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Unexplained Weight Loss in Dogs: What You Can Do at Home

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Dr. Mark is a veterinarian. He works mostly with dogs and also spends time training and caring for his own canine family.

Cheap food may cause severe weight loss.

Cheap food may cause severe weight loss.

Is Your Dog Losing Weight but Acting Normal and Appears Healthy?

If your dog is more active in the spring and summer, a little weight loss is normal. If it is excessive, however, the most common causes of losing weight are:

  1. Feeding low-quality food, even if it is only missing one vital nutrient.
  2. Not getting enough food, either because of not being given enough or not managing to eat it.

If you are feeding low-quality food, unless your dog has access to other food sources, you may be starving him without even realizing it. Some dogs will even stop eating cheap food that does not taste good. Unlike cats, they will not starve themselves to death, but they can become thin and weak if the food is very bad.

The solution? Switch your dog to a better diet right away. I recommend feeding a raw diet—natural whole foods like nature intended. Feeding a paleo diet is not expensive if you do not buy the “prepackaged” commercial raw foods sold in plastic. There are a lot of benefits to a natural whole diet, and dogs enjoy the taste.

It is also possible that your dog is not getting enough food, even if it is good quality. Watch the dog when he eats.

  • Does he have at least 15 minutes to eat his food?
  • Is there another dog in the household taking over the bowl before he even finishes?

What Can I Do at Home to Help My Dog Gain Weight?

  • Find out what is causing your dog's weight loss. Many medical problems will respond to a diet change but cannot be treated at home until you know what is wrong. If your dog is allergic to wheat, and you change him to a high fiber diet with a lot of wheat, do you think he is going to get better?
  • Treat your dog appropriately. (Feed a better diet, medicate for internal parasites, treat chronic infection, regulate sugar levels in cases of diabetes, treat cancer, etc.)

If your dog is healthy, and there are no medical reasons for his weight loss, you can try several things:

  • Try a different food or feeding schedule. If you are feeding him with another dog, try allowing him to eat in a separate room. If he is eating alone, allow him to eat with your other dog or feed him when you are sitting down for your own meal. (Dogs are social and almost always prefer to eat with others.)
  • Watch your dog and make sure he is eating what you give him.
  • Supplement his diet. Coconut oil is a great supplement for his weight and contains antioxidants that will keep him in even better shape. Every dog should also receive some fresh food, so even if you feed your dog a commercial dry diet, you can give him a raw chicken wing every night as a calorie supplement.
  • Yogurt is a great natural supplement. You can put this on his food or just give it in a bowl, and in either form, it is going to improve the bacterial flora in his GI tract.

Are you sure that your dog is healthy? If he is urinating excessively, having loose stools when you take him out, is straining when he needs to go, or having accidents in the house, there is something abnormal going on.

Common Causes of Weight Loss

  • Dental disease
  • Chronic inflammation and infections
  • Diabetes
  • Protein-losing diseases (Parasites, draining wounds, etc.)
  • Cancer
  • Maldigestion/malabsorption
  • Elevated metabolic rate
  • Less common diseases (Addisons, copper toxicity, esophageal paralysis, and others)

Weight Loss in Dogs Despite a Healthy Appetite and Eating

Dental Disease

Open your dog's mouth and take a look inside. Some problems are obvious. Are there any broken teeth, swelling in the gums, or a pus discharge when you press down on his gums? If your dog has any of these dental problems, he is probably in pain and needs to see his vet right away. This should always be the first thing to check in a senior dog that is losing weight.

Chronic Inflammation and Infection

Dogs with a chronic inflammatory condition, like arthritis, may stop eating normally because of pain. A chronic infection can be something as simple and easy to treat as worms, something more serious like heartworms or Rocky Mountain Spotted Fever, or even something like a chronic skin infection that your dog is using all of his energy to combat.

Sometimes, a dog with a chronic infection will appear normal. An infection, however, is one of the most common causes of sudden weight loss. Like most of the diseases that cause weight loss, your dog will need to be diagnosed through simple blood work before he can be treated. An elevated white blood cell count will tell the vet that your dog has an infection, even if it is not obvious at the first examination.

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If your dog is losing weight and also has hair loss and pale gums, which is a sign of severe anemia, internal parasites should be suspected. The vet will check a stool sample for eggs from worms, and his skin might need to be scraped under a microscope to examine for mange.


If your dog is losing weight and drinking lots of water, be sure to find out if he has diabetes. Besides losing weight, one of the common symptoms of diabetes in dogs is excessive thirst. With excessive thirst, of course, the dog will have to urinate excessively, and it is unlikely that he will be able to hold his urine all night. If your dog is losing weight and drinking a lot, having “accidents” in the house even after being housetrained, the first thing to do is have a physical exam and blood work.

Diabetes is only one of the problems that can cause excessive thirst and urination. Diabetes is most frequently diagnosed in older dogs, and usually in females. Once your dog has lost the fat in her body, she will start to lose muscle mass. If your dog is losing weight and having accidents, be sure to get her to your vet for a physical exam and blood test today. A new diet will help, but the most important thing that can be done is to regulate blood glucose.

