Why is my dog losing weight but still eating and drinking

By Isabella Storyclaire

last updated November 18, 2024

Contributions sourced from

Why Your Dogs Losing Weight and What to Do

Its normal for a dogs weight to vary a little bit over time. If you change their diet to one that isnt to their liking, theyll probably lose a few pounds. Or maybe they are staying inside more during the winter; in this case, theyll probably gain a little.

But what about a dog that keeps losing weight and you dont know why? Unexplained weight loss can be the first sign that a health problem is brewing.

Why Is My Dog Losing Weight?

Weight loss in dogs has many causes. Problems with a dogs diet, environment, and health could all be to blame. Here are a few of the most common causes of unexplained weight loss:

A problem with their food: Dogs may eat less when there is something they dont like about their food. A change in diet may be to blame, or perhaps a large bag of food has started to go bad before your dog has finished it. Feeding too little or giving your dog low-quality dog food can also lead to weight loss.
Stress:A dog thats anxious or stressed may find it hard to relax and eat because they feel like they always need to be on alert.
Exercise: Dogs that start exercising more but dont take in more calories will lose weight.
The environment: Dogs require extra energy to stay warm when they spend lots of time in the cold. Conversely, hot temperatures can reduce a dogs appetite.
Reproduction:Pregnancy and lactation (nursing puppies) put extra nutritional demands on dogs. If they dont take in more calories, they will lose weight.
Dental disease and other oral problems: Any problem that makes chewing and swallowing painful or difficult will discourage a dog from eating.
Intestinal worms and other parasites: Parasites get their nutrition from their hosts, which can lead to weight loss in dogs.
Cancer: Cancer cells use energy to grow and divide, and this means that the energy is not available to the dog, so they often lose weight. Cancer can also directly affect a dogs digestive system and appetite.
Gastrointestinal (GI) disorders: Problems that affect the functioning of the digestive tract can reduce a dogs appetite or their ability to digest and absorb nutrients. Inflammatory bowel disease, lymphoma, adverse food reactions, or partial intestinal blockages could be to blame.
Nasal problems: Any condition that affects a dogs ability to smell their food can lead to a reduced appetite.
Diabetes mellitus: The changes in glucose metabolism seen with diabetes mellitus frequently lead to weight loss in dogs, even when they have a good appetite.
Exocrine pancreatic insufficiency (EPI): When dogs have EPI, they dont produce enough of the digestive enzymes needed to break down food and absorb nutrients.
Infections: Bacterial, viral, or fungal infections can directly affect the GI tract and lead to weight loss. Fighting an infection anywhere in the body requires extra energy, and if dogs dont eat more, they will lose weight.
Kidney and liver disease: When the kidneys or liver dont function properly, waste products of metabolism build up in the bloodstream, which can make a dog nauseated and not feel like eating. Dogs with kidney disease may also lose protein in their urine, which can lead to weight loss.
Heart disease: Weight loss is common as heart disease progresses. The exact causes of this are unknown, but the condition goes by the name cardiac cachexia.
Addisons disease:Dogs with Addisons disease (hypoadrenocorticism) dont produce enough of certain types of adrenal hormones, which can lead to poor appetite and weight loss.
Hyperthyroidism: Although hyperthyroidism is rare in dogs, it can increase their metabolic rate and lead to weight loss.
Neurologic conditions: Any disease that adversely affects a dogs ability to eat and swallow can result in weight loss.

Is My Dog Too Skinny?

Regularly checking your dogs weight by using an accurate digital scale is the best way to monitor for weight loss or gain. However, evaluating a dogs body condition score can also help you determine if your dog is too skinny. In general, a dog might be too skinny if:

You can easily see their ribs or other bony points.
When looking down from the top, they have a very pronounced waist.
When looking from the side, they have an exaggerated abdominal tuck.

