Faecal Testing (Fecal Dx & Parasite Screens)

• Faecal flotation (the traditional method). The sample is mixed with a dense solution so parasite eggs float to the surface to be identified under a microscope. Its weakness is fundamental: worms shed eggs intermittently, immature worms shed none at all, and single-sex infections produce no eggs — so a negative flotation genuinely does not exclude infection. Centrifugal flotation performs better than simple passive flotation.
• Faecal antigen testing (Fecal Dx and equivalents). These detect proteins produced by the worms themselves, so they can identify an infection regardless of whether eggs are being shed at that moment. They cover the major intestinal nematodes — roundworm (Toxocara), hookworm (Ancylostoma/Uncinaria), and whipworm (Trichuris) — and detect a meaningful number of infections that flotation misses.

Because each catches things the other doesn't, running antigen testing alongside flotation is now the recommended approach.

Giardia is tested separately, usually by a dedicated antigen ELISA (often a SNAP-type in-clinic test), sometimes with direct smear or flotation. An important interpretive nuance: Giardia is commonly found in healthy animals without causing disease, so a positive result in a well pet with normal stools does not automatically require treatment — it is judged in clinical context. Coccidia and, in cats, Tritrichomonas are other protozoa identified on faecal examination.

Tapeworm segments are shed intermittently and their eggs are heavy and float poorly, so tapeworms are frequently missed by routine faecal testing. They are often diagnosed instead by an owner seeing rice-grain-like segments around the tail or in bedding. If you have seen those, say so — it is better evidence than the lab test.

A negative faecal test reduces but does not eliminate the likelihood of parasites, for all the shedding reasons above. In a symptomatic animal, repeat testing (often three samples over several days) or empirical treatment may be appropriate. This is a test where a negative is genuinely weaker than a positive.

Both species are screened the same way and share the major parasites, with roundworm particularly important in kittens and puppies (often infected from the mother) and as the leading zoonotic risk to children. Cats additionally get Tritrichomonas foetus, a cause of persistent large-bowel diarrhoea in young cats that needs specific testing. Lungworm in dogs is not detected by standard faecal antigen panels and requires its own test where suspected.

This page shows no range strip. Faecal testing yields qualitative results (detected / not detected, or organisms identified) rather than a numeric value with a reference band. Read results against the report from the testing laboratory.

For routine wellness, ask about antigen testing combined with flotation rather than flotation alone, and remember that faecal screening supports — but does not replace — regular parasite prevention. In a pet with diarrhoea, a negative result may warrant repeat sampling. And because several of these parasites infect people, good hygiene and prompt faeces disposal matter alongside whatever the test shows.