https://www.pcgamer.com/boomer-the-far-cry-5-dog-can-be-healed-by-rubbing-his-tummy/

The problem with dogs in videogames is that their presence inevitably changes the parameters of the mission. No matter what The Sarge says in the briefing, it's your second priority: Job number one is always—always—ensuring that your canine companion doesn't get smoked.   

This is a problem compounded by the fact that AI-controlled dogs are even dumber and more aggressive than their real-world counterparts. Dogmeat of Fallout fame was notorious for driving players absolutely berserk with his penchant for charging powerful enemies and environmental hazards with great and reckless enthusiasm, usually forcing a quick reload no matter how well the fight was going.