I don't think it's really much different than the unsolicited advice that is often given for raising children, dogs, etc. Everyone knows the basics of food, water and shelter, but how to best provide those in a healthy and happy environment differ tremendously from home to home, from circumstance to circumstance.
And then there will always be those that ask why you need a dog, or another dog, or chickens, and those that even have the audicity to question people who have more than two children.
None of this is EVER anyone's business but your own (unless you are an unfit, wreckless or neglectful caregiver). But to safeguard and maintain the relationships you have with your family and friends, it's probably best to just say "Thank you", take it with a grain of salt, and go about your business.