Choosing a laboratory for your horse’s worm egg count

test tubesHow do you go about choosing a laboratory for a worm egg count? Both the quality of the test and then the quality of the follow up advice are very important. Of course we hope you will choose Westgate because we strive to offer the best on both scores.

We can all appreciate a healthy price point and recognise good customer service when we experience it but you may know slightly less about the scientific side of things to ensure you are also getting an accurate test result possible for your horse.

When it comes to worm egg counts not all tests are created equal – here at Westgate we have a purpose built laboratory specialising in worm egg counts for grazing animals and we test thousands of samples every week. We have rigorous processes to ensure you get the correct result for each animal using the industry standard ‘Modified McMaster test’ process to generate your result.

All samples are tested on the day they are received in the lab with results returned on the same day too.

The Modified McMaster Egg Count Method

lab processing

The sample is weighed upon arrival and the whole sample is used for analysis so the more that is provided the more accurate a reading we give. The faecal samples are spun in a centrifuge at 3000 RPM for a set time before any worm eggs are floated off in a saturated salt solution.  Two slides are then run out into counting chambers for examination under the microscope and the result averaged between the two.

The centrifuge helps to separate out any eggs as well as removing the sediment from the sample, making it much easier to identify them under the microscope – this method is far superior to a simple strained method.

In this way a known volume of dung and water enables a statistical result to be generated for the level of infection of adult, egg laying redworm and roundworm eggs in horses. (Because of the way tapeworm eggs are excreted worm counts are not a definitive test for this, instead use the EquiSal saliva test to determine accurate infection levels.) Results are reported to the nearest  25 eggs per gram reading ( 25 e.p.g) 

lab process - worm egg count

Eggs Per Gram

Your worm count result will be reported as a number of eggs per gram (epg). It is quite common for there to be no worm eggs seen in a sample and this will be reported as <50 epg. The sign < means ‘less than’. If you are following a reduced worming programme you will not need to worm at this level.

A count of less than 200 epg is regarded as a LOW count and shows that your worming measures are working. In most situations you won’t need to worm at this level.

A count between 200 epg and 1200 epg it is a MEDIUM count and the horse will need worming.

If the count is over 1200 epg it is a HIGH count, the horse needs worming and the worming programme also needs attention.

The aim is not to eradicate all parasites, even if this were possible, but rather to keep them at an acceptable level for the good health of your horse.

Follow-up help and advice

Of course it’s the advice which makes a test based programme work. Westgate’s experienced, friendly team of SQP’s are here if you need any further help with interpreting your result, implementing your worm control programme or worming in general. Our veterinary approved advice is freely available at no extra cost, just ask.

Westgate Labs was the first direct to owner worm count service, established in 1999. We think we have met every conceivable horse worming problem over the years, until you find us a new one that is. When it comes to looking after our horses only the best will do and experience counts where good worm control is concerned.