Get

In Your Inbox

Dogster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

What Causes Weight Loss & Diarrhea in Senior Dogs? Vet Explained Health Facts

sick goldendoodle dog lying on a carpet

Nobody likes dealing with diarrhea, especially when it’s plaguing your aging canine companion. But what can be even more concerning is if your senior dog also starts losing weight. In combination, weight loss and diarrhea in a senior dog can have various causes, many of which can be serious. These include inflammatory bowel disease, pancreatic insufficiency, food allergies, an infection, or even cancer.

We delve into this topic here to help you find the reason for your dog’s weight loss and diarrhea so your pup can better enjoy their golden years.

divider dog paws 2 oct 2024

The 8 Common Causes of Weight Loss and Diarrhea in Senior Dogs

There are many possible causes of weight loss and diarrhea in dogs. Keep in mind that this list just scratches the surface of possibilities, so be sure to seek veterinary attention for a proper diagnosis.

Speak to a veterinarian so you can rule out any serious health conditions and get advice on what approach might be best to help your dog.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the personalized advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content Savings V1

1. Inflammatory bowel disease

This is when the intestines become so inflamed that they have a hard time absorbing nutrients. What you get is chronic diarrhea that can lead to weight loss over time because the dog simply can’t absorb the required nutrients.


2. Exocrine pancreatic insufficiency

The pancreas is a major player in the production of digestive enzymes to help break down food. Sometimes, as a dog ages, pancreatic cells can shrink or become damaged by chronic pancreatitis, causing them to decrease production. What happens next is that digesta can pass through the system without being fully broken down and absorbed. Chronic diarrhea and weight loss can then ensue.


3. Chronic pancreatitis

We can relate exocrine pancreatic insufficiency to pancreatitis, which is when the pancreas becomes inflamed. One case of pancreatitis can cause diarrhea but is unlikely to lead to weight loss. However, if this happens repeatedly over time, it can damage the pancreatic cells so they no longer produce digestive enzymes. Be aware that dogs that experience one case of pancreatitis may be more prone to future cases.


4. Food allergies/intolerances

Dogs can develop allergies to food ingredients that they have eaten without trouble for many years. When this happens, their digestive system has a reaction to the food that can lead to diarrhea, vomiting, and stomach pain. If they continue to eat the food with these issues, it can lead to weight loss.

You are free to use this image but we do require you to link back to Dogster.com for credit

5. Digestive imbalance

A dog’s gut is a wonderful concoction of good bacteria, called the microbiome, that aid in digestion, immune function, and absorption of nutrients. If that balance gets out of whack due to diet, an infection, or medications, it can result in diarrhea and over time, weight loss.


6. Infections/parasites

Many germs and worms can affect a dog’s digestive system, more so in senior dogs that have decreased immune function. Any bacterial, viral, or parasitic infection can result in a disruption to digestion that can bring on diarrhea and weight loss.


7. Cancer

Many types of cancer can lead to weight loss and diarrhea in senior dogs.


8. Other organ issues

The health of a dog’s digestive system is in the hands of many organs, not just the stomach and intestines. Pancreatic issues can cause diarrhea and weight loss, and so can liver and kidney diseases and diabetes, to name a few.

beagle dog sick sad on bed
Image Credit: Iryna Imago, Shutterstock

What to Do for a Senior Dog With Weight Loss and Diarrhea

The previous list can give you an idea of the variation in causes of weight loss and diarrhea in senior dogs. Nearly any issue from the mouth to the anus can lead to these signs, so you’ll want to see a veterinarian to help you on this diagnostic journey.

Expect your vet to run blood work, a fecal sample, and potentially, X-rays, and ask you questions about what you’re feeding your dog, their appetite, and any other signs that you’ve noticed.

From there, your vet can recommend a treatment plan aimed at the underlying disease. This may include a diet change, deworming, antibiotics, enzyme supplements, surgery, or probiotics. Don’t take a wait-and-see approach for a dog with weight loss and diarrhea. The sooner you can treat your pet, the better.

How Do You Know If Your Senior Dog Is Suffering?

Diarrhea and weight loss are two things that definitely don’t boost a dog’s quality of life, but most of their causes are fixable. See your veterinarian to determine the reason for your dog’s weight loss and diarrhea, and follow any treatment plan that they recommend.

Some causes will need lifelong management, which may include a diet change or medication that needs to be given with every meal. Others can be cleared up with one round of antibiotics, probiotics, or a dewormer.

