. ### Make Meals Easier to Eat Warm the food slightly to boost the smell. Add a little warm water to kibble to soften it. Hand-feeding a shy puppy or feeding away from littermates can help a puppy who gets pushed off the bowl. ### Ask About a Higher-Calorie Diet Your veterinarian may recommend a specific therapeutic or high-calorie growth diet. Commercial weight-loss diets are designed for the opposite problem, so do not use them for a thin puppy. If you are wondering what to give your dog for weight gain, the answer is a complete growth diet with the right calorie density, not table scraps or supplements you picked yourself. ### Supplements and Appetite Stimulants Some products are marketed for weight gain. Do not start any supplement without asking your veterinarian first. Doses depend on your puppy's weight and health, so your veterinarian calculates them for your individual puppy. Never guess a dose from a label or an online chart. ### Help for the Runt of the Litter Runts need extra attention, not extra pressure. Weigh them daily for the first weeks, feed them separately so they get their share, and keep them warm. Birth weight and early weight changes are key monitoring tools that let you spot a puppy who needs special care before a crisis develops [1]. ## Treatment Options for the Underlying Cause Treatment depends on what is found. - Parasites: deworming medication chosen by your veterinarian, repeated on a schedule. - Giardia or bacterial infection: specific medication plus supportive care. - Food intolerance: a limited-ingredient or hydrolyzed diet trial. - Underfeeding: a written feeding plan with measured amounts and a recheck weight. - Rare inherited disease: management focused on comfort and quality of life, since these conditions often cannot be cured [3]. If your puppy is not pooping normally, that can also affect appetite and growth. See [Dog Not Pooping but Eating Normally: Causes and Solutions](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-not-pooping-eating-normally) for that specific problem. ## Recovery, Outlook, and Long-Term Management Most puppies who are simply underfed or carrying parasites catch up quickly once the cause is treated. Expect to recheck weight in one to two weeks. Steady weekly gain is the goal, not a sudden jump. Puppies with chronic gastrointestinal disease may need long-term diet management and regular monitoring. Puppies with inherited muscle or metabolic conditions have a more guarded outlook and need ongoing veterinary care [3]. Keep weighing your puppy until they reach adult size. Once they are grown, weight management still matters. Obesity raises the risk of arthritis and makes anesthesia riskier because of the extra load on the lungs and respiratory system [2]. Overweight and obese dogs can lose weight with a structured program, and one study found that success in reaching ideal body condition was higher in overweight dogs than in obese dogs [4]. That is a reminder to keep your puppy lean from the start instead of fixing a problem later. ## Prevention - Start with a growth diet and measured meals from day one. - Follow your veterinarian's deworming and vaccine schedule. - Weigh weekly and log the numbers. - Keep the environment clean and pick up stool promptly. - Spay or neuter timing and diet both affect adult weight, so plan with your veterinarian. - Do not let well-meaning family members sneak extra treats, which unbalances a growth diet. ## Limitations and When to Contact a Veterinarian This article cannot tell you why your individual puppy is not gaining weight. Only a veterinarian who examines your puppy can do that. Call your veterinarian the same day if your puppy: - Has not gained weight for two weeks in a row - Has vomiting or diarrhea lasting more than a day - Refuses to eat for more than 12 hours - Has a potbelly with a thin body Go to an emergency clinic now if your puppy: - Is limp, unresponsive, or too weak to stand - Has a distended, painful abdomen - Has bloody diarrhea or repeated vomiting - Is a newborn who is not nursing or is cold to the touch Newborn puppies can decline fast. Early weight changes are a key prognostic factor, so do not wait to seek help if a very young puppy is not gaining [1]. ## Frequently Asked Questions ### How much weight should my puppy gain each week? There is no single number that fits every breed and size. Small breeds gain less per week than large breeds, and growth slows as puppies approach adult size. Your veterinarian can give you a target range based on your puppy's breed, age, and current weight. ### Can I just feed my puppy more to make them gain weight? More food helps only if underfeeding is the cause. If parasites or gastrointestinal disease are involved, extra food will not fix the problem and can cause diarrhea. Have your puppy checked first, then follow a measured feeding plan. ### Is it normal for the runt of the litter to stay small? Runts often stay smaller than littermates, but they should still gain steadily. A runt who stops gaining or loses weight needs veterinary attention. Daily weighing and separate feeding times give runts the best chance to catch up. ### What dog food is best for gaining weight? A complete diet labeled for growth or all life stages is the right choice for a puppy. These diets are more calorie dense than adult maintenance foods. Your veterinarian can recommend a specific brand or a therapeutic diet if your puppy needs extra calories. ### Can parasites really stop a puppy from gaining weight? Yes. Intestinal worms and other parasites take nutrients from the gut and can cause poor growth, a potbelly, and diarrhea. Deworming on your veterinarian's schedule is one of the most effective ways to protect a puppy's growth. ## Related Articles - [Why Is My Dog Gaining Weight?](/knowledge/veterinary-medicine/nutrition/why-is-my-dog-gaining-weight) - [Why Is My Dog Not Eating?](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-not-eating) - [Why Is My Dog Losing Weight?](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-losing-weight) - [Why Is My Dog rapidly gaining weight? Hypothyroidism Cushings and Spay Weight](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-rapidly-gaining-weight-hypothyroidism-cushings-and-spay-weight) - [Dog Not Pooping but Eating Normally: Causes and Solutions](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-not-pooping-eating-normally) - [Cat Weight Gain Causes](/knowledge/veterinary-medicine/nutrition/cat-weight-gain-causes) ## References 1. [Birth Weight and Early Weight Changes in Newborn Dogs: Analyzing Key Influencing Factors in Dobermann Puppies](https://pubmed.ncbi.nlm.nih.gov/42121829/). Animals : an open access journal from MDPI, 2026. 2. [Obesity and weight loss in dogs](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-topics/obesity-and-weight-loss-dogs). Cornell University College of Veterinary Medicine. 3. [Dystrophin-Deficient Muscular Dystrophy in a Jack Russell Terrier With a Large Deletion in the Canine DMD Gene](https://pubmed.ncbi.nlm.nih.gov/42499298/). Veterinary medicine and science, 2026. 4. [Metabolic and urinary profiles in normal-weight, overweight and obese dogs: clinical response to an individualised weight loss programme](https://pubmed.ncbi.nlm.nih.gov/42166942/). Research in veterinary science, 2026. ## Further Reading - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)