A University of Guelph study has found that using a combined local anesthetic and pain reliever when dehorning young calves will reduce the animals’ stress.
The study involved use of caustic paste for dehorning, a method that is becoming more common for disbudding dairy calves. However, there is little available research into controlling the animals’ pain during the procedure.
Why it matters: Caustic paste is used by nine per cent of dairy farmers in Canada for disbudding. The use of this material is growing, yet little research has been done on it.
Cassandra Reedman, a Masters of science candidate in health management at the Ontario Veterinary College, is completing her thesis on pain control for disbudding dairy calves.
Her first clinical trial focussed on assessing pain control when caustic paste is used in disbudding calves at younger ages than what has previously been studied.
Currently, few producers use pain medication when using caustic paste for disbudding.
A randomized trial was completed by Reedman and her team in the summer of 2018 on a large commercial dairy farm in Grey County milking about 600 cows.
Reedman presented her findings at the 2019 Campbell Centre Study of Animal Research Symposium held in May at the Ontario Veterinary College.
Calves in the study were heifers aged one to nine days, and considered healthy as marked by a University of Wisconsin app.
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Reedman looked to find the efficacy of meloxicam and lidocaine individually and together to understand the outcomes associated with disbudding pain and inflammation in young dairy calves.
The treatment groups consisted as follows:
- commercial paste with no pain control
- sham group
- paste with meloxicam
- paste with lidocaine
- paste with meloxicam and lidocaine
Reedman hypothesized that calves receiving lidocaine and meloxicam would have decreased cortisol, algometry (pressure sensitivity) and haptaglobin, all of which would improve the outcome compared to other treatment groups.
The team studied those levels 25 minutes before paste application.
The algometry was then analyzed for three hours following the application, as well as three to four and six to seven days later.
For standing and lying behaviour, activity monitors were attached for seven days after the treatment application.
“For cortisol we took our samples only on the day of because it shows more of an acute response. With haptoglobin we took the samples at the end of the disbudding day, as well as the next two visits because it is an indicator in calves and it is released much more slowly,” says Reedman.
Researchers found a large cortisol spike in calf groups not treated for pain in the study within the first 15 to 30 minutes. The levels then dropped.
“Neither of these groups have lidocaine, which would protect from the pain at the beginning. But the difference is the meloxicam group which (received) an anti-inflammatory, the cortisol levels dropped faster than the no-pain-control group because it’s mitigating some of that later-on inflammatory pain,” says Reedman.
The group that received lidocaine alone did not have the initial cortisol spike in the beginning but as time passed the cortisol values began to increase because absence of meloxicam resulted in later pain.
The treatment group that received both the meloxicam and the lidocaine showed a protection against the acute pain right after disbudding and during the later inflammatory pain.
“They don’t have the same increase in cortisol levels as the lidocaine group alone, which I think is great as it really highlights the importance of these drugs used together to best mitigate the pain that the calves are feeling and these patterns are very similar to work that has been done in older calves and this is what we expected to see,” says Reedman.
Results showed the lidocaine nerve blocks successfully desensitized the calves and those also given meloxicam has less sensitivity to pain than the other groups.
When looking at the haptoglobin levels, the only results showing some significance were the two treatment groups receiving both lidocaine and meloxicam — their haptoglobin levels were lower.
The results for the standing and lying behaviour are still being analyzed.
