Feed-room note

Reading the box colors

Merck did the feed room a quiet favor when it colored the Panacur C line. You do not have to remember gram counts at the store shelf or in a 7 a.m. fog — you have to remember your dog's weight and a color. Yellow is the 1 gram box and answers for dogs up to 10 pounds. White is 2 grams, up to 20 pounds. Orange is 4 grams, up to 40 pounds.

The colors also make stacking legible. A 30-pound dog eats a yellow packet and a white packet together each morning; a 50-pounder eats yellow plus orange; a 60-pounder white plus orange; an 80-pound dog gets two oranges. Line the torn corners up on the counter and you can see at a glance whether today's dose went out.

One wrinkle worth knowing: older stock and A+ photos sometimes show the 2 gram box in dark green rather than white. Same granules, same gram count — Merck refreshed the packaging, and both liveries are genuine. The gram number printed beside the color is the fact that matters.

If your dog's weight sits between two boxes, the label's instruction is cheerfully simple: round up. A 15-pound terrier is a 2 gram dog. Fenbendazole's safety margin is wide enough that the next size up is the recommended move, not a risky one.