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What Can Cause a Dog to Lose Weight

Updated by Sheryl on Jan 11, 2022

What should you do if your dog seems to be losing pounds? Sudden weight loss in dogs might indicate some health problems. If your dog losing weight more than 10% in a very short period and there are no obvious external influences, you should be concerned.

Being alarmed and worried when you see your dog is losing weight. Dogs that are overweight and underweight are less likely to live long and healthy lives, so it's critical to maintain your dog's weight.

dog symptoms unexplained weight loss
  • Why Does Your Dog Look Normal and Healthy but Lose Weight?
  • Unhealthy Weight Loss
  • Causes Of Weight Loss
  • What Can You Do to Help Them Gain Weight?

Despite eating the same amount as before, your dog continues to lose weight. What can be the problem? Dogs' weight loss is typically not a reason for worry unless it occurs abruptly or without apparent cause. Losing weight may be a sign of a variety of health problems.

Here are 3 typical causes for your dog's weight loss:


Your dog may be losing weight because of stress. Here are two typical causes of stress for your dog: your recent relocation and the arrival of a new pet.

Poor Diet

A dog's weight loss might be attributed to improper nutrition. The following are some questions you should ask yourself about your dog's food. Is your dog getting the proper nutrients? Do you feed your dog high-quality dog food? Have you changed your pet's diet without veterinary approval?


Weight loss in dogs may be influenced by factors such as the surrounding environment and the outside temperature. Is it too cold in your dog's room?

Your veterinarian should know about any additional signs you've seen if your dog is underweight. These include:

  • Vomiting
  • Lethargy
  • Drinking more or less than usual
  • Peeing more than usual
  • Coughing
  • Increased appetite
  • Decreased appetite
  • Diarrhea
  • Panting or struggling to breathe

It's critical to follow your gut feelings if you suspect your dog suffers from a major medical condition due to its recent weight loss. Your veterinarian is the only one who understands your dog.

dog lose weight

An unhealthful weight loss in your dog occurs suddenly and rapidly and is accompanied by signs of weakness. Even slightly underweight dogs live longer than those who are overweight, but unexplained weight loss in dogs is a warning indication that your dog can be ill.

Since your dog's body contains around two-thirds of water. It's more likely that dehydration, rather than fat loss, may be the reason for rapid weight loss in dogs. Your pet may get dehydrated and lose weight under certain circumstances. So, it's critical to understand what's going on since dehydration can be fatal—unhealthy weight reduction results in mortality over time.

Weight loss in dogs can be caused by a variety of factors, including those listed below:

Intestinal Worms or Heartworms

Even though worms cause weight loss in dogs, the process is varied depending on the species. The nutrients are drained from dogs with intestinal worms. Heartworm-infected dogs spend a lot of energy because their hearts no longer contract properly. Due to the worms, their lungs no longer have regular blood flow.

Chronic parasite abuse affects the kidneys and liver of dogs with heartworm infections, making them work harder than usual.

Dental Disease

Eating becomes a difficult task for your dog if their mouths are sore due to hard tartar and plaque buildup, tooth root abscesses, or even fractured teeth. Finding out whether the dental disease is the root cause of your dog's weight loss might be as simple as watching how much food your pet consumes daily.
If you're unsure, ask your veterinarian to do a thorough oral examination of your dog.

Liver Disease

Sudden weight loss and a steady decrease in body weight can be linked to liver disease. The liver is a critical organ for detoxification and the production of coagulation factors and enzymes, that help in digesting, which is important to your dog's health.

Taking some toxins or drugs can harm the liver, as can having a disease related to the pancreas or the gallbladder system. Vomiting, a yellowing or jaundiced appearance of the skin, and fatigue are all frequent symptoms, as well as weight loss.

Failure Of the Kidney

Weight loss in dogs is often linked to renal disease. When this happens, the kidneys start to leak, and protein molecules flow out into the urine. No matter how much a dog eats, he will eventually go into starvation mode because his body cannot produce enough protein to sustain him.
There are many indicators of renal failure in older dogs, including increased water intake and urine and an increase in vomiting and diarrhea.

