Giardia parasite in dogs

Giardia parasite in dogs

Giardia parasite in dogs


Giardia parasite is one of the most commonly identified intestinal parasite in dogs and cats. Infection in the dog is usually subclinical and inapparent. However, clinical disease is seen in young or debilitated dogs and during the course of immunosuppression. In humans, Giardia parasite is implicated in a number of conditions, including chronic diarrhoea, malabsorption syndrome, and chronic fatigue syndrome. In young dogs, giardiasis can cause diarrhoea or can be associated with chronic constipation. In the cat, it is not infrequently diagnosed as an enteric disorder causing chronic diarrhoea. Because of the clinical importance, the parasite has been the subject of many studies and is widely acknowledged as the most important pathogen in human and animal diarrhoeal diseases. This article reviews the aetiology, diagnosis, treatment and management of Giardia in dogs.

What is Giardia?

The dog and cat are the main definitive hosts of the Giardia parasite. This parasite is transmitted by faecal contamination of food, water or other environmental surfaces. The organism is highly resistant to adverse conditions and environmental extremes. The life cycle of Giardia includes stages that are obligate to the animal in which the parasite replicates and different stages that are obligatory to the insect in which the parasite completes its life cycle. These two hosts have different preferences in the time of the year that it is active. Both the dog and cat have the potential to become a primary host during the entire life cycle, from the first stages to the sexual stages.

Infection in humans can occur from the consumption of contaminated water or food. Ingestion of contaminated raw meat, dairy products, fruits and vegetables can also result in the infection. Although it is usually acquired from contact with infected dogs and cats, it is also possible to contract the disease by ingesting contaminated water.

The life cycle of the parasite

Giardia has a complex life cycle (Fig. 1) that consists of three stages in different animals.

The most stable stage is the cyst, which is formed by the attachment of 4-5 trophozoites within an external cover. The cover can resist harsh environmental conditions, such as long periods in sea water, where this parasite cannot be found in other stages.

The trophozoites and cysts are environmentally fragile, and the host must ingest the cysts to become infected. The trophozoites are small and can be passed through the digestive tract, making them easily detectable in stools of infected individuals. However, the cysts are large and can survive for many years in contaminated water.

The sexual stage is in the insects, where mature females are produced. These can reproduce via mating with several males and can produce numerous oocytes and embryos. In the dog, the sexual stage occurs when the animal ingests the infective cysts. The sexual forms are called trophozoites.

The main symptoms

Giardiasis can affect the entire digestive system, but the infection may be asymptomatic in some people.

The main symptoms are:

A watery diarrhea which is usually accompanied by abdominal cramping.

Other gastrointestinal symptoms, such as weight loss, flatulence, stomach pain, and vomiting.

Intestinal malabsorption. The intestinal wall becomes inflamed, which can lead to decreased nutrient absorption and a general feeling of malaise.

Other clinical signs can be associated with giardiasis. These include low white blood cell counts, low levels of magnesium and calcium in the blood, and metabolic acidosis. These symptoms can occur in severe cases.

The long-term effects

Giardiasis can remain asymptomatic, causing the patient to have an acute or chronic disease.

Giardia is considered an opportunistic pathogen, which means that the patient is most vulnerable when his immune system is compromised. This can happen, for example, during a malnourished situation or other infectious diseases such as HIV.




The diagnosis is usually based on a positive test, but it may be necessary to perform other laboratory tests to confirm this. When the infection is severe, antibiotics should be administered.

It is also important to note that the infection can pass from humans to other animals, such as cats and dogs. For this reason, it is advisable to avoid contact with dogs when swimming or camping.

Although it has a high rate of asymptomatic cases, Giardia can cause diarrheal illnesses in infants and young children and, in these cases, treatment is generally recommended.

The recommended treatment for Giardia is different depending on the presence or absence of symptoms.

Treatment of asymptomatic cases

The recommended treatment in the absence of symptoms is metronidazole. It is an effective drug, but it can cause severe side effects such as severe headaches, loss of balance, and severe stomach pain.

Treatment of symptomatic cases

Fenbendazole and tinidazole are the drugs of choice for the treatment of symptomatic cases of giardiasis. There is no difference between these two drugs, but the recommended dose of fenbendazole is a double dose of that of tinidazole.

The main side effects associated with the administration of these drugs are mild and similar to those of metronidazole. However, fenbendazole can cause abdominal pain, severe headache, and tinnitus.

When administering these drugs to an adult, the drug should be given at a dose of 100 mg twice daily. An example of a tinidazole dose is 500 mg/day. For pediatric patients, doses should be adjusted to the child’s weight and may be divided into three doses throughout the day.

Prevention of giardiasis

The prevention of Giardia can be achieved with improved hygiene practices.

Prevention of giardiasis is important in the event of a major outbreak.

However, for minor outbreaks, it is recommended to treat symptomatic individuals only and not proactively.

In asymptomatic cases, treatment is advised to prevent the dissemination of the parasite to other humans.

Giardiasis, also known as amebiasis or intestinal parasitic infection, is one of the most common gastrointestinal diseases. The most common symptoms are persistent diarrhea, abdominal discomfort, and weight loss. Giardiasis infection is caused by a parasite called Giardia. Giard

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