A fecal float is a routine veterinary diagnostic procedure used to detect the presence of internal parasites in animals. This test involves examining a stool sample under a microscope to identify the eggs or cysts of various parasites. It is a common and relatively inexpensive method for veterinarians to assess an animal’s gastrointestinal health.
Purpose of Fecal Floats
Veterinarians perform fecal floats to identify internal parasites that can negatively impact an animal’s health, allowing for timely treatment. Routine wellness checks often include a fecal float to screen for hidden infections, even in animals that appear healthy.
This diagnostic tool also plays a role in public health, as some animal parasites can be transmitted to humans. Regular testing helps reduce environmental contamination and the risk of transmission. Fecal floats are also recommended when an animal shows symptoms such as diarrhea, unexplained weight loss, or failure to gain weight as expected, indicating a possible parasitic infection.
How Fecal Floats Are Performed
Performing a fecal float involves mixing a small amount of the animal’s stool with a special solution. This flotation solution is denser than most parasite eggs and cysts, causing them to float to the surface while heavier fecal debris sinks. The specific gravity of these solutions ensures the buoyancy of most parasite elements.
There are two primary methods for performing a fecal float: passive (simple) flotation and centrifugal flotation. In passive flotation, the fecal sample is mixed with the solution, and a coverslip collects floating eggs after a standing period, usually around 20 minutes. This method is simpler and requires less equipment.
Centrifugal flotation is considered more accurate and sensitive. This technique involves mixing the fecal sample with the solution in a centrifuge tube, then spinning it at a high speed, typically 1000 to 1500 revolutions per minute for 3 to 5 minutes. The centrifugal force rapidly separates lighter parasite eggs and cysts from heavier fecal matter, concentrating them at the surface for microscopic examination.
What Fecal Floats Reveal
Fecal floats are effective at revealing the eggs of various internal parasites commonly found in animals. These include roundworms (e.g., Toxocara canis), hookworms, and whipworms. The test can also detect protozoal oocysts, such as Coccidia and Toxoplasma.
Some parasites, however, may not be reliably detected by a standard fecal float. For instance, tapeworm eggs are not consistently found because they are shed in segments rather than as free eggs, making them difficult to detect. Giardia cysts can also be challenging to identify, as some flotation solutions may distort them or they may not float well. In such cases, additional diagnostic tests, like fecal antigen tests or different microscopic techniques, might be recommended.
Ensuring Accurate Fecal Float Results
The accuracy of fecal float results depends on several factors, starting with proper sample collection. A fresh stool sample, collected within 24 hours, is preferred to prevent parasite eggs from hatching or becoming distorted. A sufficient sample size, typically around 1 to 5 grams of feces, is also important for a reliable test.
Laboratory technique and the type of flotation solution used also impact accuracy. Solutions with specific gravities between 1.18 and 1.27 are effective for floating most common parasite eggs.
However, even with proper technique, fecal floats have limitations. A “false negative” can occur if parasites are in a pre-patent period, if egg shedding is intermittent, or if the infection is mild. Therefore, a negative result does not always rule out a parasitic infection, and veterinarians consider an animal’s symptoms and history when interpreting results.