Blue Chips End Down, Merck Recall Weighs  NEW YORK (Reuters) - The U.S. Dow Jones Industrial average  declined on Thursday after drug maker Merck   Co.&lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=MRK.N target=/stocks/quickinfo/fullquote"&gt;MRK.N&lt;/A&gt;  recalled its widely sold Vioxx painkiller and its stock sunk 27  percent.