Electroacupuncture is a specific acupuncture technique that involves electrical stimulation of acupuncture needles and has been recommended for treatment of various painful conditions, neurologic deficits, muscular weaknesses, and muscle spasms.1–3 In previous studies,3–6 it was shown that stimulation of acupuncture points induces release of endogenous opioids and neurotransmitters, such as β-endorphins, met-enkephalin, dynorphin, orphanin Q, endomorphin, serotonin, and noradrenalin. Acupuncture has also been shown to activate the endogenous antinociception system in humans as well as the descending pain-inhibiting system.4,5 On the other hand, studies6–10 evaluating the effects of acupuncture on pain in humans and animals have had conflicting results, with some studies reporting positive effects and others unable to identify any significant effects.
In a previous clinical study11 involving 50 dogs with thoracolumbar intervertebral disk disease, significantly higher proportions of dogs recovered at least some degree of proprioception and at least some degree of ambulation following treatment with a combination of conventional medical treatment and EAP than following conventional medical treatment alone. In addition, for dogs with grade 3 or 4 neurologic dysfunction, time to recover ambulation was significantly shorter for dogs that received EAP than for dogs that did not. In human patients, treatment with acupuncture before and after lumbar disk protrusion surgery has been associated with a significant reduction in severity of postoperative pain,12 but to our knowledge, the effects of EAP in dogs undergoing surgery for treatment of thoracolumbar intervertebral disk disease have not been determined. The purpose of the study reported here, therefore, was to compare severity of postoperative pain in dogs undergoing hemilaminectomy because of acute thoracolumbar intervertebral disk disease treated with a combination of conventional analgesics and EAP or with conventional analgesics alone. We hypothesized that dogs that received adjunct EAP would experience less severe pain.
Materials and Methods
Dogs evaluated at the University of Berne veterinary teaching hospital because of acute intervertebral disk disease between March 2007 and February 2008 were considered for inclusion in the study. Dogs were included in the study only if they weighed < 12 kg (26.5 lb) and had a history and clinical signs of acute (< 48 hours' duration) thoracolumbar (T13-L3) disk disease. Dogs were excluded if they were a large breed; had a history of traumatic disk disease, severe heart disease, cardiac pacemaker implantation, or epilepsy; or were pregnant. In addition, dogs were removed from the study if they were so fearful, nervous, or aggressive that examination and EAP were not feasible or if they died during the observation period. Owners of dogs included in the study provided their consent.
For all dogs included in the study, a complete physical and neurologic examination was performed at the time of hospital admission. For purposes of pain scoring, baseline heart rate was recorded at the time of admission, prior to any other examinations. All dogs were examined by 1 of 3 residents in neurology. The diagnosis of acute thoracolumbar disk disease was made on the basis of magnetic resonance imaging findings and confirmed at surgery. In all dogs, a standard hemilaminectomy was performed; all surgical procedures were performed by or under the direct supervision of a single neurosurgeon (FF).
Following surgery, dogs were assigned to treatment and control groups, with dogs that underwent surgery on even-numbered days assigned to the treatment group (conventional analgesic treatment and EAP) and dogs that underwent surgery on odd-numbered days assigned to the control group (conventional analgesic treatment alone).
Anesthetic protocol—Dogs were sedated with diazepam (0.2 to 0.4 mg/kg [0.09 to 0.18 mg/lb], IV) and fentanyl (1 to 3 μg/kg [0.45 to 1.36 μg/lb], IV). Anesthesia was induced with propofol (2 to 6 mg/kg [0.9 to 2.7 mg/lb], IV, to effect) and maintained with isoflurane in oxygen. Anesthetic monitoring included continuous ECG and measurement of end-tidal partial pressure of CO2.
