From mild discomfort to life-threatening illness, parasites pose a serious threat to your dog — and in some cases to humans as well. While many pet owners think parasites are only a concern during the warmer months, the truth is that dogs can be infected at any time of the year.
Left untreated, common parasites like fleas, ticks, heartworms and intestinal worms can cause a range of health problems for dogs, from uncomfortable itching and digestive upset to heart failure and other conditions.1
The good news is that most of the time, dogs are able to make a full recovery. That’s why it’s essential to be proactive and not wait until a problem pops up. Year-round prevention is one of the most important steps you can take to help keep your dog happy and healthy.
What Is a Dog Parasite?
Parasites are organisms that feed off your dog’s blood and/or nutrients. They can be internal, like roundworms, heartworms or giardia or external, like fleas and ticks.1
Types
The common types of dog parasites fall into two categories:1
- Internal parasites. These live in the gastrointestinal tract and include roundworms, hookworms, whipworms and tapeworms. They also include giardia and coccidia, which can affect the intestines. Heartworms are blood-borne parasites that come from infected mosquitoes and reproduce in your dog’s bloodstream, eventually becoming adult heartworms.
- External parasites. These include fleas, ticks and mites. They live on your dog’s skin and coat, feeding on their blood through the skin.
Climate considerations
Where you live can impact your dog’s susceptibility to parasites. For example, fleas are much less prevalent in dry climates.2 And the Southeast region of the United States, especially along the lower Mississippi Delta, is a hotspot for heartworm disease because mosquitoes thrive in the wet, humid conditions in that area.3
Transmission to humans
While unlikely, some internal parasites can infect humans who come into contact with an infected dog's feces.4 Fleas, on the other hand, can easily jump onto humans, and ticks pose a threat for Lyme disease in both animals and people.1 Good hygiene, thoroughly cleaning spaces your dog frequents and preventative measures are the key to keeping everyone healthy.
Signs Your Dog May Have a Parasite
If left untreated, parasites can lead to significant health issues for your dog. Many symptoms of internal parasites can mimic other conditions or diseases, so if you notice any of the following, it’s worth a trip to the vet:4
- Diarrhea or bloody stool
- Dull coat or patchy hair5
- Unusual fatigue or weakness
- Weight loss or bloated stomach
Some worms can also be found in your dog’s feces or in/around your dog’s anus.4
The following table gives examples of symptoms from specific parasites:4
Name of parasite | How it's contracted | Symptoms |
---|---|---|
Fleas | Exposure to another dog or animal who is infested, or an environment where an infested animal has been5 | Excessive scratching, biting or chewing skin, skin irritation, redness, scabs or other lesions or fur loss (You can often see fleas on your dog — check their belly and groin area, and if you see specks that look like dirt, look closer to see if the specks are moving.)5 |
Giardia | Exposure to contaminated water, food or environment | Vomiting, diarrhea and dehydration that can lead to weight loss and lethargy |
Heartworms | Transmitted by an infected mosquito6 | Mild persistent cough, reluctance to exercise, fatigue, decreased appetite and weight loss (Advanced stages can lead to heart failure and the appearance of a swollen stomach due to excess fluid in the abdomen.)6 |
Hookworms | Ingesting contaminated soil or feces | Weakness due to anemia |
Mites | Through direct contact with another dog with mites or through exposure to an infested environment7 | Excessive licking, itching or scratching; skin irritation, redness or inflammation; fur loss and bald patches; visible debris (Black, waxy debris in your dog's ear may indicate ear mites, while scabs or lesions on their skin could mean sarcoptic mites, also called scabies.)7 |
Roundworms | Exposure to contaminated feces | Severe bloating and gastrointestinal distress |
Tapeworms | Ingesting an infected flea | Gastrointestinal distress in all dogs, stunted growth in puppies |
Ticks | Exposure to an environment where ticks are living (high grass, areas with lots of foliage)8 | A tick crater (a wound where the tick’s head was buried into the skin); swollen, red skin around the area of the bite; itchiness; pale gums due to anemia if there is a heavy tick infestation8 |
Whipworms | Exposure to contaminated soil or water | Diarrhea, weight loss and sometimes anemia |
Treatment Options for Dogs With Parasites
Treatment for dog parasites varies based on the severity of the infection or infestation, but may include over-the-counter medications and/or prescription medications.4 Internal parasites are most often treated with an oral medication.4 Meanwhile, a flea infestation may require oral medication, but also topical treatments like a specialized bath and/or skin cream.5
Treatment can take up to several months to ensure that all of the parasites are dead, especially in the case of heartworm disease.4
There are some over-the-counter medications available, but because parasites can lead to serious health conditions, it’s important to consult your vet for treatment and any natural remedies that you’d like to try.
Tips to Prevent Parasites in Your Dog
Parasites are easiest to treat when caught early. Your vet will likely do a routine check for parasites during your dog’s annual wellness checkup, but there are things you can do at home to prevent parasites in the meantime:4
- Check for fleas and ticks after being outside, especially in high grass.
- Ensure your dog always has clean water and fresh food.
- Give your dog preventative medication year-round.
- Keep your dog well-groomed.
- Regularly clean your dog and their living spaces (including blankets, bedding and more).
You may also want to talk to your vet about giving your dog a probiotic to help boost their immune system and promote overall gut health. The organisms in probiotics can also help restore your dog’s gastrointestinal balance post-parasite.9
The Takeaway on Parasites in Dogs
Parasites are more than just a nuisance — they can have a serious impact on your dog’s health. With proactive, year-round prevention and quick action when symptoms appear, most dogs can recover fully and avoid serious complications.
Regular vet checkups, consistent preventative care, good hygiene and awareness are your best defenses against parasites. By staying vigilant, you can help ensure your dog lives a long, happy and healthy life.
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Author Bio
Abbie Mood is a freelance writer with more than 15 years of experience. She has worked with clients of all sizes to create compelling content and she has written for the American Kennel Club, Marriott Bonvoy, Women’s Health Online, Headspace and more.