Dog Losing Weight: Causes, Solutions, and When to Act

dog losing weight
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It is typical for a dog’s weight to fluctuate slightly over time. If you shift their diet to something they don’t like, they’ll probably lose a few pounds. Or if they are staying indoors more throughout the winter, in which case they will likely gain weight. But what if your dog keeps losing weight and you’re not sure why? Unexplained weight loss can be the first indicator of a health issue. Here’s all you need to know.

Why Is My Dog Losing Weight?

There are numerous causes of weight loss in dogs. Diet, environment, and health issues in dogs could all be at fault. The following are some of the most common reasons for unexplained weight loss:

  • A problem with their diet
  • Stress
  • Exercise
  • The surroundings
  • Reproduction
  • Dental disease and other oral health issues
  • Worms in the intestines and other parasites
  • Cancer
  • Gastrointestinal (GI) tract disorders
  • Nasal issues
  • Type 2 diabetes
  • Exocrine pancreatic insufficiency (EPI)
  • Infections
  • Kidney and liver problems
  • Cardiovascular disease
  • Addison’s syndrome
  • Hyperthyroidism
  • Neurological disorders

Why Is My Dog Losing Weight But Still Eating?

It is totally natural for your dog’s weight to fluctuate during its life. Diet, age, breed, and health issues can all have an impact on your dog’s weight and cause weight loss. If you see that your dog is eating well but still losing weight, consult your veterinarian as soon as possible. 

While dogs might lose weight for a variety of reasons, losing weight is never natural unless your dog is on a diet. Don’t be alarmed if your dog suddenly drops a lot of weight despite having a strong appetite! Instead, take your dog to the veterinarian so that they can diagnose the problem and treat your canine. 

The following are the most prevalent reasons why your dog is losing weight while eating:

#1. Dietary Modifications

Diseases do not always cause weight loss in dogs. You might be shocked to find that one of the most prevalent reasons of weight loss in dogs is changing their food. 

You might believe that this can’t be true because I haven’t changed my dog’s food in years. However, just because your dog is eating the same brand of kibble as before does not guarantee that the manufacturer hasn’t changed the formula. 

You continue to feed your dog the same amount of dog food as previously, not suspecting anything, yet the new formula has 10% fewer calories. At the end of the day, your dog consumes fewer calories than it requires and, as a result, begins to lose weight sooner or later. 

Because many dog diets are labeled in a confusing manner, these modifications are easy to overlook. So, before you assume your dog is unwell, read the ingredient label and see how many calories are in each serving. 

If the diet remains the same, make an appointment with your veterinarian. However, if the formula has been changed and has fewer calories, simply feed your dog more of it. 

#2. Intestinal Parasites

Weight loss caused by intestinal parasites is not as common as it once was, but it is still a possibility. 

While the majority of dog owners keep up with monthly deworming treatments, which protect against intestinal parasites and heartworms, there are many different types of intestinal parasites, and not all deworming treatments are equally effective. Many treatments, for example, cannot eliminate whipworms, but your dog can become infected by consuming the eggs from polluted water or dirt. 

The biggest problem with intestinal parasites is that they consume all of the dog’s food, depriving it of all essential nutrients. If your dog is eating a lot but losing weight, intestinal parasites could be to reason. 

#3. Diabetes

Unfortunately, diabetes is frequently detected in older dogs, particularly females. Diabetes causes dogs to lose weight quickly because their bodies can’t acquire energy from glucose and instead try to convert fat or protein into energy.

If your senior dog is losing weight but eating and is also drinking a lot of water, you should take them to your veterinarian. Most diabetic dogs lose weight quickly and may begin to lose muscle mass. 

Furthermore, because diabetes causes extreme thirst, your dog may need to urinate frequently and may have accidents in the house even if fully housetrained. 

#4. Maldigestion 

Exocrine pancreatic insufficiency, for example, impairs the body’s capacity to break down meals into useful nutrients. This means that all of the vital nutrients that your dog consumes on a daily basis just flow through their digestive system without being absorbed by the body. 

A dog suffering from maldigestion will have a healthy appetite but will continue to lose weight. Aside from the noticeable weight loss, your dog may also experience diarrhea, loose yellow stool, and gas. However, these signs are insufficient to detect the condition.

As a result, you must take your dog to the veterinarian, who will perform a comprehensive physical exam and run tests on him. Your veterinarian will most likely collect a stool sample and do a blood test for digestive enzymes in your dog. 

#5. Malabsorption

Malabsorption disorders impair the body’s capacity to absorb nutrients from the GI tract. One of the most prevalent malabsorption illnesses in dogs is inflammatory bowel disease. 

If your dog is eating a lot yet losing weight, as well as vomiting, diarrhea, or foul-smelling loose feces, he or she may have inflammatory bowel syndrome. The actual etiology of this condition is unknown. However, it causes inflammation of the intestines. 

