Why Is My Dog Gaining Weight: Is It the Food?

Let’s address gradual unexplained weight gain in dogs. The potential causes are different than when the weight gain happens suddenly.

How fast something happens is an important part of the picture. The more acute the onset, the more urgently you need to seek answers. With weight gain, the faster it happens, the closer you are to an emergency situation, particularly when there are any other concerning symptoms.

In other words, acute weight gain is more likely distention or swelling rather than true weight gain.

Why Is My Dog Gaining Weight: Is It the Food?

Recognizing the change

The biggest problem is that gradual changes are hard to recognize. Your veterinarian, friends or family members who don’t see your dog daily are more likely to notice that your dog became chubby easier than you can. If they point that out to you, please don’t be offended. It is in your dog’s best interest that you hear them out and evaluate what your dog’s weight should be.

Ideal body score

The first step is knowing what your dog’s body should look and feel like.

There is an objective way to determine whether your dog packs more fat pad than is good for their well-being. It is called body condition scoring. This system allows you to easily determine your dog’s condition regardless of their breed and individual differences. The evaluation involves the following:

  • can you feel your dog’s ribs easily?
  • does your dog have a visible waistline?
  • is their tummy tucked upward?
Canine body condition scale
Purina Body Condition Score

If the curves on your dog start disappearing, your dog is putting on some extra pounds. Dogs shouldn’t be shaped like tubes.

Obesity is not an aesthetic problem, it comes with ramifications to your dog’s health.

Further reading: Obesity in Pets – Common Causes & Consequences

Don’t be deceived

“Look how she’s beautifully filling in.” Today, if somebody says that about my dog, I break out in cold sweat.

That’s what people kept saying when Jasmine started losing her youngster all-legs look. We were none wiser. After all, she was a Rottweiler – those are supposed to be big, right? Then we adopted Bruin who was huge. Just seeing the two side by side made Jasmine look tiny.

It wasn’t until we were trying to get to the bottom of a completely different problem when her vet finally noticed that she might be chubbier than she should be. As it turned out, she had an under-active thyroid.

Once treated, the extra weight just melted away.

As we became more aware of what Jasmine’s body condition should be, I got serious about keeping her that way. Then she started getting heavier again. I kept reducing her food to the point where I felt that she could not get any less. When discussing her weight with the vet I insisted that I cannot and will not feed her any less food.

We tested her thyroid again, and, in spite of being well managed with medication for quite some time, her levels had suddenly dropped. Adjusting her meds got things normalized once more.

Your dog put on some extra weight. Why?

It is always the “why” that leads to a solution. Quite often the answer to weight gain is simple:

  • too much food
  • too many treats
  • wrong food or treats
  • insufficient activity …

Be honest with your vet and particularly yourself. If the answer is simply too many bacon bits, the solution is unpleasant but straightforward.

What if you are positive, like I was, that your dog does not get an excessive amount of calories? There is, actually, a formula that allows you to calculate roughly how many calories a day your dog needs. The formula does look a bit scary but these days, there is an app for everything.

If you do want to calculate your dog’s energy requirements, the formula and instructions can be found on petMD.

The next important step is to add up how many calories your dog gets in a day. The tricky part is to calculate EVERYTHING, including any treats, table scraps, or supplements.

Medical reasons behind weight gain

What if your dog gets just the right amount of calories and still gaining weight?

If the answer isn’t in the bowl, it is in the body.

There are a number of medical causes behind weight gain or the appearance of weight gain. It does make sense that metabolic diseases would have a direct impact on weight gain or weight loss.

Some of the conditions that cause weight gain in dogs include:
  • pregnancy
  • parasites
  • hypothyroidism
  • Cushing’s disease
  • some medications
  • conditions that cause fluid retention
  • tumors

Each of the above problems comes with their own array of additional symptoms which can help to solve the puzzle.

For me, if my dogs start gaining weight without eating more or exercising less, hypothyroidism is a prime suspect. Low thyroid function leads to a sluggish metabolism which means that however little energy is consumed it gets stored as fat instead of being used.

Other signs of hypothyroidism in dogs include:
  • skin and coat changes
  • exercise intolerance
  • lethargy
  • behavioral changes
  • intolerance to cold

Cushing’s disease is caused by an overproduction of hormones that are involved in protein, carbohydrate, and metabolic regulation. A dog with Cushing’s disease will gain weight while muscles are wasting. The typical potbelly seen with Cushing’s disease is caused by fat shifting into the abdomen and a weakening of abdominal muscles as well as enlarging liver.

Other symptoms associated with Cushing’s disease include:
  • increased thirst and urination
  • urinary accidents
  • increased appetite
  • excessive panting
  • hair loss

As you can see that many symptoms are similar across various medical problems. That is another reason you need to work with your veterinarian to get to the bottom of things.

If your dog starts putting on weight, do pay attention.

Related articles:
Sudden Weight Gain in Dogs: Why Has My Dog Expanded in Front of My Eyes?
Is Your Dog Struggling with Weight in spite of Diet and Exercise? Cookie Is Hypothyroid

Symptoms To Watch For In Your Dog: Unexplained Weight Loss

Further reading:
7 Medical Causes Behind Weight Gain

Categories: SymptomsUncategorizedUnexplained weight gain

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Jana Rade edited by Dr. Joanna Paul BSc BVSc

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience. Dr. Joanna Paul BSc BVSc is our wonderful sponsor and has been kind to edit and fact-check my important articles.

  1. Great article.Buffy is on the heavy side, although no where near as heavy as when I got her from my mom. It’s my fault, since I give her too many treats. She also gets to help clean the dinner dishes, which she loves. But I do weigh her once a week by picking her up and weighing myself, so I keep her at about the same weight and feed her less if there is an unexplained gain. She’s not very active and that is part of the problem. Blind dogs can’t chase the ball very fast or she runs into things.

  2. Marjorie Dawson

    The body score chart is so interesting! I would have thought the ‘ideal weight’ is a little bit too thin, so I got that wrong. There are so many things that can make a dog loose weight aren’t there?Your post is not only helpful, it could help a dog owner save a pet’s life. As usual I would be at the vet like a shot if I was worried about weight gain.

    Thank you.

  3. Cathy Brockway

    I always learn something new from your posts. Thanks for including the body condition score chart. I think it really helps to have a visual to compare with your own dog.

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