Assessment of potential neuropathic changes in cattle after cautery disbudding
Introduction
Removing horn buds in young dairy and beef calves to reduce the risk of injuries to other cattle and farm workers is a common practice on cattle farms. Cattle without horns are easier to handle and require less space during transport and at the feed trough (Faulkner and Weary, 2000; Duffield et al., 2010; Stock et al., 2013). Moreover, it has been shown that injuries caused by horns may have a substantial impact on milk production and growth (Laden et al., 1985).
Depending on whether the horn bud is destroyed at an early stage or whether fully developed horns need to be amputated in mature cattle, different techniques are used. In young calves up to 8 weeks, when the horn buds are 5 to 10 mm long, animals are commonly disbudded with a heated disbudding iron (Stafford and Mellor, 2005), with a caustic paste in the first week of life, or by mechanical removal using a dehorning spoon (Stock et al., 2013). Regardless of the method, disbudding is painful for at least 2 h after the procedure (Petrie et al., 1996) and possibly up to 44 h (Faulkner and Weary, 2000). Acute pain or distress due to disbudding pain have been corroborated by changes in plasma cortisol (Petrie et al., 1996; Sutherland et al., 2002), heart rate (Grondahl-Nielsen et al., 1999; Stewart et al., 2008), eye temperature (Stewart et al., 2008), electroencephalogram (Gibson et al., 2007), calf behavior (McMeekan et al., 1999; Faulkner and Weary, 2000) and peripheral sensitization (Mirra et al., 2018). It has been shown that the cortisol response following hot iron disbudding without anesthesia or analgesia is lower than when either a dehorning spoon or a caustic paste are used (Stafford and Mellor, 2011).
The horn and the surrounding tissue are mainly innervated by the Ramus cornualis, a branch of the trigeminal nerve. Disbudding and dehorning are painful and, therefore, are regulated by animal welfare laws. To meet the Swiss legal requirements, local anesthesia is mandatory (cf. Art. 16 TSchG) and allows to alleviate acute pain (Laden et al., 1985; McMeekan et al., 1998; Stafford and Mellor, 2005). Cornual nerve block with local anesthetic is currently the accepted technique to anesthetize the horn bud prior to its removal (Fierheller et al., 2012), ideally in combination with a systemic analgesic to improve pain relief (McMeekan et al., 1998; McMeekan et al., 1999; Faulkner and Weary, 2000; Duffield et al., 2010).
It has long been recognized in human medicine that surgery often entails chronic pain (Kehlet et al., 2006; Macrae, 2008; Nikolajsen, 2012). Peripheral nerve injury is presumably the most frequent cause of postsurgical long-term pain. The distal end of a cut axon degenerates and is encased with inflammatory cells, a process which may lead to an abnormal activation of sensory neurons (Zimmermann, 2001) and pain hypersensitivity (Watkins and Maier, 2003). With respect to disbudding, research has concentrated on acute pain during and immediately after the procedure. However, little is known about chronic pain. Additionally, to date, there is no definitive method to detect chronic pain after disbudding in calves.
It is known from several studies in laboratory animals that functional changes of sensory neurons go along with a different expression of cellular markers (Brown et al., 1997; Matteis et al., 1998; Ohtori et al., 2000 Dec 28; Chiang et al., 2005). Based on this knowledge, it can be hypothesized that after disbudding, similar changes occur in the trigeminal nerves innervating the horn bud and its surrounding tissue due to peripheral nerve damage. Overall, neuropathic pain has been associated with hyperinnervation (Buonocore, 2013) and both sensory as well as tyrosine hydroxylase-reactive fibers have been shown to be involved in neurogenic pain (Lindqvist et al., 2000).
The goal of the present study was to investigate possible morphological changes in the cornual nerve as a result of cautery disbudding. The vast majority of the primary afferents from the horn base travel with the R. cornualis of the trigeminal nerve making this branch an ideal target for morphological analysis. The infraorbital nerve was selected as a methodological check as it may not be affected by the surgical treatment. To assess possible changes, different parameters were assessed and comparisons made between cornual and infraorbital nerves, between disbudded and sham-disbudded calves and between disbudded calves with and without signs of chronic pain. Parameters used included 1) the size distributions of minimal axon diameters in both the cornual and infraorbital nerves by means of fiber labelling with neuron-specific class III beta-tubulin (Tuj-1) as a pan-neuronal marker; 2) the proportion of sympathetic fibers in cornual and infraorbital nerves by means of fiber labelling with tyroxine hydroxylase (TH); 3) the average glial envelope, i.e. the glial fibrillary acidic protein (GFAP)-positive area per cell body in the trigeminal ganglia and 4) the percentage of cyclic adenosine monophosphate-dependent transcription factor 3 (ATF3)-positive neurons in the trigeminal ganglia. Therefore, the aim of this study was to evaluate potential histopathological effects of cautery disbudding on the R. cornualis taking into account evidence of chronic pain.
