Signs Your Dog May Have Worms

As a veterinary assistant here in Frisco, Texas, I can tell you this with a lot of compassion: worms are common, treatable, and nothing to be ashamed of. The tricky part is that the signs can look like everyday tummy trouble or itchy skin, and some dogs show very few symptoms at first. In this article, I will walk you through the most important symptoms, what they can mean, and what to do next so you can protect your dog and your household.

Quick overview: common worms in dogs

Different parasites cause different symptoms, and a dog can have more than one at the same time. These are the big ones veterinarians see most often:

• Roundworms: very common in puppies; can look like spaghetti in stool or vomit.
• Hookworms: feed on blood; can cause anemia and weakness, especially in small dogs and puppies.
• Whipworms: live in the large intestine; often cause chronic, on and off diarrhea.
• Tapeworms: usually spread by fleas; segments can look like grains of rice around the rear or in bedding.
• Heartworms: spread by mosquitoes; affect the heart and lungs and can be life-threatening.

If you take only one thing away, let it be this: you cannot reliably identify the worm type from symptoms alone. Testing and a vet-guided plan are the safest path.

Signs of worms (what you may notice)

1) Changes in stool

Many intestinal worms irritate the gut lining, which can change stool quality. Watch for:

• Diarrhea or soft stools that do not fully resolve
• Mucus in stool
• Blood in stool (bright red streaking or darker, tarry stool)
• Accidents in a dog who is normally house-trained

Tip: Take a fresh stool sample to your vet in a sealed bag or container. If you can, bring a second sample from a different bowel movement because some parasites shed eggs intermittently.

2) Vomiting (sometimes with visible worms)

Vomiting can happen with many illnesses, but it is especially concerning if you see long, pale worms that resemble cooked spaghetti. Puppies are the most common patients for this sign.

3) Potbelly (especially in puppies)

A round, distended belly can occur with a heavy roundworm burden. Many puppies still eat well and act playful, which is why this can be missed.

4) Weight loss or poor growth

Worms compete for nutrients. You might notice ribs becoming more visible, loss of muscle tone, or a puppy that does not gain weight as expected, even if appetite seems normal.

5) Scooting, licking, or rear irritation

Scooting is not always worms, but it is a classic clue. Common causes include anal gland issues, allergies, and tapeworm irritation. Tapeworm segments may stick to the fur and can look like small rice grains or sesame seeds.

6) Dull coat or “not thriving”

Chronic parasite burden can show up as a lack of shine, increased shedding, or a coat that feels dry even with good grooming. This is not a sure sign on its own, but it belongs on your radar.

7) Coughing or breathing changes

This is where we shift from intestinal worms to heartworm disease. Dogs with heartworms may cough, tire easily, lose weight, or have decreased stamina. Advanced cases can cause fluid buildup, collapse, or severe weakness.

Important: heartworms are not treated with the same dewormers used for roundworms or tapeworms. Many monthly preventives work by killing heartworm larvae before they mature, which is one reason consistent prevention and routine testing matter. Heartworm prevention and heartworm treatment should always be managed by your veterinarian.

8) Pale gums or sudden drop in energy

Hookworms can cause blood loss. Pale gums, lethargy, and weakness are red flags, particularly in puppies. If your dog seems unusually tired or the gums look light pink to white, treat it as urgent.

What you might see

Many dogs with worms never pass anything visible. When you do see something, it can help your vet narrow the possibilities.

• Tapeworm segments: small, flat pieces that look like rice grains near the rear or in bedding.
• Roundworms: long, spaghetti-like worms in stool or vomit.
• Whipworms and hookworms: usually not visible to the naked eye. Whipworms are thin and small, so even when present they are easy to miss. Diagnosis typically requires a fecal test.

If you find something suspicious, place it in a sealed container or bag and bring it to your appointment. A quick photo can also help if it is not practical to transport.

How dogs get worms

• From the environment: eggs and larvae can live in soil, parks, yards, and dog runs.
• From mom to puppies: roundworms and hookworms can be transmitted during pregnancy and or nursing.
• From fleas: tapeworms often come from swallowing a flea during grooming.
• From prey and scavenging: rodents, rabbits, and wildlife feces can spread parasites.
• From mosquitoes: heartworm disease is spread through mosquito bites.

