Signs and Symptoms of Worm Infestation in Dogs: What Every Pet Owner Should Know

Worm infestations are a frequent canine health issue, but they usually go unnoticed until signs turn serious. Learning to recognize signs of worms in dogs can enable you to take proactive action and save your furry companion from pain—and in some instances, life-threatening illness.

In this guide, we’ll cover the most common signs of worms in dogs, behavioral changes to watch for, symptoms by worm type, and how to tell if your dog has worms. Plus, we’ll explain when it’s time to see your vet.

Common Visible Symptoms of Worms in Dogs

Worms can affect your dog’s digestive system, appearance, and even their growth and energy levels. Here are some of the most common visible symptoms of a worm infestation:

1. Vomiting
   If your dog is vomiting frequently, especially if you notice worms in the vomit, this could be a strong indicator of a roundworm or tapeworm infestation.
2. Diarrhea
   Loose, watery, or bloody stool can point to intestinal parasites, particularly hookworms. Chronic diarrhea is a major red flag.
3. Pot-Bellied Appearance
   A swollen, round belly—especially in puppies—is a classic sign of a heavy worm load. This is commonly associated with roundworms.
4. Weight Loss
   Despite eating normally or even more than usual, a dog with worms may lose weight because the parasites are absorbing vital nutrients.
5. Dull Coat or Skin Issues
   A lackluster coat, itchy skin, or the appearance of sores can be a sign your dog isn’t absorbing nutrients properly due to a worm infestation.
6. Scooting or Licking the Rear
   Dogs may drag their bottoms across the floor or excessively lick their anal area due to irritation caused by worms, especially tapeworms.

Behavioral Changes Caused by Worm Infestation

Worms don’t just affect your dog’s body—they can also influence their behavior.

• Lethargy: A normally playful dog becoming unusually tired or uninterested in activities may be suffering from a parasite.
• Increased Appetite: Some dogs may eat more in an attempt to make up for the nutrients the worms are stealing.
• Restlessness or Irritability: Discomfort caused by worms can make your dog anxious or cranky.

Symptoms by Type of Worm

Different worms affect dogs in different ways. Understanding which worms cause which symptoms can help in identifying the problem more accurately.

• Roundworms
  • Vomiting (sometimes with visible worms)
  • Pot-bellied appearance
  • Diarrhea
  • Weight loss
• Hookworms
  • Bloody diarrhea
  • Weakness or anemia (pale gums)
  • Weight loss
  • Lethargy
• Tapeworms
  • Scooting
  • Visible segments (like grains of rice) in stool or around the anus
  • Increased appetite
  • Mild weight loss
• Whipworms
  • Chronic diarrhea (may contain mucus or blood)
  • Weight loss
  • Dehydration
• Heartworms (Spread by mosquitoes; not intestinal)
  • Persistent coughing
  • Fatigue after mild exercise
  • Difficulty breathing
  • Swollen abdomen due to fluid buildup
  • Collapse in severe cases

How to Tell If Your Dog Has Worms

While visual symptoms help, the only sure way to tell if your dog has worms is through a veterinary examination, including fecal testing or blood work (especially for heartworms).

Here are some cues to look for:

• Any of the visible or behavioral symptoms listed above
• Worms or segments in vomit, feces, or around the anus
• Sudden changes in appetite, energy, or stool quality

When to See a Vet

If you notice any of the above symptoms, especially if they persist for more than a couple of days, it’s time to contact your veterinarian. Prompt treatment is crucial to prevent complications and to stop the spread of worms to other pets—or even humans, in the case of zoonotic parasites like roundworms and hookworms.

Seek veterinary care immediately if:

• Your dog has bloody diarrhea or vomit
• You see live worms in their stool or vomit
• They become lethargic or unresponsive
• There's significant weight loss or anemia

Final Thoughts

Dogs can develop worms which can lead to a variety of health problems ranging from mild discomfort to severe illness. By being aware of the symptoms of worms in dogs and how to recognize if your dog has worms, you can act early and maintain your pet's well-being.

Prevention is key—through routine deworming, regular checkups at the vet, and proper hygiene practices. Always seek the advice of your vet if you have questions or suspect your dog has worms.

Frequently Asked Questions (FAQs)