MRI protocol—Dogs were positioned in dorsal recumbency for MRI of the spine. The smallest applicable receiving coils were used, depending on the size of the dog. Sequences that were obtained included sagittal (repetition time, 2,850 milliseconds; echo time, 125 milliseconds) and transverse (repetition time, 3,186 milliseconds; echo time, 125 milliseconds) T2-weighted images, transverse T1-weighted images (repetition time, 450 milliseconds; echo time, 20 milliseconds), and dorsal T1-weighted gradient echo images (repetition time, 30 milliseconds; echo time, 12 milliseconds). The T1-weighted sequences were repeated after administration of gadodiamide (0.15 mmol/kg [0.068 mmol/lb], IV). The severity of spinal cord compression was classified as mild, moderate, or severe by a radiologist.
Surgical protocol—Surgery was performed immediately after MRI. A continuous rate infusion of fentanyl (2.5 to 10 μg/kg/h [1.14 to 4.5 μg/kg/h], IV) was begun immediately prior to surgery and continued throughout the surgical procedure, along with a continuous infusion of lactated Ringer's solution (10 mL/kg/h, IV). Methylprednisolone sodium succinate (30 mg/kg [13.6 mg/lb], IV, once) and cefazolin (20 mg/kg [9.1 mg/lb], IV, once) were administered immediately prior to the initial surgical incision. Esophageal temperature and blood pressure were measured and pulse oximetry was performed throughout the surgical procedure.
Dogs were positioned in slightly oblique sternal recumbency with the side to which disk material had been extruded facing upward. A skin incision was made 1 cm lateral to the midline on the side of the lesion, extending at least 1 vertebra cranial and caudal to the intervertebral space to be approached. A conventional hemilaminectomy13 was performed, and extruded disk material was removed. Bladder volume was assessed at the end of surgery, and the bladder was manually emptied if it was palpable.
Postoperative pain assessment and care—In all dogs, standard postoperative monitoring, including monitoring of heart and respiratory rates, was performed. Rectal temperature was measured immediately after and 1 and 3 hours after surgery. Bladder volume was assessed every 4 hours after surgery, and the bladder was manually emptied as necessary. Lactated Ringer's solution (4 mL/kg/h [1.82 mL/lb/h], IV) and ranitidine (0.5 mg/kg [0.23 mg/lb], IV, q 12 h) were administered for the first 12 hours after surgery. Twelve hours after surgery, dogs were moved to a rehabilitation unit, where they remained until the end of the study period and where they were given physiotherapy.
In all dogs, fentanyl was administered as a continuous rate infusion at a dosage of 2.5 μg/kg/h for the first hour after surgery. One and 3 hours after surgery, a subjective pain assessment (mild, moderate, or severe) was made by the attending neurology resident, and the fentanyl dosage was adjusted (2.5 μg/kg/h for dogs in mild pain, 5 μg/kg/h [2.27 μg/lb/h] for dogs in moderate pain, and 10 μg/kg/h for dogs in severe pain) as necessary. Following the adjustment in dosage 3 hours after surgery, fentanyl was administered at the same dosage until 12 hours after surgery.
Dogs were reexamined 12 hours after surgery and every 12 hours thereafter for up to 72 hours after surgery by the attending neurology resident. At these times, no medication was given if the patient was considered to have no signs of pain, carprofen (2 mg/kg, SC, q 12 h) was administered if the dog had signs of mild pain, buprenorphine (0.01 mg/kg [0.005 mg/lb], SC, q 8 h) was administered if the dog had signs of moderate pain, and both carprofen and buprenorphine were administered if the dog had signs of severe pain. Throughout the study period, the attending neurology residents were not aware of whether dogs had been assigned to the treatment or control group.
Dogs were also examined 1, 3, 12, 24, 36, 48, 60, and 72 hours after surgery by one of the authors (AL) who assigned an MPS, as describeda (Appendix). To assign an MPS, patients were first observed from a distance and were then addressed by their name so the reaction could be evaluated. The cage was then approached and opened, and the heart rate was measured. Finally, the wound was palpated, and the reaction was recorded. Potential pain scores ranged from 0 to 18. Dogs with a score of 0 were considered to have no pain, dogs with a score of 1 through 5 were considered to have discomfort, dogs with a score of 6 through 10 were considered to have moderate pain, and dogs with a score of 11 through 18 were considered to have severe pain.