Diabetes Mellitus

Diabetes in dogs is a common medical condition that can result in significant weight loss. In dogs, diabetes-related weight loss is typically accompanied by additional symptoms, such as food aversion and deteriorating health. If your dog has drastically reduced its weight without any apparent cause, it can be showing indications of diabetes.
Some of the indications are excessive use of water, increased appetite, forming of cataracts, and frequent urination. Dog diabetes mellitus is the same as human diabetes mellitus in that it occurs when a dog does not produce enough insulin to break down blood sugar for nourishment properly.
Without adequate insulin levels, a dog's body will start metabolizing proteins and lipids for energy, resulting in catastrophic physical deterioration.

Gastrointestinal Illnesses

Food allergies, inflammatory bowel disease, and parasites are among the most prevalent gastrointestinal illnesses that cause dogs to lose weight. A dog's weight and muscle mass will decrease if it isn't getting enough nutrition and has chronic diarrhea. Examine the stool and other diagnostics with your veterinarian to rule out any of the issues mentioned above.


A dog's weight loss may be due to undiagnosed cancer. Dogs above the age of 6 tend to get cancer more often. Cancer, particularly malignant form, can be fatal. A dog's weight loss has been related to many malignant diseases, including lymphoma, osteosarcoma, and hemangiosarcoma.
Malignant tumors can induce weight loss in dogs because the tumor's metabolic needs, discomfort, and pain make dogs less active and reduce appetite. Other malignancies in dogs, such as oral melanoma, can cause swallowing and eating unpleasant, leading the dog to quit eating.

Several factors can contribute to your dog's weight loss, some of which are severe, while others are simple to address. As a result, if you find your dog is losing weight fast, make an appointment with Vets immediately.

Listed below are a few suggestions for your dog to gain weight. It's vital to keep a healthy diet and exercise regimen for good health.

snacks for weight

Snacks For Weight Gain

Snacks for weight gain can be an excellent way to enhance your dog's diet. To maintain a regular eating pattern, they make their diets more exciting and varied. Nutritionally packed dog snacks include elements that keep your pup feeling energized while also helping to minimize the negative impacts of weight loss.
Be aware of calorie count and age group recommendations so that your dog doesn't receive too much or too little of any of those things.

Foods With More Protein or Fat

Fat and protein are essential for puppy growth and development, as well as for healthy maturity. Even though these meals are more costly than standard dog food. Dogs in need of weight gain benefit greatly from diets high in protein and fat.
Changes in your dog's diet might cause an upset stomach, so start with a small amount of the new food in your dog's original diet to see whether it affects his digestion.

New Feeding Routine

Dogs and humans digest and metabolize food in slightly different ways, but they are otherwise quite similar. Consider feeding your dog a smaller piece of food in the morning and a larger portion at night if your dog eats twice daily like most dogs. Instead of burning fat while sleeping, this will boost his body's ability to retain fat.

More Exercise

It's common knowledge that exercise helps humans lose weight, but the goal of your dog's weight increase should be to add more muscular tissue. The easiest method to keep your dog at a healthy weight is to make sure it gets enough exercise regularly.


When to be concerned and see the vet?

Always consult your veterinarian if you suspect that your dogs & rsquo; weight loss has occurred rapidly. Weigh your dog every few days (for a couple of weeks) and bring this record to your visit if you're unclear whether or not he's losing weight.
A smart suggestion is to keep track of the food your dog has been consuming up to the visit, particularly if you recently altered the kind or quantity of food.

What should be fed for a dog that is losing weight?

Start giving your dog extra calories if you want him to gain weight. Try for the greatest quality meals you can afford, and make sure it's created with nutritious and healthful components. As a bonus, providing four smaller meals throughout the day will help your dog gain weight.


You should plan an appointment with your dog's veterinarian if you find your dog has abruptly lost weight. Sudden weight loss is sometimes an indication of serious chronic diseases like renal failure or diabetes. Once the reason of your pet's weight loss has been determined, your veterinarian will create a treatment plan just for him.

You could be requested to assist them in regaining their ideal weight by making dietary changes. If you're worried about your dog's weight, don't hesitate to contact your doctor right away. They'll be able to provide you with some guidance.

Sheryl is an editor from iPetor, owns extensive pet care experience. As a professional writer, she can provide useful pet care tips for all "parents".
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