Dewormers are separated into classes based on their chemical structure and how they kill worms. There are only 3 classes of dewormers, though there are many different brand names available for sale.
| CLASS | DRUG | COMMON TRADE NAME |
|---|---|---|
| Benzimidazoles | Thiabendazole Fenbendazole Albendazole Oxfendazole | TBZ® Panacur®, Safeguard®** Valbazen® Synanthic® |
| Nicotinic agonists Imidazothiaoles Tetrahydropyrimidines | Levamisole Morantel Pytrantel | Prohibit®, Levasol, Tramisol® Rumatel®**, Nematel® Strongid® |
| Macrolytic Lactones Avermectins Milbemycins | Ivermectin Eprinomectin Doramectin Moxidectin | Ivomec®, Primectin™ Eprinex® Dectomax® Cydectin®, Quest® |
**FDA approved for use in goats.
All of the drugs in a class will kill worms in the same manner, though their effectiveness varies depending on the type of worm and local region.
When changing dewormers you need to change chemical classes, not just brand name products (such as switching from Safeguard to Valbazen). On the other hand, it is NOT recommended to rotate dewormers, but rather to selectively deworm goats, using specific dewormers for specific situations.
Continually switching from one dewormer to another causes parasite resistance over time and eventually none of them will work very well. Be sure to have fecal checks done at least twice a year no matter which dewormer you are using. You can either have your vet office do the fecal checks or learn to do them yourself.
For internal parasites, Ivermectin products need to be given orally, not by injection or topically. Ivermectin has been greatly overused on livestock throughout the US and doesn’t work near as well as it used to in many areas.
If you are using an Ivermectin product be sure to do your fecal egg counts regularly.
Internal parasites are the number one cause of illness and death in goats under 1 year old.
DO NOT under-dose dewormers. In most cases it is better to give too much than not enough.