Experimental treatment—For dogs in the treatment group, acupuncture was performed as soon as the dog was awake after surgery and every 12 hours after surgery until MPS was 0 or the end of the study period (ie, 72 hours after surgery) was reached. All acupuncture treatments were administered by a single individual (AL), who was supervised by an experienced veterinary acupuncturist (OG). Acupuncture treatments were performed in a separate room or out of the sight of the attending neurology resident who performed subjective pain assessments and determined analgesic drug treatments. Acupuncture points were stimulated with sterile disposable Hwato acupuncture needlesb (13 × 0.25 mm and 25 × 0.25 mm). Needles were inserted to a depth of 2 to 20 mm, depending on the location of the point, and 8 needles were used during each treatment. Electroacupuncture was applied with a digital EAP unit.c Treatments were performed for 20 minutes with dense disperse (modulated) waveforms ranging from 2 to 100 Hz. Intensity was gradually increased until muscle contraction or a slight reaction was seen. Two acupuncture procedures consisting of different sets of points were used in each patient. The first procedure consisted of 2 points on the bladder meridian bilaterally rostral and caudal to the incision, stomach 36 unilaterally, spleen 6 unilaterally (contralateral to stomach 36), and bladder 60 bilaterally. The second procedure consisted of governing vessel 14 unilaterally, Bai Hui (lumbosacral site) unilaterally, bladder 11 unilaterally, bladder 40 unilaterally, gallbladder 34 bilaterally, gallbladder 30 unilaterally, and liver 3 unilaterally (contralateral to gallbladder 30). Pairs of bladder acupuncture points on the same side of the body were connected with an electrode from a set; for the other acupuncture points, 1 point from each body side was connected to 1 set as well as to governing vessel 14 and Bai Hui (lumbosacral site).
Statistical analysis—The Kolmogorov-Smirnov test was used to determine whether pain scores assigned by the acupuncturist and fentanyl dosages immediately after and 1 and 3 hours after surgery were normally distributed within groups. Because data were normally distributed, they were summarized as mean and SD. Heart rate measurements obtained every 12 hours from 12 to 72 hours after surgery were summarized for each animal as an area under the curve. Repeated-measures ANOVA with the Geisser-Greenhouse adjustment was used to simultaneously assess the effect of treatment group and time on MPS 1, 3, 12, 24, 36, 48, 60, and 72 hours after surgery; scores for 2 of the variables used to calculate MPS (response to palpation of the surgical wound and intensity of reaction to wound palpation) 1, 3, 12, 24, 36, 48, 60, and 72 hours after surgery; fentanyl dosage 1, 3, and 12 hours after surgery; and carprofen and buprenorphine dosages 24, 36, 48, 60, and 72 hours after surgery. Total drug dose and area under the heart rate versus time curve were compared between the treatment and control groups by means of the equal variance 2-sample t test, Aspin-Welsh unequal variance t test, or Mann-Whitney U test, depending on the distribution of the data. All statistical analyses were performed with standard software.d Values of P ≤ 0.05 were considered significant.
Results
A total of 39 dogs were evaluated because of possible thoracolumbar intervertebral disk disease during the study period. Sixteen dogs did not meet inclusion criteria (7 were large-breed dogs, 3 had lumbosacral intervertebral disk disease, 3 did not have acute disk disease, 2 had traumatic disk disease, and 1 had concurrent cardiac disease), and 8 dogs were removed from the study (3 dogs because a second surgery was required during the study period, 2 dogs because of aggression, 2 dogs that could not be evaluated during the first hour after surgery because of emergence delirium requiring administration of additional tranquilizer, and 1 dog that was euthanatized 24 hours after surgery because of gastric torsion). The remaining 15 dogs were included in the study.
