Giardia in cats is one of the most widespread parasites in the world. Giardia is infectious to felines, dogs, and humans. It is also infectious to an enormous variety of other animals. This infection has a growing presence in our environment.
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Giardia in Cats - Here Is Why It Is Especially Dangerous
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Giardia in cats is a type of protozoan parasite of the gastrointestinal system. This parasitic disease is associated with diarrhea and chronic digestive and metabolic disease.
In this article, we are going to outline the most important details about this Giardia in cats:
- Its life cycle.
- Its transmission.
- The main symptoms.
- What you should do if you have an infected cat?
The Highlights:
- Giardia in cats or Giardiasis is a disease caused by microscopic parasites.
- Giardia in cats is contagious and needs to be treated by a veterinarian.
- Symptoms of Giardia in cats include:
- Diarrhea
- Weight loss
- Digestive symptoms.
- Good hygiene is the most important preventative measure to control Giardia in cats and limit the spread in the household.
- Recommended product for keeping the litter box as clean as possible is the Little-Robot.
What Is Giardiasis?
Giardiasis is a diarrheal disease caused by the Giardia parasite. This parasitic disease commonly occurs in:
- Cats
- Dogs
- Other Wild and Domestic Mammals
- Birds
- People.
There are several strains of Giardia in cats, but the most important is G. intestinalis, also known as G. lamblia and G. duodenalis, which can infect cats, dogs, and people.
Cats may also contract Giardiasis felis. However, cross-infections can also occur.
What Is Giardia?
Giardia intestinalis (also known as G.lamblia or G. duodenalis) is a water-borne parasite that can infect all mammals. Giardia in cats is a serious illness, that can move from humans to cats and from cats to humans (zoonosis).
This happens because the same pathogen is infectious to both people and animals. It is a flagellated (has a flagellum that enables it to move) single-celled microorganism.
Giardia in cats commonly causes diarrheal disease all over the world. And it is the most common cause of water-borne outbreaks of diarrhea in the United States.
How Does Infection with Giardia Occur?
Infection occurs when the host (cat, human, or other mammals) ingests Giardia cysts with:
- Contaminated water
- (Less commonly) Contaminated food
- Via direct fecal-oral contact (unwashed hands).
For Giardia in cats, the contamination usually occurs when they drink water from:
- Rivers
- Lakes
- Puddles
- Other contaminated water sources.
Cats that live outdoor are more exposed to the disease.
How do indoor cats get Giardia?
Indoor cats from households that also include dogs are at greater risk. This is because the dog can get infected when it goes outside.
If one of the human members of the household becomes infected with Giardiasis, he or she could transmit the disease to the cat, as well. It is important to follow solid hygiene protocols.
The Life Cycle of Giardia
Giardia in cats has two main stages in its life cycle:
- The cyst
- The trophozoite.
While both of these are passed in the infected host's feces.
The cysts are the most infectious because they can survive in the environment for a long time. Trophozoites, on the other hand, do not survive in the environment but can cause infections in some cases (fecal-oral contact), too.
Giardia cyst in a microscopic examination. The cyst has an oval shape and it has a strong outer layer that is adapted to protect it from the harmful effects of the environment.
The main role of the cyst is to help the parasite located inside it to survive outside of its host. Cysts are not mobile, so they will remain in the area where the infected host has excreted them, waiting for a new host to come and pick them up.
Giardia in cats occurs when the cat ingests the cysts, these pass through the digestive tract. When they are exposed to the highly acidic environment in the stomach, the outer layer which had protected them outside of their host finally breaks down, unleashing the parasite into the host's digestive tract.
When the cysts reach the first portion of the small intestine, the duodenum, they exocyst into trophozoites. As opposed to the cystic stage, the trophozoite is mobile. It has 4 pairs of flagella that enable it to move in the intestine.
When they reach the brush border of the intestinal wall, they adhere to it using a sucking disk.
Can you see giardia in cat poop?
Giardia trophozoites as seen in a microscopic examination. When the trophozoites feed, they adhere closely to the villi on the brush border and suck in the nutrients, damaging the intestinal wall in the process.
