My neighbor here in Irrigon has apparently put out mice poison, resulting in dozens of mouse carcasses laying around. I have a fixed tomcat, so am concerned with his health. I am also concerned with the dead mice carrying hantavirus. The mice have a long tail with a tuft at the end.
This is a very concerning situation, certainly for your cat, but also for wildlife. From your description of the tail tufts, I suspect your neighbor has killed either Ord's kangaroo rats or possibly wood rats. Depending on what product they used, how they distributed it, where they distributed, and what species the chemical was labeled (i.e., legal uses) for, this could be a pesticide application violation. In which case, you might find out from your neighbor exactly what they used and/or call the 24-hour hotline at 503-986-6470.
Hantavirus is not common in Oregon, but also remember that an open-air (outdoor) situation is the lowest-risk environment if the virus was present. Also, animals wouldn't "catch" hantavirus by eating a dead animal - The disease organism is inhaled, generally from aerolized waste products in closed rooms, etc. Here is a great CDC brief on the disease that you'll find of interest https://www.cdc.gov/hantavirus/pdf/hps_brochure.pdf