Of the 15 dogs in the study, 8 were assigned to the acupuncture group and 7 were assigned to the control group. There were 6 Dachshunds (5 males and 1 female) and 2 Pekingese (both females) in the acupuncture group. Dogs ranged from 2 to 11 years old at the time of surgery; body weight ranged from 3.6 to 11 kg (7.9 to 24.3 lb). Severity of pain at the time of initial assessment, as determined by the attending neurology resident, was rated as severe pain in 1 dog, moderate pain in 4 dogs, discomfort in 2 dogs, and no pain in 1 dog. Severity of spinal cord compression on magnetic resonance images was classified as severe in 3 dogs, moderate to severe in 3 dogs, and moderate in 2 dogs.
There were 4 Dachshunds (1 male and 3 females), 2 mixed-breed dogs (1 male and 1 female), and 1 Pekingese (male) in the control group. Dogs ranged from 2 to 13 years old at the time of surgery; body weight ranged from 3.7 to 10.5 kg (8.1 to 23.1 lb). Severity of pain at the time of initial assessment, as determined by the attending neurology resident, was rated as severe pain in 1 dog, moderate pain in 4 dogs, discomfort in 1 dog, and no pain in 1 dog. Severity of spinal cord compression on magnetic resonance images was classified as severe in 4 dogs and moderate in 3.
Hemilaminectomy was performed over 1 intervertebral space in 13 dogs and over 2 intervertebral spaces in 1 dog from each group.
In both groups, mean MPS decreased significantly (P < 0.001) over time (Figure 1). Mean MPS was significantly (P = 0.018) lower for dogs in the acupuncture group than for dogs in the control group 36 hours after surgery, but did not differ significantly between groups at other times in the study. The significant difference between groups 36 hours after surgery was attributable to significant differences between groups for scores assigned for the variables response to palpation of the surgical wound (P = 0.011; Figure 2) and intensity of reaction to wound palpation (P = 0.021; Figure 3).
For dogs in the acupuncture group, mean heart rate was high at the time of hospital admission and decreased during the postoperative period. In contrast, for dogs in the control group, heart rate was increased 1 hour after surgery, compared with baseline heart rate, and then decreased. However, no significant differences were identified between groups with regard to heart rate, blood pressure, results of pulse oximetry, or rectal temperature after surgery.
Although mean dosage of fentanyl did not differ between groups at any time point after surgery (Figure 4), total amount of fentanyl administered during the 12 hours after surgery was significantly (P = 0.04) lower for dogs in the acupuncture group than for dogs in the control group. Mean number of doses of buprenorphine and carprofen administered during the study period was not significantly different between groups.
Discussion
Results of the present study provided equivocal evidence that adjunct EAP might provide some mild benefit in regard to severity of postoperative pain in dogs undergoing hemilaminectomy because of acute thoracolumbar intervertebral disk disease. Specifically, we found that the total dose of fentanyl administered during the first 12 hours after surgery was significantly lower in dogs that received adjunct EAP than in dogs that received analgesics alone. However, dosages of analgesics administered from 12 through 72 hours after surgery did not differ between groups. In addition, pain score was significantly lower in the treatment group than in the control group 36 hours after surgery, but did not differ significantly between groups at any other time.
To facilitate pain evaluations in the present study, anesthetists were instructed to use the lowest possible dosage of fentanyl during surgery. In addition, all dogs received fentanyl at a dosage of 2.5 μg/kg/h for the first hour after surgery, as this has been shown to result in plasma fentanyl concentrations < 1 ng/mL13 and should have limited the effects of perioperative infusion rates on postoperative analgesia prior to the first postoperative pain evaluation.