Considering that the host usually ingests a large number of cysts, which exocyst into trophozoites, and reproduce rapidly, the number of trophozoites feeding on the small intestine is enormous. This means the damage to the intestinal wall is serious.
What happens if Giardia in cats goes untreated?
These lesions to the intestinal wall affect the absorption process, which leads to malabsorption in the host (the incomplete absorption of nutrients).
The inflammation in the intestine and the improper digestion lead to diarrhea, which has a particularly foul smell because the food has not been fully processed in the digestive tract. This is also the reason why cats suffering from Giardiasis lose weight rapidly.
The trophozoites feed on the nutrients they extract from the intestinal wall to gather the resources they need to multiply.
Multiplication of Giardia in cats occurs by binary fission, which means that one trophozoite can essentially duplicate itself. This also happens in the duodenum, the first portion of the small intestine (this is why the species is known as G. duodenalis).
Then, as they pass in the jejunum, the second portion of the small intestine, they come in contact with the biliary fluid. The parasite then senses that the surrounding environment is not suitable for it anymore, so it switches back to its survival stage, the cyst.
However, only some of the trophozoites form cysts. From the jejunum on, the parasite (both in trophozoite and cystic form) passes through the intestinal tract until it is excreted with the feces into the environment.
The trophozoites die quickly outside of the host, but the cyst can resist for a long time, waiting for a new host. Thus, the life cycle of the Giardia in cats is complete.
- Epidemiology - This intestinal parasite is distributed globally and it occurs in both developed and developing countries.
- Reservoir - The main reservoir for humans are other humans infected with the parasite.
Giardia in cats is also particularly prevalent in cattle, especially in calves, which eliminate a large number of infectious cysts in the environment, which contaminate the waters in the region.
People who live close to cattle farms should be aware of this and avoid using water from ponds and lakes. They should also:
- Wash their hands regularly
- Avoid touching their mouths with unwashed hands.
Symptoms of Giardiasis in Cats
Giardia in cats can be either very simple to diagnose or very difficult, depending on the cat's age and the health of its immune system.
Giardia in cats' kittens can have a violent revolution, which makes it easy to notice. Giardia in older cats, on the other hand, can shift into a chronic digestive disease that displays generic symptoms.
Recognizing the Infection with the Giardia parasite
Here are the main symptoms that occur when cats become infected with G. intestinalis:
Diarrhea
This is the main symptom of giardia in cats. It is caused by the damage that the trophozoites do to the intestinal wall, as well as the improper digestion that occurs as a result.
The stool has a very foul smell, it is pale in color and is poorly formed because the food is insufficiently digested, which is viardiaisible - it is mucous, with noticeable fatty portions.
When Giardia in cats occurs for the first time, the diarrhea is acute, but its evolution can be continuous or intermittent.
In older cats, with strong immune systems, diarrhea can be limited to a softening of the stool, which is usually not noticed. In cats with poor immune systems, on the other hand, diarrhea, associated with malabsorption, can be debilitating.
Digestive Symptoms
Giardia in cats also displays other digestive symptoms, such as:
- Loss of appetite
- General apathy
- Abdominal pain
- Bloating
- Vomiting.
The severity of these symptoms differs according to the evolution of the disease.
Weight Loss
As a result of the malabsorption caused by the presence of the parasite in the intestine, cats infected with Giardia do not absorb the right amount of nutrients, even though they are fed the right amount of food.
This leads to weight loss, which varies in severity according to the evolution of the Giardia in cats and the kitty's immune system.
- In kittens and cats with poor immune systems, in which the Giardia also causes severe diarrhea, the weight loss is very easy to notice because they lose a large amount of weight in a short period.
- In older cats with strong immune systems, on the other hand, the weight loss may not be so easy to notice because it happens over a longer period.
Diagnosis of Giardia in Cat
Cats can quickly become dehydrated if they continue to have diarrhea without getting medical attention, so it’s important to take your cat to a veterinarian as soon as possible for treatment.
