You’ve just picked up your new puppy and thrilled to introduce him to your family. But don’t get too eager to bring him home. As cuddly as a new dog may be, he might carry something much less appealing: a parasite.

Parasites are organisms that live in or on another organism (the host), taking from its nutrients at the host’s expense. And they’re more than just a minor annoyance. In fact, parasites in puppies can lead to illness or death, affecting even the human members of your family.

Learn to recognize, prevent, and treat puppy parasites with this helpful guide.

5 Common Types of Parasites in Dogs & Puppies

Intestinal Parasites

Internal parasites, or “worms”, are extremely common in puppies. They occur when a nursing mother transmits them to her pup.

Types and Symptoms of Intestinal Worms

Several types of worms can take hold of your puppy’s digestive system. The most common types of gastrointestinal parasites are:

• Roundworms – a very common parasite for which puppies are more at risk
• Tapeworms – a parasite that is ingested by your dog usually by way of a host that is housing a tapeworm egg like an adult flea.
• Hookworms – this parasite is usually contracted by puppies from their mothers when nursing or by adult dogs swallowing a hookworm egg, or a hookworm burrowing into their skin.
• Whipworms – a parasite that lives in your dog or puppy’s  large intestine. These can be contracted by licking or sniffing contaminated grounds

Symptoms of Intestinal Worms in Puppies

• Loose stools or diarrhea
• Vomiting
• Pale gums
• Swollen belly
• Dry coat

Treatment for Intestinal Worms in Puppies

Though effects are less obvious in the short-term, worms in puppies can lead to serious health issues if you don’t treat them right away.

It’s important to visit the vet before you take your new pup home, as dogs can transmit this parasite to humans. Thousands of children each year become blind from Roundworm transferred through the skin or accidentally ingested from dirty hands.

Your veterinarian will run an intestinal parasite exam that may include taking fecal samples. If diagnosed, your vet will prescribe deworming medication, often with heartworm preventive, to protect your pet and your family.

Heartworms

Heartworms in dogs are one of the most dangerous canine parasites. Transmitted into the bloodstream through the bite of a mosquito with heartworm larvae in its blood, these parasites pose a serious risk to your dog’s health.

Rather than settling in the digestive tract, heartworms migrate to the heart where they grow and multiply. If left untreated, heartworms cause heart failure and death.

Symptoms of Heartworms in Puppies

The symptoms don’t show until it’s become serious. Symptoms include:

• Loss of energy/lethargy
• Coughing or hacking
• Difficulty breathing
• Swollen belly from retained fluid
• Heart rhythm changes like heart murmur
• Eventually, collapse or death

Treatment and Prevention of Heartworm in Puppies

It takes six months for heartworms to cause serious problems. By then, it may be too late. Therefore, early diagnosis to start preventative measures as soon as 8 weeks old is your best bet for long-term health.

If your pet is diagnosed with a mild-moderate case of heartworm infestation, he will be given strong medicine to kill the heartworms. He will also need complete rest and IV fluids, and possibly corticosteroids.

Overall, it can take 6-7 months to treat canine heartworm disease—to make sure these deadly parasites are fully removed.

Single Cell Parasites

Single cell parasites known as protozoa may always be present in the digestive tract but stay quelled due to your dog’s immune system. If he gets sick or very stressed, however, these parasites may start to manifest in an unwelcomed way.

Symptoms of Single Cell Parasites in Puppies

• Repeated diarrhea, watery and smelly with possible mucus and/or streaks of blood
• Vomiting
• Weakness or lethargy
• Weight loss
• A fever of or over 102F

Treating Single Cell Parasites in Puppies

Coccidiosis – or coccidia – is one of the most common types of single cell parasites, is an extremely contagious and oftentimes severe illness. Your vet will observe a stool sample to diagnose your dog. If it proves positive, he or she will likely prescribe a sulfa-based antibiotic to stop the reproduction of the parasites, eventually removing these organisms over time.

Fleas and Ticks

Unlike the previous parasites, fleas and ticks are external parasites that show on the skin. Fleas live in the fur, biting and feeding on the blood of their host and causing severe itching in puppies. This itch can lead to raw, scabby, and/or swollen skin.

Ticks are just as bad, but feed on blood at a much larger scale. They also spread infections such as Lyme Disease.

The good news is, fleas and ticks can be treated through leading medications. Your vet may prescribe topical liquids, natural body oils, and/or chewable tablets.

Skin Mites

Another external parasite, mites are part of the spider family (as are ticks). They tend to live on the skin or in the hair follicles but also occur in the ear – ear mites. Unlike fleas, these are hard to catch with the naked eye.

Mites cause skin irritation, rashes, red or scaly skin, hair loss, and the appearance of severe dandruff in dogs. They also cause a skin disease called Mange.

Fortunately, like fleas and ticks, medication is available to treat these pests. Topical gels, baths in benzoyl peroxide shampoo, and anti-parasitic applications are often used in combination for treatment.