The MPS system used in the present study was specifically developed for assessing severity of postoperative pain in dogs and has been validated for use in dogs.a Although the initial pain in the dogs of the present study was caused by compression of the nerve roots, irritation of the meninges, and inflammation,14 postoperative pain was mainly a result of muscle and tissue damage, the surgical incision, and inflammation.15,16
In the present study, analgesic treatment was adjusted on the basis of subjective pain assessments made by the attending clinician. In general, these clinicians were not aware of whether dogs were assigned to the treatment or control group, although they were aware that dogs were enrolled in a study of the effects of adjunct EAP. The use of subjective pain assessments to adjust the analgesic regimen reflected the clinical situation, but may have introduced some degree of bias into the study. In particular, we believe the attending clinicians may have been more likely to administer analgesics if they had any doubts about whether pain was present. One dog in the acupuncture group, for example, was treated with buprenorphine and carprofen for several days because of kyphosis, which was interpreted as a sign of pain. However, it was later discovered that the dog had had kyphosis ever since undergoing surgery 3 years earlier.
Fentanyl is a potent opioid agonist and binds strongly with μ-receptors,17 whereas buprenorphine has a high affinity for μ-receptors18 and potent antagonist effects on κ-receptors.19 On the other hand, the effects of EAP are mediated by μ, δ, κ, and orl-1 receptors,4 and it is unclear whether or to what extent the effects of EAP may be enhanced or blocked by administration of drugs that interact with the same receptors. Further studies into the interaction of these drugs with EAP as well as studies involving NSAIDS are required to evaluate these possibilities.
In the present study, heart rate was used as 1 parameter to assess pain. However, heart rate may increase with pain, stress, fear, or any unusual circumstances.20 In a previous study,21 only a weak association was found between commonly employed subjective and objective measures of pain in dogs, indicating that some of these measurements (eg, heart rate, respiratory rate, and blood pressure) do not predictably reflect the severity of postoperative pain in dogs. Moreover, various studies have reported disparate results regarding the relationship between heart rate and pain severity, and in human medicine, a positive correlation between heart rate and pain was found in women but not in men.22 In veterinary medicine, heart rate has often been found to be of little use as an indicator of pain. Therefore, clinicians should not rely too heavily on these variables when assessing the severity of postoperative pain in hospitalized dogs.20,21
Acupuncture points used in the present study were empirically chosen on the basis of recommendations from previous authors23–26 for treatment of pain and neurologic deficits; such recommendations have been largely grounded in traditional indications, positions on a specific meridian related to the site of surgery, or general analgesic functions. The value of these acupuncture points as analgesic points has been discussed previously.10,27,28
The present study had several important weaknesses. First, only 15 dogs met the inclusion criteria during the study period, and the small number of dogs made it difficult to identify differences between groups. Second, the same person who performed the EAP treatments assigned pain scores, introducing an unknown degree of bias. Third, dogs that received EAP had more contact time, and it was not possible to determine what effect this had on our findings without including additional control groups. Potentially, this additional contact time could have had a positive impact, in that dogs were not alone during this time and were in contact with a person. On the other hand, the EAP could have had a negative impact if dogs felt uncomfortable when manipulated for acupuncture treatments or needling itself. Further studies involving larger numbers of animals and strict blinding procedures are therefore required before any statements can be made about potential benefits of acupuncture or the lack thereof.
The selection of acupuncture points for the treatment of postoperative pain also needs further investigation. A protocol allowing placement of needles on only 1 side of the animal may be beneficial for patients in which pain might be increased by moving the animal from side to side. However, in a previous study29 examining the effects of unilateral versus bilateral stimulation of acupuncture points for analgesia in dogs, it was found that bilateral stimulation produced a better analgesic effect. Importantly, 2 dogs in the present study reacted strongly to EAP and to skin palpation after 2 and 3 treatments, and in these dogs, it was unclear whether hyperesthesia was present as a result of opioid treatment during or after surgery or EAP.30
An important confounding factor in the present study was that treatments administered by referring veterinarians prior to referral varied from one dog to the next. However, treatments administered by referring veterinarians were similar for the 2 groups, and all but one of the dogs had received only a single injection prior to referral.
Abbreviations
EAP | Electroacupuncture |
MPS | Multiparametric pain score |
References
- 1.