Reinfection is common when prevention is inconsistent, fleas are not controlled, or poop is not cleaned up promptly in the yard.

When to call your vet

Some situations should not wait for a wait-and-see approach. Contact your veterinarian promptly if you notice:

• Blood in stool, black tarry stool, or repeated vomiting
• Weakness, pale gums, or collapse
• Labored breathing, persistent cough, or severe exercise intolerance
• A very young puppy with diarrhea or a potbelly
• Signs of dehydration (sticky gums, sunken eyes, very low energy)

Diagnosis: why testing matters

Over-the-counter dewormers can help in some cases, but they can also miss the parasite you are dealing with. A veterinary fecal test (and, for heartworm, a blood test) answers three key questions:

• Is it worms or something else? Giardia, coccidia, diet intolerance, stress colitis, and other issues can mimic worm symptoms.
• Which parasite is it? Treatments are specific.
• Is the treatment working? Follow-up testing is often needed, especially when symptoms persist.

Treatment basics

Your vet may prescribe one or more medications depending on the parasite and your dog’s age, weight, and health status. A few evidence-based realities to know:

• Many deworming protocols require repeat dosing because medications often kill adult worms but not all immature stages.
• Tapeworm treatment usually requires a specific medication, and you must treat fleas too or the problem will come back.
• Puppies often need multiple dewormings on a veterinarian-set schedule, even if they seem fine.
• Heartworm treatment is a different pathway and can involve strict activity restriction and staged medical therapy.

Please avoid using leftover medications or dosing “just in case” without guidance, especially in small dogs, seniors, pregnant dogs, and puppies.

Home care and prevention

Clean-up and hygiene

• Pick up poop promptly in your yard and on walks.
• Wash hands after cleaning up stool and before handling food.
• Wash bedding if you have seen tapeworm segments or diarrhea accidents.

Flea control

If tapeworm is on the table, think “fleas until proven otherwise.” Ask your vet about safe and effective flea prevention for your dog’s lifestyle.

Monthly prevention and routine testing

• Use veterinarian-recommended parasite prevention that covers your region and your dog’s risk factors, including heartworm protection.
• Keep up with wellness visits and fecal testing as advised.
• Test for heartworm on schedule, even if your dog is on prevention, because missed doses happen.

Here in Texas, mosquitoes are not just a summer issue. For many dogs in the Frisco area, heartworm prevention is a year-round conversation. Your veterinarian can help you choose the right plan for your household.

Nutrition supports recovery

Worms can be hard on the gut. After treatment, ask your vet if a short course of a probiotic is appropriate, and focus on a consistent, high-quality diet. If you are transitioning foods, go slowly to avoid adding diet-related diarrhea on top of an already irritated digestive tract.

What not to do

• Do not use pet dewormers on people (or people meds on pets). If you are worried about human exposure, call a human healthcare provider.
• Do not skip flea control if tapeworm is suspected. It is part of the fix.
• Do not guess based on appearance alone. “Rice-like” bits can be tapeworm segments, but they can also be debris. Bring a photo or a sample and let your vet confirm.

Can people catch worms?

Some intestinal parasites are zoonotic, meaning they can infect people, especially children and anyone with a compromised immune system. Two common examples are roundworms and hookworms, which are most often linked to contact with contaminated soil or feces. The risk goes down dramatically with good hygiene, prompt stool clean-up, and consistent veterinary prevention.

If someone in the home is experiencing symptoms and you suspect parasite exposure, contact a human healthcare provider. Let them know there is a pet in the home with a possible or confirmed parasite infection.

Bottom line

If your dog has diarrhea that will not quit, a potbelly, scooting, rice-like segments near the rear, unexplained weight loss, or low energy, worms should be on the checklist. The best next step is simple and empowering: get a fecal test and follow your veterinarian’s treatment plan. With the right diagnosis, most dogs feel better quickly and stay healthier long-term.