Mechanical nociceptive thresholds in endurance horses

2019 ◽  
Vol 186 (4) ◽  
pp. 124.1-124 ◽  
Author(s):  
Morgane Schambourg ◽  
Polly M Taylor

BackgroundAlteration of limb sensitivity is forbidden in equine sports but difficult to enforce. We aimed to develop an objective field method to assess mechanical nociceptive threshold (MNT) in endurance horses.MethodsA remotely controlled pneumatic actuator (1 mm tip) was used to measure forelimb pastern MNT in 108 endurance horses.ResultsMedian (IQR) MNT at rest was 1.9 N (0.9–3.5). Icing had no significant effect on limb sensitivity. MNT measured at weekly intervals increased from week 1 (1.2 N (0.6–1.8)) to week 3 (1.9 N (1.2–2.8)) (P<0.05). In 17 horses without impaired sensitivity, MNT increased from 1.2 N (0.6–2.3) before to 2.4 N (1.2–5.2) after racing (P=0.0017). In desensitised horses, MNT after racing was higher (8 limbs—23.1 N (21.4 to >25)) than in horses without impaired sensitivity (42 limbs—2.2 N (1.2–4.3)) (P<0.0001). Desensitisation with mepivacaine increased MNT to above the safety cut-off (25 N) at 10 minutes; sensitivity return to baseline varied between individuals but was restored by 330 minutes. None of the horses became averse to the technique.ConclusionMNT was practical, non-traumatic, repeatable and well tolerated under field conditions in endurance horses. The technique differentiated postracing MNT in horses with normal sensitivity from those with impaired sensitivity.

2021 ◽  
Vol 17 ◽  
pp. 174480692110113
Author(s):  
Paul G Green ◽  
Pedro Alvarez ◽  
Jon D Levine

Fibromyalgia and other chronic musculoskeletal pain syndromes are associated with stressful early life events, which can produce a persistent dysregulation in the hypothalamic-pituitary adrenal (HPA) stress axis function, associated with elevated plasm levels of corticosterone in adults. To determine the contribution of the HPA axis to persistent muscle hyperalgesia in adult rats that had experienced neonatal limited bedding (NLB), a form of early-life stress, we evaluated the role of glucocorticoid receptors on muscle nociceptors in adult NLB rats. In adult male and female NLB rats, mechanical nociceptive threshold in skeletal muscle was significantly lower than in adult control (neonatal standard bedding) rats. Furthermore, adult males and females that received exogenous corticosterone (via dams’ milk) during postnatal days 2–9, displayed a similar lowered mechanical nociceptive threshold. To test the hypothesis that persistent glucocorticoid receptor signaling in the adult contributes to muscle hyperalgesia in NLB rats, nociceptor expression of glucocorticoid receptor (GR) was attenuated by spinal intrathecal administration of an oligodeoxynucleotide (ODN) antisense to GR mRNA. In adult NLB rats, GR antisense markedly attenuated muscle hyperalgesia in males, but not in females. These findings indicate that increased corticosterone levels during a critical developmental period (postnatal days 2–9) produced by NLB stress induces chronic mechanical hyperalgesia in male and female rats that persists in adulthood, and that this chronic muscle hyperalgesia is mediated, at least in part, by persistent stimulation of glucocorticoid receptors on sensory neurons, in the adult male, but not female rat.


2014 ◽  
Vol 44 (3) ◽  
pp. 517-523 ◽  
Author(s):  
Leandro Guimarães Franco ◽  
Juan Carlos Duque Moreno ◽  
Antônio Raphael Teixeira Neto ◽  
Moisés Caetano e Souza ◽  
Luiz Antônio Franco da Silva

This study assessed the clinical effects and the mechanical antinociceptive potential of intravenous (IV) tramadol in horses.A blinded and randomized study was designed with 7 horses treated with 1 (Tr1), 2 (Tr2) or 3 (Tr3) mg kg-1 of tramadol IV. The heart rate, respiratory rate (fR), arterial pressure, degree of sedation, gastrointestinal motility (GI), behavior changes and the mechanical nociceptive threshold (MNT) were evaluated. The MNT was determined with von Frey device method.Tr3 had a significant increase in their fR and more pronounced behavioral changes than other treatments.The Tr1 showed a significant increase in arterial pressure. The GI reduced significantly, mainly in Tr2. The tramadol did not change the MNT of the horses.The clinical alterations observed with the different treatments were considered mild and transitory, being most evident in Tr2. However the tramadol did not have any analgesic effect with any of the doses evaluated.


Author(s):  
Cailey L. Nichols ◽  
Thomas J. Doherty ◽  
James Schumacher ◽  
Philip D. Jones ◽  
Xiaocun Sun

Abstract OBJECTIVE To determine whether palmar digital nerve (PDN) blockade in horses with a combination of dexmedetomidine and mepivacaine would block the response to mechanical force applied to the digit longer than would anesthetizing these nerves with mepivacaine alone or dexmedetomidine alone. ANIMALS 8 mares with no signs of lameness. PROCEDURES In a randomized, crossover, blinded, experimental study, both PDNs of the same forelimb of each horse were anesthetized by perineural injection with either 30 mg mepivacaine alone, 250 µg of dexmedetomidine alone, or 30 mg mepivacaine combined with 250 µg of dexmedetomidine. Each horse received each treatment, and treatments were administered ≥ 2 weeks apart. The mechanical nociceptive threshold was measured at a region between the heel bulbs with the use of a digital force gauge before (baseline) and at 15-minute intervals after treatment. RESULTS The mean duration of sensory blockade of the digit was 2-fold longer when a combination of mepivacaine and dexmedetomidine was administered (371 minutes), compared with when mepivacaine alone was administered (186 minutes). Treatment with dexmedetomidine alone did not change the mechanical nociceptive threshold substantially from baseline and resulted in no clinical signs of sedation. CLINICAL RELEVANCE Results indicated that relief from digital pain provided by perineural treatment with mepivacaine for PDN blockade can be extended by adding dexmedetomidine to the injectate.