How to diagnose Giardia in cats?
Be sure to tell the vet when the symptoms began and how often diarrhea has occurred. Giardia in cats is characterized by strong-smelling, soft fecal matter.
The vet will need to know if this is how your cat’s fecal matter looks and smells.
You should also let your vet know about your cat’s diet. Cats can often get diarrhea from changes in their diet, so if you haven’t made any changes, it’s important to rule this out as a potential cause.
The vet will need to test your cat’s stool to provide an accurate diagnosis.
How do you test for Giardia in cats? Either a fecal smear or fecal flotation test will be done on the sample. If your cat has Giardiasis, the parasite will be present in his fecal matter.
However, it’s not guaranteed that every stool sample will contain the parasite. Therefore, the vet may need to test multiple samples to confirm it is. He may ask to test samples from three different days before making an official diagnosis.
Numerous diagnostic comparison studies have been undertaken to determine the best test for detecting Giardia in cats, with one common result — no single test detects all infections.
Types of tests for Giardia in cats
Usually, for detecting Giardia in cats in practice is to perform a direct smear of the feces in conjunction with a veterinary-approved antigen test (PCR). This combination of diagnostic tests maximizes the chances of detecting Giardia in cats.
Diagnosis of Giardia in cats via microscopy alone is difficult. In routine practice, antigen tests for use in humans should not be used for cats, as they are not optimized for or approved for clinical use in animals.
Molecular testing to detect Giardia in cats is available at reference laboratories and some university laboratories, but it is generally more expensive than performing or sending out a fecal flotation or using an antigen test.
Follow-up testing with centrifugal fecal flotation, a PCR test, should be performed within 24 to 48 hours after completion of therapy if clinical signs have not resolved.
The timing of follow-up testing is critical because the pre-patent period of Giardia in cats is as short as 5 days, and it is imperative to test before that time has passed.
Often, what is suspected resistance or treatment failure is reinfection, and the source of infection cannot be determined if follow-up testing is done 5 or more days later.
Treatment
In the United States, no drugs have been approved for the treatment of Giardia in cats.
However, they can be treated with medicine that has been approved for the disease in Europe: a combination of antiparasitic medications. Several types are needed because some are efficient for the cysts, and others for the trophozoites.
Aside from the antiparasitic medication, cats also need the symptoms to be treated, as well. A change in the diet that will help them regain the correct amount of nutrients is required, too.
However, Giardia in cats has been treated safely and with varying degrees of efficacy with:
- Febantel (which is metabolized to fenbendazole after oral administration)
- Fenbendazole
- Metronidazole.
Metronidazole (25 mg/kg) administered orally, twice a day, for 5 to 7 days was successful in clearing Giardia in cats.
Febantel (37.8 mg/kg), in a combination product also containing pyrantel (7.56 mg/kg) and praziquantel (7.56 mg/kg), successfully cleared infections in experimentally infected kittens when given for 5 days.
A pilot study investigating the use of secnidazole (30 mg/kg) in 18 laboratory cats found it was effective in eliminating cyst shedding, but the follow-up period only lasted 8 days.
Additionally, 11 out of 18 cats exhibited hypersalivation following administration, and 4 out of 18 cats had inappetence for 2 days.
However, there are some limitations to the study given the small number of cats in each trial and the lack of comparison to either metronidazole or fenbendazole.
Prevalence of Giardia
Giardia in cats has a worldwide distribution and is found in every region of the U.S. The prevalence of Giardia in cats varies greatly depending on:
- Population, including:
- Individual pets
- Group-housed pets
- Breeding colonies
- Shelter animals
- Stray animals
- Geographic location
- Diagnostic method used.
For example:
- In a survey that used a patient-side antigen test in symptomatic cats from throughout the U.S., 10.8% (512/4977) of cats were positive for Giardia.
- Another survey identified Giardia infection in 31% (36/117) of tested cats from international catteries.
- In 2020, the national prevalence of Giardia in cats in the U.S. was 4%. These data were generated by the CAPC from more than 1.8 million feline fecal samples tested for the presence of Giardia by reference laboratories.