When to See Your Vet About Your Dogs Weight Loss

A little bit of weight loss isnt always an emergency. As long as your dog doesnt have any other signs of illness, you could try to change their diet or environment to see if it solves the problem. But there are times when you should get your dog to a veterinarian ASAP:

Puppies shouldnt lose weight! As they grow, puppies should be gaining weight, so call your veterinarian immediately if your puppy is losing weight or getting too skinny.
Weight loss in a dog thats older or has an underlying health problem is always concerning. The risk of serious diseases that cause weight loss increases as dogs get older.
Weight loss combined with symptoms of illness is never normal. Make an appointment with your veterinarian if your dog has difficulty breathing, vomiting, diarrhea, coughing, sneezing, weakness, lethargy, increased thirst and urination, or any other worrisome symptoms. If your dogs symptoms are severe, call a vet immediately to determine if you should head to the clinic right away.
Rapid or pronounced weight loss should always get your attention. Any health problem can lead to serious weight loss. Make an appointment with your veterinarian if your dog has lost more than 10% of their normal body weight or is losing 2% or more of their body weight per week. Heres what that can look like for dogs of different sizes:

Serious Weight Loss in Dogs

Normal Weight in Pounds	Current Weight in Pounds	Rapid Weight Loss
10	9	0.2 pounds/week
25	22.5	0.5 pounds/ week
50	45	1 pound/week
75	67.5	1.5 pounds/week
100	90	2 pounds/week

How Do Vets Treat Unexplained Weight Loss in Dogs?

A veterinarian will start by asking you a lot of questions about your dogs diet, appetite, environment, behavior, medical history, and any current medications (including parasite preventives) or supplements that you are giving. They will also determine how many calories your dog is taking in each day and if this amount should be meeting their energy needs.

Next, they will perform a complete physical examination and use the information they uncover to recommend treatment or further diagnostic testing. A basic laboratory workup includes a fecal examination, bloodwork, and a urinalysis. Additional testing can involve x-rays, ultrasound examinations, specialized lab tests for specific health problems, endoscopy, exploratory surgery, and tissue biopsies.

Whenever possible, veterinarians will recommend treatment for a dogs weight loss that aims to cure or at least improve its underlying cause. For example, they will prescribe a dewormer if a dog has intestinal parasites, dental care for damaged teeth, or antibiotics for a bacterial infection. Oftentimes, a change in diet can also help dogs regain the weight theyve lost. Options include:

High-calorie, nutrient-dense dog foods for generalized weight gain
Highly digestible diets when GI function is impaired
Dog foods with added fiber may be appropriate for some types of GI problems or for dogs with diabetes
Hypoallergenic dog foods made from novel ingredients, hydrolyzed proteins, or individual amino acids for food allergies and intolerances
Disease-specific diets like those designed to help manage kidney or liver disease

The right food and other treatments will depend on the specifics of your dogs case. Dont wait too long to get your dog the care they need. Its easier to manage a dogs weight loss when it hasnt had a chance to progress too far.

Featured Image: iStock/Capuski

Dog Losing Weight But Is Eating: Discover 5 Reasons Why

The food dish is full at mealtimes, and its practically licked clean by your dog at the end of the meal.

Yet, your dog or puppy doesnt seem to be maintaining a normal weight.

Its a worry:

This is naturally an alarming development and something that sparks stress in dog parents.

Its an issue you want answers to sooner rather than later before your beloved pet wastes away.

A dog losing weight but acting normally, and eating normally, usually has an underlying health problem or an issue with their diet.

Is it a serious issue?

Not always but it is necessary to rule out serious causes and find a solution to your dogs weight loss.

Well cover some of the reasons your dog could be losing some weight and some things you can expect to encounter at the vet as they search for a diagnosis.

Lets find out more.

Turning to the Vet if Your Dog Is Losing Weight

How do you define weight loss in dogs that are cause for concern?

If their diet and exercise routines havent changed, but they lose10% of their body weightor more in a short period of time, its time for them to see a vet.

This is a problem we dont recommend you attempt to self-diagnose or treat at home for two reasons.

What are they?

The first reason is that while rare, some serious health issues can be the culprit for your dogs weight loss.

Its critical to get to the bottom of these ailments and start treatment soon for the best prognosis possible.

The second reason is that even if the issues arent serious, they can require medications and treatments that can only be overseen by a trained vet.

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Below is a list of a few causes of weight loss that require swift vet care.

1. Heart Disease

Although dogs withheart diseasemight experience weight loss due to a lack of appetite, they can also have inexplicable weight loss as a symptom.

It might be scary to learn there isnt a cure for heart disease, per se.

However, it is a manageable condition, and dogs who are being treated for it can still live full lives.

The crucial part is getting a vets diagnosis so a treatment plan can begin.

2. Cancer

Its a terrifying thought and one of the reasons you should have your dog tested if they have weight loss for no reason.

The clock is ticking when it comes to cancer, and the sooner your vet can narrow down the type and stage of the disease, the better.

