Why is My Dog Suddenly Losing Weight? Dog Losing Weight But Eating (Early access for our Patreon community)

Google Adsense—>

Raising Your Pets, Dogs and Cats Naturally

My Dog is Losing Weight

Why is my dog losing weight?
Learn why your dog may be suddenly losing weight.

There are times when you may need to put your dog on a weight-loss program, but sometimes a dog may have sudden, unintended weight loss. If your dog suddenly and unexpectedly starts to lose weight or can’t put on weight, you’ll want to continue reading and hear what our veterinary professionals had to say.

Possible Causes of Sudden Weight Loss in Dogs

I spoke with a few leading veterinarians regarding possible causes of sudden weight loss in a dog.

Dr. Amanda Nascimento, DVM at NHV Natural Pet said, “Like us humans, our furry friends’ body weight varies over the years; they can experience periods of weight gain and loss. However, it is essential to identify what is causing this varying weight.”

Dr. Nascimento also stated, “Weight variations in and of themselves may be temporary and do not necessarily pose a health risk. Such variations could be caused by factors like seasons. For example, during summertime, it is common that your pet’s food consumption decreases and activity may increase.” She continued by saying, “Stress may cause minor fluctuations in body weight. Diet changes can also affect a dog’s weight.”

When I spoke with Dr. Joel Navratik of MRVL Pet, he informed me that, “Pets can lose weight due to a number of medical conditions. These may include liver, kidney, heart, gastrointestinal, infectious, or respiratory disease.”

Dr. Nascimento discussed some serious diseases that may cause unexpected weight loss in a dog. She stated, “Gastrointestinal diseases, which generally present as vomiting, diarrhea, constipation, and/or lethargy. These symptoms can cause a lack of appetite and weight loss.”

She went on to say, “Chronic kidney failure, or when the excretory and/or metabolic function of the kidneys is affected. This can cause loss of appetite. Megaesophagus can also be a concern. Dogs with this condition have an enlarged esophagus that is unable to transport food effectively.”

Dr. Nascimento also informed me, “Diabetes is a common disease in dogs (especially in senior dogs) that can lead to weight loss. Cancer, especially intestinal cancer such as lymphoma and/or lymphosarcoma, can be one of the causes of weight loss in dogs. Again, this is more common in senior dogs.”

Why is my dog losing weight
Suddenly losing weight

Dr. Sarah Wooten, DVM, CVJ, a veterinarian for Pumpkin Pet Insurance added, “Unintended weight loss in a dog is almost always a cause to visit the vet.” Dr. Wooten said, “Cachexia refers to severe weight loss and wasting secondary to an underlying disorder like cancer or heart disease. Dogs with cachexia lose a significant amount of fat and muscle.”

She also said, “Sarcopenia refers to muscle loss without a change in body weight. This is common in older dogs and may also happen secondary to disease conditions.”

Dr. Wooten continued by stating, “Loss of lean body mass, in both cachexia and sarcopenia, is debilitating to dogs, and can result in fatigue, weakness, shortness of breath, and shortened life span. Causes can include: Systemic disease (cancer, heart disease, hormonal disorders like Addison’s disease or diabetes, kidney failure, sepsis, chronic fever, inflammatory bowel disease, severe intestinal parasites, protein-losing gut or kidney disease, exocrine pancreatic insufficiency, etc.), dental disease, loss of sense of smell, difficulty swallowing, or problems with vomiting or regurgitation.”

How to Diagnose the Cause of Weight Loss in a Dog

When I asked Dr. Navratik the best route in diagnosis, he offered this advice, “Diagnosis would be determined by following the symptoms first to identify a set of tests necessary to determine the cause. For instance, if the pet is vomiting or having diarrhea the first test might be a series of radiographs and an intestinal parasite screen. If there is a fever, a blood test would be chosen first. If there is excessive thirst or urination then likely a blood and urine screen.”

Dr. Nascimento also explained, “Your veterinarian may ask you some questions, such as how the appetite of your pet is, if he has difficulty swallowing, or how is the appearance of the stool. Your vet will also ask if your dog is spayed or neutered, if he/she receives heartworm preventive treatment, etc. These questions are usually complemented by a physical examination, bloodwork, analyses of the urine, feces, and even x-rays or ultrasounds.”

Are Senior Dogs at More Risk for Sudden Weight Loss?

Now that Dexter is officially a senior (almost 14), I always like to be aware of what might happen down the road. I asked our veterinary panel if senior dogs were at more risk for sudden weight loss and why.

Dr. Nascimento told me, “Senior dogs are more prone to certain diseases, and metabolic alterations from disease can contribute to weight loss or gain.” As she mentioned earlier, diabetes and intestinal cancer are prevalent in senior dogs.

Dr. Navratik agreed, “Yes, senior pets can develop sarcopenia which is basically just muscle atrophy due to not using the muscles. This may be due to arthritis, pain moving, or just inactivity.”

When to take your dog to the vet
Seek veterinary assistance.

Final Thoughts

As you can see, there are many possible reasons why a dog may suddenly lose weight. It’s always important to seek the guidance of your dog’s holistic veterinarian. Dr. Nascimento agreed saying, “If you observe that your dog is losing body weight without any explanation, it is advisable to visit a veterinarian as soon as possible.”

Remember, online pet blogs like mine, offer you insights, not a medical diagnosis. Your dog is counting on you to ensure he receives the proper veterinarian care.


Your questions or comments are welcome below.

Are you looking for even more ways to stay up to date with Raising Your Pets Naturally? Sign up for the newsletter for more tips and promotions. Don’t forget to be social and Like, Follow and Subscribe. Comments below are always welcome.

Facebook   Twitter   Pinterest   Instagram  YouTube

Cavalier King Charles Spaniel Facebook Group
Cavaliers, join us on Facebook!

Natural Pets Facebook Group
Dogs and Cats, join us today!


Pets at home cards, keychains and decals
Order your pets at home window decals and key chains.

Support our Work

If you found my blog helpful, please consider a small contribution. Dexter and I thank you!

Google Adsense—>

Why is My Dog Suddenly Losing Weight? Dog Losing Weight But Eating (Early access for our Patreon community)