# Puppy Not Thriving: Signs, Causes, and What to Do A puppy not thriving is a puppy that fails to gain weight, grow, or act like a normal puppy for its age. The problem can start before birth, in the first days of life, or during the weeks after weaning. Because puppies can decline quickly, early veterinary assessment matters more than home remedies. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - A puppy that is not gaining weight, is losing weight, or is much smaller than littermates needs a veterinary exam, often the same day. - Birth weight and weight change in the first day of life are important prognostic factors, and puppies with low values may need special care [1]. - Congenital defects such as cleft palate are among the leading causes of neonatal mortality in small animals and often require nutritional and surgical management [2]. - Weakness, collapse, trouble breathing, crying constantly, or a body that feels cold are emergency signs. - Do not change milk replacer, feeding amounts, or supplements on your own. A veterinarian calculates what your puppy needs based on weight and health. ## What "Puppy Not Thriving" Means in Plain Words Failure to thrive is not a single disease. It is a pattern. The puppy does not grow or develop the way it should. Some puppies are small but healthy. Others are small because something is wrong. In newborn puppies, the first clue is often weight. Puppies should gain weight steadily after birth. A puppy that stays the same weight, loses weight, or falls far behind its littermates is at higher risk. In one study of Dobermann puppies, both birth weight and weight on day 1 were linked to the risk of death within 15 days after birth [1]. Those weights were also influenced by the puppy's sex and by maternal factors, so a veterinarian looks at the whole picture, not one number [1]. In older puppies, failure to thrive can look like poor muscle development, low energy, or a puppy that never seems to catch up. A 6-month-old Jack Russell Terrier with failure to thrive, lethargy, muscle atrophy, and exercise intolerance was later diagnosed with a form of muscular dystrophy caused by a genetic variant [3]. That case shows why a puppy that simply "seems behind" deserves a real medical workup. ## Signs Owners Notice First ### Newborn and neonatal puppies (birth to about 2 weeks) - Weight that does not rise, or drops, over 24 hours - A puppy that feels cool to the touch - Constant crying or restlessness - Weak suckle, or milk coming out of the nose during feeding - Separation from the litter, or being pushed away by the mother - Trouble breathing, or a blue tint to the gums ### Older puppies (3 weeks and up) - Much smaller than littermates - Poor muscle tone or muscle wasting - Low energy, sleeping more than expected - Exercise intolerance, tiring after short play - Drooling or trouble swallowing - Coughing, gagging, or vomiting during or after meals - Slow growth despite eating Some of these signs overlap with normal puppy behavior problems, but a puppy that is also not growing needs a medical exam before any training plan. If your puppy is eating poorly on top of slow growth, see our guide to a [dog not eating](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-not-eating-when-to-worry). If your puppy is anxious or clingy, that can be normal, but it should not be confused with the weakness of a sick puppy. You can read more about [dog anxiety signs](/knowledge/veterinary-medicine/behavior/dog-anxiety-signs) to tell the difference. ## Causes and Risk Factors Causes fall into a few broad groups. Often more than one is present. ### Congenital (present at birth) Congenital defects are a leading cause of death in newborn puppies [2]. Cleft palate is one of the most common malformations in dogs [2]. A puppy with a cleft palate cannot form a proper seal while nursing, so milk enters the nose and the puppy does not get enough nutrition. In a report of ten brachycephalic puppies (French Bulldogs, Pugs, and an American Bully), cleft palate was managed with clinical and nutritional support, then surgically repaired at four months of age [2]. Other congenital problems include heart defects, brain and spinal defects, and inherited muscle disease. The Jack Russell Terrier case involved a deletion in the DMD gene that caused dystrophin-deficient muscular dystrophy, with muscle atrophy and exercise intolerance [3]. In that litter, the only other male puppy died young, while the female puppies developed normally, which fits the pattern of an X-linked condition [3]. ### Nutritional Nutrition matters before the puppy is even born. A diet with about 20% carbohydrates is typically recommended for pregnant bitches, and carbohydrate-free diets have been listed as risk factors for low birth weight, higher newborn death, stillbirths, and problems in the mother [4]. That said, a small case series of seven dams fed raw diets with 0 to 6% of energy from carbohydrates produced 41 puppies with 100% survival among live-born puppies [4]. This does not mean carbohydrate-free diets are safe for every dog. It means the relationship is not as simple as once thought, and your veterinarian should guide pregnancy feeding. After birth, common nutritional causes of poor growth include: - Incorrect formula mixing (too weak or too strong) - Not enough total volume per day - Feeding on a schedule that does not match the puppy's needs - Starting solid food too early or too late - Parasites or gut disease that block nutrient absorption ### Infectious Newborn puppies have immature immune systems. Infections can spread quickly through a litter. Common culprits include bacterial infections from the birth canal or environment, viral infections such as parvovirus in older puppies, and intestinal parasites. A puppy that was fine yesterday and is limp today may have sepsis, which is an emergency. ### Environmental and maternal Cold, poor hygiene, overcrowding, and a mother who is not producing enough milk or is rejecting a puppy all raise the risk. Maternal factors also affect birth weight and early growth [1]. ## How Veterinarians Diagnose the Problem Diagnosis starts with history and a physical exam. Your veterinarian will want to know birth weight if you have it, daily weights, feeding method, and how the puppy compares to littermates. ### What to expect at the visit - A full physical exam, including temperature, hydration, and heart and lung sounds - A weight check and comparison to expected growth - A check of the mouth for cleft palate or other defects - Blood work, including glucose and a blood cell count - Fecal testing for parasites - Imaging such as X-rays or ultrasound if a heart or structural problem is suspected For inherited muscle disease, testing may include electromyography (EMG), which can show abnormal electrical activity such as complex repetitive discharges and fibrillation potentials, and muscle biopsy, which can show degenerative and regenerative changes [3]. Genetic testing may also be used when a specific variant is suspected [3]. If a puppy dies, a necropsy can identify the cause. Neonatal mortality in dogs is high, ranging from about 5% to 35%, yet investigations into its causes remain scarce [5]. A standardized neonatal necropsy protocol helps pathologists find answers, because neonatal organs look different from adult organs under the microscope [5]. | Clue | Possible cause | Typical next step | |---|---|---| | Milk out the nose, poor suckle | Cleft palate [2] | Oral exam, nutritional support, surgery planning [2] | | Muscle wasting, exercise intolerance | Inherited muscle disease [3] | EMG, muscle biopsy, genetic testing [3] | | Low birth weight, poor day 1 gain | Neonatal risk factors [1] | Close monitoring, supportive care [1] | | Sudden weakness in a whole litter | Infection or environment | Urgent exam, cultures, warming, fluids | ## Treatment Options Treatment depends on the cause. There is no single protocol. ### Supportive care Many failing puppies need warmth, fluids, and nutrition before anything else. A veterinarian may place a feeding tube. In the cleft palate cases, puppies were fed through an esophageal tube for 10 days after surgery [2]. Tube feeding is not something to attempt at home without instruction. ### Treating the specific cause - Cleft palate: nutritional and immunological support first, then surgical repair. In the reported cases, repair was done at four months of age [2]. - Infection: antibiotics or antivirals chosen by your veterinarian, plus supportive care. - Parasites: deworming based on fecal results. - Inherited muscle disease: there is no cure for dystrophin-deficient muscular dystrophy, so care focuses on nutrition, activity management, and monitoring. - Heart or other congenital defects: may need medication, surgery, or both, depending on the defect. Doses for any medication are calculated by your veterinarian from your puppy's weight and health. Never give human medications or leftover pet medications to a puppy. ## Recovery, Outlook, and Long-Term Management Outlook varies widely. A puppy with a simple problem, such as parasites or a feeding error, can catch up quickly once the issue is fixed. A puppy with a severe congenital defect may need lifelong care. For cleft palate, the reported cases did well with early nutritional support and later surgery [2]. For inherited muscular dystrophy, the condition is progressive, and management focuses on quality of life [3]. For puppies that survive a rough neonatal period, growth may still lag, so regular weight checks at home are useful. Long-term management often includes: - Scheduled weigh-ins, at the same time of day - A diet chosen with your veterinarian for the puppy's specific condition - Routine veterinary rechecks - Watching for new signs, such as coughing, collapse, or trouble eating If your puppy is also showing behavior changes as it grows, our article on [puppy behavior problems](/knowledge/veterinary-medicine/behavior/puppy-behavior-problems) can help you separate normal development from something that needs a veterinary look. Hair loss or a poor coat can also be a sign of underlying illness, which is covered in [dog hair loss after puppies](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-after-puppies). ## Prevention