I understand what you mean, possibly make it so you can only do it once per life so it can't be abused or the only pet that can increase health when used. I would also be okay with nerfing the health giving if its permanent Honestly 60 Seconds would be fire as well, It would be more useable than 10 seconds.
Also after more testing the pet increases health based on your current health. if I'm at 313 it gets me up to 713 and at 10 hp it got me to 222. 1 hp goes to 202 hp So essentially doubles your health after adding 200