But as they do not include cats not taken to the veterinarian or stray cats, and not all veterinary clinics use reference laboratories, 4% can be considered a baseline minimum prevalence is largely asymptomatic individuals.
Prevention of Giardia in Cats
Complete elimination of Giardia in cats is difficult because the cysts are immediately infective when shed, making reinfection highly possible. Therefore, preventing fecal contamination of the environment is crucial to preventing reinfection.
Bathing to remove fecal debris containing cysts from the fur is a must.
Disinfection of the cattery or home is also recommended, including:
- Crates
- Litter boxes
- Bedding.
Quaternary ammonium products, boiling water, and chlorine are described as effective against cysts.
Washing/shampooing of animals, or at least the perianal area, with shampoo containing chlorhexidine at the beginning and during the treatment, can help to eliminate the cysts.
Testing could be proposed for new cats entering a multi-cat environment to avoid the introduction of the parasite. This can be done during the quarantine period.
Care staff (nurses, vets, veterinary students) should be aware of and should respect the hygiene rules.
A vaccine, based on inactivated trophozoites, has been used in the USA but not in Europe. But it is no longer available. It was used for treatment, as well as prevention.
Zoonotic Implication of Giardia in Cats
Many European studies (in Germany, Italy, Spain, Greece, and Poland) demonstrated the presence of subgroup A in cats, either alone, or as a dual infection.
Genotype B has also been identified in cats, but A is most prevalent, according to the different European studies and a Canadian one.
The risk of harboring zoonotic Giardia seems to be higher in young cats in less than one year compared to older cats.
A recent study failed to detect zoonotic assemblages in 3 Giardia positive dogs and 2 positive cats living in the Alava region of Spain, suggesting that household transmission of Giardia by pets, if it occurs, is infrequent.
In this study, no simultaneous infections in human and canine/feline hosts by G. duodenalis were demonstrated. Although 29% of dogs and 5.9% of cats tested positive and there was a presence of zoonotic assemblage A was detected in cats in a shelter in the same region.
On the other hand, a study conducted on children from poor environmental conditions in Slovakia showed that cat-specific assemblage F is present in humans in Europe.
To date, there is no study demonstrating direct transmission of Giardia from cats to humans and the main sources of contamination for people appear to be raw vegetables and water.
Moreover, the prevalence of Giardia infection in asymptomatic cats is low in most European countries.
Although there is no proof of direct transmission of Giardia from cats to humans and considering that zoonotic species are sometimes detected in infected (young) cats, the zoonotic potential of Giardia in cats should be considered.
Especially where young cats are living with immunocompromised people. Testing such cats is therefore recommended.
FAQs About Giardia in Cats
Can I get a Giardia infection from my pet?
This is possible but it rarely happens. Since most cases of Giardia in cats are a result of drinking contaminated water, Giardiasis is one of the most common intestinal parasitic infections. And, it can potentially be passed from cats to humans.
In the past, it was assumed that cats and dogs, along with wildlife, were the main source of infection for humans.
Genotypes or Assemblage A can infect:
- Humans
- Dogs
- Cats,
while B can infect both humans and dogs.
However, human-to-human transmission is also important and contaminated water supplies are responsible for many outbreaks.
How is Giardia in cats spread?
The most common medium of transmission is through contaminated water and food.
Giardia in cats can be transmitted by:
- Eating or sniffing the cysts from contaminated ground
- By drinking contaminated water.
Ingestion of food, and soil contaminated with human feces, is a phenomenon particularly common in many developing countries.
How does my cat get infected with Giardia?
A cat becomes infected with Giardia after swallowing the cyst stage of the parasite. This can happen from several causes such as:
- Being in contact with infected feces (poop) from another dog or cat.
- Rolling and playing in contaminated soil.
- Licking its body after contact with a contaminated surface (for example, a dirty litter box, or dog cage or crate).
- Drinking water from a contaminated creek, pond, or other body of water.
Who is at risk of getting infected with Giardia?
