hey i found this on a website.....Cyathastomes (small red worms). These damaging parasites burrow into the lining of the cecum & colon and can remain there for a minimum of 45-60 days or as long as 2 to 3 years. When they finally emerge, they leave behind cellular debris which is the time they cause sickness to the horse - typically in winter & spring. Symptoms may include cow pat manure or scours, mild recurring colic, lethargy, rapid weight loss, swollen legs, loss of appetite.
According to the information sheet from the NSW Department of Agriculture, moxidectin is the only drug which is effective against them. However information from American expert Dr David Laird of Texas says that a double dose of fenbendazole for 5 days is effective. He explains that this drug has a very low toxicity level and is therefore safe to use in this way. He also says that several worm drugs have extremely high and varying toxicity levels which is why the dosage rate is critical. He also points out that faecal counts will not show up the encysted stages of small red worms also known as small strongyles or Cyathastomes. http://www.herbalhorse.com/articles...worms.html
sorry couldn't find any pictures but thought this infomation might help