All About Giardia in Cats

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In the U.S., giardiasis is the most common intestinal parasitic disease among humans, reports the Centers for Disease Control and Prevention (CDC). But did you know that giardia can also wreak havoc on the intestines of your beloved cat?

Though sometimes confused with intestinal worms, giardia is actually a type of parasite called a protozoan that invades the gastrointestinal tract. Though the parasite can cause severe diarrhea, giardia in cats treatment is typically very effective and carries a great prognosis.

How Do Cats Get Giardia?

There is little research about how giardia causes disease in cats, so much of the information that veterinarians have is based on studies of giardia in humans. It is believed that cats become infected with giardia when they swallow the organism in its immature state. Once inside the cat's intestine, the organism matures into a cyst. Eventually, the cat passes more infected cysts in their stool. If other cats come in contact with the stool, they can get infected. Cats may also ingest giardia in contaminated drinking water, outdoor puddles, or ponds.

Symptoms of Giardiasis

Many cats who become infected with giardia are asymptomatic, meaning they don't show any signs of illness. Kittens, old cats and cats who are stressed, have a weakened immune system or are housed in close quarters are most likely to show signs of clinical illness. These signs can include severe, watery diarrhea and weight loss. Giardiasis can be fatal if left untreated.

How Is Giardiasis Diagnosed?

Giardia in cats can be detected through a microscopic examination of their stool for ova and parasites. Occasionally, the parasites may be seen on a direct smear of the feces. If giardia is suspected, your vet can test your cat's blood or feces for specific antigens of giardia. These tests are more accurate than the stool exam but take longer, as the sample usually needs to be sent to an outside laboratory.

What is the treatment for Giardia?

In the U.S., no drug is officially approved for the treatment of giardia in cats. However, the typical cat giardia treatment is metronidazole, an antibiotic, which cats usually need to take for five to seven days. Your vet may also suggest another similar medication, like albendazole or fenbendazole.

Orange cat drinking from a coy pond with fish nearby.

Eliminating Giardia

If your cat is diagnosed with giardiasis, environmental disinfection is key to preventing them from getting reinfected and from infecting you, says the CDC. First, remove your kitty from any potentially contaminated areas. To clean the space, use a diluted chlorine bleach solution of one cup of bleach in a gallon of water. Alternatively, you can steam or chemically clean with a disinfectant containing quaternary ammonium. Giardia cysts easily die in dry conditions, so keep the area as dry as possible for several days.

Your cat's coat may also be carrying giardia. The best way to remove the organisms from their coat is by bathing them with a pet shampoo and thoroughly rinsing. After this initial bath to remove organic material, you should bathe them again with a quaternary ammonium disinfectant. Limit application to three to five minutes, as prolonged contact with this chemical can irritate a cat's skin and mucous membranes. After bathing them, paying close attention to the anal region, thoroughly rinse off the solution. Because bathing cats is rarely an easy task, you might wish to have your vet do this. If your cat is too stressed, gentle sedation can be administered by your veterinarian.

Vaccination and Prevention

To date, no drug has been shown to convincingly prevent cats from giardiasis. While there is a reported giardia vaccine available, there isn't enough evidence to determine its efficacy. While one study showed that young kittens who received the vaccine were immune to infection six to 12 months later, the vaccine has been shown to lead to local reactions. Other studies suggest that the vaccine may not be successful in cats who are already infected and may fail to prevent reinfection.

The best prevention remains environmental control, which includes decontaminating potentially infected areas of your home and ensuring there are no giardia organisms on your cat's coat. Additionally, the best line of defense is understanding your cat's normal behavior and health. Any signs that it is changing, you should contact your veterinarian to get their expert opinion.

Contributor Bio

Dr. Laci Schaible

Dr. Laci Schaible, is a small-animal veterinarian and veterinary writer. She has won numerous awards for her commitment to pet owner education and is considered a leading veterinary telehealth expert.

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