I have 2 horse on 5 irrigated acres NE Bend, Deschutes county. I have been pulling ticks off them for a few weeks. I dewormed with an Ivermectin which kills any that were attached at the time, but more climb on and attach. What's an effective way of getting rid of ticks from property and livestock? Thanks for any help.
Worming with Ivomec is a good start. Next I would look at doing everything possible to remove their habitat. Ticks often climb grasses and brush so they can come into contact with people and animals passing by. Wherever possible I would recommend mechanically removing brush, leaf litter and any debris on the ground. If it is safe to burn and legally allowed in your area, burning dead grass and brush to kill the ticks and take away their habitat will help. Use of fencing to restrict access of wildlife (deer), stray dogs, raccoons, etc. to your horses is also helpful.
Finally, there are wipe-on and spray-on products containing cypermethrin or permethrin that can provide several hours of protection or more. Here is an article that might be of help: Protecting Horses from Ticks. In addition, consulting your veterinarian may be a good idea as they may have a product they recommend.