Dr Kirstie Pickles offers 10 tips to help you ace collecting your horse’s poo and your approach to deworming.
In continuation of her three-part series on worming, Dr Kirstie Pickles, a European specialist in equine medicine, brings us Part 2 – a special 10-step guide to collecting the perfect poo sample for successful faecal worm egg count (FWEC) sampling, as well as how to optimise your approach to testing and treatment.
The advice is designed to help our members along the path towards sustainable equine worming programmes. Only by maximising the use of targeted treatments can we tackle the growing resistance to anthelmintic worming drugs in the UK.
By Dr Kirstie Pickles
Targeted strategic deworming treatments (only treating your horse with a deworming product when it actually has worms), alongside good pasture management, lie at the heart of sustainable equine worming programmes.
These two factors considerably decrease the risk of resistance to anthelmintics (deworming drugs) developing.
Unfortunately, due to previous widespread overuse of anthelmintics resulting from routine interval treatment programmes being considered the norm, considerable anthelmintic resistance is already present within the UK.
Going forwards, therefore, it is essential that we maximise the use of targeted treatments.
For cyathostomins (small redworm) and Parascaris (roundworm), this means only worming in response to a positive faecal worm egg count (FWEC) whilst tapeworm infection requires a blood or saliva test to identify antibodies.
Compared to interval worming programmes, the use of these targeted strategic worming treatments has also been shown to save owners money!
Everyone thinks that collecting a poo sample for FWEC is simple but to be useful it is imperative that the sample is collected correctly, otherwise results can be very misleading leading to situations such as a FWEC of 0 eggs per gram (EPG) followed by very high counts only several weeks later.
Faecal egg count showing numerous small strongyle eggs (E).
Follow these 10 steps to ace your targeted strategic worming treatments
1. Ensure the poo is fresh
Eggs hatch and larvae migrate out of dung so ensure that the sample is less that 4 hours old when collected. The warmer the temperature, the more essential this is as eggs hatch in a temperature-dependent manner. As the result is eggs per gram of faeces, the result will be falsely low or, even worse, falsely negative if eggs have hatched.
2. Collect a pinch of poo from several different faecal balls
Eggs are not distributed evenly throughout the dung pile, so taking samples from 5 different faecal balls is required to ensure the sample is representative.
3. Remove air from the sample bag
You want to remove oxygen from the environment so squeeze air out of the bag before closing. Using bags is better than pots for this reason.
4. Store sample at 4°C
The sample should be analysed as soon as possible but if it needs to be stored before delivery, it should be kept in the fridge to minimise egg hatching. Never post samples on a Friday!
5. Test all horses on pasture at the same time
Within a herd of horses under good pasture hygiene conditions, 20% of the horses will contribute over 80% of the worms shed. Identifying these high-shedding horses will vastly reduce pasture contamination.
6. Treat high FWEC horses with an adulticide wormer
Low levels of worms are not harmful to the horse and stimulate the horse’s immunity against the worms, so horses are only treated above a certain threshold, usually around 200 EPG. The actual figure used to determine treatment is best guided by the individual property size and pasture management; for instance, a 5 acre field with 2 horses and daily poo picking could have a higher threshold to treat than a 2 acre field with 5 horses and no poo picking. An adulticide (kills adults) wormer is appropriate as adult worms (which produce eggs) have been identified.
7. Repeat FWEC approximately every 8 weeks during the grazing season
The aim is to decrease egg shedding during periods when weather conditions favour the hatching of eggs and larval development with potentially high rates of transmission. This is roughly from April to September in the UK. Properties with fewer horses and good pasture management can extend this testing period to 12 weeks.
8. Young stock
Horses less than 3 years old have an increased risk of clinical disease from cyathostomins and may also have Parascaris infections, so targeted worming strategies are not recommended for this age group. Egg reappearance time following worming can be shorter in young stock, therefore frequent FWEC should be used to identify worm burdens and direct treatment.
9. Worm egg count reduction tests
Ideally, efficacy of any anthelmintics used on a property should be tested regularly using a faecal egg count reduction test (FECRT) to ensure resistance has not developed. However, often FECRTs are only performed when there is a suspicion of drug failure and worming is perceived to have failed to reduce FWEC, although, most frequently, this is due to other reasons such as poor pasture management or incorrect dosing. To perform a FECRT, faecal samples are collected before and 14 days after treatment from positive horses. The percentage reduction of eggs is then calculated from the two FWEC results.
10. Cyathostomin larval detection
Remember that FWEC identify egg-laying adults only and are therefore not useful for detecting cyathostomin larvae as adult burdens are not correlated with larval burden. The only way to identify if the horse has a larval burden is to use a licenced larval antigen assay.
Read Part 1 and Part 3 on Worming below:
Worming Part 1: Evaluating the Small Redworm Blood Test
Worming Part 3: The dos and don’ts of pasture management
Read more on worming:
