7 Tips To Help An Old Dog That is Eating But Still Losing Weight

old dog losing weight

Losing weight can be a concern when you notice your once well-conditioned old dog starting to shed pounds. Weight loss in senior dogs can occur gradually over time or rapidly, leaving you perplexed and eager to intervene.

Understanding the common causes of weight loss and ensuring your dog’s overall health is essential to address this issue.  Today in this blog, we aim to shed light on the causes of weight loss in older dogs and provide guidance on maintaining their health.

Read on to discover the secret to helping your old dog regain a healthy weight while continuing to enjoy their meals.

Why Is My Dog Losing Weight Even Though He Is Eating?

There are various reasons why dogs may experience weight loss despite eating.  Here, we will discuss some common causes of weight loss in older dogs with a healthy appetite.

Diabetes Mellitus

Diabetes occurs in dogs when a dog is unable to produce insulin to allow the body to utilize glucose.  Because of that, diabetic dogs will often drink and urinate a lot but can also lose weight. 

Diabetic dogs may lose weight quickly due to insufficient insulin production, affecting their ability to convert food into energy.  In addition to increased drinking, urination and weight loss- diabetic dogs also tend to develop cataracts.

Kidney Disease

Another disease that can lead to weight loss is kidney disease, especially as it gets to more advanced stages.  As dogs age, their organs, including the kidneys, may experience decline.  Chronic kidney disease is fairly common in older dogs with one study indicating that over 10% of dogs over the age of 15 can have it.

Patients with chronic kidney disease are also more susceptible to sudden worsening of the kidney disease, called acute kidney disease.  These pets can have difficulty maintaining muscle mass and often need to be on special prescription diets that have limited phosphorus among other things, to help manage the chronic kidney disease. 

Dogs with later stages of kidney disease can often have decreased appetite, lethargy and weight loss in addition to drinking and urinating more.  If you notice any of these signs, you should contact your vet.


Cancer can be one of the most common causes of an older dog losing weight despite eating.  Weight loss and loss of muscle mass are often early signs of cancer in old dogs.

Depending on the type of cancer and where it is located in the body, there can be many different signs.  Diarrhea, vomiting, lethargy, increased rate of breathing, a swelling or mass can all be different signs of cancer in a pet. 


For some dogs with more severe weight loss despite eating, you can see their hip bones stick out. If this is seen, it is very important to have them checked out.

Heart Disease

Weight loss can occur in older dogs with advanced heart or lung disease due to cachexia. This process leads to muscle wasting. If your dog has a heart murmur and you notice weight loss, consult your veterinarian for further evaluation.

Gastrointestinal Disease 

Chronic vomiting or diarrhea can lead to weight loss in dogs. Sometimes disease that is within the gastrointestinal walls can also cause weight loss and this can be anything from inflammation to cancer.

A few different causes of gastrointestinal disease that you can see in an older dog losing weight include inflammatory bowel disease, parasites, chronic foreign bodies or cancer.  In the clinic we will see a variety of gastrointestinal ailments causing weight loss in dogs.

Though not as common as other diseases like cancer in older dogs, you can even see older dogs eat foreign bodies! Last year, one of my favorite patients came in for weight loss, and it turned out she had eaten a bunch of hair ties that were stuck in her stomach. The hair ties caused a partial foreign body where they partially blocked the passage of food causing her to lose weight and regurgitate for months prior to seeing us. We were able to pick that up after bloodwork and x-rays and take her directly to surgery to get those hair ties removed. This is not commonly the case for an older dog, but still something we can see.   

Diagnostics such as bloodwork, ultrasound, and fecal tests may be necessary.

Inadequate Calories

In some cases, insufficient calorie intake can result in weight loss. Monitoring your dog’s food consumption and calculating their daily caloric needs is crucial. 

If multiple dogs share a bowl, switching to individual feeding is best to accurately track each dog’s intake.  Do not allow each dog to switch to other bowls, especially if you have a younger dog with an older dog.  This may prevent the older dog from getting the calories they need.

In other situations, if the dog is getting a lower calorie food but eating the same amount, that can cause inadequate calories and inadvertent weight loss as well.



