This tunnel from Amazon has completely changed how my cat and dog interact. The cat used to want nothing to do with our dog, but now they are play buddies.
https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Dpets&field-keywords=3+Way+Cat+Tunnel&rh=n%3A2619533011%2Ck%3A3+Way+Cat+Tunnel
