Giardia is a species of protozoan parasite, meaning that it is not a worm, bacteria, or virus, but rather a microscopic, one-celled organism. These parasites are found worldwide and cause an irritating intestinal infection in humans and animals knows as giardiasis.
While the infection tends to have unpleasant symptoms, it is typically not life-threatening except in senior pets, very young pets, or those with compromised immune systems. Read on to learn everything you need to know about Giardia in dogs and cats.
Causes of Giardia in Dogs
Dogs and cats become infected with Giardia when they swallow the cyst form of the parasite found in contaminated feces, water, food, and fur.
For example, your pet may:
- Eat the contaminated feces of another animal
- Drink from a contaminated stream, lake, or other body of water
- Roll around in contaminated grass or dirt
- Lick their body after touching a contaminated surface (such as a dog bed at a kennel)
Once the cyst form of the parasite is ingested and enters a pet’s intestines, it transforms into a trophozoite, which is the active form of a protozoan parasite. This trophozoite attaches to the intestinal wall to feed, and reproduces by dividing. If enough trophozoites are present, they can cause serious intestinal damage.
When trophozoites divide and multiply, some turn into the cystic form of the parasite. Eventually, the pet will pass these cysts in its stool, thus contaminating their environment. Giardia can survive for weeks or months in cool and moist environments. It usually survives for only a few days in dry, warm environments.
While humans can also become infected by Giardia, the risk of acquiring it from your pet is small. The type of Giardia that infects humans is usually different than the type that infects animals. Regardless, if your pet is infected with Giardia, you should still disinfect your house and yard to reduce the chance of exposure.
Symptoms of Giardia in Dogs and Cats
Some pets infected by Giardia may show no symptoms at all, but many will exhibit the following:
- Diarrhea that comes on suddenly. Tends to be foul-smelling, soft, watery, and greenish in color. May also contain blood.
- Excess mucus in the feces
- Abdominal pain
- Weight loss
Diagnosing and Treating Giardia in Dogs and Cats
Diagnosing Giardia can be tricky. Because cysts are shed inconsistently in the feces, fecal testing tends to be hit-or-miss. In some cases, repeated fecal testing may be necessary. Other times, a veterinarian may diagnose the condition on the basis of medical history and clinical symptoms.
Giardia infections are usually treated with medication. Some pets may also require hospitalization if they are suffering from dehydration or severe diarrhea.
The most commonly prescribed medications for a Giardia infection include:
- Metronidazole: A potent antimicrobial antibiotic. It is typically administered for 5 to 7 days.
- Panacur (fenbendazole): A broad-spectrum dewormer. Often used in conjunction with Metronidazole.
Because cysts can stick to the fur and re-infect, pets should also be bathed during the course of treatment.
Most cases of Giardia are treatable. See your veterinarian if your pet is showing any symptoms or you suspect that your pet has come into contact with a contaminated substance.
How to Prevent Giardia in Dogs and Cats
To protect your pet from Giardia, keep them away from situations where they may come into contact with contaminated substances. For example:
- Do not let your pet drink from bodies of water such as streams, lakes, and ponds
- Do not let your pet ingest animal feces
- Stay away from parks or areas where animal feces is often left on the ground
- Be sure that any boarding facility your pet stays in is clean, and that any crates and beds are regularly disinfected
If your pet has become infected, you should thoroughly clean your environment:
- Floors and surfaces can be washed with a bleach and water solution.
- Wash clothes, bedding, and soft toys in the washing machine, then dry on the highest heat setting.
- Disinfect food and water bowls in hot water and soap, either in the dishwasher or sink.
- Contaminated lawns or plants cannot be disinfected. You’ll have to remove and discard the grass or plants, and then allow the area to be exposed to direct sunlight
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