According to CDC, those at greater risk are:
- People in childcare settings.
- People who are in close contact with someone who has the disease.
- Travelers within areas that have poor sanitation.
- People who have contact with feces during sexual activity.
- Backpackers or campers who drink untreated water from springs, lakes, or rivers.
- Swimmers who swallow water from swimming pools, hot tubs, fountains, or untreated recreational water from springs, lakes, or rivers.
- People who get their household water from a shallow well.
- People with weakened immune systems.
- People who have contact with infected animals or animal environments contaminated with feces.
How do I protect myself if my cat has a Giardia infection?
1. Wash the cat frequently and keep it isolated until all symptoms have cleared up.
2. Disinfect your home properly with disinfectant.
- Always wear protective gloves when gardening to reduce the risk of coming in contact with infected poop.
- Wash your hand properly after using the toilet.
- Wash your hand properly with soap and water after handling cat feces.
- Wash your hand before handling, preparing, or serving food.
How long does Giardia survive in the environment?
In the soil
In cold temperatures (around 4ºC/39.2ºF), Giardia can survive for approximately 7 weeks (49 days).
At room temperature (around 25ºC/77ºF), Giardia can survive for approximately 1 week (7 days).
Dry vs. moist surface or environment
In a dry, warm environment that experiences direct sunlight, Giardia can survive for only a few days.
In a moist, cool environment, Giardia can survive for up to several weeks.
Water
In water temperatures below 10ºC/50ºF (for example, lake water or puddle water during the winter, refrigerated water), Giardia can survive for 1–3 months.
In water temperatures above 10ºC/50ºF (for example, river water during the fall, tap water, and puddles during the summer), Giardia can survive for shorter periods of time in colder temperatures.
For example, in water above 37ºC/98.6ºF, Giardia can survive less than 4 days.
How often and for how long should I clean and disinfect my after my dog or cat is diagnosed with Giardia?
Clean and disinfect regularly (for as long as your pet is sick) all potentially contaminated items:
- Toys
- Water bowls
- Food bowls
- Pet bedding
- Floors
- Dog crates
- Linens
- Towels
- Litter box
- etc.
If your pet is taking medication, you need to clean and disinfect frequently (daily if possible), until a few days after the last dose of medicine is given.
Giardia's survival depends on many factors, so we strongly advise that you consult your veterinarian for further advice.
How do I prevent my dog or cat from getting reinfected, or getting my other pets sick, during treatment?
If you have other dogs or cats, make sure you tell your veterinarian, even if they are not showing signs of diarrhea.
Other pets may also be put on medicine depending on the situation.
Even animals showing no signs of Giardia infection could be infected and shedding Giardia into the environment.
Bathe all household pets with pet shampoo, following the medical treatment, to ensure no fecal residue is in the pet’s coat.
Clean dogs’ and cats’ environment (holding areas, floors, crate, etc.) and wash their water bowls daily with soap and water.
Limit your dog’s access to untreated surface water (creeks, ponds, lakes). Do this to avoid re-infecting your animal or contaminating the water, which could make other animals sick.
Best Advice for Giardia from Veterinarians:
Best Advice for Giardia
Hygiene is the most important preventative measure to control Giardia infections in cats and spread in the household.
Do not allow your cat to drink from contaminated water sources or eat contaminated food.
Bathe infected animals to remove feces that may contain cysts from their fur coat.
Also, make sure to wear gloves and wash your hands when cleaning and dealing with feces.
Dr. Michelle Burch, DVM @ Safehounds.com
Will Giardia go away on its own in cats?
Giardia will usually not go away on its own and many cats need to be on prescription medication to treat it.
How contagious is Giardia in cats?
Giardia is very contagious in cats. It is not uncommon to have outbreaks of it if many cats live in the same home or environment.
Will vinegar kill giardia?
No, vinegar will not kill giardia. Treating giardia requires a course of an antibiotic, called metronidazole, and sometimes also requires fenbendazole, a dewormer.
How do I disinfect my house from Giardia?