Initial inflammatory bowel disease testing includes a fecal examination, blood tests, and an X-ray or ultrasound of the intestines. This disease has no cure, and therapy comprises a particular diet, probiotics, and anti-inflammatory medications. While inflammatory bowel disease is a chronic condition, with a change in diet and adequate treatment, your dog can live a normal life. 

#6. Dental Disease

Many dogs, particularly senior dogs, suffer from dental disease. Broken or diseased teeth, gingivitis, or gum disease can be excruciatingly uncomfortable and make it difficult for your dog to eat correctly. 

Because dental problems make chewing difficult, many dogs stop eating and begin to lose weight. Dogs who aren’t in significant oral pain, on the other hand, may continue to eat but lose weight because they can’t chew properly. 

Dental illness is relatively straightforward to cure when detected early, and most dogs resume eating normally after the problem is resolved. Because dental issues can have serious consequences for your dog’s overall health, you should be proactive and begin brushing your dog’s teeth at an early age. 

#7. Kidney Illness

Your dog’s organs can’t function as well as they used to as it ages. While weight loss can be a symptom of a variety of diseases, dogs with renal disease typically not lose weight right away. Weight loss, on the other hand, is often associated with advanced forms of kidney disease. 

Acute and chronic renal failure can occur in dogs. The latter condition progresses slowly over time and is typically diagnosed in older dogs. An underlying sickness, inherited disorders, and dental problems can contribute to chronic kidney disease. 

#8. Liver Illness

Another possible cause of your dog’s weight loss is liver illness, which is a prevalent problem in dogs. Because the signs of liver illness are similar to those of other health concerns, many owners may not recognize something is wrong until it is too late. 

Most occurrences of liver disease are caused by aging, but it can also be caused by an infection, fatty foods, or some plants and medications. In addition to weight loss, dogs with liver disorders may display the following symptoms:

  • Vomiting 
  • Diarrhea
  • Increased thirst
  • A shaky stroll
  • Confusion
  • Jaundice

While liver illness is more common in older dogs, it can also affect young canines. If your dog is losing weight and exhibiting any of these signs, take them to the vet right once. The treatment for your dog will be determined by the severity of the liver damage and the underlying reason.

#9. Cardiovascular Disease

Heart illness, like kidney failure, does not cause immediate weight loss in dogs. Early signs of cardiac disease in elderly dogs are so modest that most owners attribute them to normal age-related slowing. 

Because heart illness can develop to congestive heart failure, it’s critical to recognize the symptoms so you can get your dog the care he or she requires. 

Early-stage cardiac disease in dogs can cause the following symptoms:

  • Coughing
  • Tired easily
  • Intolerance to exercise
  • Panting excessively
  • Restlessness

As the condition worsens, your dog may exhibit additional symptoms such as:

  • Swollen abdomen as a result of fluid accumulation
  • Fainting
  • Changes in the color of the tongue and gums
  • Weight reduction

Because heart disease is a serious ailment, you should take your dog to the vet as soon as you see any of these signs. Heart disease can be treated if detected early, and with good care and frequent exams, your dog can enjoy a long and happy life. 

#10. Cancer

Another probable ailment that can cause your dog to lose weight despite eating the same amount as previously is cancer. There are many different types of cancer in dogs, and some do not exhibit symptoms until they have spread. 

Cancer is more common in older dogs, but this does not mean that adult and younger canines are immune. Malignant types of cancer, like humans, can be lethal, even when detected early and actively treated. 

Weight loss has been linked to various types of malignant malignancies in dogs, including osteosarcoma, hemangiosarcoma, and lymphoma.  A dog suffering from various types of cancer may begin to lose weight as a result of the tumor’s metabolic needs or because the dog is in so much agony that it cannot eat. 

While it is extremely tough, try not to worry and believe that your dog’s weight loss is the result of cancer! There are numerous disorders that can cause weight loss in dogs, so take your pet to the vet for a thorough examination. If your dog’s weight loss is caused by cancer, speak with your veterinarian about all available treatment choices and do what is best for your dog in the long term. 

How Do Vets Treat Unexplained Dog Weight Loss?

A veterinarian will begin by inquiring about your dog’s nutrition, appetite, environment, temperament, medical history, and any current drugs (including parasite preventives) or supplements that you are administering. They will also assess how many calories your dog consumes each day and whether or not this quantity is adequate to meet their energy requirements.

Following that, they will conduct a thorough physical examination and utilize the results to propose treatment or more diagnostic testing. A fecal examination, bloodwork, and urinalysis are all part of a basic laboratory workup. X-rays, ultrasound examinations, specialized lab tests for specific health conditions, endoscopy, exploratory surgery, and tissue biopsies are examples of additional testing.

