If the dog is not doing well, the dog owner usually suffers too. Diseases of the gastrointestinal tract, which often include diarrhea, vomiting and general exhaustion as symptoms, are particularly unpleasant and should be clarified by the vet as soon as possible. One of the possible causes is Giardia in dogs – this article explains what Giardia is and how this disease manifests itself.
Giardia in dogs – what is it?
The pathogen Giardia intestinalis is one of the most common parasites that occur worldwide and is a protozoan that attaches itself primarily to the small intestine of the dog (or other host animals) and leads to pathological changes there. There are two different stages of development:
- Trophozoites are the reproductive form of Giardia; they settle in the small intestine of the host, multiply by division and feed on intestinal contents. Their attachment to the intestinal cells disrupts the absorption of nutrients, ultimately leading to increased permeability of the intestinal wall and damage to the mucous membrane. Trophozoites that enter the dog’s large intestine convert into cysts, which are then excreted in the feces.
- Cysts are the precursors of trophozoites, are found in the environment, for example in water, food, or in the faeces of infected dogs, and are extremely resistant to external influences. After a dog ingests a few cysts, these convert to trophozoites in the stomach and the cycle begins again.
There are different genotypes of Giardia, which in turn prefer different host animals. Dogs are predominantly genotypes C and D. However, genotype A, which is also contagious for humans, can also occur in dogs or cats in rare cases and can thus be transmitted from the four-legged friends to their humans as a zoonosis. An intestinal disease caused by Giardia is called giardiasis in humans and giardiasis in animals.
There are different statements about the actual spread of Giardia in our domestic dogs, but these are only based on estimates. Some scientists assume an approximately 20% infection rate, others even speak of up to 70% infected dogs, most of which do not become clinically ill. Giardia intestinalis is probably the most common endoparasite in dogs.
How does a dog who has Giardia behave?
Not every dog shows symptoms of illness when infected with these parasites. Slimy-bloody diarrhea, often recurring, or vomiting and fever can indicate giardiasis.
The dog has giardia – an overview of typical symptoms
The course of the disease and the course of giardiasis in dogs are highly dependent on how infectious the strain of the pathogen is and how well the defense system of the four-legged friend works. A clinically visible to severe course is likely, especially in puppies, young, very old or previously ill dogs or animals that live in larger groups (e.g. in animal shelters, dog boarding houses or dog kennels), while adult, otherwise healthy dogs can become infected with Giardia can even take place silently, i.e. without any recognizable symptoms of the disease. However, dogs that are not clinically ill are also a source of infection for other four-legged friends, as they also excrete cysts in their faeces. However, very serious or even fatal courses of the disease are extremely rare and usually affect dogs whose immune system has already been severely damaged in other ways or who are so young that their defenses have not yet developed sufficiently.
After a dog has ingested Giardia cysts, it takes about 4-15 days before it sheds cysts again or the first signs of the disease appear. The symptoms of clinically manifest giardiasis are diverse. Affected dogs usually show one or more of the following signs:
- mushy, watery diarrhea, often recurring
- stomach pain
- Vomit
- loss of appetite and weight loss
- Fatty feces, yellowish-green, putrid or smelling rancid
- Mucus and/or blood in the faeces
- light fever
Diarrhea or vomiting are common symptoms in dogs, which indicate a wide variety of diseases or can simply be triggered by stress, too much food or spoiled food. Sometimes home remedies like bland food can help. If the problems last longer than one or two days or if the dog’s general condition deteriorates significantly (especially in puppies), a veterinarian should be consulted as soon as possible.
Is Giardia Dangerous to Dogs?
Many healthy dogs have giardia without actually getting the disease. Especially very young, old or previously ill dogs are at risk of clinically developing giardiasis. In most cases, however, the disease is not really dangerous because it is easy to treat.
Diagnosis & detection of Giardia in dogs
After a comprehensive anamnesis and questioning of the dog owner about the observed symptoms and the conditions under which the dog is kept (single dog, several dogs, kennels, breeding, staying in a dog boarding house or attending a dog school), the veterinarian will first carry out a thorough general examination of the dog carry out. You can often feel a bloated, painful stomach. A stool sample from the dog is then examined to confirm the diagnosis of Giardia. At best, the dog owner should bring several such samples of his dog’s (diarrhoea) faeces that are as fresh as possible with him to the practice. Otherwise, the veterinarian will ask him to collect the dog’s feces in special sample tubes over a period of two to three days and bring them for examination.
