Losing Weight in Dogs

Why is my dog losing weight?

What is Losing Weight?

Your dog appears thinner to you so, you rub your hand over his side and notice that his ribs are more prominent.  Then you look down and realize that you can see his waistline; just a few weeks ago he was borderline overweight. Do not delay in visiting the veterinary clinic, particularly if your companion has accompanying symptoms like nausea, lethargy, or lack of interest in food. Rapid loss of weight may be from:

  • A change of diet
  • Anxiety
  • Periodontal disease
  • Parasites
  • Malabsorption disorder
  • Pancreatitis
  • Diabetes

Rapid weight loss or weight loss of more than 10 percent of the dog’s body weight may be an indication of a serious problem. Consult your veterinarian for an evaluation of your pet if you are concerned that the scales are showing a loss.

Why Losing Weight Occurs in Dogs

The reason your dog is losing weight will depend upon its cause. For example:

Change of Diet

A change of diet may make a dog turn his nose and rebel against his new food.  A new diet may have fewer calories, which will cause weight loss. A few pieces of boiled chicken or broth on top of the new diet may entice him to eat his new diet.


Anxiety can cause a dog to lose his appetite.  A recent move, the death of a loved one, a new pet, or construction work in the neighborhood may cause a dog to be to be stressed and not want to eat. He will need lots of love and reassurance. Hand feeding him in a quiet room may get him to start eating.

Periodontal Disease

Periodontal disease can include gingivitis, and loss of bone and soft tissue. Periodontal disease can lead to loose painful teeth, which can deter your dog from eating. 


Dogs with intestinal parasites can experience weight loss.  Parasites such as tapeworms and hookworms rob your dog of nutrients. Even though your dog is eating, he is rapidly losing weight.

Malabsorption Disorder

A malabsorption disorder causes the deficiency of nutrients in the GI tract. Conditions such as inflammatory bowel disease, intestinal cancer, intestinal bacterial overgrowth and villous atrophy can cause weight loss.


Pancreatitis is the inflammation of the pancreas. The pancreas produces enzymes, which aid in food digestion, and also makes hormones such as insulin. When the pancreas is inflamed it can overflow enzyme into the abdominal cavity.  These enzymes can cause damage to the other organs such as the liver, stomach, gallbladder, bile duct and intestines.


Insulin-deficiency diabetes is the most common type of diabetes in dogs.  This condition is caused when your dog’s pancreas is not producing enough insulin. The pancreas may be damaged and/or not functioning properly.

What to do if your Dog is Losing Weight

If your dog has been losing weight rapidly, he should be seen by a veterinarian. A veterinarian can go over the patient’s medical history, perform a physical exam and run diagnostic tests, which can help determine the cause of the weight loss.  The diagnostic tests the veterinarian may recommend are a complete blood count (CBC), serum chemistry panel, x-rays, ultrasound, urinalysis, fecal exam and a biopsy. 

The treatment of the weight loss will depend on the diagnosis. Periodontal disease may be treated with dental cleaning, removal of diseased gums, periodontal surgery and antibiotics. Loose teeth may need to be extracted. Parasites will be treated with a de-wormer. Malabsorption disorders may need a change of diet, antibiotics, and anti-inflammatory medications.  Patients diagnosed with cancer will need to be seen by an oncologist veterinarian, who may suggest surgery, chemotherapy and radiation therapy. Pancreatitis may be treated with smaller more frequent meals and anti-inflammatory medications.  Diabetes is usually treated with daily insulin injections. 

The seriousness of the weight loss will depend on the diagnosis.  Dogs suffering from anxiety will be fine with behavior modifications and patience. On the other hand, patients diagnosed with cancer will have a more guarded prognosis.

Prevention of Losing Weight

A balanced and nutritional diet is essential to your pet’s health.  Table scraps and fatty treats are not good for your pet. Additionally, most commercial dry dog foods are full of additives, dyes and preservatives. They are made with by-products and plant sources, which are not good sources of protein for a dog. It is important to read the ingredient label.  The first ingredient on the label should be a protein such as chicken, beef or lamb.

Commercial dog food has been linked to autoimmune diseases, allergies, kidney, pancreatic and liver disease.  In addition, the preservatives and additives in some foods can be carcinogenic.  The preservatives butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) should be avoided. A better quality dog food or a homemade diet may help prevent future health issues in your pet.

Yearly teeth cleaning for dogs may help prevent periodontal disease. Many conditions and diseases cannot be prevented but they can be diagnosed in the early stages, during yearly wellness visits. The earlier a condition is diagnosed and treated the better the recovery prognosis is.

Cost of Losing Weight

The treatment cost for dogs that are losing weight can vary, depending on the underlying condition diagnosed. For example, treating anxiety may have no costs, while the treatment of diabetes may be around $3000.

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Losing Weight Questions and Advice from Veterinary Professionals


American Bulldog




9 Years 5 Months


0 found this helpful


0 found this helpful

My pet has the following symptoms:
Weight Loss
Problems Uriniating
She wasn't eating at all for a few days now she is eating but there isn't a gain in weight

Aug. 30, 2017

0 Recommendations

After a bout of illness when a dog has lost weight, it may take a while for the body to fully recover and to start putting weight again; to is more important that Rayne doesn’t lose any more weight. Offering more food or a high-calorie canine supplement may help but if Rayne had a severe case of gastrointestinal upset, it may take her system a little bit of time to start working properly again (malabsorption or fast digestive transit). If you are not noticing any improvement in weight over the next week or you are noticing she is losing more weight visit your Veterinarian for a check over. Regards Dr Callum Turner DVM

Aug. 30, 2017

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Rhodesian Ridgeback mix




12 Years


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0 found this helpful

My pet has the following symptoms:
Weight Loss
My dog has been slowly losing weight over the last 18 months after being diagnosed with hypothyroidism and Cushings disease. He was put on thyroxine and Vetoryl. While he did have symptoms of Cushings (excessive drinking and panting), he did not have symptoms of hypothyroidism (weight gain, lethargy), other than his T4 blood test. His eating habits, energy level, etc have not really changed and he seems as normal as ever, but yet he still loses weight. He has lost about 15 lbs during this time and continues to lose. Following an ultrasound, One vet thinks it’s likely cancer of the gall bladder, but can’t be sure without expensive exploratory surgery and biopsy.

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