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Mellor DJ. Mouth Pain in Horses: Physiological Foundations, Behavioural Indices, Welfare Implications, and a Suggested Solution. Animals (Basel) 2020; 10:ani10040572. [PMID: 32235343 PMCID: PMC7222381 DOI: 10.3390/ani10040572] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 03/26/2020] [Accepted: 03/26/2020] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Mouth pain in horses, specifically that caused by bits, is evaluated as a significant welfare issue. The conscious experiences of pain generated within the body generally, its roles, and its assessment using behaviour, as well as the sensory functionality of the horse’s mouth, are outlined as background to a more detailed evaluation of mouth pain. Bit-induced mouth pain elicited by compression, laceration, inflammation, impeded blood flow, and the stretching of tissues is considered. Observable signs of mouth pain are behaviours that are present in bitted horses and absent or much less prevalent when they are bit-free. It is noted that many equestrians do not recognise that these behaviours indicate mouth pain, so that the magnitude of the problem is often underestimated. The negative experiences that are most responsible for welfare compromise include the pain itself, but also, related to this pain, potentially intense breathlessness, anxiety, and fear. Finally, a series of questions is proposed to clarify issues that are relevant to increasing the adoption of bit-free bridles in order to avoid bit-induced mouth pain. Abstract A proposition addressed here is that, although bitted horses are viewed by many equestrians as being largely free of bit-related mouth pain, it seems likely that most behavioural signs of such pain are simply not recognised. Background information is provided on the following: the major features of pain generation and experience; cerebrocortical involvement in the conscious experience of pain by mammals; the numerous other subjective experiences mammals can have; adjunct physiological responses to pain; some general feature of behavioural responses to pain; and the neural bases of sensations generated within the mouth. Mouth pain in horses is then discussed. The areas considered exclude dental disease, but they include the stimulation of pain receptors by bits in the interdental space, the tongue, the commissures of the mouth, and the buccal mucosa. Compression, laceration, inflammation, impeded tissue blood flow, and tissue stretching are evaluated as noxious stimuli. The high pain sensitivity of the interdental space is described, as are likely increases in pain sensitivity due to repeated bit contact with bruises, cuts, tears, and/or ulcers wherever they are located in the mouth. Behavioural indices of mouth pain are then identified by contrasting the behaviours of horses when wearing bitted bridles, when changed from bitted to bit-free bridles, and when free-roaming unbitted in the wild. Observed indicative behaviours involve mouth movements, head-neck position, and facial expression (“pain face”), as well as characteristic body movements and gait. The welfare impacts of bit-related pain include the noxiousness of the pain itself as well as likely anxiety when anticipating the pain and fear whilst experiencing it, especially if the pain is severe. In addition, particular mouth behaviours impede airflow within the air passages of the upper respiratory system, effects that, in their turn, adversely affect the air passages in the lungs. Here, they increase airflow resistance and decrease alveolar gas exchange, giving rise to suffocating experiences of breathlessness. In addition, breathlessness is a likely consequence of the low jowl angles commonly maintained during dressage. If severe, as with pain, the prospect of breathlessness is likely to give rise to anxiety and the direct experience of breathlessness to fear. The related components of welfare compromise therefore likely involve pain, breathlessness, anxiety, and fear. Finally, a 12-point strategy is proposed to give greater impetus to a wider adoption of bit-free bridles in order to avoid bit-induced mouth pain.
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Affiliation(s)
- David J Mellor
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Palmerston North 4474, New Zealand
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Saunders NR, Dziegielewska KM, Whish SC, Hinds LA, Wheaton BJ, Huang Y, Henry S, Habgood MD. A bipedal mammalian model for spinal cord injury research: The tammar wallaby. F1000Res 2017; 6:921. [PMID: 28721206 PMCID: PMC5497825 DOI: 10.12688/f1000research.11712.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/12/2017] [Indexed: 12/16/2022] Open
Abstract
Background: Most animal studies of spinal cord injury are conducted in quadrupeds, usually rodents. It is unclear to what extent functional results from such studies can be translated to bipedal species such as humans because bipedal and quadrupedal locomotion involve very different patterns of spinal control of muscle coordination. Bipedalism requires upright trunk stability and coordinated postural muscle control; it has been suggested that peripheral sensory input is less important in humans than quadrupeds for recovery of locomotion following spinal injury. Methods: We used an Australian macropod marsupial, the tammar wallaby
(Macropuseugenii), because tammars exhibit an upright trunk posture, human-like alternating hindlimb movement when swimming and bipedal over-ground locomotion. Regulation of their muscle movements is more similar to humans than quadrupeds. At different postnatal (P) days (P7–60) tammars received a complete mid-thoracic spinal cord transection. Morphological repair, as well as functional use of hind limbs, was studied up to the time of their pouch exit. Results: Growth of axons across the lesion restored supraspinal innervation in animals injured up to 3 weeks of age but not in animals injured after 6 weeks of age. At initial pouch exit (P180), the young injured at P7-21 were able to hop on their hind limbs similar to age-matched controls and to swim albeit with a different stroke. Those animals injured at P40-45 appeared to be incapable of normal use of hind limbs even while still in the pouch. Conclusions: Data indicate that the characteristic over-ground locomotion of tammars provides a model in which regrowth of supraspinal connections across the site of injury can be studied in a bipedal animal. Forelimb weight-bearing motion and peripheral sensory input appear not to compensate for lack of hindlimb control, as occurs in quadrupeds. Tammars may be a more appropriate model for studies of therapeutic interventions relevant to humans.