7 Tips to Help an Old Dog Eating But Losing Weight


If you notice your old dog eating but still losing weight, here are a few tips to help them.  It is very important to work closely with a vet when you notice any of the signs we mentioned above. Things like uncontrolled diabetes can quickly become life-threatening, and any disease left unchecked can lead to discomfort that can be inobvious even to a loving pet parent. 

1. Vet visit

To help an old dog that is losing weight despite eating, it’s essential to identify the underlying cause. Schedule a visit to your veterinarian for diagnostic tests to uncover any diseases or illnesses. The appropriate treatment plan can be determined based on the diagnosis.

Often, for many older pets with weight loss, your vet will need to start with a physical exam and bloodwork, urine and fecal.  Many older dogs with weight loss will also need x-rays and even ultrasound to look further into the cause if the answer is still unclear.  Getting a weight on your dog when you’re there is key, too.

2. Keep A Food Journal

Keeping a food journal can really help quantify how much food your pet is eating.  To quantify exactly how many calories your dog eats daily, you want to measure their meals AND treats.  Yes, even that spoon of peanut butter you gave them!  Measure everything! 

This can be done with a cup for measuring kibble or even a gram scale for other foods.  Write all the food they eat into their food journal. If a pet does not finish an entire meal, subtract the amount left from the total calories eaten. 

3. Weigh Them Periodically

Weighing a dog once a week is reasonable to do at home. For some owners, their dog is small enough that they can weigh themselves and then weigh themselves with the dog and subtract the difference. 

For more accurate weights for smaller dogs, you can use a baby scale like this one here. For bigger dogs, I like this scale here, which is fairly easy to get onto and set up at home.

I do find that if you weigh your dog more than once a week, the mild fluctuations that can occur day to day may just cause panic so sticking to once a week or whatever frequency your vet recommends is better. That way, you can establish an actual trend, not just minute fluctuations.

4. Get a Food Plan

Talk with your vet about a food plan and an ideal amount of calories for your pet to get in order to gain or at least maintain weight. Having an idea of this and comparing to what they are eating can shed more light on what is happening. You can also ask your vet is a probiotic (sharing one of our favorites) would be helpful to support their GI disease.

5. Pursue New Tests

Sometimes after you’ve gone to the vet and done diagnostics- you still won’t have an answer. What I’ve found with many patients is that sometimes, the disease does not declare itself until a little later in the disease process. So, I will often recommend repeating a test like chest X-rays or bloodwork to compare and see if there are changes in them.  If you’ve already done X-rays but have not done an abominable ultrasound- you can consider that as well.

6. Quality of Life

Remember always to discuss quality of life with your vet. If you have worked through diagnostics and still can’t find an answer and feel your pet’s quality of life is decreasing, you will need to have a heart-to-heart with your vet about next diagnostics.  Sometimes, they will recommend a medication change other times they may recommend humane euthanasia if they think your pet is suffering. 

7. Enhance Their Diet

Pay attention to the amount and quality of food your dog consumes. Enhancing their diet with small amounts of boiled chicken breast (never give bones) or white rice can be helpful for those with a decreased appetite.  

If you notice a low appetite that is one very important reason to get your dog to the vet.  Dogs do not have great ways of telling us that they are not feeling good so any sign of decreased energy, lying around more, or a decrease in appetite is important to get checked out. 

If you want to learn more about what a senior dog needs for a diet, you can take our senior dog nutrition mini-course here.  We include basics of senior dog nutrition, complete and balanced homemade recipes for healthy senior dogs, and discuss how diet is important in common senior dog diseases.  Always consult your veterinarian before introducing any dietary changes.  Fresh food diets may also be something worth trying if your vet is okay with it.  


Key Takeaways!

When your old dog experiences unintentional weight loss, it’s crucial to determine the underlying cause to provide the best care. Schedule a visit to your veterinarian for diagnostics that can uncover any hidden issues. 

Dogs are experts at hiding illnesses, so even if they seem outwardly fine, weight loss often indicates an underlying problem.  By working closely with your veterinarian and making necessary dietary adjustments, you can address weight loss in your Senior Dog and ensure their overall health and well-being.



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