15 Signs Your Dog Is Sick: Symptoms Every U.S. Dog Owner Should Know

Have you ever looked at your dog and thought, “Something just doesn’t seem right today?”

You’re not alone. Dogs can’t tell us when they feel sick, and sometimes the first signs of a problem can be surprisingly easy to miss.

Maybe your dog is sleeping more than usual. Maybe they suddenly stop eating. Or perhaps they just aren't acting like their normal, happy self.

Some changes can be temporary, but others may be signs that your dog needs veterinary attention.

In this guide, we’ll cover 15 common signs your dog may be sick, what each change can mean, and when it’s important to contact a veterinarian.

Important: These signs do not automatically mean your dog has a specific disease. Many different conditions can cause similar symptoms, so a veterinarian is the right person to determine the cause.

15 Signs Your Dog May Be Sick

1. Your Dog Suddenly Stops Eating

One of the easiest changes to notice is a sudden loss of appetite.

If your dog normally gets excited about meals but suddenly refuses food, pay attention.

A temporary decrease in appetite can happen for different reasons, but loss of appetite can also occur with illness, pain, gastrointestinal problems, infections, and other conditions.

Pay attention to how long the change lasts and whether other symptoms appear.

If your dog is refusing food and also seems weak, lethargic, or unwell, contact your veterinarian. (Vca)

2. Your Dog Is Much More Tired Than Usual

Does your normally playful dog suddenly want to sleep all day?

A noticeable decrease in activity can be a sign that something is wrong.

Dogs may become lethargic because of illness, pain, infection, dehydration, or other health problems.

Of course, dogs also have lazy days.

The important thing is to notice a significant change from your dog's normal behavior.

If your dog is unusually weak, difficult to engage, or becoming less responsive, veterinary advice is appropriate. (Vca)

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3. Vomiting

Occasional vomiting can happen in dogs, but repeated vomiting should not be ignored.

Vomiting can have many possible causes, ranging from an upset stomach to more serious problems such as toxins, pancreatitis, or an intestinal obstruction. (Vca)

Pay attention if vomiting happens repeatedly or is accompanied by:

• Lethargy

• Loss of appetite

• Diarrhea

• Abdominal pain

• Dehydration

• Other unusual symptoms

If your dog is vomiting repeatedly or appears sick, contact your veterinarian.

4. Diarrhea or Sudden Changes in Stool

Loose or watery stool is another common sign that something may be wrong.

Dogs can develop diarrhea after eating something unusual, changing foods, or experiencing digestive upset.

However, diarrhea can also occur with infections, parasites, toxins, and other health problems. (Vca)

Pay particular attention to severe or bloody diarrhea, especially when your dog also has weakness, vomiting, loss of appetite, or other signs of illness.

5. Drinking Much More Water

Have you noticed your dog visiting the water bowl much more frequently?

Increased thirst can sometimes be related to hot weather, exercise, diet, or other normal factors.

But a persistent change in drinking habits can also occur with certain medical conditions.

That's why it's useful to know what is normal for your individual dog.

If your dog suddenly starts drinking significantly more water than usual, mention the change to your veterinarian.

6. Drinking Much Less Water

The opposite change can also matter.

If your dog normally drinks regularly but suddenly seems uninterested in water, keep a close eye on them.

Illness can affect a dog's appetite and water intake, and vomiting or diarrhea can increase the risk of dehydration. (Vca)

If your dog isn't drinking and also appears weak, is vomiting, or has diarrhea, contact your veterinarian.

7. Coughing or Frequent Sneezing

An occasional sneeze may not be a major concern.

But persistent coughing, frequent sneezing, nasal discharge, or changes in breathing deserve attention.

Respiratory problems can have many causes, and your veterinarian can determine whether your dog needs an examination.

If your dog has rapid, labored, or difficult breathing, seek veterinary care promptly. (Vca)

8. Difficulty Breathing

Breathing problems are one of the signs dog owners should take seriously.

Watch for unusual breathing effort, rapid breathing, or a dog that seems to be struggling to breathe.

A dog with significant breathing difficulty needs prompt veterinary attention.

Don't wait for the problem to become severe before seeking help.

9. Changes in Your Dog's Bathroom Habits

Sudden changes in urination or bowel movements can sometimes indicate a health problem.

For example, you may notice:

• More frequent urination

• Less frequent urination

• Accidents inside the house

• Difficulty urinating

• Changes in stool

• Straining

Because bathroom changes can have many different causes, it's useful to tell your veterinarian exactly what you've noticed.

