A faecal egg count (FEC) is a test undertaken in a laboratory to owners an indication of a worm burden.
A sample of dung is diluted and viewed under a microscope and the number of eggs it contains is counted. This is taken to represent the level of egg laying adult worms present in the horse. It is important to remember that the count is only a snapshot and is not definitive, but as a general guide, if fewer than 200 eggs are present per gram of dung (EGP), the burden is considered low. Greater than 200 epg could suggest that the worm burden may be too high. In this case a detailed history and assessment is likely to indicate that worming is required or that an existing programme is not working effectively.
FECs are inexpensive and offer many benefits but they have l'lmitations and can't replace the need for worming. So when and how should you be advising clients to use them - and when are alternaflves required?
FECs - The practical diagnostic tool
· They provide evidence of a horse's worm burden · As is explained above, in the first instance a FEC can help owners assess the worm burden in their horse and whether worming is actually required at that time.
It is especially useful for new horses as there may be limited worming history available and the treatment can be tailored more correctly.
· They help owners monitor the success of their worming regime . Informed owners worm more effectively. Used regularly, FECs take the guesswork out of worming and over time this can allow owners to build an accurate picture of how their horses are coping with their environment. FEC data can be combined with the horse's age, management and history to indicate whether worming and pasture management programmes are working, or if changes are required. Ideally, good management should reduce the reliance on chemical wormers.
· They help in the battle against resistance
This is true in two ways:
· FECs can be taken before and after worming treatments to assess treatment success. A failure to completely reduce the worm burden in the horse may indicate resistance to the type of wormer used. If there is a problem then an alternative worming product should be used in the future, with a different active ingredient.
· Some owners 'blanket-worm.' This means they use the same worming product for all their horses at the same interval every year. This may be wellintentioned but can be overkill in some circumstances. All horses are differentsome naturally carry higher parasite numbers than others and some cope better with he same environment and level of challenge. Worming a horse with a clear or low count is not just a waste of money, it's also one of the drivers for the development of anthelmintic resistance in parasites.
FECS - their limitations
· They cannot replace worming treatments
· FECs are an important element of a worming regime but they do not treat worms and are not a substitute for a worming product
· They offer probabilities not absolutes
· Because FECs show egg counts at a particular date and time, they can never be completely accurate. Eggs are not shed at a constant rate, plus recently ingested or immature parasites which have not yet reached the egg laying stage will not be represented. This is where knowing the history of the pasture is very important.
. They don't detect encysted small redworm . Cyathastome larvae have the ability to encyst in the gut wall and delay their development to adult egg laying stages. These can be present in large numbers and still remain undetected in FEe. Unless a comprehensive history is known then these encysted small redworm should be controlled at least once every year, ideally in late autumn with a product licensed for their treatment.
. They only include worms which lay eggs as part of their lifecycle · Tapeworms are not detected in standard FECs. A vet will take a blood test to detect the presence of this parasite or treatments can be given as specific times of year. Despite their limitations, FECs provide owners with useful data regarding most of the key parasites affecting horses. As such they are rapidly becoming accepted as a valuable tool in the des'lgn of effective, responsible worming programmes. SQPs can play a vital role in helping educate owners as to how FECs can be incorporated into a worming regime.
Here are four pieces of advice:
· Make sure they know what the FEC will test for and why they're doing it - remind them that an SQP or their vet will give them a quick refresher if needed
· Encourage them to use all the information at their disposal about their horse, not just the FEC, when devising a worming programme
· Recommend that they use the same lab for all their FECs as this will ensure more consistent results
· Don't ignore pasture management as one of the main components of worm control.