Giardia

Giardia is a parasite found worldwide. It is highly prevalent in every US state, Canada, Europe, and Asia. “Giardia is the most common gut parasite in the United Kingdom” (Nazar). As Bengal owners, we are all likely to come across Giardia. Because breeders will face Giardia from time to time, knowing what to do can save kittens from a miserable and potentially life-threatening experience.


What is Giardia

Giardia is a protozoan parasite that infects many mammal species. Most often, we think of worms when we think of internal parasites. Giardia is not a worm and consists of just a single cell. Despite being a single-celled life form, Giardia differs from bacteria as it contains a nucleus and other cell structures similar to the cells of plants and animals. The full species name of this protozoan is Giardia duodenalis. Within this species, there are “seven genotypes, A through G, with dogs being most commonly infected by C and D, cats with F, and humans most commonly infected with A and B” (Ward). Giardia is a common diagnosis for kittens suffering from either sudden-onset or chronic diarrhea.


Symptoms of Giardia infection

Adult cats infected with Giardia will show few to no symptoms in many cases. Symptoms may show in adults working through another health issue, as this can lower the body’s ability to deal with the Giardia infection. Very high levels of giardia are also likely to cause symptoms in adult cats. 

The most affected cats are kittens, particularly around and shortly after weaning. Diarrhea is the main clue that Giardia may be present. It may develop over a few days or begin quite suddenly. This diarrhea is strong smelling and may contain traces of blood or mucus. Some kittens will continue with diarrhea and seem otherwise to be quite happy. More often, kittens will lose weight, fail to thrive, become lethargic, vomit food or just bile and saliva, and sometimes exhibit fever.


How did my cat get infected?

Giardia infection happens after cats ingest cysts from the environment. Initially, an infected animal passes cysts in the feces. These cysts “are immediately infectious when passed in the stool or shortly afterward, and the cysts can survive several months in cold water or soil” (“Parasites”). Once inside the body, the cysts release two active cells, known as trophozoites. These trophozoites attach to the intestinal lining, where they feed and reproduce. They can reproduce without passing out of the body, although some trophozoites will form cysts and pass out of the body to infect new hosts.

The cysts will not typically last as long at room temperature or higher, but some can remain infectious for up to seven days. Cysts can remain infectious for several months in cooler temperatures or moist conditions. Cats pick up cysts by drinking infected water or licking or sniffing surfaces with cysts on them. Cysts may cling to fur for an extended period, so cats can get them from grooming infected cats or grooming themselves after walking through an infected area. Infected cats will also continually reinfect themselves and the environment after passing feces.

Maintaining a dry environment around your cats and kittens will reduce Giardia cysts’ ability to remain infectious and the overall load in the environment. Because birds also carry some genotypes of Giardia and shed cysts in their feces, keeping outdoor cat enclosures covered from above reduces the risk of Giardia spreading in this way.


Diagnosing Giardia

After seeing diarrhea in kittens, it is important to address it fast. Kittens become dehydrated easily and go downhill fast. It is important to do a fecal analysis. Some vets perform this in-house, providing results in less than an hour. However, in-house testing can be challenging as “cysts are small (10 to 12 µm in length), shed intermittently, are transparent, and are fragile in flotation solutions” (Saleh). Some vets prefer to send the sample off to a testing laboratory for analysis.

It is advisable to run a broad spectrum fecal PCR panel. This will test for the presence of DNA from multiple species of protozoa, bacteria, and viruses that could be the cause of diarrhea. Working out the exact cause of diarrhea saves valuable time and stress from dosing kittens with the wrong treatment.

People who are comfortable dealing with diarrhea in kittens can use an at-home Giardia Snap Test kit available online. They come as a sheathed swab connected to a vial of solution and a test strip to test for Giardia antigens. In my experience, a positive result will usually come up pretty fast. Still, it is always advisable to wait until the end of the testing time as a low Giardia count may make results take longer to display. Using these at-home test kits saves valuable time and allows treatment to start faster than waiting for results to come back from a lab. If you have any suspicions that there could be any other cause for diarrhea or if you are simply unsure, please check with your vet.


Treating the cats

Treating Giardia is very important to get kittens back on track, healthy, and growing well again. Initially, supportive care may be required to assist kittens struggling with dehydration. Providing fluids and electrolytes will help kittens focus their energy on recovering. Bentonite clay and other antidiarrheal treatments can help reduce the loss of fluids and electrolytes. I have also found DiaGel to be very effective in helping kittens slow down their gastrointestinal system.

Finding the best treatment for Giardia can be tricky. Traditionally, fenbendazole (Panacur) or metronidazole have been the go-to treatments for Giardia. For years these have been effective treatments in ridding the digestive tract of Giardia, but over time there has been some resistance development to these drugs. Over the years, I have seen recommended treatment times increase from 3-5 days to 5-7 days. I have personally found that ten days of treatment is required to get good clearance from the digestive tract. Treating simultaneously with both medications has proven to be more effective, but whichever treatment you use, it is essential to complete the full course of treatment to clear the infection and prevent building stronger resistance to the treatment options.

A big problem with these drugs is that fenbendazole does not taste very good and metronidazole tastes downright terrible. I have tasted both, and I can confirm that metronidazole, in particular, is just vile! Both treatments may cause drooling, which can trigger vomiting. This is stressful and means the complete dose is not received. Once the cats know what is coming, they will not be pleased to see you. Metronidazole also has the downside of working as an antibiotic which is problematic as it can strip out healthy gut flora. While metronidazole has worked well at killing the Giardia, the gut can be left with an overrepresentation of bad bacteria. It is advisable to give a good quality probiotic designed for cats (or carnivores in general) for a few weeks after any type of antibiotic treatment.

In 2019 I learned about another drug effective against Giardia. The drug is called secnidazole and is usually used to treat Giardia infections in human children. Secnidazole is advantageous over metronidazole or fenbendazole as Giardia does not seem to have developed resistance to it yet. It also has another major advantage - it is effective as a single-dose treatment. One dose of Secnidazole will clear most Giardia infections. Follow-up treatment after seven days should not be needed but can be used to prevent any ongoing infection if cats have picked up further cysts from the environment after the first treatment.

While secnidazole does not typically require multiple treatments, it is still not a fun experience for the cat or the person giving it. Like Metronidazole, Secnidazole is bitter and disgusting. Yes, I have tasted it too! Compounding pharmacies can add in a flavor to make medications more palatable. So far, I have not found any flavor that can cut through the taste of Secnidazole. Tuna and peanut butter flavors have been the closest, but the taste of the medication is still strong, and the cats know it is in there. My advice is to draw up the dose in the syringe, wipe off the tip, so no trace of flavor is on the outside, have someone secure the cat so it cannot struggle, and then put the syringe as far back in the mouth as you can before releasing the dose. If you can avoid the medication touching the tongue, the cat should have no issue. If it touches the tongue, be prepared for a stringy saliva show! Observe the cats for a few minutes after dosing to ensure nobody vomits and loses their dose.

Secnidazole is not currently licensed for use in cats in many countries; however, if you talk to your vet, she may be able to prescribe it for you. The pharmacy I have found in the US that can compound it at a good price is Wedgewood Pharmacy in Arizona.


Treating the Environment

With the cats and kittens being cleared up, you will want to be sure they won't be reinfected again. For adult cats in outdoor enclosures, this is very challenging. Bleach solution at a rate of 1:32 will effectively destroy cysts in the environment. This is very useful outdoors. Bleach solution can also be used indoors on floors and hard surfaces. Bedding and blankets can be washed with normal laundry detergent and then put through the dryer to kill all cysts. For soft furnishings and other surfaces around the house, a steam mop is one of the best tools you can have. Hot steam will effectively destroy cysts and make cleaning up in your home very easy. Since cysts can stay on the fur for some time, it can be advisable to bathe kittens - especially if they are badly affected. A shampoo containing Chlorhexidine digluconate will kill any cysts present. Sterilizing all litter boxes and scoops with bleach solution will prevent this source of reinfection.

Works Cited

Nazar, Hisham. “What is the global incidence of giardiasis?” www.medscape.com/answers/176718-120626/what-is-the-global-incidence-of-giardiasis

“Parasites - Giardia” www.cdc.gov/parasites/giardia/pathogen.html

Saleh, Meriam N. PhD “Feline Giardia: Transmission, Diagnosis, and Treatment” todaysveterinarypractice.com/feline-giardia-transmission-diagnosis-and-treatment/

Ward, Ernest. DVM, updated by Panning, Amy. DVM.  “Giardia in Cats.”  vcahospitals.com/know-your-pet/giardia-in-cats