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Giardia is one of the most common intestinal parasites. In most cases, an infection is asymptomatic. However, cats with diarrhea can suffer from giardia. This article answers questions about Giardia in cats:

What is Giardia?

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Giardia are microscopic, single-celled creatures. Their turnip-shaped body is up to 20 micrometers long. With the help of small threads, so-called flagella, Giardia move in a whip-like manner. Giardia lead a parasitic lifestyle. Their preferred habitat is the small intestines of mammals, birds, amphibians and reptiles. There, the giardia can trigger a diarrheal disease, giardiasis or giardiasis.

The life cycle of Giardia

During the course of its life, the protozoa exists in two different forms – as a trophozoite (active life form) and as a cyst (inactive, contagious life form). As a fragile trophozoite, the parasite lives and feeds in the small intestines of animals. If the trophozoite gets into the large intestine, the pathogen converts into an inactive cyst. The cyst is then passed out with the host’s feces. Giardia cysts are very resilient. They can survive in the environment for several months and even survive freezing. The preferred habitat of the cysts is the water or a humid environment. Cysts also tend to stick to the animal’s fur (especially in the anal area). In this way, the infection process can be maintained. Reinfections are a common problem in Giardia infections.

How does a cat get giardia?

Cats become infected by ingesting Giardia cysts. The cysts can be found in the feces of other infected animals. These are often littermates. This is also one of the reasons why giardiasis is more common in multi-cat households and in cats under the age of one. After ingesting cysts, it takes five to 16 days for a cat to show signs of illness. A cat does not always become infected with a single exposure to the cysts. Multiple exposures are often required to trigger an infection.

Can Giardia in dogs infect cats?

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Giardiasis is a zoonosis. Zoonoses are diseases that can be transmitted from animals to humans and vice versa from humans to animals. This means that Giardia in dogs can result in transmission to humans or cats. Over 40 different Giardia strains are known worldwide, not all of which cross species boundaries.

Overall, the risk of Giardia infection in dogs resulting in transmission to humans is very low. The Giardia strain that infects humans does not usually infect cats or dogs.

How common is Giardia?

Giardia is one of the most common intestinal parasites in cats and dogs. In a 2017 and 2018 study by the IDEXX laboratory, 2188 cat samples were tested for the presence of Giardia protein. About 9.4 percent of the examined animals showed a Giardia infection. People in Germany rarely contract Giardia. Around 4 – 5 diseases per 100,000 inhabitants are recorded every year. The infection often occurs on holiday trips to warm regions or countries with a rather poor hygienic situation. Children, the elderly and the sick are at risk. An infection with Giardia in humans must be reported.

Giardia in cats – symptoms

Although it is probably the most common intestinal parasite, the majority of cats infected with Giardia do not show any visible signs of the disease. However, these animals remain a source of infection for other animals and also humans.

Whether Giardia causes symptoms in cats depends on various factors.

Age: Kittens under the age of 12 months fall ill more often than adult cats
Already existing intestinal infections: Giardia often occur together with other protozoa such as Cryptosporidium or Isospora
Intestinal flora and intestinal immunity: The majority of all immune cells in the body are located in the intestinal mucosa. Immune cells play an important role in the defense against pathogens. Intestinal bacteria are in direct contact with these cells and thereby regulate the immune system. A healthy cat’s gut can fight off Giardia. If, on the other hand, there are disturbances in the composition of the intestinal bacteria, the parasites can spread.
Signs of Giardia infection in cats can include acute or chronic diarrhea. The diarrhea droppings of infected cats tend to be light-colored and watery-slimy. Sometimes the stool smells very bad and may contain traces of blood. A massive Giardia infestation in cats causes nausea. Sick cats appear lethargic and lose weight. The fur appears dull and shaggy. The course of the disease can drag on for months despite therapy due to the risk of reinfection.

How does the vet diagnose giardiasis in cats?

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A stool sample is examined to diagnose giardiasis. Cysts in the stool can be identified by the vet using a microscope. In addition, molecular biological and antibody-based test methods are available to detect the genetic material (DNA) of Giardia or Giardia proteins in the feces of the cat. An examination of the DNA also gives conclusions about the Giardia strain and the zoonotic potential of the pathogen. In some cases, several fecal samples must be analyzed for a clear diagnosis, since cysts are not continuously shed.

