Healing progression of tail docking and ear tag wounds in lambs

Abstract

Tail docking and ear tagging are common husbandry practices in lambs, but little is known about subsequent wound healing or how it may be affected by performing both procedures concurrently. Our objectives were to: (1) describe wound healing following tail docking and ear tagging, and (2) compare healing of ear wounds in docked and undocked lambs. Within 28 female Polypay twin pairs, one lamb was docked using a rubber ring between 1 and 2 days of age and the other lamb's tail was left intact. Tags were attached to both ears of all lambs. We photographed tail and ear wounds twice weekly until weaning (mean ± SD; 64 ± 5 days of age). Tail wounds took 43 ± 9 days to heal (range: 30-60 days). Pus, a sign of infection, was present at least once in 89% of tail wounds and was associated with delayed healing. Only 49% of ear wounds had healed by weaning, and tail docking did not predict the probability of healing. Pus and sanguineous exudate (i.e., bleeding) were present at least once in 21% and 96% of ear wounds, respectively. Pus was not associated with the probability of ear wound healing, but ears with more frequent bleeding were less likely to have healed by weaning. The duration of healing and likelihood of infection following both procedures raise welfare concerns and suggest refinements or alternatives are warranted.

Keywords: Animal welfare; Infection; Painful procedures; Sheep; Wound healing.

Fig. 1

Three images showing, from left to right, the rubber ring placed at the distal end of the caudal folds for tail docking, the anterior side of a lamb’s left ear with an orange ear tag placed between the ribs at the midpoint between the base and tip of the ear, and the posterior side of a lamb’s right ear with a gray ear tag.

Fig. 2

The scoring system used to evaluate the tissue and fluid types present or absent (1/0) in tail docking wounds. Each tissue/fluid was scored from photos taken twice weekly until weaning, resulting in 16 to 22 observation days/lamb.

Fig. 3

The scoring system used to evaluate the tissue and fluid types present or absent (1/0) in ear tag wounds. Orange visual identification and gray RFID tags were placed on the lamb’s left and right ear, respectively. Photos of the anterior and posterior sides of each ear were taken twice weekly until weaning, resulting in 16 to 22 observation days/lamb.

Fig. 4

Boxplot displaying the days that each tissue or fluid was observed in the tail wounds relative to docking. The median, 75th quartile, and 25th quartile are indicated by the midline, and top and bottom edges of the boxes, respectively. Whiskers indicate the minimum and maximum. The number of lambs (out of 28) in which the tissue or fluid was observed at least once over the course of the study is displayed above each box.

Fig. 5

Tail photos of the lamb that developed edema 4 days after the application of the rubber ring. The photo on the left and in the middle show a view of the ventral and left side, respectively. The photo on the right shows the tail 3 days after cutting off the portion below the ring with a hot cautery knife.

Fig. 6

The percent of ear tag wounds (n = 110) healed in docked (solid line; n = 28) and undocked (dashed line; n = 27) lambs relative to days since ear tagging. 53 wounds were healed when observations ended between 55–74 days after ear tagging. One undocked lamb was excluded from this analysis due to an injury sustained on her stomach.

Fig. 7

The percent of ears with pus (solid line) and sanguineous exudate (dashed line) by the days since ear tagging. The numbers above the plot indicate the number of ears that were sampled for each observation day.