Many of you already perform regular faecal worm egg counts which is great, however these are not a reliable way of detecting tapeworm infections in horses. Historically many horses have been covered for tapeworm with combination wormers (like Equest Pramox or Equimax) either annually or biannually in Spring and Autumn (at the start and end of the grazing seasons) – however this should be replaced with testing which allows us to target treat only those who need it. In one of our previous blogs on worming we discussed the importance of only using wormers when they are indicated, usually by a positive test result, to help prevent resistance developing to the few products available to us.
Testing for tapeworm involves measuring tapeworm-specific antibodies – these antibodies are produced by the body in response to recognition of a tapeworm infection. There are two ways that we can measure antibodies – a simple blood test can be taken by the vet or a saliva test can be performed by horse owners. The saliva test is most commonly used and is simple to perform with a specially designed swab for collecting saliva.
We recommend testing for tapeworm in Autumn to allow us to make an educated decision on which wormer, if any, needs to be given in the Autumn-Winter period. Some horses which are higher risk may also need to repeat the testing in Spring. It is important not to test for tapeworm until four months after the last tapeworm treatment was given as testing too soon can affect the results.
The equine tapeworm’s (Anoplocephala perfoliata) body is made up of segments called proglottids, as these proglottids mature they are eventually passed into the faeces where they will rupture and release their eggs onto the pasture. The tapeworm eggs are then ingested by orbatid mites which live in the soil – these mites are what horses ingest whilst grazing leading to re-infection with tapeworm. A horse may be harbouring various life-stages of the tapeworm at once and the release of egg-containing proglottids into faeces is intermittent therefore faecal worm egg counts are not a reliable way of detecting tapeworm burden.
Tapeworm burdens can cause inflammation of the gut wall and are linked to various types of colic. The greater the tapeworm burden, the greater the likelihood of developing clinical signs. Tapeworm are commonly found in the caecum (a blind-ending sac at the beginning of the large intestine) and at the ileo-caecal junction (the junction between the end of the small intestine and the caecum) therefore these are the locations we commonly find disease. Clinical signs can range from mild colic to severe colic which may require surgical intervention!
Don’t forget about encysted redworm too – this time of year it is also important to consider your horses redworm risk. Your horse may still need treating for encysted redworm despite a negative tapeworm test, depending on your horses individual risk. Similarly to tapeworm we can measure redworm antibodies to assess redworm burden, there is currently only a blood test available for this. We strongly recommend only worming for encysted redworm if there is evidence to suggest your horse needs it - e.g. a positive test result or your horse falls into the high risk category. Risk assessment is based on clinical history, age, worming testing history and pasture/herd management - please contact us if you would like more information on this/want to discuss your horses individual risk.
As always if you have any questions about worming or want to know how to go about testing in your horse, please do get in touch!
Holly x