Ulett GA, Han S, Han JS. Electroacupuncture: mechanisms and clinical application. Biol Psychiatry 1998;44:129–138.
- 2.
Hab J-S, Wang Q. Mobilisation of specific neuropeptides by peripheral stimulation of identified frequencies. News Physiol Sci 1992;7:176–180.
- 3.
Hsieh CL, Kuo CC, Chen YS, et al. Analgesic effect of electric stimulation of peripheral nerves with different electric frequencies using the formalin test. Am J Chin Med 2000;28:291–299.
- 4.↑
Irnich D, Beyer A. Neurobiological mechanisms of acupuncture analgesia [in German] Schmerz 2002;16:93–102.
- 5.
Fukazawa Y, Maeda T, Hamabe W, et al. Activation of spinal anti-analgesic system following electro-acupuncture stimulation in rats. J Pharmacol Sci 1999;99:408–414.
- 6.
Kapatkin AS, Tomasic M, Beech J, et al. Effects of electrostimulated acupuncture on ground reaction forces and pain scores in dogs with chronic elbow joint arthritis. J Am Vet Med Assoc 2006;228:1350–1354.
- 7.
Lewith GT, White PJ, Pariente J. Investigating acupuncture using brain imaging techniques: the current state of play. Evid Based Complement Alternat Med 2005;2:315–319.
- 8.
Yang JW, Jeong SM, Seo KM, et al. Effects of corticosteroid and electroacupuncture on experimental spinal cord injury in dogs. J Vet Sci 2003;4:97–101.
- 9.
Jaeger GT, Larsen S, Soli N, et al. Double-blind, placebo-controlled trial of the pain-relieving effects of the implantation of gold beads into dogs with hip dysplasia. Vet Rec 2006;158:722–726.
- 10.
Yim YK, Lee H, Hong KE, et al. Electro-acupuncture at acupoint ST36 reduces inflammation and regulates immune activity in collagen-induced arthritic mice. Evid Based Complement Alternat Med 2006,3:1–7.
- 11.↑
Hayashi AM, Matera JM, Fonseca Pinto AC. Evaluation of electroacupuncture treatment for thoracolumbar disc disease in dogs. J Am Vet Med Assoc 2007;231:913–918.
- 12.↑
Wang RR, Tronnier V. Effect of acupuncture on pain management in patients before and after lumbar disc protrusion surgery—a randomized control study. Am J Chin Med 2000;28:25–33.
- 13.↑
Sano T, Nishimura R, Kanazawa H, et al. Pharmacokinetics of fentanyl after single intravenous injection and constant rate infusion in dogs. Vet Anaesth Analg 2006;33:266–273.
- 14.↑
Vandevelde M. Spinal cord compression. In: Bojrab MJ, ed. Pathophysiology of small animal surgery. Philadelphia: Lea & Febiger, 1981;228–232.
- 15.
Wheeler SJ, Sharp NJH. In: Small animal spinal disorders: diagnosis and surgery. 2nd ed. London: Elsevier Mosby, 2005;121–157.
- 16.
Rytz U, Bandscheibenerkrankungen A, Jaggy H. Altas und Lehrbuch der Kleintierneurologie, 2. überarbeitete Auflage 2007. Hannover, Germany: Schlütersche Verlagsgesellschaft mbH & Co, 2007;10.3:206–214.
- 17.↑
Flecknell PA, Waterman-Pearson A, Nolan M. Pain management in animals. In: Birchard SJ, Sherding RG, eds. Saunders manual of small animal practice. 2nd ed. Philadelphia: WB Saunders Co, 2000;21–52.
- 18.↑
Adams HR, Branson KR, Gross ME. Opioid agonists and antagonists. In: Adams HR, ed. Veterinary pharmacology and therapeutics. 8th ed. Ames, Iowa: Iowa State University Press, 2001;268–291.
