Parasite Problems: Part III (Squeamish Horse Owners Read with Caution)

Updated: Apr 8

How often do we confuse parasite problems with gastric ulcers? That is the question that came to mind this morning as I picked pens in the rain. Unfortunately, I do not have the answer to that question, and I don't have any way to find out, but it's an interesting question to ponder considering my own experiences (read Parasites are STILL a Problem Part I and Part II) and a new experience told recently by a friend in Oregon. Just last week, she told me the harrowing story of her horse being scoped for ulcers and finding a terrible bot parasite problem instead! *Squeamish horse owners read ahead with caution!



Before I tell you the story of Star and Lori, I'd like to share with you the results of my follow-up fecal egg count. Stella and Coulee, the highest strongyle shedders in my little herd, were retested three weeks after deworming with the Zoetis QuestPlus (moxidectin + prazinquantel). No parasite eggs were found in either sample which was great news! However, I am going to do a follow up fecal egg count this summer before deworming again.


In retrospect, I think the following most likely factored into my high strongyle egg count in January...

  1. Introducing two young horses into the herd from questionable management conditions. I'm assuming that the unthrifty 2 year old brought in a huge load of parasites to my property.

  2. Not allowing the compost to do its thing long enough to thoroughly heat the bin and kill most of the parasites.

  3. Not being able to remove the manure waste from my property is posing a problem. Four horses on 5 acres is a lot even with regular manure pickup and composting.

Results of follow up fecal egg count after deworming.

Back to the story of Lori and her gelding Star! I called her up last week to discuss the conditions and factors that led to the stomach scoping, what they found, and what she learned.


Star is relatively new to Lori's small herd group in Southwest Oregon. Not long after arriving in his new home, Star developed an exercise induced cough that Lori assumed was caused by smoke from a severe fire season in 2020. The vet thought the cough could be allergies, but it got worse through the winter. Other symptoms developed such as weight loss, finicky eating, and excessive anxiety. With such symptoms, Lori decided to scope for gastric ulcers, and what was found surprised both of them! The vet said it was the worst bot infestation he had ever seen. You can see them embedded into the lining of the stomach in several pictures below!