Gaining Weight in Dogs

Why is my dog gaining weight?
Why is my dog gaining weight?

What is Gaining Weight?

Like humans, dogs can gain weight for a number of reasons, including poor diet, inadequate exercise, changes in metabolism, and certain types of illness. Although certain breeds are somewhat predisposed to weight gain, any dog can become obese. Although gradual weight gain can occur with some diseases, illnesses are more likely to be characterized by rapid weight gain. 

  • Cushing’s disease
  • Diabetes
  • Genetic predisposition
  • Lack of exercise
  • Medication
  • Overeating
  • Pregnancy
  • Stress
  • Thyroid disease

Why Gaining Weight Occurs in Dogs

Canine weight gain is initiated by many of the same circumstances as weight gain in people. Although disorders and diseases may trigger weight gain in some dogs, most animals gain the weight due to poor diet, overeating, or a lack of exercise. Some of the possible causes of weight gain can include: 

Cushing’s Disease

Dogs who develop this endocrine disorder end up with an imbalance in the hormones that are secreted by the adrenal glands. If your dog exhibits rapid weight gain that is centered around the abdomen even in the absence of increased caloric intake, your veterinarian may want to evaluate the hormone levels in your pet’s blood.


Diabetes is a chronic metabolic disorder involving imbalances in the amount of sugar in the blood and the amount of insulin released in response. Weight gain can be considered both a trigger and a result of blood sugar imbalances.

Genetic Predisposition

Although any dog may develop obesity, certain dog breeds have an increased chance of gaining too much weight. Some of the breeds that are prone to weight gain can include Labrador Retrievers, Dachshunds, Beagles, and Cocker Spaniels. Dogs that belong to breeds that are prone to this disorder should be carefully monitored to prevent its development. 

Lack of Exercise and Overeating

Although either of these circumstances can cause obesity on their own, they are quite frequently seen in conjunction. This particular cause of weight gain is generally harder to reverse than it is to prevent. Some dogs require more exercise than others due to differences in metabolism that can be caused by medical procedures like spaying or neutering, by differences in breed, or just to natural aging processes.


Several types of medication are known to stimulate an increase in weight, including the common anticonvulsant phenobarbital as well as glucocorticoids. If your pet suddenly begins to gain weight soon after starting a new prescription, you will want to inform your veterinarian to see if adjustments need to be made to the medication.


If the dog in question is an unsterilized female, the weight gain may be due to pregnancy. If you know that the dog has recently gone through a heat cycle or has had contact with any intact males, then this possibility should be examined. 


Dogs that experience stress and anxiety in their lives frequently stress eat and may consume more food than they need. Stress is also known to increase levels of cortisol, and when cortisol levels are increased for too long, it can cause wasting of the muscles and reduced calorie expenditure. 

Thyroid Disease

The thyroid disease most often responsible for weight gain in canines is hypothyroidism. If your dog experiences rapid weight gain accompanied by lethargy, a dull coat, or oily, greasy skin, your veterinarian should be contacted in order to run standard blood tests such as a complete blood count and biochemical profile to help detect any underlying disorders.



What to do if your Dog is Gaining Weight

If your dog is experiencing weight gain, you should consult your veterinarian to have a physical examination completed and to run the appropriate tests in an attempt to uncover any underlying conditions.

The treatment for overweight and obese dogs will vary somewhat from individual to individual. If your pet has recently started taking new medications, these drugs may require replacement or adjustment, and disorders such a thyroid disease, diabetes, or Cushing’s disease may require lifelong medication to manage. Stress can often be controlled through additional exercise, routine changes, and positive enforcement training, however, antianxiety medications may be recommended for severe cases. Once any underlying conditions have been addressed then dogs that have acquired additional weight will need to change both their diet and their exercise routine to reverse the situation. Your veterinarian may be able to assist you in designing an effective program of exercise and healthy food for your particular circumstances.



Prevention of Gaining Weight

Ensuring that your animal receives the correct amount of food for their individual metabolism and activity levels will go a long way in preventing weight gain. This includes reevaluating the animal’s daily diet and exercise routine on a regular basis in order to compensate for things like advancing age, neutering or spaying, and other factors that can influence changes in metabolism.

Regular veterinary screenings may also help catch imbalances in the levels of hormones or sugar in the patient’s blood before they become problematic. If these disorders are treated promptly, it may prevent some or all of the weight gain that they frequently cause.



Cost of Gaining Weight

The cost of treating this situation depends a great deal on if there are any underlying conditions affecting the animal’s weight and what those conditions might be. The general cost for treating obesity itself averages around $220, where diseases such as Cushing’s disorder or diabetes typically run in the $2000-$3000 range for the initial treatment. Many of these disorders also incur monthly prescription costs on top of the general treatment fees.



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Gaining Weight Questions and Advice from Veterinary Professionals



Irish Doodle


Two Years


0 found helpful


0 found helpful

Has Symptoms

Dry Patches

I have 2 female Irish Doodle dogs from the same litter. They had the same coat and skin, until one (Chloe)started to lose hair in very large patches and her skin began to get incredibly dry. Chloe lives with my mom and has pretty severe separation anxiety and anxiety more generally. We aren’t sure why her coat/skin is so dry or why her hair hasn’t fully grown back. Do you think that if we incorporated fresher, human grade foods that her coat might improve? She takes trazadone for her anxiety and our vet put her on a medical grade kibble with 3 pumps of added fish oil every day, no improvement.

Oct. 20, 2020



Dr. Linda S. MVB MRCVS


0 Recommendations

Hi there, you are through to Dr Linda. Fur loss is not typical and usually indicates an underlying issue. At her age, we would consider: Underlying skin disease (this would usually mean the skin is red and/or scabby and the dog would be itchy). Seasonal Alopecia (dogs lose fur, mainly on their flank and this tends to happen in Winter time). Alopecia x (though she is not the typical breed). A hormonal disorder such as hypothyroidism (though this would be rare at her age and we would expect other signs such as weight gain and lethargy). If these more common issues are ruled out, we may consider a skin biopsy to get a diagnosis. I doubt a diet change will have much effect as it sounds as if you are already addressing her dietary needs and providing skin and fur supplements. Feeding human grade, fresh dog food (assuming it is a prepepared, balanced diet) certainly won't do any harm but is unlikely to change things. Hopefully we get to the bottom of this soon!

Oct. 22, 2020

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