I bought the cow....

What is truly involved in the purchase and owning of the cow? Beyond her purchase price, she will require food, water, housing and hygiene.  If she gets sick, her owner is responsible for her treatment and care. She might require medications or a special diet. 

Even long ago when this saying began, people recognized that there is responsibility involved in animal ownership.  These people also realized that there is benefit, the milk.

One needs to decide if the benefits of the relationship outweigh the responsibilities involved. It frustrates me when we get calls in which someone declares that they spent all of their money on the purchase price of a puppy or kitten and now they cannot afford to do the medical care. Remember, animals are a luxury, not a necessity.  One gets to choose if and how they obtain a pet.  Rescue animals have an adoption fee but it usually covers most of the preventive care. If you know that you have several expenses, like a large family or a debt burden, you should consider worst case scenarios of pet ownership.  What if my fur friend becomes very ill? Can I afford to do the vaccines and preventive care to help avoid illness? Do I have an environment that is animal friendly and safe to help avoid injury? Will my animal be alone most of the time where he or she might become bored and destructive? Ask yourself these questions and be honest with yourself.  Make sure that what you want is also what you need.

Sometimes having a human baby is a surprise that came with that "free milk",  but we ALWAYS get to choose if we want a fur-friend. Plan wisely. Examine your life and your situation carefully before taking on the responsibility of a pet.