Section snippets
Animals
Samples were collected from 38 male animals, i.e. 17 Holstein bulls and 21 Holstein bull calves. While the bulls were selected from a random group of disbudded animals, the calves were part of a study in which chronic pain and hypersensitivity were assessed clinically (Mirra et al., 2018). This study had received ethical approval from the Canton of Fribourg, Switzerland (2014_52_FR).
The bulls where disbudded at 17–68 d of age and slaughtered at 300–400 d. From the 21 calves, 7 animals were
Immunolabelling
Substituting pertinent primary antibodies with irrelevant antibodies resulted in complete absence of immunostaining. Similarly, omission of primary antibodies did not reveal any unspecific labelling. Therefore, immunostaining for Tuj-1, TH, GPG, GFAP and ATF3 was considered specific. Signal was adequate to allow accurate segmentation and analysis with the Investigator software (Fig. 1).
Axon diameter
In bulls, the median axon diameters for the N. infraorbitalis (1.11 μm) was slightly larger than for the R.
Discussion
Although being a well-known problem in human medicine (Zimmermann, 2001; Stacey, 2005; Wolff et al., 2011), neuropathic pain resulting from peripheral nerve injury has received little attention in veterinary medicine so far. With the raised public awareness of animal welfare (Huertas et al., 2014; Mellor and Webster, 2014), however, concerns about traumatic pain in animals has increased considerably (Ferdowsian and Merskin, 2012). This also applies to iatrogenic interventions such as the
Conclusion
Keeping in mind the limited number of available animals especially the few showing signs of chronic pain, the present study provided no evidence that disbudding and clinical signs of chronic pain are associated with significant changes in the parameters studied in either the R. cornualis or the trigeminal ganglion.
Acknowledgments
The obliging assistance of Mr. Magaletti, Slaughterhouse, Estavayer-le-lac was much appreciated. This study was funded in part by an earmarked, private donation through the “Fondation Sur-la-Croix”.
The authors have no conflict of interest to declare.
References (48)
Environment- and activity-dependent dopamine neurotransmitter plasticity in the adult substantia nigra
J. Chem. Neuroanat.
(2016)- et al.
Can disbudding of calves (one versus four weeks of age) induce chronic pain?
Physiol. Behav.
(2019) - et al.
Skin denervation, neuropathology, and neuropathic pain in a laser-induced focal neuropathy
Neurobiol. Dis.
(2005) - et al.
Trigeminal ganglion neuronal activity and glial fibrillary acidic protein immunoreactivity after inferior alveolar nerve crush in the adult rat
Pain
(1997) - et al.
Reducing pain after dehorning in dairy calves
J. Dairy Sci.
(2000) - et al.
Onset, duration and efficacy of four methods of local anesthesia of the horn bud in calves
Vet. Anaesth. Analg.
(2012) - et al.
Staining of glial fibrillary acidic protein (GFAP) in lumbar spinal cord increases following a sciatic nerve constriction injury
Brain Res.
(1991) - et al.
Behavioural, endocrine and cardiac responses in young calves undergoing dehorning without and with use of sedation and analgesia
Vet. J.
(1999) - et al.
Kidins220/ARMS modulates the activity of microtubule-regulating proteins and controls neuronal polarity and development
J. Biol. Chem.
(2010) - et al.
Perceptions and practices of Finnish dairy producers on disbudding pain in calves
J. Dairy Sci.
(2015)
Neuropathic changes in equine laminitis pain
Pain
Persistent postsurgical pain // persistent postsurgical pain: risk factors and prevention: risk factors and prevention
Lancet
Effects of stress from electrical dehorning on feed intake, growth, and blood constituents of Holstein heifer calves
J. Dairy Sci.
Chronic post-surgical pain: 10 years on
Br. J. Anaesth.
Acute pain and peripheral sensitization following cautery disbudding in 1- and 4-week-old calves
Physiol. Behav.
Empathic veterinarians score cattle pain higher
Vet. J.
Substance P and calcitonin gene-related peptide immunoreactive sensory DRG neurons innervating the lumbar facet joints in rats
Auton. Neurosci.
Comparison of the electrophysiological and immunohistochemical properties of acutely dissociated and 1-day cultured rat trigeminal ganglion neurons
Neurosci. Lett.
Dehorning and disbudding distress and its alleviation in calves
Vet. J. (London, England : 1997)
Addressing the pain associated with disbudding and dehorning in cattle
Appl. Anim. Behav. Sci.
Eye temperature and heart rate variability of calves disbudded with or without local anaesthetic
Physiol. Behav.
Bovine dehorning: assessing pain and providing analgesic management
Vet. Clin. North. Am. Food Anim. Pract.
Cortisol responses to dehorning of calves given a 5-h local anaesthetic regimen plus phenylbutazone, ketoprofen, or adrenocorticotropic hormone prior to dehorning
Res. Vet. Sci.
Dairy producer attitudes to pain in cattle in relation to disbudding calves
J. Dairy Sci.
Cited by (2)
Alleviating pain in neonatal procedures
2021, Encyclopedia of Dairy Sciences: Third edition
- 1
These authors contributed equally.