Tapeworm treatment in horses, how useful are the tests?

significance of the test. Once treated horses can easily become reinfested. 
The results will typically say low borderline or moderatehigh rather than a specific number
The clinical signs associated with tapeworm infestation can be correlated with the level of burden with low levels unlikely to produce clinical disease. These tests have been validated by a number of sources and both have been found to be effective at identifying infested animals. False negative results when the test fails to identify a burden are uncommon. 
It is recommended that higher risk herds with new animals documented moderate or high levels or poor pasture management be tested every 6 months and treated accordingly. For those at low risk testing every 12 months usually in the autumn is likely to be sufficient. 
However
The test is not useful in foals preweaning as they will have maternally derived antibodies in the blood. This means that they may return a positive test based on the fact that their mother has a tapeworm infestation. 
Why dont we just use a dewormer instead of testing?
Currently we have very few choices when it comes to anthelmintics suitable for horses. Many of these drugs are already starting to lose efficacy due to widespread emerging resistance in parasites. The two main drugs used for tapeworms are Praziquantel and Pyrantel. They are available without prescription with the exception of praziquantel without the addition of another drug. However it is still important to consult your veterinary surgeon about the suitability of these drugs for your specific circumstances. There is already a suspicion that tapeworms may have developed a level of resistance to praziquantel. And many helminths have developed a resistance to pyrantel or to moxidectin another drug frequently used in combination with praziquantel. 
It is very difficult to create new drugs and it has been many years since the most recently developed drug was first marketed. It is of utmost importance that we continue to preserve these drugs for as long as possible to ensure that they remain effective. The best way of doing this is by only treating horses that need to be treated. This will reduce the amount of these drugs entering the environment. With a combination of good pasture management and regular testing to identify affected animals are the best ways of achieving this. 
Treatment does not just involve the administration of a suitable dewormer
Pasture management is critical for success. One very