Disinfect with diluted bleach - the litter box and areas the cat frequents. Clean the litter box frequently to prevent reinfection.
Dr. Leslie Brooks, DVM, MPH Verternary Advisor @ Betterpet
Giardia in Cats - A Reader's Experience
Jinxy and Giardia - written by Jinxy's mom, Judy.
My kitten, Jinxy was born June 11, 2018, and I picked him up when he was approximately 3 months old. He was a wonderful kitten, extremely loving and playful but immediately started to have consistent diarrhea, sneezing, and eye discharge.I initially took him to my veterinarian for a wellness check and testing just to ensure everything was okay.
It was quickly determined that he had several issues including calicivirus and mycoplasma.
My breeder was excellent in helping me to ensure Jinxy was getting proper treatments and also covered the cost of my vet visits. She suggested giving him plain Greek yogurt and pumpkin to help with the diarrhea issue.
After a few weeks and after taking all of his medications, Jinxy was still experiencing diarrhea, so the breeder offered to take him back to her veterinarian to have him checked there.
She was concerned because Jinxy has received the calicivirus vaccine and thought he possibly reacted to it. At that time her veterinarian discovered he had hookworms which he was immediately treated for.
The breeder kept Jinxy for one month to ensure he was diarrhea-free and gave me frequent updates on my kitten’s health which was comforting.
Once we got Jinxy back home, he was fine for a day or two but then diarrhea returned. At that point, I took him back to my veterinarian who did a thorough exam including bloodwork and an extensive intestinal parasite lab test that a normal fecal exam and lab did not include.
Several days later we received the lab results confirming our boy had Giardia.
Jinxy’s Giardia was treated with metronidazole. He was on this medication for 2 weeks and his persistent diarrhea was eliminated, as was the giardia after that.
It never returned and neither did diarrhea. The metronidazole cleared diarrhea up within 2 days.
During the time of Jinxy’s giardia treatment, I did extensive research on cat foods and slowly began changing his diet. He had been eating Science Diet dry kitten food and Royal Canin can kitten food. Through research, I discovered neither is good. So I gradually switched him to high-quality canned food and a variety of freeze-dried raw foods. Currently, at 2 1/2 years old he is eating Dr. Elsey’s Clean Protein can food mixed with Stella & Chewy’s freeze-dried raw chicken, duck, rabbit, and Primal freeze-dried raw turkey. I add quite a bit of water to this mixture to form a wet paste. He also gets about a tablespoon of Vital Essentials freeze-dried raw mini nibs in the chicken and turkey for a bit of crunchy food. Jinxy eats twice daily. I add Dr. Mercola Complete Probiotics to the wet food each time and I also add in 1/2 teaspoon of The Missing Link feline formula. He gets one spirulina tablet daily made by Dr. Mercola. I order everything from Chewy.com.
The combination of his giardia medication and the food switch completely cured my boy. He has not had one bout of diarrhea in 2 years and has one bowel movement daily that is almost odorless. I have never had to clean his bottom. I believe the food change worked miracles. Jinxy is extremely healthy with great kidney numbers so I’m confident the giardia had no long-lasting effects.
I feel fortunate to be able to work with a veterinarian who is focused on resolving issues and taking the time for that.
When I learned Jinxy had Giardia I was worried because I thought it would be difficult to resolve.
But with persistence in ensuring he had his litter box cleared 4-5 times daily, making certain he took all medications as directed, and changing his diet, I am fortunate to now have a very healthy cat with no gastric or respiratory issues.
Jinxy is currently recovering from a broken hind leg and femoral head removal surgery. That’s a story for another time. Sometimes I think there may be truth in a name.
Patti Johnson
HAPPY NEW YEAR'S EVE! TYSVM for such a SUPER PAWESOME & FABULOUS POST, Jenny honey! What a horrible illness! Yikes! So glad Jinx recovered! A BIG TYSVM to Jinx' mom, Judy, for sharing! <3
Big hugs & lots of love & purrs & HAPPY NEW YEAR!!!
Patti & Miss Pink Sugarbelle 🙂 <3 <3 <3