You cannot prevent every congenital problem, but you can lower risk. - Feed the mother a balanced diet during pregnancy and nursing. Work with your veterinarian on carbohydrate levels, since the research is mixed [4]. - Weigh puppies at birth and daily for the first two weeks. Record the numbers. - Keep the whelping area warm, clean, and quiet. - Ask about genetic testing before breeding, especially if a previous litter had problems. - Keep up with deworming and vaccines on your veterinarian's schedule. - Seek help early. A puppy that is not gaining weight for 24 hours should be seen. ## Limitations and When to Contact a Veterinarian This article cannot tell you what is wrong with your puppy. Only a veterinarian who examines your puppy can do that. Contact a veterinarian the same day if your puppy: - Has not gained weight in 24 hours - Is losing weight - Is much smaller than littermates - Has a weak suckle or milk coming from the nose - Is vomiting or has diarrhea Go to an emergency clinic now if your puppy: - Is limp, unresponsive, or collapsing - Feels cold despite warming - Is breathing fast, hard, or with a blue tint to the gums - Is crying constantly and cannot settle - Has a seizure For routine concerns, such as slow growth without other signs, schedule a visit within a few days. Bring your weight log and feeding records. ## Frequently Asked Questions ### How do I know if my puppy is failing to thrive? Your puppy is likely failing to thrive if it is not gaining weight, is losing weight, or is far behind its littermates in size and energy. A veterinarian can confirm this with a physical exam and weight history. Do not wait to see if it catches up on its own. ### Can a puppy catch up after a slow start? Yes, many puppies catch up once the underlying problem is treated. Puppies with feeding errors, parasites, or mild infections often recover well with supportive care. Puppies with serious congenital defects may have a more guarded outlook and need long-term management. ### Is it normal for the smallest puppy in a litter to stay small? Sometimes, but not always. A small puppy that is active, nursing well, and gaining weight may simply be the runt. A small puppy that is weak, cold, or not gaining needs a veterinary exam. Birth weight and early weight change are linked to survival risk, so tracking weight matters [1]. ### Can a puppy with a cleft palate survive? Yes, with proper care. Cleft palate is one of the most common birth defects in dogs and a leading cause of newborn death, but nutritional support and surgical repair can lead to survival [2]. In reported cases, puppies were fed by tube after surgery and repaired at four months of age [2]. ### Should I breed a dog that had a puppy with a birth defect? Talk to your veterinarian before breeding again. Some defects, such as the DMD variant found in the Jack Russell Terrier case, have a genetic basis and can be tested for [3]. A veterinarian or reproductive specialist can help you decide on testing and breeding plans. ## Related Articles - [Puppy Behavior Problems](/knowledge/veterinary-medicine/behavior/puppy-behavior-problems) - [Dog Not Eating: When to Worry and What to Do](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-not-eating-when-to-worry) - [Dog Hair Loss After Puppies: Causes and What to Do](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-after-puppies) - [Dog Separation Anxiety in Puppies: Early Signs and Prevention](/knowledge/veterinary-medicine/anxiety-and-behavior-support/dog-separation-anxiety-puppies) - [Dog Anxiety Signs: What Should Owners Watch For?](/knowledge/veterinary-medicine/behavior/dog-anxiety-signs) - [How Do I Know If My Dog Has Behavior Problems](/knowledge/veterinary-medicine/behavior/how-do-i-know-if-my-dog-has-behavior-problems) - [Sick Puppy Symptoms: How to Tell and What to Do](/knowledge/veterinary-medicine/symptom-guides/sick-puppy-symptoms-warning-signs) - [Why Is My Puppy Not Gaining Weight?](/knowledge/veterinary-medicine/nutrition/puppy-not-gaining-weight) - [Dog Not Feeling Well: Signs, Causes, and What to Do](/knowledge/veterinary-medicine/symptom-guides/dog-not-feeling-well-signs) - [Ancylostoma caninum Hookworm Infection in Dogs: Clinical Signs, Diagnosis, and Treatment](/knowledge/parasites/pet-parasites/ancylostoma-caninum-hookworm-dogs-clinical-signs-diagnosis-treatment) ## 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. [Clinical Approach to Cleft Lip and Palate with or Without Surgical Correction in Ten Brachycephalic Puppies](https://pubmed.ncbi.nlm.nih.gov/40431567/). Veterinary sciences, 2025. 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. [Dams fed diet with no or minimal amounts of carbohydrates during pregnancy and lactation produce normal and healthy puppies: seven case reports](https://pubmed.ncbi.nlm.nih.gov/41960353/). Frontiers in veterinary science, 2026. 5. [Necropsy Technique and Histological Characterisation of Organs From Neonatal Puppies: What Do We Know?](https://pubmed.ncbi.nlm.nih.gov/40364605/). Veterinary medicine and science, 2025. ## 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)