Comparing hot iron branding and microchipping in foals

Research shows that foals find both hot iron branding and microchip implantation stressful, but the effects of microchip implantation do not last as long.

The study, by R Erber and colleagues, compared the response of groups of foals to the two methods of identification..

Fourteen warmblood foals from the Brandenburg State Stud were divided into two groups. Seven foals were branded with a hot iron on the right thigh; the others had a microchip implanted in the neck.

Throughout the procedure the researchers monitored the foals for signs of stress by recording heart rate, and concentration of cortisol in saliva. They also monitored how the foals behaved in response to the procedures.

Both procedures caused stress. Foals showed an increase in heart rate and in saliva cortisol concentration. In fact, foals showed two peaks in heart rate - initially when they were first restrained, and again when the actual identification (branding or microchipping) procedure was carried out.

Although there was no difference in the degree of stress (measured by salivary cortisol and heart rate) between the two procedures, the researchers point out that it was possible that the foals' response to restraint could have masked that due to the procedure itself.

However, the researchers did find a difference between the two procedures. Hot iron branding resulted in skin necrosis that got worse for three days after application. It also produced an increase in skin temperate.

In fact, not only did foals show an increase in skin temperature at the site of the hot iron branding, they had increased skin temperatures on the opposite thigh and on both sides of the neck as well.

So although both procedures appeared to cause similar degrees of stress, hot iron branding produced more persistent changes. It resulted in skin necrosis that lasted for at least seven days. Hot iron branding also resulted in a generalised increase in body temperature that was not seen after microchip implantation.

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