Giardia in Catteries

Introduction

Giardiosis is caused by Giardia, a flagellate protozoan parasite found in the intestinal tract of animals and humans. Giardia duodenalis (also called G. intestinalis or G. lamblia) is often found in catteries with an infection rate of 50%-100%.

The parasite pass via the feces into the environment, where they develop into cysts that can survive for weeks to months. The life cycle is direct and a host is infected after ingestion of the cysts. New cysts are passed in the feces one to two weeks after infection. The incidence of clinical giardiosis is highest in young animals. In mature animals the infections are subclinical.

Clinical problems and diagnosis of giardiosis

The organism remains in the lumen of the intestine and damage the mucosa resulting in altered digestion and absorption (giardiosis). The clinical signs consist of large volumes of acute, chronic or intermittent foul-smelling, light in color, or watery diarrhea, weight loss, growth disturbances and occasional rectal prolapse. Loss of appetite is uncommon. Giardia infections make cats more susceptible to upper respiratory viruses and other disease.

Giardiosis is probably one of the most misunderstood and under-diagnosed of all infectious animal diseases. Many cases are not diagnosed due to intermittent shedding of the parasites (false negative diagnosis) and the need for special laboratory examination techniques and tests. The signs are often diagnosed as inflammatory bowel disease or dietary intolerance. With diets and symptomatic medications the cats will improve, but the problem persists and continues to be transmitted to offspring. Clinicians should consider therefore chronic diarrhea in cats as giardiosis and get confirmation by lab tests or by the response to therapy.

Treatment

The key to resolve giardiosis in catteries is cleanliness in combination with treatment. Frequent disinfecting of the cattery environment, including water bowls, bedding materials, grooming equipment, and litter boxes, and frequent bathing of the animals will interrupt the direct life cycle of Giardia.

For treatment two major drugs are effective against Giardia infections, metronidazole and fenbendazole. Due to possible side-effects, metronidazole is not recommended for use in pregnant and nursing animals. The protocol for metronidazole is 5 days, while a longer duration is often required to eliminate the parasite.

Although not approved, the anthelmintic fenbendazol at a dosage of 50 mg/kg daily for three days, has been shown to be effective and safe in animals with giardiosis.

It is important to treat all cats and it may take a couple of weeks before the stools return to normal. One of the reasons for this is the presence of intestinal bacterial overgrowth. For this purpose, the use of a intestinal prescription diet may be helpful during the recovery. It is important to treat all cats in the cattery, because asymptomatic cats can act as carriers and may continue to shed cysts, placing other cats and people at risk (giardiosis is a potential zoonoses with a special threat to immune-compromised individuals). On the last day of dosing, the cats should be moved to a clean area which is created by removing all fecal material and steam cleaning or disinfection. Because cysts are susceptible to drying out, it is preferable to wait until the area has dried. Moreover the cats should be shampooed and washed before entering the clean area, especially around the perianal area to remove fecal material from the hair coat.

Prevention

New cats in the cattery should be isolated for 6 weeks and tested during this period by fecal exams. A prophylactic, anti-giardial medication can be given before introducing the cat in the group. In some countries a vaccine against Giardia is available for use in cats from 8 weeks of age. The vaccine aids in preventing disease and the shedding of the parasite.