Pain and sickness behavior associated with corneal lesions in dairy calves

Brandon J Woods,Annette M O'Connor,Natalia A Da Silva,Reneé D Dewell,Chong Wang,Suzanne T Millman,Rebecca L Parsons

doi:10.12688/f1000research.6649.1

Abstract

Infectious bovine keratoconjunctivitis (IBK) is a common corneal disease of calves that adversely affects animal welfare by causing pain and weight loss. Identifying behavioral indicators of pain and sickness in calves with IBK is necessary for designing studies that aim to identify effective means of pain mitigation. Consistent with principles of the 3Rs for animal use in research, data from a randomized blinded challenge study was used to identify and describe variation of behaviors that could serve as reliable indicators of pain and sickness in calves with corneal injuries. Behavioral observations were collected from 29 Holstein calves 8 to 12 weeks of age randomly allocated to one of three treatments: (1) corneal scarification only, (2) corneal scarification with inoculation with Moraxella bovoculi and (3) corneal scarification with inoculation with Moraxella bovis. Behavior was continuously observed between time 1230 - 1730 h on day -1 (baseline time period) and day 0 (scarification time period). Corneal scarification and inoculation occurred between 0800 - 1000 h on day 0. Frequency of head-directed behaviors (head shaking, head rubbing, head scratching) and durations of head rubbing, feeding, standing with head lifted, lying with head lifted and sleeping were compared between study days and groups. Following scarification, the frequency of head-directed behavior significantly increased (p = 0.0001), as did duration of head rubbing (p=0.02). There was no significant effect of trial, trial day, treatment or treatment-day interaction on other behaviors studied. Our study demonstrated that head-directed behavior, such as head shaking, rubbing and scratching, was associated with scarification of eyes using an IBK challenge model, but sickness behavior was not observed.

Highlights

Infectious bovine keratoconjunctivitis (IBK) is a disease of cattle, causing corneal edema and ulceration, photophobia, blepharospasm and ephiphora (Gelatt, 2008; George, 1984)
Our study showed that frequency of head-directed behaviors was associated with ocular scarification, and together with changes in nociception thresholds, suggestive of ocular pain
As beef calves are often observed at a distance on pasture and corneas are difficult to evaluate remotely, head rubbing, shaking and scratching, may be early behavioral indicators that producers could use to identify calves to be more closely evaluated for the presence of corneal lesions or other ocular abnormalities

Summary

Introduction

Infectious bovine keratoconjunctivitis (IBK) is a disease of cattle, causing corneal edema and ulceration, photophobia, blepharospasm and ephiphora (Gelatt, 2008; George, 1984). Blepharospasm and photophobia suggest IBK is painful (Williams, 2010) and pain mitigation therapies may be useful adjuncts to antibiotic therapy by improving animal welfare and reducing weight loss. Photophobia and ocular discharge are the earliest indications of IBK (Postma et al, 2008), suggesting that detection occurs only once the condition is quite advanced. Mechanical injury to the eye increases susceptibility of cattle to IBK infection (Postma et al, 2008), and identification of behavior responses to injury may provide opportunity for early detection of corneal injury and preventive treatment. Subjective scoring of behavior associated with acute IBK infection has been described in the literature as an aspect of signalment and clinical assessment, scientific investigation of behavioral responses to ocular injury and infection is needed

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