Before we're buffaloed by this bovine bon mot, let's see if we can beef up our understanding of what "don't have a cow" actually conveys.
What is the meaning of the popular phrase, "Don't have a cow"?
This often-used exclamation is a sarcastic saying that basically argues against overreacting or excessive emotional response to any given situation. A person might say, "don't have a cow" to caution another individual to calm down, ease up or stop and think about the circumstances that seem to be upsetting him or her so much.
"Don't have a cow" might be interpreted as a less-than-cordial admonition to revisit reality, round up the facts and reconsider what level of response a current situation may actually warrant.
Similar expressions to "don't have a cow" might include "don't blow a gasket," "hold the phone," "take a breath" or "take a chill pill."