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Affiliation(s)
- Norman R Saunders
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Katarzyna M Dziegielewska
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Sophie C Whish
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Lyn A Hinds
- Health and Biosecurity Business Unit, Commonwealth Science and Industrial Research Organisation (CSIRO), Canberra, ACT, 2601, Australia
| | - Benjamin J Wheaton
- Centre for Evolutionary and Theoretical Immunology, The University of New Mexico, Albuquerque, NM, 87131, USA
| | - Yifan Huang
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Steve Henry
- Health and Biosecurity Business Unit, Commonwealth Science and Industrial Research Organisation (CSIRO), Canberra, ACT, 2601, Australia
| | - Mark D Habgood
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
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Mellor DJ, Lentle RG. Survival implications of the development of behavioural responsiveness and awareness in different groups of mammalian young. N Z Vet J 2015; 63:131-40. [PMID: 25266360 DOI: 10.1080/00480169.2014.969349] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This paper focuses on the development of behaviours that are critical for the survival of newborn and juvenile mammals of veterinary and wider biological interest. It provides an updated, integrated and comparative analysis of how postnatal maturation of sensory, motor and perceptual capacities support and constrain behavioural interactions between mammalian young and the mother, any littermates and the environment. Young that are neurologically exceptionally immature, moderately immature and mature at birth are compared, and include, for example, marsupial joeys, rodent pups and ruminant offspring. Mothers in these three groups exhibit distinctive patterns of birthing and postnatal care behaviours. To secure survival of the young, maternal care must compensate for behavioural inadequacies imposed by the limited sensory capacities the young possess at each stage. These sensory capacities develop in a predictable sequence in most mammals such that before birth the sequence progresses to an extent that parallels the degree of neurological maturity reached at birth. The extent of neurological maturity is likewise reflected in how long it takes after birth for the necessary brain circuit connectivity to develop sufficiently to support cortically based cognitive modulation of behaviour. This takes several months, days-to-weeks or minutes-to-hours in young that are, respectively, neurologically exceptionally immature, moderately immature, or mature at birth. Once achieved, cognitive awareness confers a high degree of behavioural flexibility that allows the young to respond more effectively to the unpredictability of their postnatal environments. It is shown that the onset of this cognitively based flexibility in the young of each group coincides with their first exposure to a variable environment that requires such behavioural flexibility.
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Affiliation(s)
- D J Mellor
- a Animal Welfare Science and Bioethics Centre , Institute of Veterinary, Animal and Biomedical Sciences, Massey University , Palmerston North 4442 , New Zealand
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Kaka U, Hui Cheng C, Meng GY, Fakurazi S, Kaka A, Behan AA, Ebrahimi M. Electroencephalographic changes associated with antinociceptive actions of lidocaine, ketamine, meloxicam, and morphine administration in minimally anaesthetized dogs. BIOMED RESEARCH INTERNATIONAL 2015; 2015:305367. [PMID: 25695060 PMCID: PMC4324106 DOI: 10.1155/2015/305367] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/02/2014] [Accepted: 11/04/2014] [Indexed: 12/24/2022]
Abstract
Effects of ketamine and lidocaine on electroencephalographic (EEG) changes were evaluated in minimally anaesthetized dogs, subjected to electric stimulus. Six dogs were subjected to six treatments in a crossover design with a washout period of one week. Dogs were subjected to intravenous boluses of lidocaine 2 mg/kg, ketamine 3 mg/kg, meloxicam 0.2 mg/kg, morphine 0.2 mg/kg and loading doses of lidocaine 2 mg/kg followed by continuous rate infusion (CRI) of 50 and 100 mcg/kg/min, and ketamine 3 mg/kg followed by CRI of 10 and 50 mcg/kg/min. Electroencephalogram was recorded during electrical stimulation prior to any drug treatment (before treatment) and during electrical stimulation following treatment with the drugs (after treatment) under anaesthesia. Anaesthesia was induced with propofol and maintained with halothane at a stable concentration between 0.85 and 0.95%. Pretreatment median frequency was evidently increased (P < 0.05) for all treatment groups. Lidocaine, ketamine, and morphine depressed the median frequency resulting from the posttreatment stimulation. The depression of median frequency suggested evident antinociceptive effects of these treatments in dogs. It is therefore concluded that lidocaine and ketamine can be used in the analgesic protocol for the postoperative pain management in dogs.
