Intestinal Parasites
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Our guide has been authored by qualified veterinarians, but should not be taken as substitute for medical advice or professional veterinary consultation. If your pet displays any unusual symptoms, we strongly advise seeking guidance from a veterinarian
Understanding Intestinal Parasites in dogs
Parasites are organisms that use other living organisms as hosts. As the name might imply, intestinal parasites in dogs reside within the animal’s intestines. These parasites are typically eukaryotes, which are multicellular organisms with a nucleus, meaning bacteria and viruses are not considered parasites. Intestinal parasites may be present in the digestive system without causing any clinical signs – or may cause recurrent diarrhea, vomiting, and even severe illness.
Parasite types include:
- Protozoans: Coccidia, Giardia, Cryptosporidium are examples. These unicellular organisms are not bacteria or viruses, but rather their own class of organism. They can be found in small amounts even in healthy pets, but can lead to severe disease in some cases.
- Worms: Several worm families may infest the dog’s digestive system, the most well-known being roundworms, hookworms, whipworms and tapeworms.
- Algae: Prototheca is a type of algae capable of causing severe hemorrhagic diarrhea and other systemic disease in dogs.
Juno's story
Juno, a 5-month-old Fox Terrier, was adopted with overly-visible ribs and never-ending hunger. Her owners first thought she was just malnourished and made sure to pamper her. When they saw no improvement and noticed her stool was very soft, they took Juno to the clinic. The vet sent a stool sample to the lab for microscopic examination, and discovered a massive number of unicellular organisms and worm eggs. Juno had roundworms and coccidiosis. The vet ordered a comprehensive treatment protocol including medication, supplements, and a bland diet. Her owners also washed her bedding and water bowls, and bathed her to prevent re-infection. After a few days, her stool was noticeably firmer, and she was back to her normal, bouncing self!
Intestinal Parasites's Causes: Uncovering Triggers
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- Contact with infected feces: This can happen when licking another dog’s anus or ingesting infected feces from a dog or other susceptible species.
- Vertical transmission: Puppies can get infected in utero or via the mother’s milk during nursing. The common canine roundworm, Toxocara canis, is often transmitted this way.
- Contaminated materials: Food or water may contain intestinal parasites, which can potentially transmit worm eggs, unicellular organisms, and algae when ingested.
- Host ingestion: Fleas can carry the tapeworm Dipylidium caninum. When a dog licks a flea infected with this worm larvae, it may hatch and infest the dog’s digestive system. Dogs can also get infected with parasites if they ingest an infected host, such as eating a rabbit or mouse they catch in the backyard.
- Skin penetration: Hookworms can penetrate the skin, especially if wounds are present, and enter the body through the paw pads.
Contributing risk factors:
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- Age: Puppies are the most vulnerable to this health issue, and many are born with worms from their mother. There are no known breed predispositions for intestinal parasites.
- Compromised immune system: Dogs suffering from chronic conditions or receiving immunosuppressants are more vulnerable to severe disease associated with parasites because their immune systems are less capable of handling them.
- Intestinal diseases: Certain diseases, such as parvovirus, IBD, dysbiosis, intestinal tumors, and food intolerance or allergies might increase the risk of more severe symptoms associated with intestinal parasites.
- Lifestyle: Dogs who hunt, swim in stagnant water or live on acres of land with wildlife present are more likely to be exposed to intestinal parasites and may benefit from more regular stool sample screening.
Recognizing Intestinal Parasites: Signs and Symptoms
- Diarrhea: This is the most common symptom and can manifest as watery diarrhea or soft stool. It may be persistent or intermittent and can vary in color, including brown, black, or red if blood is present.
- Vomiting: This is particularly common in puppies with intestinal worms. Worms may be visibly present in the vomit.
- Visible parasites: Worms can be seen in the dog's stool or vomit. They may appear as sesame seed-like eggs or noodle-like mature worms.
- Stunted growth or lack of growth in puppies: Puppies may appear emaciated and not grow as quickly as expected.
- Unexplained weight loss and a decline in overall physical condition: Worms steal the nutrients for the dog’s food intake, leaving them malnourished. This can cause loss of weight and muscle mass.
- Loss of appetite: In some cases dogs may feel nauseous, especially with a high worm burden or with worms residing in the stomach.
- Abdominal distension: This is most common in puppies. The worms can take some of the protein from their blood that usually helps hold fluid within the blood vessels. This leads to excess fluid outside the blood vessels, often accumulating in the abdomen leading to distension.
Intestinal Parasites Diagnosis: How it's Identified
- Clinical examination: Typical visual symptoms, such as a puppy with a bloated stomach or a very thin young dog, may raise initial suspicion. A rectal exam can sometimes detect worms.
- Stool samples: Examination under a microscope using various methods may reveal unicellular organisms, worm eggs, or algae.
- Antigen tests: ELISA tests can identify various parasite-related antigens. This method is particularly useful for detecting Giardia, which can be challenging to diagnose using microscopy methods.
Treating Intestinal Parasites: Options and Approaches
- Prevention: Routine flea prevention and avoiding raw animal-based food, contaminated water sources, and contact with feces in the dog park can help reduce risk of contracting intestinal parasites.
- Anthelmintics: Deworming medications can be administered every few months in the form of a liquid or pill, especially for those more at risk.This will also eliminate worms in patients that do not present with clinical signs.
- Antimicrobial medication: Some unicellular parasites like Coccidia and Giardia can be treated using certain antibiotics. Sadly, parasites are showing growing resistance to these medications, therefore they should only be used for confirmed cases.
- Supplements: Probiotics and fiber can aid in forming and maintaining a healthy microbiome within the digestive system.
Intestinal Parasites: Surprising Facts
Surveys have shown that 10%-60% of dogs have been infected with digestive parasites, depending on the region and other factors. In most cases, infected dogs showed no symptoms, and many had more than one type of parasite.
Giardia is one of the most common causes of diarrhea in dogs. Under the microscope, its shape resembles a face with eyes, a mouth, and hair.
Tapeworms reproduce at an alarming rate and have multiple egg sacs as they mature. A mature worm can lay more than 100,000 eggs in its lifetime.
Vet's Tip: Dealing with Intestinal Parasites
Fortunately, the prevalence of intestinal parasites has decreased among the general pet population thanks to improved hygiene, better food quality, and the growing use of effective flea prevention and routine deworming. The treatment of intestinal parasites remains crucial for preventing serious illness in both dogs and humans. Some intestinal parasites are zoonotic, meaning they can be transmitted directly from pet to human. This speaks to the importance of regular fecal screening and deworming as well as appropriate hygiene and disposal of pet waste.
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Latest in Research and Treatments
Intestinal parasites are a global problem affecting both animals and humans. Efforts are being made to develop vaccines to some parasites, but this is challenging due to the complex nature of these organisms. In recent years, recombinant vaccines, which do not require injecting the pathogen itself, have opened the door to many new possibilities in this field. Overall, routine deworming and fecal screening is essential to reduce the risk of severe outcomes associated with intestinal parasites.
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