Keeping track of your dog's normal bathroom routine can make unusual changes easier to recognize. (Vca)

10. Your Dog Seems to Be in Pain

Dogs don't always make pain obvious.

You might notice more subtle changes such as:

• Reluctance to move

• Avoiding stairs

• Changes in posture

• Becoming unusually quiet

• Not wanting to be touched

• Trouble getting comfortable

A sudden behavior change can sometimes be your dog's way of showing that something hurts.

If you believe your dog is experiencing pain, contact your veterinarian rather than trying to diagnose the cause yourself.

11. Sudden Weight Loss

Have you noticed that your dog's body condition seems to be changing even though you haven't intentionally changed their diet?

Unexpected weight loss can have many possible causes.

Sometimes it may be related to appetite or diet, while other cases can involve an underlying medical condition.

If your dog is losing weight without an obvious explanation, make an appointment with your veterinarian.

12. Changes in Your Dog's Eyes

Your dog's eyes can provide useful clues about their health.

Pay attention to new or unusual changes such as:

• Redness

• Discharge

• Squinting

• Cloudiness

• Excessive tearing

• Keeping one eye partly closed

Eye problems can sometimes require prompt attention, so don't ignore a noticeable change.

If your dog seems painful or suddenly develops a significant eye change, contact your veterinarian.

13. Changes in Your Dog's Gums

Healthy gums normally have a consistent appearance appropriate for your individual dog.

A noticeable change in gum color can be a warning sign.

If your dog's gums suddenly look unusually pale, blue, gray, or otherwise abnormal, seek veterinary advice promptly.

Don't rely on gum color alone to determine whether your dog is healthy, but treat major changes as something worth checking.

14. Excessive Scratching or Skin Changes

Does your dog suddenly seem much itchier than usual?

Repeated scratching, licking, chewing, hair loss, redness, or new skin lesions can indicate that something is irritating your dog's skin.

Possible causes can include allergies, parasites, infections, or other skin problems.

If the problem continues or your dog is causing damage to their skin by scratching or chewing, contact your veterinarian.

15. Your Dog Just Isn't Acting Normal

Sometimes there isn't one obvious symptom.

Your dog may still eat and drink, but something about their behavior feels different.

Maybe they're:

• Hiding more often

• Less interested in play

• Following you differently

• Sleeping at unusual times

• Acting restless

• Avoiding normal activities

Dog owners often know their pet's normal personality better than anyone.

If you notice a persistent or significant change in behavior, don't automatically dismiss it.

Dogs can hide pain and illness, so behavioral changes can be worth discussing with your veterinarian. (Vca)

When Should You Call the Veterinarian?

Not every symptom requires an emergency visit.

However, certain combinations of symptoms deserve prompt attention.

Contact a veterinarian if your dog has concerning signs such as:

• Repeated vomiting

• Multiple episodes of diarrhea

• Blood in vomit or stool

• Severe lethargy or weakness

• Significant loss of appetite

• Difficulty breathing

• Severe pain

• Difficulty standing or walking

• A suspected toxin exposure

• A major or sudden change in behavior

VCA's urgent-care guidance recommends veterinary evaluation for situations such as repeated vomiting, lethargy, multiple episodes of watery stool, or blood in the stool. (Vca)

If your dog appears severely ill or is having difficulty breathing or standing, seek emergency veterinary care.

Why Is It Important to Know Your Dog's Normal Behavior?

Here's something many new dog owners don't realize:

There is no single "normal" dog.

A young Labrador may naturally have much more energy than an older dog.

One dog may drink more water than another.

Some dogs are picky eaters, while others act like they haven't eaten in weeks.

That's why the most useful comparison is often your dog's normal behavior versus today's behavior.

Keep an eye on:

• Appetite

• Water intake

• Energy level

• Bathroom habits

• Weight

• Sleeping patterns

• Breathing

• Skin and coat

• Behavior

Knowing your dog's normal routine makes unusual changes easier to spot. (Vca)

What Should You Do While Waiting to See a Veterinarian?

If your dog is sick, follow your veterinarian's instructions carefully.

Keep your dog in a quiet, comfortable environment and monitor changes in eating, drinking, urination, bowel movements, vomiting, diarrhea, coughing, and other unusual signs. (Vca)

Most importantly, don't give your dog human medication unless a veterinarian specifically tells you to do so. Some human medications can be dangerous for dogs. (Vca)

If your dog has potentially eaten a toxic substance, contact a veterinarian promptly rather than trying to treat the problem yourself.