Veterinarians will always propose treatment for a dog’s weight loss that tries to cure or at least improve the underlying reason. For example, if a dog has intestinal parasites, they will prescribe a dewormer, dental care for broken teeth, or antibiotics for a bacterial infection. A change in food can often help dogs regain the weight they’ve lost. Among the options are:

  • High-calorie, nutrient-dense dog foods for weight gain in general
  • When GI function is impaired, highly digestible foods are recommended.
  • Fiber-enriched dog meals may be beneficial for some types of GI issues or for diabetic canines.
  • For food allergies and intolerances, hypoallergenic dog diets created from innovative components, hydrolyzed proteins, or specific amino acids are available.
  • Disease-specific diets, such as those developed to aid in the management of kidney or liver disease

The best diet and other therapies will be determined by the circumstances of your dog’s situation. Don’t put off getting your dog the care he or she requires for too long. When a dog’s weight loss hasn’t progressed too far, it’s easier to manage.

Why Is Your Senior Dog Losing Weight?

While it is more normal for dogs to gain weight as they age, certain circumstances may cause your dog to lose weight. This may make you worry about your beloved friend and make you wonder what is causing the weight loss. This answer can fall into one of two categories: there is an underlying ailment and it is a signal of a larger problem, or your dog’s age process necessitates a different balance in their diet.

When Is Weight Loss in Senior Dogs a Problem?

There is a good possibility that weight loss in senior dogs is caused by an underlying health condition. These problems include liver/gallbladder illness, dehydration, dental, kidney, heart, diabetes, cancer, and arthritis. Each of these conditions must be assessed and managed by your veterinarian. The majority of these underlying causes will manifest as secondary symptoms associated with weight loss.

The greatest thing you can do for your senior dog if they are losing weight is to document all of their symptoms and bring them to their vet to be evaluated. Here are some of the disorders that might cause weight loss in your pet, as well as the usual symptoms for each of these conditions:

Liver/gallbladder disease

  • Lethargy
  • Increased thirst
  • Vomiting/diarrhea
  • Fever
  • Pain 
  • Pale or yellow gums
  • Yellowing of skin/eyes


  • Dry gums 
  • Lethargy 
  • Sunken eyes
  • Loss of skin elasticity
  • Less urination
  • Dark urine

Dental Issues

  • Excessive drooling
  • Difficulty eating/chewing
  • Bad breath
  • Swollen or bleeding gums

Kidney disease

  • Increased thirst
  • Excessive urination (may contain blood)
  • Vomiting
  • Loss of appetite
  • Pale gums
  • Lethargy

Heart disease

  • A chronic cough
  • Tires easily
  • Exercise intolerance
  • Excessive panting
  • Irregular heartbeat
  • Restlessness


  • Excessive thirst
  • Excessive urination
  • Increased appetite
  • Lethargy
  • Repeated urinary tract infections


  • Lethargy
  • Unusual bleeding
  • Lumps, bumps, or swelling
  • Distended abdomen
  • Limping or lameness
  • Unusual urination – frequency or amount


  • Wobbling
  • Lameness
  • Scuffing the toes
  • Incontinence

What Happens If There Isn’t a Diagnosis?

If your vet cannot uncover an underlying cause for your dog’s weight loss, it may be time to adjust his nutrition. Consult your veterinarian about their current diet, including the amount of protein, fat, and fiber they consume.

If your elderly dog is rapidly losing weight, consult your veterinarian as soon as possible. If you are concerned about your senior dog’s weight, discuss it with your veterinarian at a routine exam.

Why Is My Dog So Skinny All Of A Sudden?

When dogs consume fewer calories than their bodies require, they lose weight. High energy demand linked with excessive physical activity or prolonged exposure to a chilly environment may produce this imbalance.

When Should I Be Concerned About My Dog Losing Weight?

A progressive loss of weight in a dog is acceptable and even good if it is expected or for a clear reason (such as increased exercise or a purposeful change in food). Unexplained rapid weight loss, on the other hand, is cause for concern and should be investigated by your veterinarian as soon as you become aware of it.

How Can I Help My Dog Gain Weight?

Set up a feeding schedule for your dog so that he eats three or four modest meals each day instead of one or two huge ones. This is an excellent weight-gain strategy since tiny quantities allow your dog to properly absorb and metabolize their food throughout the day.

Can Worms Make A Dog Lose Weight?

Worms and other parasites can cause your dog to lose weight. This is normally only seen in severe cases, so make sure your pet is well-maintained! Your dog’s weight should return to normal after their coat is clean.

What Foods Fatten Up A Dog?

Food with a high fat and protein content. Sweet potato with pumpkin cooked. High-fat snacks, especially before bed. Peanut butter has been added to their food.


Unexpected and unexpected weight loss in dogs is never natural and may indicate a more serious health concern. If your dog is losing weight while eating, it is critical to determine what is causing the rapid weight loss.

Because sudden weight loss in dogs is always concerning, call your veterinarian as soon as possible and make an appointment.

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