Data and code from: Characterizing neuroma-like formation after tail docking in sheep

Tail docking is a routine husbandry procedure in lambs that causes acute
pain. Studies of tail docking performed between 4 and 8 weeks of age have
also reported neuromas in the tail stump, which are characterized by
aberrant nerve proliferation and fibrotic scarring and represent a
potential source of chronic pain. However, it remains unclear whether
similar lesions develop after rubber ring docking in the first week of
life, the age at which this method is commonly recommended. This study
examined the histological characteristics of tail stumps in lambs docked
with a constrictive rubber ring at 1-2 days of age compared with undocked
controls. Eighteen Polypay female lambs (8 docked, 10 undocked) were
slaughtered at 7.5 to 8 months of age and their tails collected and
decalcified for histology and immunohistochemistry. Tissues were evaluated
for abnormalities characteristic of neuromas followed by blinded
semi-quantitative scoring of key histologic features on a 5-point severity
scale. Neuroma-like axon proliferation and fibrosis ranged from mild to
severe and were significantly more severe in docked than undocked tails.
In addition to neuromatous lesions in the soft tissue, axon proliferation
was particularly prominent in the periosteum of the docked vertebral bone.
Masson’s trichrome staining showed that neural proliferation was
accompanied by fibrosis, and immunohistochemistry confirmed that lesions
included proliferation of both axons and Schwann cells, characteristic of
traumatic neuromas. These findings provide evidence that tail docking with
a rubber ring, even when performed at an early age, causes neuroma-like
lesions, which may represent a source of chronic pain in sheep.