Then, there are certain cases that can’t be cured, such as specific types of cancer. In these situations, it’s best to work closely with your veterinarian to determine the best course of action to keep your pup as comfortable and as happy as possible. You’ll want to watch for signs like inappetence, lethargy, or severe discomfort to determine if your dog is suffering.

divider dog paws oct 2024

Conclusion

Aging presents a unique set of challenges for our canine companions, including weight loss and diarrhea. Your dog will need your and your veterinarian’s help to determine the cause and best course of treatment so they can live out their golden years in the best way possible.


Featured Image Credit: Brad K Covington, Shutterstock

How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Dogster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

What Were Jack Russell Terriers Bred For? History, Traits & Characteristics

Ah yes, the Jack Russell Terrier—a fantastic, energetic, and naturally hunting breed. These working dogs are hugely popular and for good reason. They...

Border Collie Grooming: 15 Vet-Approved Tips

Did you know Queen Victoria loved Border Collies? In fact, she became an active enthusiast in the 1860s. If you have a Border...

Are There Prenatal Vitamins for Dogs? Health & Care Facts (Vet Answer)

Prenatal vitamins are highly discussed and recommended in human pregnancy. So, what about a pregnant dog? Should a pregnant dog receive prenatal vitamins?...

16 Signs Your Dog Has an Upset Stomach: Vet-Approved Health Facts

If you’ve ever been woken in the middle of the night by a symphony of gurgling and rumbling coming from your dog’s stomach,...

More related

Can Dogs Eat Brownies? Vet-Approved Facts, Risks & FAQ

Brownies have long been an American favorite for those who love sweets. They are gooey, sweet, and filled with chocolaty heaven. For dog...

Is My Dog Pregnant? 9 Vet-Verified Signs to Look For

Whether your dog was intentionally or accidentally bred, it can be challenging to determine if your dog is actually pregnant. Illnesses, pseudopregnancies, and...

Chihuahua Dog Breed: Info, Pictures, Care & Facts

If there was ever a creature that proves size doesn’t matter, it is the diminutive Chihuahua. These pint-sized canines are a walking contradiction....

How Much Exercise Does My French Bulldog Need? Vet Approved Advice

French Bulldogs are among the most popular and desirable dog breeds. They are lively, outgoing, affectionate, and have personalities that are hard to...

Keep reading

Can Dogs Eat Froot Loops? Vet-Reviewed Nutrition Facts

Many of us grew up eating cereal in front of the television while watching cartoons. Of the many cereal choices on the market, one of the most popular is Fruit Loops. These colorful loops are certainly tasty but not very...

Can Dogs Eat Froot Loops

Purina Pro Plan vs. Kirkland Dog Food: Pros, Cons & What to Choose

Trying to choose the right dog food can be an overwhelming experience. Comparing ingredient lists, calories, nutrition tables, and flavors seems like a never-ending, confusing battle. You want to give your dog the best food possible, but it’s difficult to...

Dogster_Dog Food Purina Pro Plan VS Kirkland

Can Dogs Eat Mayo? Vet-Verified Nutritional Facts & FAQ

Mayo, or mayonnaise, is not something that you should be offering to your dog. If they sneak a lick of your mayo spoon, they will probably be just fine. But you shouldn’t make it a habit, as mayo has no...

Can Dogs Eat_Mayo

Why Do Dogs Eat Their Vomit? 4 Vet-Reviewed Reasons & What to Do

Dogs have some really weird habits that disgust us, but we just chalk it up to them being dogs. For example, your dog sniffing other dogs’ butts is normal to dogs but weird to humans. Another disgusting thing they like...

Toy poodle dog vomits yellow substance

Can Dogs Eat Artichokes? Vet-Verified Nutrition Facts & FAQ

Artichokes are large thistle-like perennials grown for their edible flower buds. Their leaves, stems, and roots are often used to make extracts for medicines, but the plant can also be used in recipes like dips and side dishes. The plant...

Can Dogs Eat Artichokes

9 Best Dog Foods for Toy Poodles in 2025 – Reviews & Top Picks

The Toy Poodle is a small dog breed popular for its boisterous personality and fluffy, curly coat. These Poodles, like other toy breeds, are susceptible to digestive upset and require a diet that’s ideal for their sensitive stomachs. In addition,...

poodle dog eating

Dr. Harvey Dog Food Review 2025: Pros, Cons, Recalls & FAQ

Review Summary Dr. Harvey’s Dog Food isn’t a standard dog food. The brand does make a limited range of complete foods, but their main lines are called pre-mix bases that are meant to be combined with protein and oils and...

Dogster_Dr. Harvey Dog Food Review

Can Dogs Have Peppermint? Vet-Verified Safety Facts & FAQ

Peppermint (Mentha piperita) makes an appearance in so many things we eat and drink, particularly around the holidays! But many also use peppermint for its homeopathic uses, of which there are a number of potential benefits to humans. But can...

peppermint plants