What helps if my cat has giardia?

Giardia in a cat can usually be combated with three measures:

  • Optimizing nutrition and strengthening the immune system
  • hygiene measures
  • medication

What should I feed my cat if she has Giardia?

The balance of all microorganisms in the intestine, the so-called microbiome, is important for optimal intestinal function and stool consistency. Prebiotics (a special form of fiber) and probiotics (viable microorganisms) can help restore balance to the microbiome. The nutritional components support normal bowel function and help control the diarrheal symptoms of giardiasis.

Prebiotics are certain dietary fibers made from long-chain carbohydrates that are not absorbed by the intestines but by desirable bacteria. Prebiotics support the growth of already existing, useful intestinal bacteria and thus contribute to the restoration of the natural intestinal flora. In addition, a high-fiber diet reduces the adhesion of the pathogens to the intestinal wall. Examples of prebiotically effective additives are pectin-rich apple pomace and psyllium husks.

Probiotics are products that contain live microorganisms. By adding them, specific bacteria and yeast fungi can be supplied to the cat’s intestines. They support the intestine in the production of a biofilm. This can prevent the attachment and invasion of the Giardia cysts. Probiotics for cats are available in powder or capsule form. The products vary in the amount and composition of the microorganisms offered. Enterococcus faecium is one of the most commonly used strains of bacteria.

In many cases, prebiotic food supplements for cats are also enriched with prebiotic fiber and are therefore referred to as synbiotics. Synbiotics have the advantage that gut bacteria are delivered along with their “food”. A cat with diarrhea due to Giardia will particularly benefit from these products.

Some online content recommends a low-carb diet for Giardia. So far, however, there is no scientific evidence that a low-carbohydrate diet influences the Giardia infection – neither positively nor negatively. Carbohydrates are rather easily digestible food components. In comparison, fats and proteins are difficult to digest. The intestines of a cat with an acute giardia infection may at times be so damaged that a drastic change in diet seems impractical. Therefore, cat owners should seek the advice of a veterinarian before changing their diet. He has experience in the treatment of Giardia in cats and can give you professional advice.

Hygiene measures for Giardia in cats

Special hygiene measures and thorough cleaning of the area can reduce the risk of ingesting Giardia cysts. This includes:

  • Always collect animal droppings and dispose of them harmlessly (plastic bag, garbage can).
  • Clean the litter box, food and water bowl regularly with boiling water and then dry them carefully
  • Provide fresh water to drink as other water sources may be infected by other animals.
  • Long-haired cats in particular should shampoo after treatment, as infectious cysts can adhere to the hair coat.
  • Wash cat blankets regularly in hot water.
  • Clean toys and scratching posts carefully.

Drug treatment of giardia in cats

The drug fenbendazole can be given for giardiasis. However, fighting Giardia in cats is difficult because the risk of reinfection is very high. Therefore, all animals in a herd should be treated at the same time, regardless of whether they show symptoms.

Giardia in Cats – Pure Scaremongering?

Not every animal that carries the pathogen has to show symptoms. It is controversial whether healthy cats with a giardia infection should be treated with medication. Therefore, for each infected cat without symptoms, an individual decision should be made as to whether treatment is necessary or not. A veterinarian has experience in treating feline Giardia and can give you expert advice.

Speaking against treating asymptomatic cats:

  • Drug treatment of Giardia can cause side effects
  • Typically, symptom-free pets pose no health risk to healthy people or animals
  • Giardia cysts are found everywhere in the environment, increasing the risk of reinfection
  • Strict hygiene measures are not feasible for many cat owners, which increases the risk of reinfection
  • Repeated drug treatments can negatively affect the gut microbiome

In favor of treating symptom-free cats:

  • The infected cat lives in a household with immunocompromised high-risk patients

Giardia in cats – conclusion

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Fortunately, stubborn intestinal parasites are mostly harmless. However, since they can be uncomfortable for weakened animals and humans, you should definitely go to the vet if you suspect Giardia in your cat.