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Everything you need to know about Wormcount and our parasite testing service including ordering, sampling, testing and receiving your results.
Yes, a false negative is possible. A worm count only detects parasites that are physically present in the sample sent to the lab. They must have reached reproductive maturity and are actively shedding eggs at the time of sampling. Immature parasites and intermittent egg shedders may not appear on a standard worm egg count. It should be noted this limitation is the same as many wormers which will only treat the mature larvae and leave the immature ones in the animal. This is why combination tests and regular repeat screening and/or treating are recommended for comprehensive parasite monitoring.
It is not statistically possible to ever be certain an animal is worm free, even directly after a chemical wormer has been given. A worm count is a snapshot of what is present in the faeces at the moment the sample is taken. It detects parasites that are actively shedding eggs, meaning immature worms and dormant stages will not be detected. A negative result indicates no detectable egg burden at the time of testing, but does not confirm that the animal is entirely parasite free. Even chemical wormers have limitations in what species and larval stage they can treat, so regardless of the choice of parasite control method, being entirely worm free is not something that can be guaranteed by any lab or pharmaceutical company.
Wormcount’s lungworm screen detects live larvae in the faecal sample and is capable of identifying all five species of lungworm currently present in the UK. The Baermann technique used is the most sensitive method available for larval detection of all five species from faecal material. Because larvae are shed intermittently, the test requires a three consecutive day sample collection to maximise the chance of detection. A blood test is available for one of the five species, but not for the remaining four, so blood tests are not recommended for a routine general lungworm screen.
Antigen detection is considered more accurate than cyst identification for Giardia screening. Wormcount uses antigen detection as its standard method because it rates highly on both specificity and sensitivity, reducing the risk of false negatives compared to cyst-based methods. No test can be claimed to be 100% accurate, but antigen detection rates are considerably higher than cyst float testing.
PCR (polymerase chain reaction) tests are highly sensitive and species-specific, detecting the DNA of target pathogens with a greater degree of precision than microscopy-based methods. They are particularly useful for confirming the presence of specific pathogens such as Giardia, Campylobacter, Tritrichomonas foetus, and Toxoplasma gondii. PCR tests are not affected by egg shedding patterns, making them valuable for organisms that are difficult to detect by conventional methods.
Once the sample arrives with us, test methods in the lab are repeatable and controlled. Several factors prior to reaching the lab can affect the accuracy of a worm count result: insufficient sample quantity reduces the amount available for analysis; incorrect sample collection or contamination can compromise results; samples that are too old or stored incorrectly may degrade; and the intermittent shedding patterns of some parasites mean they may not be present in any given sample. Following the collection instructions carefully and sending a full sample collection box helps ensure the most accurate result.
For healthy adult dogs, a worm count at least every three months is the general recommendation. Higher-risk dogs (such as those with access to livestock or game, immunosuppressed, age related risks, or those with a history of high worm burdens) may benefit from more frequent testing. Wormcount’s clinical team is available to advise on the most appropriate testing frequency for individual animals or you can use our online tool to determine the frequency.
Healthy adult cats should ideally be tested every three months as a routine parasite monitoring measure. Cats that hunt, have outdoor access, or live in multi-cat households may warrant more frequent screening. For Giardia specifically, an annual screen is recommended to confirm the animal is not a carrier, even in the absence of symptoms.
A popular approach for horses is three worm counts per year (typically in spring, early summer, and early autumn) followed by a winter treatment for tapeworms, bots, and encysted redworms. Wormcount recommends testing in March/April, June/July, and September/October, with a targeted winter worm treatment in December/January. Individual horses with consistently high counts may require more frequent monitoring.
Carnivorous and omnivorous reptiles, and herbivores with outdoor access, should be tested at least every three months. Very low-risk reptiles (such as tortoises kept entirely indoors with no access to unwashed food and with daily water changes) may be tested every six months, though all reptiles are capable of picking up a parasite burden. More frequent testing is appropriate for animals showing symptoms or where results are being monitored under veterinary care.