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Affiliation(s)
- Ubedullah Kaka
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Faculty of Animal Husbandry & Veterinary Sciences, Sindh Agriculture University Tandojam, Sindh 70060, Pakistan
| | - Chen Hui Cheng
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Goh Yong Meng
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Institutes of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Sharida Fakurazi
- Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Department of Human Anatomy, Faculty of Medicine and Health Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Asmatullah Kaka
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Faculty of Animal Husbandry & Veterinary Sciences, Sindh Agriculture University Tandojam, Sindh 70060, Pakistan
| | - Atique Ahmed Behan
- Faculty of Animal Husbandry & Veterinary Sciences, Sindh Agriculture University Tandojam, Sindh 70060, Pakistan
- Department of Animal Sciences, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Mahdi Ebrahimi
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
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Grint NJ, Johnson CB, De Sa Lorena S, Luna S, Hussni CA, Whay HR, Murrell JC. Electroencephalographic Responses to a Noxious Surgical Stimulus in Mules, Horses, and Ponies. J Equine Vet Sci 2014. [DOI: 10.1016/j.jevs.2014.04.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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McGowan KT, Elfenbein JR, Robertson SA, Sanchez LC. Effect of butorphanol on thermal nociceptive threshold in healthy pony foals. Equine Vet J 2012; 45:503-6. [PMID: 23126609 DOI: 10.1111/j.2042-3306.2012.00673.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 09/09/2012] [Indexed: 12/01/2022]
Abstract
REASONS FOR PERFORMING STUDY Pain management is an important component of foal nursing care, and no objective data currently exist regarding the analgesic efficacy of opioids in foals. OBJECTIVES To evaluate the somatic antinociceptive effects of 2 commonly used doses of intravenous (i.v.) butorphanol in healthy foals. Our hypothesis was that thermal nociceptive threshold would increase following i.v. butorphanol in a dose-dependent manner in both neonatal and older pony foals. METHODS Seven healthy neonatal pony foals (age 1-2 weeks), and 11 healthy older pony foals (age 4-8 weeks). Five foals were used during both age periods. Treatments, which included saline (0.5 ml), butorphanol (0.05 mg/kg bwt) and butorphanol (0.1 mg/kg bwt), were administered i.v. in a randomised crossover design with at least 2 days between treatments. Response variables included thermal nociceptive threshold, skin temperature and behaviour score. Data within each age period were analysed using a 2-way repeated measures ANOVA, followed by a Holm-Sidak multiple comparison procedure if warranted. RESULTS There was a significant (P<0.05) increase in thermal threshold, relative to Time 0, following butorphanol (0.1 mg/kg bwt) administration in both age groups. No significant time or treatment effects were apparent for skin temperature. Significant time, but not treatment, effects were evident for behaviour score in both age groups. CONCLUSIONS Butorphanol (0.1 mg/kg bwt, but not 0.05 mg/kg bwt) significantly increased thermal nociceptive threshold in neonatal and older foals without apparent adverse behavioural effects. POTENTIAL RELEVANCE Butorphanol shows analgesic potential in foals for management of somatic painful conditions.
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Affiliation(s)
- K T McGowan
- Department of Large Animal Clinical Sciences, University of Florida College of Veterinary Medicine, Florida, USA
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Renfree MB, Pask AJ. Reproductive and developmental manipulation of the marsupial, the tammar wallaby Macropus eugenii. Methods Mol Biol 2011; 770:457-473. [PMID: 21805276 DOI: 10.1007/978-1-61779-210-6_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The developing marsupial is an ideal animal for use in biomedical research. Marsupials are mammals that have been separated from eutherian mammals for over 130-140 million years. They all deliver altricial young that complete their growth and development after birth usually in a pouch, but not all marsupials have a pouch. Their lactation changes dynamically throughout the period of pouch life, and the mother controls their growth via the production of milk that is tailor-made for each stage of development. The tammar wallaby, Macropus eugenii, has been the experimental marsupial of choice for over five decades, as it is highly amendable to handling and breeds well in captivity. The tammar is especially interesting because it has both a lactational and a seasonal control of its reproduction and embryonic diapause that normally lasts 11 months. Standard molecular techniques can be used for most manipulations in marsupials. However, there are several special techniques for treating the young for experimental surgery and for organ culture that we detail below.
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Affiliation(s)
- Marilyn B Renfree
- Department of Zoology, The University of Melbourne, Melbourne, VIC 3010, Australia.
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