10 Signs of Illness in Dogs: What Every Dog Owner Should Know

Dogs are experts at hiding discomfort. In the wild, showing weakness could mean trouble, so their survival instincts kick in—even when they’re in the comfort of your home. 

That’s why as a responsible pet parent, it’s crucial to recognize the subtle (and not-so-subtle) signs that your furry friend might be sick.

In this article, we’ll break down the top 10 signs of illness in dogs, so you can catch potential health problems early. Let’s dive in!

1. Changes in Appetite or Drinking Habits

A sudden loss of appetite? That’s a red flag. While dogs may skip a meal here and there, refusing food for more than 24 hours could signal an issue—anything from dental pain to digestive problems, infections, or even organ failure.

On the flip side, excessive eating or drinking isn’t necessarily good news either. If your dog is suddenly gulping down water like they’ve been stranded in the desert, it could be a sign of diabetes, kidney disease, or Cushing’s disease. If you notice abnormal eating or drinking patterns, a vet visit is in order.

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2. Lethargy or Low Energy

We all have lazy days, and sometimes, dogs just want to lounge around. But if your usually energetic pup is suddenly acting like they’ve lost their spark—sleeping more than usual, avoiding playtime, or seeming uninterested in walks—it could mean something’s wrong.

Lethargy can be caused by infections, pain, heart disease, or even anemia. If your dog’s energy level takes a noticeable dip for more than a day, don’t brush it off.

3. Vomiting or Diarrhea

Every dog throws up now and then—maybe they ate too fast or snuck a piece of something they shouldn’t have. But frequent vomiting, blood in vomit, or persistent diarrhea is a major cause for concern.

Dehydration can set in quickly, and it could indicate something serious like poisoning, pancreatitis, gastrointestinal infections, or even an obstruction (especially if your dog is a chewer). If vomiting or diarrhea lasts more than 24 hours or is accompanied by other symptoms, seek veterinary care ASAP.

4. Unexplained Weight Loss

Weight loss can sneak up on you, especially if it happens gradually. If your dog’s ribs or spine are suddenly more noticeable, and you haven’t changed their diet or exercise routine, something’s up.

Unintentional weight loss could point to parasites, metabolic disorders, cancer, or digestive issues. A vet visit is necessary to rule out serious conditions.

5. Coughing, Wheezing, or Breathing Issues

Coughing in dogs isn’t always a minor issue. A persistent, honking cough could mean kennel cough, heart disease, or even tracheal collapse (especially in small breeds).

If your dog is wheezing, struggling to breathe, or coughing up blood, it could be an emergency. Pneumonia, heart failure, lung disease, or allergies might be at play, so don’t wait to get them checked out.

6. Changes in Behavior or Mood

Is your friendly pup suddenly snapping or hiding under the bed? Dogs in pain or discomfort often exhibit behavioral changes.

Watch for signs like:

• Increased aggression or irritability
• Hiding or avoiding interaction
• Unusual clinginess or neediness
• Pacing or restlessness

Pain, neurological issues, or internal discomfort could be causing these shifts. Trust your gut—if your dog seems “off,” something might be wrong.

7. Scooting or Excessive Licking

If your dog is dragging their butt across the floor (scooting), it’s more than just a funny TikTok moment—it could indicate worms, anal gland issues, or allergies.

Likewise, obsessive licking (especially of their paws, belly, or genitals) can point to skin infections, allergies, or even anxiety. If your dog is fixated on certain areas, it’s best to get them checked out.

8. Bad Breath or Dental Issues

Dog breath isn’t supposed to smell like roses, but if your pup’s mouth suddenly smells like a sewer, it’s time to investigate.

Bad breath (halitosis) can signal:

• Gum disease or infections
• Rotten teeth
• Kidney disease
• Diabetes (which can cause a fruity smell)

Regular dental check-ups can prevent painful infections and other complications. If your dog’s breath takes a nasty turn, book a vet appointment.

9. Skin Changes or Unusual Lumps

Not every lump is cancerous, but finding a new lump or bump on your dog’s body should never be ignored. Some could be harmless fatty tumors, but others might be cancerous growths.

Other skin-related signs of illness include:

• Red, irritated, or flaky skin
• Excessive shedding
• Open sores or wounds that won’t heal
• Persistent itching

Early detection is key, so if you notice any abnormal changes, let your vet take a look.

10. Trouble Walking or Stiffness

If your dog is limping, avoiding stairs, or hesitating to jump onto the couch, they could be dealing with arthritis, hip dysplasia, or an injury.

Other signs include:

• Difficulty getting up after resting
• Yelping when touched
• Sudden lameness or dragging a leg

Older dogs often develop joint issues, but young dogs aren’t immune either. If mobility issues persist, your vet can determine the best course of action.

When to Call the Vet

If you notice any of these signs, don’t wait too long to act. Some issues resolve on their own, but others can escalate quickly. Here’s a general rule of thumb:

• Emergency vet visit: Severe difficulty breathing, seizures, unconsciousness, uncontrolled bleeding, or sudden collapse.
• Same-day vet visit: Persistent vomiting, bloated stomach, bloody diarrhea, or extreme lethargy.
• Schedule a check-up: Subtle changes in behavior, appetite, or minor symptoms that persist for more than a couple of days.

Final Thoughts

Being a pet parent comes with responsibilities, and recognizing the early warning signs of illness can make all the difference. Trust your instincts—if your dog seems off, they probably are.

Regular vet check-ups, a healthy diet, and plenty of love go a long way in keeping your pup happy and healthy. When in doubt, always check with a vet. After all, our four-legged friends rely on us to keep them safe!

Have you noticed any of these signs in your dog? Don’t hesitate to share your concerns with your vet—it could save your pup’s life!