See that smiling cow over yonder? She's happy because there's now a competitor for the thrombin made from her blood.

Today, the FDA approved Omrix Biopharmaceuticals' (NYSE:OMRI) human thrombin product Evithrom for controlling minor bleeding during surgery. In the 1950s, companies switched from human-based blood products to those made from cattle to avoid potential contamination from viruses such as hepatitis C. Recent advances in detection technology have alleviated that fear, and Omrix has begun marketing protein-based products made from human plasma.

The new human-based product should be widely accepted, because it avoids the possibility of an adverse reaction, which some patients experience after exposure to bovine proteins contained in the thrombin products currently on the market.

Like Omrix's other biosurgical products, Evithrom will be marketed by Johnson & Johnson's (NYSE:JNJ) wound-management division. It also markets Evicel in the U.S. and Quixil outside the U.S. -- fibrin sealants designed to stop more serious bleeding during surgery.

Last week, Omrix's competitor ZymoGenetics (NASDAQ:ZGEN) got a major paper cut from the FDA. The agency moved back its approval decision date by three months, because of extra paperwork the company submitted. ZymoGenetics' thrombin is a recombinant product -- it's the same human protein, but it's produced in cells in a laboratory. ZymoGenetics claims that gives it a leg up in the safety department, but I'm not sure that surgeons who pump patients full of other peoples' donated blood will be too worried about whether the drug came from humans or lab cells.

The main battle between ZymoGenetics' and Omrix's thrombin products will come down to ease of use by the surgeon, and probably more importantly, the effectiveness of each firm's sales force in convincing doctors to use its product. Right now, Omrix has a clear advantage, because its representatives may have as much as a four-month head start in targeting doctors. Those reps also have an existing relationship with doctors, since they also market Omrix's other biosurgical products.

ZymoGenetics isn't throwing in the towel, though, and it plans to be right on Omrix's heals. It's already making product, and it's prepared to launch its drug just 10 days after it's approved.

The cows aren't the only ones smiling. I'm smiling, too, because I love a good competition. We'll probably have to wait until the end of next year to see who's the clear-cut winner. Until then, pull up a chair and watch round one begin.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Johnson & Johnson is an Income Investor selection. The Fool's disclosure policy prefers chicken to beef.