What is a fecal flotation?
Fecal flotation is a routine veterinary test used to diagnose internal parasites or "worms." The test detects the eggs of mature parasites that live inside the body and pass their eggs to the outside by shedding them into the host's stool. Some of these parasites are worm-like, while others are tiny single-celled organisms called protozoa. Most of the parasites live in the intestine, but a few live elsewhere in the body.
How does the test work?
Stool material is mixed with a special liquid that causes the parasite eggs to float to the surface. The eggs are collected from the surface using a glass slide. The slide is examined under a microscope, and the appearance of the eggs identifies what type of adult parasite is present. The number of eggs found may reflect the severity of the infection, but this is not always reliable.
What sample is needed?
All that is needed is about a one inch piece of fresh stool. Ideally, the stool sample should be no more than 24 hours old and should be as free as possible of grass, gravel, kitty litter, etc. Your veterinarian may provide a container to collect the sample, but any clean, dry container with a tightly fitting lid can be used, such as a jar or plastic tub.
When should fecal flotation be done?
Kittens and puppies are frequently infected with intestinal parasites and are susceptible to re-infection. Therefore, multiple fecal flotations are recommended for young animals. Pet owners should bring a fresh stool sample to each appointment for the initial series of veterinary visits. If a pet is found to have parasites, follow-up fecal flotations may be recommended to monitor the response to treatment. Fecal flotation may also be recommended if a pet develops diarrhea or fails to gain weight as expected. Mature pets are less likely to be infected with parasites. A yearly fecal flotation done as part of the annual check-up is usually sufficient to monitor the healthy adult pet. However, more frequent fecal testing will likely be recommended if an adult pet develops diarrhea, exhibits unexplained weight loss, or has a history of recurrent parasitic infections.
Does the test work every time?
No. Fecal flotation is only a basic screening test and may fail to detect infection in some situations.
"Some intestinal parasites just cannot
be reliably detected with fecal flotation."
A fecal flotation test may fail to detect parasite infection because:
1. The parasites themselves are too young to produce eggs. If no eggs are being shed, then the infection cannot be detected. The fecal flotation will be negative, even though infection is present. This is most common in very young pets, which is why multiple stool tests in puppies and kittens are recommended.
2. The infection is mild and there are only a few adult parasites present. In this case the number of eggs in the stool may be too low to be detected by fecal flotation.
3. Some parasites only produce small numbers of eggs and infection may be missed on a single test.
4. Some parasites just cannot be detected reliably with fecal flotation (see article Fecal Baermann).
Are there other tests that can be done?
Yes. Fecal flotation is just the first step. If repeat fecal flotation tests are negative and a parasitic infection is still suspected, then your veterinarian may recommend other tests such as doing a fecal wet mount, using concentration methods, using stool preservatives, or doing a fecal Baermann etc.