Since cysts are not always excreted with the dog’s feces, it is advisable to examine several fecal samples. The tiny cysts are immobile and could be overlooked if they occur infrequently. The somewhat larger and above all mobile trophozoites can also occur in very fresh diarrheal faeces and are then easier to recognize under the microscope.
More reliable than the microscopic examination are modern antigen test procedures or a DNA pathogen detection. Such rapid tests can be carried out immediately in many veterinary practices, otherwise the exact stool examination is carried out in a specialized laboratory. Appropriate treatment should only be initiated if Giardia can actually be detected as the pathogen.
How long does it take for giardia to go away in dogs?
Since the Giardia cysts can survive for a long time in the area, the success of treating the dog depends above all on how well the hygiene regulations are observed. The infection is only over when the veterinarian has repeatedly examined the dog’s stool samples negatively.
Giardia in dogs – treatment
If the examination of the faeces clearly confirms the suspicion of giardiasis, there are various antiparasitic agents that have to be administered to the dog according to a clear scheme in order to really reach all developmental stages of the parasites. By examining further stool samples, it is then checked whether the treatment was successful and whether the Giardia were effectively combated. If necessary, the drug must be changed again. A dog infected with Giardia is contagious as long as it is shedding cysts.
Since the Giardia cysts can remain in the dog’s environment for a very long time and new infections could occur again and again, it is of great importance to also rid the environment of the pathogens through appropriate hygiene measures. Lying surfaces, blankets, food and water bowls, toys, leashes, brushes and other objects that the dog comes into contact with must be washed regularly with hot water (over 60°C) or hosed down. This also includes the transport box or the trunk of the car. Exercise areas such as kennel floors should be disinfected with appropriate agents. At the beginning of the treatment, the dog should also be washed several times with antiparasitic shampoo to remove cysts adhering to the coat. In the case of long-haired dogs, shortening the fur around the anus and on the hind legs should also be considered.
How do you get rid of giardia in dogs?
If the veterinarian has detected an infestation with the protozoa, the dog must be treated with appropriate medication. In addition, all objects and lying surfaces that the dog comes into contact with are disinfected or washed with hot water. Only if a stool test is clearly negative, the dog is considered pathogen-free.
If there are several dogs or cats in the household, the veterinarian must decide whether these also need to be treated. Since animals that are not clinically ill also excrete Giardia cysts, there could otherwise be constant new infections. In larger dog populations such as animal boarding houses or animal shelters, a hygiene concept for the entire population must be specified by the veterinarian in the event of a Giardia infection.
In order to avoid spreading the pathogens to other dogs, the droppings of an infected dog should always be completely removed with a plastic bag and disposed of with household waste. Larger exercise areas or dog parks where there are many dogs should be avoided until no more Giardia can be detected. Above all, parks, playgrounds, sandpits or other places frequented by children must be avoided with the dog, as in rare cases the pathogens can be transmitted to humans.
Prognosis – what are the chances of recovery?
If a Giardia infection is detected, the chances of recovery for an otherwise healthy dog are very good. Consistent treatment and implementation of the hygiene measures mentioned is important. It is essential to examine the dog’s faeces several times after the treatment has been completed, in order to be able to quickly counteract a renewed spread of the parasites.
The disease only becomes dangerous in very young puppies, especially if they live under poor hygienic conditions, or in very old dogs or dogs that are already weakened by other previous illnesses. A heavy infestation with recurring diarrhea can permanently weaken the general condition of the dog due to the large loss of fluids.
Can Giardia be transmitted from dogs to humans?
Only one of the different Giardia genotypes is infectious for humans. However, this genotype A is rather rare in dogs. Nevertheless, when handling a dog that has tested positive for Giardia, special hygiene measures should be observed and, for example, you should wash your hands thoroughly after every petting.
Prophylaxis and prevention – Can I protect my dog?
There is no basic protection for dogs against Giardia infestation, as these parasites are widespread and can persist in the environment for a long time. However, a healthy, balanced diet, regular health checks, and sufficient exercise in the fresh air do a lot to strengthen the dog’s immune system and healthy intestinal flora, so that it can cope better with possible infections. If possible, heavily frequented dog run areas should be avoided, as there can be an increased risk of infection from the droppings of other four-legged friends.
If a dog has been infected with Giardia, the dog owner should make sure that the four-legged friend does not come into contact with other dogs and remove the remains of his fur nose quickly and cleanly. A brief explanation to other dog owners as to why the dog is not allowed to play or sniff for the time being will certainly be gratefully and sympathetically accepted.