10 Things to Track When Your Dog Is Sick

If your dog doesn't seem well, write down what you're seeing.

1. Appetite

Is your dog eating normally?

2. Water

Are they drinking more or less than usual?

3. Energy

Are they acting normally?

4. Vomiting

How often has it happened?

5. Stool

Is it normal, loose, or watery?

6. Urination

Have you noticed a change?

7. Breathing

Does breathing look normal?

8. Behavior

Is your dog's personality different?

9. Pain

Does your dog seem uncomfortable?

10. Timing

When did the change begin?

This information can be extremely useful when speaking with your veterinarian.

Quick Reference: Signs Your Dog May Be Sick

Sign	What to Do
Loss of appetite	Monitor and contact veterinarian if persistent or accompanied by illness
Unusual lethargy	Watch closely; seek veterinary advice if significant
Repeated vomiting	Contact veterinarian
Severe or bloody diarrhea	Seek veterinary attention promptly
Increased thirst	Discuss persistent changes with veterinarian
Decreased drinking	Monitor closely, especially with vomiting/diarrhea
Persistent coughing	Contact veterinarian
Difficulty breathing	Seek prompt/emergency veterinary care
Sudden weight loss	Schedule veterinary evaluation
Significant behavior change	Discuss with veterinarian

What If Your Dog Seems Fine Again?

Sometimes a dog may have a minor stomach upset and return to normal quickly.

That's good news.

But if symptoms return, continue, become more severe, or occur together with other concerning signs, contact your veterinarian.

For example, repeated vomiting can sometimes be more serious when it occurs alongside lethargy, loss of appetite, abdominal pain, diarrhea, dehydration, or suspected toxin exposure. (Vca)

Don't rely on one symptom alone.

Look at the whole picture.

Final Thoughts

So, how can you tell if your dog is sick?

Start by knowing your dog's normal.

If your dog suddenly stops eating, becomes unusually tired, vomits repeatedly, develops diarrhea, drinks much more or less than usual, has breathing problems, or simply starts acting very differently, pay attention.

Some changes may be minor.

Others may require veterinary care.

The most important thing is not to try to diagnose your dog from a single symptom. Many different health conditions can cause similar signs, and a veterinarian can determine what is actually happening.

Your dog can't tell you when something hurts.

But they can show you.

Sometimes, the smallest change in their normal routine is the first clue that something needs attention.

Knowing your dog's normal behavior could help you notice a problem sooner.

Frequently Asked Questions

What are the most common signs that a dog is sick?

Common signs can include loss of appetite, unusual tiredness, vomiting, diarrhea, coughing, changes in drinking or bathroom habits, weight loss, pain, and unusual behavior.

How do I know if my dog is sick or just tired?

Look for a noticeable change from your dog's normal behavior. If unusual tiredness continues or occurs with other symptoms such as vomiting, diarrhea, loss of appetite, weakness, or breathing problems, contact your veterinarian.

Should I worry if my dog vomits once?

A single episode of vomiting in an otherwise healthy dog may not always indicate a serious problem. However, repeated vomiting or vomiting accompanied by lethargy, loss of appetite, diarrhea, abdominal pain, dehydration, blood, or suspected toxin exposure warrants veterinary attention. (Vca)

When should I take my dog to the vet for diarrhea?

Seek veterinary advice when diarrhea is severe, persistent, bloody, or accompanied by vomiting, weakness, loss of appetite, dehydration, or other signs of illness. (Vca)

What should I do if my dog has trouble breathing?

Difficulty breathing can be an emergency. Seek prompt veterinary or emergency veterinary care rather than waiting for the problem to resolve on its own. (Vca)

Can dogs hide signs of illness?

Yes. Dogs can sometimes hide pain, illness, and discomfort. That's why changes in normal behavior, appetite, activity, or routine are worth paying attention to. (Vca)

Should I give my dog human medicine when they are sick?

No, not unless your veterinarian specifically instructs you to do so. Some human medications can be harmful to dogs. (Vca)

Disclaimer: This article is for general educational purposes only and is not a substitute for veterinary advice, diagnosis, or treatment. Dogs can have very different health needs, and the same symptom can have many possible causes. If your dog appears seriously ill, has difficulty breathing, has severe weakness, or you are concerned about their condition, contact a licensed veterinarian promptly.