Why is My Dog Gaining Weight?

why is my dog gaining weight

Weight is always something you should be keeping an eye on because it can lead to other health issues. Older dogs are especially susceptible to abnormal weight gain. Weight gain is also more likely to be the sign of another problem in older dogs. The weight can put other stresses on their aging bodies. Here are some reasons your older dog may be gaining weight and what you can do to help.


A poor diet will cause slow, gradual weight gain. It can be easy to miss. The main reason diet can affect older dogs is because their metabolism slows down and so does the ability to use the calories they eat. A diet problem doesn’t mean that your feeding your dog “bad” or low quality food. Your probably just not feeding your dog the right food for their size, activity level, or overall health.

Your dog is also less active when older, so the treats or extra food you give them is just building up. It doesn’t just happen overnight! You need to take into account all aspect of your dog’s life to figure out what food to feed them. A poor diet can also cause an imbalance in nutrients that can show through dry skin/coat, dull eyes, diarrhea or constipation, low energy level, and behavioral changes.

Thyroid Problems

Humans can suffer from thyroid problems that cause weight gain and dogs can too! The thyroid gland produces hormones which control metabolism. When the hormone is under produced, it is called hypothyroidism and can be seen in medium/large older dogs more frequently.

You should go to the vet if you suspect your dog is experiencing a thyroid problem. They can run a blood test to be sure. Some symptoms that your dog’s weight gain could be related to thyroid are…

  • Dry, dull coat
  • Unusual hair loss or thinning coat
  • Skin changes  (Itchy, darker, or thicker)
  • Lethargy

Cushing’s Disease

This is another disease that mostly affects older and middle aged dogs. The weight gain in Cushing’s disease is caused by too much of coristold, a steroid hormone. This hormone controls metabolism and other bodily functions. Some of the other symptoms you’ll see with Cushing’s are increased appetite, a large belly, increased thirst, excessive urination, hair loss, and loss of muscle tone and strength.


Of course, diabetes can affect dogs of all ages, shapes, and sizes, but it is more common in older dogs. Sudden weight gain AND sudden weight loss can be signs of diabetes, as well as lethargy and increased thirst and urination. Again, the only way to be confirm your dog has diabetes is to go to the vet and have a blood test done.

Other Reasons

Older dogs can also gain weight from stress, water retention, or medications. Some breeds are also more likely to gain weight than others. Dog breeds that are more prone to gain weight when they are older include Labrador Retrievers, Basset Hounds, Beagles, Rottweilers, Spaniels, St. Bernards, Bulldogs and Dachshunds.

So what’s next? The first step if you feel your dog is overweight is to go to the vet. They can do blood tests to confirm or deny any diseases. Weight gain in older dogs is just a part of their lives, so don’t worry too much!

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