How To Tell If A Dog Has Roundworms Or Hookworms

Intestinal worms are a common concern for dog owners, but not all worms are alike. Roundworms and hookworms are two of the most prevalent parasites affecting canines worldwide, yet they cause different clinical signs and carry distinct health risks. Understanding how to distinguish between them is essential for prompt, appropriate care. This guide will help you recognise the symptoms, understand the differences, and know when to seek veterinary assistance.

Quick Q&A: Common Questions

Question: What are the most obvious signs that my dog has roundworms versus hookworms?

Answer: Roundworms typically cause a potbellied appearance, vomiting (often with visible spaghetti-like worms), and diarrhoea. Hookworms often lead to dark, tarry stools (due to blood loss), pale gums, weight loss, and poor coat condition. The key difference lies in hookworms’ blood-feeding behaviour, which can cause anaemia, whereas roundworms primarily cause gastrointestinal obstruction and malnutrition.

Understanding Roundworms and Hookworms

Roundworms (Toxocara canis and Toxascaris leonina) are large, white, spaghetti-like worms that live in the small intestine, feeding on partially digested food. Hookworms (Ancylostoma caninum and Uncinaria stenocephala) are much smaller, with hook-like mouthparts that attach to the intestinal lining to feed on blood. Both parasites are zoonotic (can pass to humans) and require veterinary treatment.

How Dogs Get Infected

• Roundworms: Puppies often acquire them from their mother’s milk (transmammary) or in utero (transplacental). Adult dogs can ingest eggs from contaminated soil, faeces, or by eating infected rodents.
• Hookworms: Larvae can penetrate the skin (especially through paw pads) or be ingested. Puppies can also be infected via the mother’s milk.

Key Differences in Clinical Signs

Roundworm Symptoms

• Potbelly appearance: A distended, rounded abdomen is classic in puppies.
• Vomiting: Worms may be seen in vomit; they resemble cooked spaghetti.
• Diarrhoea or soft stool: May contain visible worms.
• Poor growth: Puppies fail to thrive, with a dull coat and poor muscle development.
• Coughing: If larvae migrate through the lungs, a mild cough can occur.

Hookworm Symptoms

• Anaemia: Pale gums, lethargy, and weakness due to blood loss. In severe cases, this can be life-threatening in puppies.
• Dark, tarry stools (melena): Digested blood makes the stool black and sticky.
• Weight loss and poor coat: Chronic hookworm infection leads to malnutrition.
• Itchy paws and skin lesions: Larvae burrowing into the skin (especially between toes) cause redness, swelling, and itching.
• Diarrhoea with fresh blood: In acute cases, the stool may contain visible red blood.

Diagnosing Which Worm It Is

Veterinarians use faecal examination (faecal flotation) to identify eggs. Roundworm eggs are round, thick-shelled, and dark brown. Hookworm eggs are oval, thin-shelled, and contain a developing embryo. A single stool sample is usually sufficient, though some vets recommend a series of tests for accuracy.

According to the American Animal Hospital Association (AAHA) and the Companion Animal Parasite Council (CAPC) guidelines, routine faecal screening every 6–12 months is recommended for all dogs, even if they appear healthy. In the UK, the British Small Animal Veterinary Association (BSAVA) advises similar protocols for annual health checks.

Treatment Overview

Both roundworms and hookworms are treated with anthelmintic medications (dewormers). Common active ingredients include fenbendazole, pyrantel pamoate, milbemycin oxime, and moxidectin. The specific drug and dosage depend on the dog’s age, weight, and severity of infection.

Important note: Hookworm anaemia may require additional supportive care such as iron supplements, blood transfusions, or fluid therapy in severe cases. Puppies with heavy hookworm burdens need close monitoring.

Home Care While Treating

• Administer all doses as prescribed; missing a dose can allow worms to survive.
• Clean up faeces immediately to reduce environmental contamination.
• Wash bedding, food bowls, and toys in hot water.
• Limit your dog’s access to contaminated soil (e.g., gardens, dog parks) during treatment.
• For hookworms, keep paws clean and dry to prevent skin penetration.

Prevention Strategies

Prevention is far easier than treatment. The CAPC recommends year-round broad-spectrum heartworm preventives that also control roundworms and hookworms (e.g., products containing ivermectin, milbemycin, or moxidectin). Many monthly chewables or topical spot-ons combine heartworm and intestinal parasite protection.

Environmental control is equally important: promptly remove stools, practise good hygiene, and avoid walking your dog in areas with high faecal contamination. For puppies, deworming begins at 2 weeks of age, repeated every 2 weeks until 8 weeks old, then monthly until 6 months old, as per AAP and AVMA guidelines.

When to See a Veterinarian

Any suspected worm infestation warrants a veterinary visit, especially in:

• Puppies under 6 months old
• Dogs showing signs of anaemia (pale gums, weakness)
• Vomiting or diarrhoea lasting more than 24 hours
• Noticeable weight loss or failure to grow

A veterinarian can confirm the diagnosis, choose the safest dewormer for your dog’s age and breed, and provide follow-up testing to ensure the worms are gone. Self-diagnosis and over-the-counter dewormers may not cover both species or may be ineffective against resistant strains.

Prognosis and Summary

Both roundworm and hookworm infections have an excellent prognosis when treated promptly. Untreated hookworm anaemia can be fatal in young puppies, but with veterinary care, most dogs recover fully. Remember that these parasites can also affect humans, especially children, so good hygiene and regular preventative care are vital.

By staying alert to the specific symptoms described above and consulting your veterinarian for routine faecal checks, you can protect your dog from these common but manageable parasites.