Fortunately, advances in veterinary medicine make it more viable than ever to successfully treat a variety of cancers in dogs.

3. Disease of the Liver or Kidneys

If your dog is suffering from an issue with their liver or kidneys, they might lose weight even if they eat normally.

The weight loss can be chalked up to chronic diarrhea and vomiting that often accompany these issues.

Their eating might seem normal, but if they cant hold onto their food long enough, theyll obviously be losing weight.

Either of these issues can be treated, but again, need to be diagnosed as soon as possible.

4. Gastrointestinal Obstruction

Dogs sometimes swallow things they shouldnt and they can become trapped in the digestive system.

Your dog can continue eating regularly, but a foreign object somewhere in their digestive tract can prevent nutrients from being absorbed properly.

Obstructions can also become dangerous if they cause internal perforations or obstruct parts of the stomach and intestines entirely.

So even if part of a toy or clothing has been hanging out in your dogs stomach for a while without any serious issues arising, its essential to get it removed before it causes bigger problems than weight loss.

5. Muscle Atrophy

Reduction in exercise and old age are common causes of muscle loss in dogs.

They can continue to eat normally but seem to shrink before your eyes.

They may also feel unusually bony and lean.

Muscle atrophy in dogs can havesome other causesthat require attention from a vet.

Parasites: The Ugly Truth

Dogs can pick up intestinal parasites very easily if they arent on preventive medication.

A puppy losing weight but eating has a high risk for parasites, as they are easily spread and young puppies cannot receive preventive medications until they reach a certain age or size.

While a minor to moderate infestation wont put a puppy or dog in any immediate danger, its a problem you dont want to ignore.

Several parasites can cause weight loss in otherwise healthy dogs.

Put down the food. You wont want it after reading this.

1. Roundworms

These nasty, spaghetti-like creatures can infect dogs, cats, and even people. Its a common infection in children as well as dogs.

Other symptoms to look out for besides weight loss include vomiting, diarrhea, and coughing.

A cough develops when the ingested parasite eggs hatch, causing the dog to swallow newly-hatched worms.

2. Coccidia

Theyre common in puppies and make their home in the GI tract.

Theyre microscopic, so you wont be tipped off to infection by seeing one in your dogs vomit or fecal matter.

Coccidia can cause severe diarrhea in some cases, exacerbating weight loss.

3. Hookworms

The nature of this parasite can cause some severe malnutrition effects in infected dogs.

Its not just nutrients they steal from their hosts its also blood.

They attach to the walls of the intestines and contribute to anemia as well as weight loss.

Lethargy and diarrhea are common symptoms of this type of parasitic infection.

4. Tapeworms

Thank fleas for this parasite. At the early stage of its life cycle, a tapeworm lives inside fleas.

A dog or cat who swallows an infected flea will then become host to the tapeworm as it matures.

This often happens during grooming or when your dog snaps at a flea that is biting them.

Countering Parasite-related Weight Loss

Lost your appetite after reading that?

Us too.

Luckily, parasites dont usually affect a dogs appetite unless the infection becomes severe.

That makes being able to treat your dog before an infestation reaches that phase all the more important.

It takes some time:

You cant expect your dog to put weight back on until the parasites are gone.

A deworming treatment that your vet will prescribe is the first step in getting your dogs weight back to normal.

The parasites listed here and others your dog might have picked up can be defeated by treatments as long as you follow the vets orders.

Once your dog has completed their deworming regimen, they should start to put weight back on normally.

Dealing with one parasite infestation is usually enough to remind pet parents that preventive medications are well worth it.

When Diet is to Blame

A dog could be gobbling up their food but losing weight because the food isnt right for them.

They might eat it anyway because its delicious to them or because theyre simply hungry.

A few diet blunders can lead to conditions in which a dog will lose weight.

1. Malnutrition

This issue can arise from feeding the wrong dog food with not enough nutrients or not feeding the right quantity.

Dog food brands come with helpful guidelines regarding how much to feed daily, depending on the size of your dog.

If that doesnt seem to be working, a vet can help you tweak your dogs food, and amounts thereof, to ensure theyre getting enough calories and nutrients.

Keep in mind that active dogs will have higher caloric requirements than more sedentary ones.

Make sure you adjust your dogs diet anytime their exercise routines are also switched up.

Some pet parents choose to feed alternative diets, such as homemade dog foods orvegetarian meals.

