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Rapid Weight Loss in Dogs - What You Need To Know!

a happy looking pit bull sitting in tall grass

Oh no, your dog is suddenly losing weight! There are many reasons that your dog may have lost weight. Some of these can be due to an underlying disease, but sometimes your dog is just a little more active and needs to shed a few extra pounds. The article below will go into some of the most common causes of dog weight loss, and what you can do about it!

Healthy Weights in Dogs

Before you worry too much about your dog's weight loss, know what a healthy weight for them is. Some breeds are known to be overweight, while others are very energetic and always on the thin side. By understanding your dog’s breed, you can estimate an ideal body weight for your dog. Make sure that you are feeding your dog a high-quality dog food and the appropriate amount for the size of your dog. With regular veterinary checkups, you can maintain your dog at a healthy weight.

Top Causes of Rapid Weight Loss in Dogs

These many causes of rapid weight loss in dogs. Some of the top and most common causes are listed below. 


Diabetes in dogs is very similar to human diabetes. Your pet will be drinking a lot of water, therefore needing to go to the bathroom all the time. Also, dogs who suffer from diabetes will have sudden weight loss. An older dog who is overweight is at a higher risk of developing diabetes than younger fit dogs.


Some dogs have separation anxiety and will not eat when their owners are gone. This will cause the to lose weight very quickly. This is very easy to identify as there are usually other signs that are coupled with this such as:

  • Peeing and pooping indoors
  • Barking and howling
  • Destructive behavior
  • Running away or attempting to escape

If your dog has anxiety, many things can be done to help them. Make an appointment with your veterinarian to discuss different options.


A brown and white bassett hound standing on a white weight scale

Your dog may be losing weight because they are not eating or not being fed enough dog food. If your dog is not eating enough dog food, you will notice that they have a low energy level. They may also be more likely to get sick or see another disease more often. You will even notice that they have a very thin appearance. You will usually see their ribs, hips, and backbone. The easiest way to fix this is to increase the amount of food you are feeding them. Make sure that they are eating high-quality dog food.


Unfortunately, cancer is a major cause of rapid weight loss in dogs. If your dog is older and is suddenly losing weight, this may be an early sign that they have cancer. Some masses can be external and easily seen while most of the time, they are internal, and the sudden weight loss is the first thing you notice. If your dog has suddenly started to lose weight, make an appointment with your veterinarian to have them checked out for a reason why.

Liver Disease

Liver disease is another cause of sudden weight loss in dogs. Signs you will see with a dog with liver disease are:

  • Loss of appetite
  • Seizures
  • Rapid weight loss
  • Blood in urine or stool
  • Increased thirst and need to pee
  • Vomiting
  • Diarrhea
  • Yellowing of the eyes and skin

If you see any of these signs in your dog, they may have a problem with their liver. Your veterinarian can run a blood test to figure out what is causing the sudden weight loss and start your dog on liver supplements.

Addison’s Disease

A veterinarian in blue scrubs showing a red and white husky his medical charts

Addison's disease is another cause of sudden weight loss in dogs. Addison's disease is when your dog adrenal glands do not make enough of a steroid hormone needed by the body. Signs seen in dogs who suffer from Addison's disease are:

  • Vomiting
  • Diarrhea
  • Fatigue
  • Low blood pressure

Addison's disease is rare in most breeds but is commonly seen in standard poodles. Your veterinarian can run blood work to see if your dog has Addison's disease. If they do have this disease, your veterinarian will start your dog on medication to make them feel much better.

Treatments for dog weight loss

Depending on what is causing your dog to lose weight, there are many different options for treating weight loss from home.

CBD products

These products have been shown to increase appetite. This would be agreat supplement to add to your pets' diet to help them gain weight. Depending on what is causing your pet to lose weight, this will help them feel much better and want to eat. CBD products have also been shown to help decrease pain and inflammation, as well as help decrease anxiety. This makes it an excellent dietary addition for any dog.

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Change to high-quality food

Make sure that you are feeding your dog high-quality dog food. Even though they are eating the correct amount of dog food, if it is not a high-quality food, they may not be gaining weight.

Decrease Stress

If your house has suddenly become stressful, try changing your routine to decrease the amount of stress. Pets can also sense when their owner is stressed, and this will cause them to not eat as much.

As soon as you notice that your pet is losing weight, make an appointment to see your veterinarian. They can help you figure out what is going on and what can be done to fix the problem. No matter what is causing your pet to lose weight, the earlier you start treatment, the quicker your dog will return to normal.

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Dr. Sara Ochoa DVM

Dr. Sara Ochoa DVM
Since she was a little girl, she knew that her dream was to become a veterinarian. With a tremendous passion and love for animals that makes her a great source of knowledge for others. She lives happily with her husband Greg and her babies Ruby the Schnoodle, and Bam-Bam the bunny.

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