Kidney Disease

One of the ways in which chronic kidney disease causes weight loss is called “protein-losing nephropathy.” In this condition, the kidneys leak and protein molecules spill out into the urine. No matter how much a dog eats, he cannot keep enough protein in his system to remain healthy, and without proper treatment, he will waste away.

Some other internal organs can also cause weight loss when they fail. The heart is one example of this, so all dogs with weight loss will have their chests examined to rule out “cardiac cachexia.”

If your dog is losing weight and is vomiting, get him checked out immediately. All of the diseases associated with kidney disease can be discovered by a simple physical exam and blood work.


This disease can strike in many different ways, but one thing you can watch out for is weight loss. If your old dog is losing weight and also appears to be losing a lot of muscle mass, and you have ruled out diabetes, this is something you should be worried about. The tumor or tumors starts drawing away the nutrients that the dog needs to keep the rest of his body healthy.

Diagnosing cancer can be difficult, but when it is found early, the chances of treatment are a lot better. If your older dog is losing weight with or without a good appetite, the cancer may have already spread so get your dog checked out right away.


Several different diseases can cause a dog to lose weight despite a healthy, even voracious, appetite. Dogs will have diarrhea and light yellow stools several times per day. Sometimes it will smell especially foul, like when dogs are suffering from Small Intestinal Bacterial Overgrowth.

When the pancreas is destroyed, no enzymes are released into your dog's GI tract, and he can suffer from maldigestion/malabsorption. All of the important nutrients that your dog eats every day pass right through his GI tract and are never absorbed. Some dogs can also be sensitive to gluten, and the little “fingers” (villi) in the small intestine die off and no longer absorb the nutrients passing through the GI tract.

Although dogs with maldigestion and malabsorption can have diarrhea and light yellow stools, that symptom alone is not enough to diagnose the problem. Like many other diseases that cause weight loss, he will need to have a physical exam from your vet and when the problem is recognized his stool can be looked at under a microscope, and his blood tested for digestive enzymes. Some dogs even need a biopsy of the intestine before this problem can be diagnosed.

If your dog is losing weight and vomiting or has diarrhea, or if your dog is losing weight and having gas, having your vet examine his stool is an important part of finding out what is wrong.

Unexplained weight loss is often caused by a disease.

Unexplained weight loss is often caused by a disease.

Tests Your Vet Might Require

These are the tests most likely to be needed. I have listed the most common tests at the top of the list, but if your dog is still sick, more of these tests will need to be done.

  • Fecal studies to look for intestinal parasites.
  • Complete blood count (CBC) to look for infection, inflammation, leukemia, anemia, and other blood disorders.
  • A biochemical profile that will evaluate kidney, liver, and pancreas function, and the status of blood proteins, blood sugar, and electrolytes.
  • Urinalysis to determine kidney function, to look for infections/protein loss from the kidneys, and to determine hydration status.
  • Chest and abdominal x-rays to observe heart, lungs, and abdominal organs.
  • Tests to evaluate the condition of the pancreas.
  • Ultrasound of the abdomen.
  • Bile acids test to evaluate liver function.
  • Hormone assays to look for endocrine disorders.
  • Using a scope to view the intestines (endoscopy) and biopsy.
  • Exploratory surgery (laparotomy).

What Should I Do to Help My Dog?

There are many reasons that a dog can lose weight. Many of those things can be managed at home, but almost none of them can really be dealt with until you find out what is going on. Even if you can tell what is going on, unless you have a specific diagnosis, you are not helping him out by trying alternative treatments.

There are several different methods to treat your dog's weight loss naturally. In order to start any treatment plan at home, however, you need to find out what is wrong.

If your dog is losing weight, make an appointment with your vet, and find out what is wrong.

Further Reading on Dogs


  • Ettinger and Feldman: Textbook of Veterinary Internal Medicine, 6th edition, St. Louis, 2005, Saunders

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2018 Dr Mark


Dr Mark (author) from The Atlantic Rain Forest, Brazil on March 20, 2020:

Leroy, I wrote this in bold above:

If your dog is losing weight, make an appointment with your vet, and find out what is wrong.

No one can tell you for sure why your dog is losing weight based on information on the internet.

Leroy on March 18, 2020:

I need help with my dog she is ill lost weight not eating properly can barely get up to walk please

Dr Mark (author) from The Atlantic Rain Forest, Brazil on June 01, 2018:

Hi Bob, for some reason I did not get an email that your comment was here. I hope you are doing well.

I saw a few of those skinny cats when i was living in the US. It is usually when the owner goes away, the animal becomes upset and stops eating, the liver sends signals that supresses the appetite, the cat eats less....Some of them become better with force feeding, some of them died. I have not read about that drug, but is sounds like a good move.

I know what you mean about obesity though. When you type in "weight loss" into search it comes up with articles about how to get your dog to lose wieght, not what to do if the dog is losing weight too fast. You have an idea of what those northeasterns are thinking: got any suggestions for a name change here?

Bob Bamberg on May 29, 2018:

Good info, Doc. It's strange that I just wrote a newspaper column on unwanted weight loss in cats. What prompted the column was that FDA just cleared the first animal drug to treat unwanted weight loss in cats. That's not a problem here in the colonies, though. Americans are loving their pets to death, with over half of dogs and cats overweight or obese. It's considered an epidemic here.

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