The latter option is something that, if you must do, you should only do under the strict guidance of a vet.

Its not something you should attempt based on your own research, as it can cause deficiencies and malnutrition.

What is the problem with restrictive diets for dogs?

There are substances they can only get through meat and meat-based protein and those thingsmustbe supplemented in a DIY diet.

Getting some of these nutrients through supplements rather than via the natural source might not be enough, either.

Theres still a question of whether dogs can actually absorb the necessary amounts of nutrients when theyre given to them supplementally.

Feeding raw food diets are a little easier, provided you include things like meat, eggs, and fish.

It can, however, be tricky to figure out how to translate proper nutrition and caloric amounts from kibble to homemade meals.

Again, asking your vet for specific amounts and volumes of raw foods will help avoid malnutrition issues in your dog.

2. Malabsorption

Your dog can be eating but still losing weight because their small intestine isnt properly absorbing all of the good stuff from their food.

What causes this to happen?

A variety of issues can lead to the malabsorption of food.

Exocrine Pancreatic Insufficiency

Also known asEPI, this condition arises when there are not adequate numbers of digestive enzymes produced.

This will lead to a variety of gastrointestinal issues and can also cause severe weight loss if left untreated.

Enzyme replacement is effective and sometimes the only treatment necessary to correct this issue.

Inflammatory Bowel Disease

Inflammation of the bowel lining isnt unique to humans.

A dog suffering from IBS can have chronic diarrhea leading to weight loss without losing their appetite.

Chronic diarrhea also can cause foods to work through the system before the small intestine has a chance to absorb anything worthwhile from it.

IBS can be caused by food allergies, stress, lack of sufficient fiber, and bacterial infections, to name a few.

It is sometimes a mystery what exactly triggers IBS in any mammal.

Luckily, if the underlying cause is discovered, it is fairly easy to treat. Even if the root cause cant be identified, there are treatments to help manage the symptoms.

Small Intestinal Bacterial Overgrowth

SIBO can prevent your dogs small intestine from receiving essential nutrients from food.

What is asmall intestinal bacterial overgrowth, and what causes it?

Simply put, the bacteria needed to break down and set the stage for healthy, normal digestion can sometimes grow out of control.

It can happen as a side effect of other health issues, or it can have no apparent cause.

Allergies

Sensitivities or allergies to certain foods can prevent your dog from absorbing anything good from them.

Food-sensitive dogs might fully enjoyeatingfood that doesnt agree with them.

They might also throw it up or have diarrhea before they can digest it.

There are other things to look for:

Other symptoms of food allergies in dogs include itchy skin and hot spots, which are uncomfortable enough.

Weight loss due to allergies is a good indicator that your dogs diet needs to be revamped.

Aging Canines Who Lose Weight

Although we might not like to face the signs that our dogs are getting older, weight loss for no apparent reason is a common sign of aging.

Elderly dogs can be every bit as enthusiastic about food as they were in their youth but dont seem to be holding their weight very well.

This can be due to health issues related to age, but it can also be purely because your dog is biologically old.

Many health issues that older dogs are susceptible to that also cause weight loss have a clear cause loss of appetite.

So if your dog is still eating, it can seem difficult to narrow down why.

We mentioned earlier in this article that there are some serious health issues that need to be ruled out when a dog suddenly loses weight.

While it is true that some of these diseases are more likely to strike elderly dogs, it is also true that old dogs are more prone to weight loss and muscle atrophy simply due to age.

Dig a little deeper:

Look out for other sneaky symptoms such as pale gums, increased thirst, yellowing of the eyes, or excessive urination.

It sometimes can seem like a dog is otherwise normal aside from losing weight, but there are some symptoms present you might not have noticed easily.

These symptoms can indicate kidney failure, liver disease, and diabetes problems that older dogs are at a higher risk for.

Pregnancy in Dogs

Eating without maintaining weight could be an indicator your dog is expecting a litter.

You might have had her go missing for a few hours during the heat cycle, or the pregnancy could be a planned one.

Maybe you rescued a stray who could be pregnant.

No matter what the case, losing weight means the puppies are taking up all the nutrients mom is getting from her food and theres not enough left over for her.

You need to take action:

Pregnant dogs need to increase their calories and other nutrients, so if you suspect your dog is pregnant, get it confirmed by a vet.

If your dog is carrying a litter, shell need an adjustment in her diet to prevent further weight loss and negate risks to the puppies shes carrying.