Whether you use hot irons, caustic paste or horn amputation, calves experience pain—and the jury is still out on which method is least painful, say Sarah Adcock and Cassandra Tucker, both with the Center for Animal Welfare at the University of California-Davis. They spoke at this spring’s virtual Dairy Calf and Heifer Association conference.
“Although it is widely believed that younger animals feel less pain, there is no scientific support for this claim,” they say. “Calves experience pain no matter how young they are and pain control is needed at all ages and with all methods.
Nevertheless, disbudding is recommended early in life, before 8 weeks of age, to avoid the need for more invasive methods to amputate horns using scoops, saws or wires, they say.
Studies show that 94 percent of dairy operations routinely disbud or dehorn calves to avoid injuries to their human handlers and other animals. Most farmers use hot iron debudding, but the use of caustic paste is growing in popularity. Use of caustic paste grew from 9 percent in 2007 to 16 percent in 2014 while amputation dropped from 45 percent to 30 percent.
“Use of pain relief for hot-iron disbudding doubled (14 to 30 percent), but is less likely to be given for caustic paste,” say Adcock and Tucker.
“Producers have also begun to disbud calves at a younger age,” they say. “On average, hot-iron and caustic paste disbudding occurs between 3 and 4 days of age or 21 percent younger than a decade ago.”
Both methods are painful. “Signs of pain (with hot-iron disbudding) are reduced if the calf receives a local anesthesia and a non-steroidal anti-inflammatory drug (NSAID) before disbudding,” they say.
Hot-iron disbudding wounds take 6 to 13 weeks to heal, and there is evidence that wounds are painful throughout this process. Some studies have shown sensitivity for at least 14 weeks after the wounds have healed.
Caustic paste also creates pain. It is only for use in calves under 1 week of age, and few studies have evaluated the pain it causes. “Although caustic paste has been recommended as a less painful alternative to hot-iron disbudding, no research supports this claim,” says Adcock and Tucker. In fact, caustic paste has been banned in some European countries because of the risk of it spreading into the eyes or onto other animals.
The FARM (Farmers Assuring Responsible Management) Program requires pain relief for disbudding. Combining a local anesthetic and an NSAID before hot-iron or caustic paste disbudding is more effective at controlling pain than either treatment alone, say Adcock and Tucker.
“To give local anesthesia, 5 ml of 2 percent lidocaine hydrochloride is injected at the cornual nerve on both sides of the head 10 minutes before disbudding,” they say. “An NSAID can be given immediately before or after the lidocaine block.
There are limited options for NSAIDs in the United States: flunixin or meloxicam. Flunixin is the only Food and Drug Administration NSAID approved for use in cattle. Meloxicam can only be used extra label under a veterinary supervision.
“A sedative can also be used to reduce handling stress, but does not provide paid relief,” note Adcock and Tucker.
Since there are no good options for long-term pain control, polled genetics is likely the best solution. The problem is that there is a gap between genetic merit of horned and polled sires, though it is shrinking. “Gene editing technologies could rapidly increase the use of polled genetics in the dairy industry, but it is still unclear how that option will be handled by the federal government,” they say.