2014 ◽  
Vol 27 (05) ◽  
pp. 351-357 ◽  
Author(s):  
P. Milner ◽  
A. Talbot ◽  
E. Singer ◽  
G. Hinnigan

SummaryObjectives: To investigate the specificity of anaesthesia of the deep branch of the lateral plantar nerve (DB-LPN).Methods: Twenty horses had DB-LPN anaesthesia performed by a single injection technique as part of a lameness investigation. The mechanical nociceptive threshold (NT) was measured using a handheld force meter at six points on the lateral aspect of the limb: before diagnostic anaesthesia (T0), and at 15 (T15) and 30 (T30) minutes post anaesthesia. Paired t-tests were performed and significance was set at p <0.05. In addition, ten cadaveric limbs were injected with 2.5 ml new methylene blue solution using a single injection technique to evaluate the extent of dye diffusion within the proximal metatarsal region.Results: Compared with T0, there was a significant decrease in NT for all points combined at T15 (p = 0.008) and also at T30 (p = 0.007). There was a significant decrease in NT at T15 on the lateral third metatarsal bone (p = 0.012). At T30 there was a significant decrease in NT at the lateral sesamoid (p = 0.007), lateral third metatarsal bone (p = 0.031), and mid metatarsus (p = 0.033). Four out of 20 horses had a NT greater than 10 N at the lateral heel bulb at T30. In the cadaveric limbs, the total diffusion distance for all limbs (mean ± SD) was 70.4 ± 20.5 mm. Dye surrounded the DB-LPN in all limbs and the lateral plantar nerve (LPN) in nine out of 10 limbs.Clinical significance: Concurrent anaesthesia of the LPN is likely to occur when DBLPN anaesthesia is performed using a single injection technique.


2018 ◽  
Vol 21 (8) ◽  
pp. 723-731 ◽  
Author(s):  
Meera Shah ◽  
David Yates ◽  
James Hunt ◽  
Jo Murrell

Objectives The aim of this study was to investigate the analgesic efficacy of methadone vs buprenorphine within the QUAD protocol for anaesthesia in cats undergoing ovariohysterectomy. Methods One hundred and twenty cats were recruited to an assessor-blinded, randomised clinical trial. Cats received either methadone (5  mg/m2) or buprenorphine (180 µg/m2) combined with ketamine, midazolam and medetomidine intramuscularly. Anaesthesia was maintained with isoflurane in oxygen. Atipamezole was administered at extubation. Pain was assessed using the feline Composite Measure Pain Scale (CMPS-F), a dynamic interactive visual analogue scale (DIVAS) and mechanical nociceptive threshold (MNT). Sedation, pain, heart rate and respiratory rate were measured prior to QUAD administration, before intubation, and 2, 4, 6 and 8 h post-QUAD administration. If indicated by the CMPS-F, rescue analgesia was provided with 0.5 mg/kg of methadone administered intramuscularly. Meloxicam was administered after the last assessment. Differences in pain scores between groups were compared using a two-way repeated-measures ANOVA and requirement for rescue analgesia was compared using a χ2 test. Results Cats administered methadone had lower CMPS-F scores over time ( P = 0.04). Eighteen of 60 cats required rescue analgesia in the methadone group vs 29/60 in the buprenorphine group ( P = 0.028). All cats that received rescue analgesia required it within 6 h post-QUAD administration. There were no differences between groups in MNT or pain measured using the DIVAS. Conclusions and relevance Methadone produced clinically superior postoperative analgesia for the first 8 h after neutering than buprenorphine when used within the QUAD protocol.


2009 ◽  
Vol 165 (4) ◽  
pp. 122-122 ◽  
Author(s):  
C. Jolliffe ◽  
D. Flack ◽  
B. Joyce ◽  
J. Keeley ◽  
P. Taylor ◽  
...  

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Qi Xu ◽  
Yong Zhou ◽  
Rong Zhang ◽  
Zhan Sun ◽  
Lu-feng Cheng

Objective. The aim was to study the therapeutic effects and mechanisms of QWRG on adjuvant-induced RA in rats. Methods. The RA rat models were manipulated and subsequently divided into five experimental groups: AIA, DEX, and QWRG groups. The paw volume, body weight, arthritic score, and mechanical nociceptive threshold were assessed. The serum levels of the RF, MDA, ALP, AST, ALT, IL-1β, IL-2, IL-16, and TNF-α were measured. The proliferative capacity of lymphocytes was evaluated, and the synovial tissue was histopathologically examined. Results. The paw swelling and arthritic scores were relieved, and the variation of relative body weight and mechanical nociceptive threshold had improved in the AIA rats. The serum levels of RF, MDA, ALP, AST, and ALT were alleviated, and the inflammation and cartilage damage were effectively attenuated in the AIA rats. Simultaneously, the inflammation of the synovial cavity was alleviated, and the grading of synovitis reduced by inhibiting the expressions of IL-1β, TNF-α, and IL-16 in the serum and synovium tissue. Conclusion. Our results suggested that the antiarthritic properties of QWRG may be due to immunodepression and downregulation of inflammatory cytokines, which may be a potential candidate for the treatment of RA.


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