Research

Background

Band castration is a common practice used nationwide in cattle production. The procedure is bloodless, but it causes short term discomfort when the band is applied, as well as significant long-term pain as the scrotal tissue necroses due to lack of blood flow. Given the practicalities of cattle handling, and the desire of producers to mitigate the stress of handling, a product that can offer near immediate as well as long term pain mitigation in a single castration handling event would represent a significant advancement in band castration pain control.

A previous project determined that castration bands impregnated with a slow-release anesthetic (lidocaine) provided therapeutic levels of pain control for at least seven days, but more work is required to determine how long the pain control lasts and fulfill other regulatory requirements before this new type of band can be commercialized. 

Objectives

1. Determine the efficacy of a slow-release anesthetic to mitigate the acute and chronic indicators of pain measured in castrated beef calves, including physiology, behaviour, and weight gain
2. Characterize the signs of pain and welfare expressed by calves at two industry-relevant ages (one and five months old) when exposed to an extended-term delivery of topical anesthesia via a castration band
3. Develop a standardized pain evaluation protocol including the use of a combination of behavioural and physiological traits indicative of pain and discomfort in cattle to facilitate the development and registration of future pain mitigation tools

What they did

A total of 96 calves were castrated either at one- or five-months of age. At each age, calves were divided into three castration protocols: regular bands with no pain control, regular bands with anesthetic injected into the scrotum, and the new bands with slow-release anesthetic. Many pain related behaviors, physiological responses and growth measurements were taken at the time of castration and in the following hours, days and weeks. An additional study with 31 bull calves was conducted to measure anesthetic levels in the scrotal tissue over time.

What they learned

The physiological and behavioural parameters assessed in this project proved to be effective at characterizing acute and chronic pain following band castration of 1- and 5-month old calves.

Physiological and behavioural indicators of pain were detected at the time of castration, up to 240 minutes after castration, and during the time the testicles sloughed off for both 1- and 5-month-old bull calves, highlighting the time when pain mitigation should be implemented.

They found limited differences between the two lidocaine treatment protocols, administered by injection into the spermatic cord or topically applied through the band. In 1-month-old calves injected lidocaine reduced the visual analog score (observations of behaviours indicative of pain or discomfort) during castration, compared to unmedicated calves. At the younger age, lidocaine banded calves tended to have lower haptoglobin (a marker of inflammation or trauma) concentrations up until 56 days after the procedure. In 5-month-old calves, injected lidocaine reduced saliva cortisol concentrations 60 and 120 minutes after castration compared to unmedicated calves.

The study investigating the effective tissue concentrations of lidocaine identified that the use of traditional pain control (a ring block with injected lidocaine) was effective in mitigating the pain associated with castration for up to 60 minutes post-procedure, highlighting the importance of long-term pain control strategies. The use of the lidocaine bands led to tissue concentrations of lidocaine approaching an effective dose by 2 hours, meeting or exceeding the peak concentration in the tissue by 72 hours, and remaining at that level for at least 28 days, indicating that local anesthesia is likely provided by the infused bands.

What it means

While the tissue concentrations of the lidocaine bands would indicate that lidocaine is successfully released into the scrotal tissue at an effective dosage for at least 28 days after application and provide some relief, these infused bands did not mitigate all of the numerous behavioural and physiological indicators of pain associated with band castration measured in this study.

A multimodal pain mitigation strategy, where the use of lidocaine bands is combined with other pain control drugs should be explored to increase their efficacy, but that approach also needs to ensure practicality and minimize the number of times animal handling needs to occur.

Additional note: As of posting, this product has been approved for use under the name LidoBand in the United States. Efforts continue to obtain regulatory approval to sell these bands in Canada.