Approach-aversion in calves following injections.

Area of Science:

• Veterinary Medicine
• Animal Behavior
• Pharmacology

Background:

• Assessing animal welfare is crucial in veterinary practice.
• Understanding injection site aversion can inform best practices.
• Holstein calves were used as a model to study aversion to injections.

Purpose of the Study:

• To evaluate the aversion associated with different injection routes in Holstein calves.
• To compare the aversive potential of intramuscular (IM), intranasal (IN), and subcutaneous (SC) injections against a control.
• To identify potential refinements for reducing injection-related stress in cattle.

Main Methods:

• An avoidance-learning paradigm was employed with 24 Holstein calves.
• Calves were trained to approach a milk reward, with the reward amount progressively reduced.
• Four treatment groups received saline via IM, IN, SC routes, or a null control during reward approach.

Main Results:

• Calves receiving IM injections exhibited significantly longer latencies to approach the reward when it was reduced to 0.25 L and 0 L.
• Calves receiving IN injections showed increased avoidance only when the milk reward was completely removed (0 L).
• No significant difference in avoidance behavior was observed between calves receiving SC injections and the control group.

Conclusions:

• Intramuscular injections are demonstrably aversive to calves, as evidenced by avoidance learning.
• Subcutaneous and intranasal routes appear to be less aversive alternatives.
• The findings suggest that SC and IN administration routes could be considered refinements to improve animal welfare during injections where feasible.