Animal Care... Equine Parasites
Parasite Control is an important part of keeping our Equine companions healthy. There is an abundance of information on this subject, often confusing and at times contradicting. I will discuss the information currently available which is supported by research.
Twenty plus years ago Ivermectin compounds became common place in treating Equine Parasites. This compound was close to 100% effective and its use over the ensuing years virtually eliminated large strongyles (blood worms). Some resistance to Ivermectin from ascarids (round worms) has been reported over the years, however, overall this product has consistently performed well.
Veterinarians, pharmaceutical companies, and other sources have supported the practice of frequent worming and rotation of products. This practice has resulted in a population of parasites, namely small strongyles (cyathostomes), which have developed resistance to several classes of wormers.
Small Strongyles have found ways to adapt and have developed resistance to many of the wormers that we use in our rotation plans. The Benzimidazole class wormers that we commonly use such as Panacur, Strongid, Anthelcide, are not as effective against these parasites as they once were.
Ivermectin and Moxidectin (Quest) continue to have good efficiency against this problem parasite. The most notable difference is that Moxidectin eliminates the cyathostomes for a longer period of time than does Ivermectin. This means that we may worm less often.
Small Stongyles larva encysts in the large intestine mucosa, upon emerging they cause damage. This damage may cause clinical signs such as diarrhea, weight loss, poor hair coat, and a general unthriftness.
In the past if we suspected disease caused by small strongyles we would utilize a product called Power Pac. This consisted of five consecutive days of Panacur to eliminate the small Strongyles. Research has shown this to not be very effective.
Quest (Moxidectin) is extremely effective in eliminating small Strongyles and keeping them away for a substantial amount of time, around 3 months.
To more effectively control parasites and to prevent further resistance, judicial use of products is warranted. Treatment less often with more effective compounds would be ideal.
Fecal egg counts to monitor parasites local can be performed by our clinic. This test can help determine frequency of treatment.
The practice of worming every other month or more frequently should be discontinued. Rotational use of wormers should be done with an understanding of their effectiveness. The practice of a parasite control strategy based on our current research and products available would be ideal.