Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What's happening: Shares of IDEXX Laboratories (NASDAQ:IDXX) fell by more than 13% today after the  the animal healthcare and diagnostics company released its first-quarter earnings. Per the report, the company generated $382 million in revenue for the three-month period, and diluted earnings per share of $0.98. Compared to the same period a year ago, revenues increased by 6% and earnings by 10%. 

Despite this strong growth, the company actually missed consensus for revenue by $13 million or 3.2%. Earning per share, though, came right in-line with the Street's estimate. 

Why it's happening: This slight revenue miss probably isn't the main catalyst behind today's fall. By contrast, what's worrying investors appears to be the company's updated 2015 outlook, calling for revenues to come in 6% lower than previously anticipated. 

Although management still believes revenue can grow organically by 12% to 13% in 2015, the negative impact of a strong dollar on exchange rates is reportedly hurting the company's sales in international markets. 

So, are investors overreacting to this revised annual guidance? Unfortunately, I don't think so. IDEXX shares have gained over 30% in the past year, and are now trading at a forward price-to-earnings ratio of 31 as a result -- far above the sector average.

While a strong dollar has hurt nearly every multinational healthcare company of late, IDEXX is particularly susceptible to this issue because of its lofty valuation. Put simply, this company needs every bit of growth it can muster to bridge its substantial valuation gap. And that's why it's probably best to wait for a pullback before jumping into this growth stock.