- 19.↑
Kajiwara M, Aoki K, Ishii K, et al. Agonist and antagonist actions of buprenorphine on three types of opioid receptor in isolated preparations. Jpn J Pharmacol 1986;40:95–101.
- 20.↑
Holton LL, Scott EM, Nolan AM, et al. Relationship between physiological factors and clinical pain in dogs scored using a numerical rating scale. J Small Anim Pract 1998;39:469–474.
- 22.↑
Tousignant-Laflamme Y, Rainville P, Marchand S. Establishing a link between heart rate and pain in healthy subjects: a gender effect. J Pain 2005;6:341–347.
- 23.
Janssens Luc AA. Akupunkturbehandlungen von thorakalen und zervikalen Bandscheibenerkrankungen beim Kleintier. In: Schoen AM, ed. Akupunktur in der Tiermedizin, Lehrbuch und Atlas für die Klein-und Grosstiermedizin, 1. Munich: Elsevier GmbH, 2003;14:203–210.
- 24.
Still Jan. Analgesic effects of acupuncture in thoracolumbar disc disease in dogs. J Small Anim Pract 1989;30:298–301.
- 25.
Draehmpaehl D, Zohmann A. Die Punkteauswahl bei der Akupunktur. In: Akupunktur bei Hund und Katze, 2. unveränderte Auflage. Stuttgart, Germany: Enke, 1998;2.5:48–53/3.0:98, 115–139, 168, 170, 181, 188.
- 26.
Kaspar M, Knafl P, Zohmann A, et al. Schmerztherapie bei bestimmten Indikationen. In: Kasper M, Zohmann A, eds. Ganzheitliche Schmerztherapie für Hund und Katze. Stuttgart, Germany: Sonntag Verlag, 2007;254–257.
- 27.
Farber PL, Tachibana A, Campiglia HM. Increased pain threshold following electroacupuncture: analgesia is induced mainly in meridian acupuncture points. Acupunct Electrother Res 1997;22:109–117.
- 28.
Zhi LX. Randomized controlled study on the analgesic effect of superficial needling plus electrostimulation of sanyinjiao (SP6) for primary dysmenorrhea [in Chinese]. Zhen Ci Yan Jiu 2007;32:342–346.
- 29.↑
Cassu RN, Luna SP, Clark RM, et al. Electroacupuncture analgesia in dogs: is there a difference between uni and bi-lateral stimulation? Vet Anaesth Analg 2008;35:52–61.
Laboissière B. Validation statistique des grilles 4A-Vet d'évaluation de la douleur postoperatoire chez le chien et le chat. Doctoral thesis, Ecole Nationale Vétérinaire de Nantes, Nantes, France, 2006.
Suzhou Medical Appliance Factory, Suzhou Jiangsu, China.
AWQ–104L digital, Scarboroughs LTD, Somerset, England.
NCSS, Kaysville, Utah.
Appendix
Scoring system for assigning MPSs.a
Variable | Criteria | Score |
---|---|---|
General subjective evaluation | ||
No signs of pain | 0 | |
Signs of mild pain | 1 | |
Signs of moderate pain | 2 | |
Signs of severe pain | 3 | |
Signs of alterations in general behavior* | ||
No signs | 0 | |
1 sign | 1 | |
2–4 signs | 2 | |
5–7 signs | 3 | |
Interactive behavior | ||
Attentive and responds immediately to voice or petting | 0 | |
Responds cautiously but immediately | 1 | |
Does not respond immediately | 2 | |
Does not respond or responds aggressively | 3 | |
Increase in heart rate compared with baseline rate | ||
< 10% | 0 | |
11%–30% | 1 | |
31%–50% | 2 | |
> 50% | 3 | |
Response to palpation of the surgical wound | ||
No visible or audible response after 4 palpations | 0 | |
Reacts after the fourth palpation | 1 | |
Reacts after the second or third palpation | 2 | |
Reacts after the first palpation | 3 | |
Intensity of reaction to wound palpation | ||
No reaction | 0 | |
Slight reaction; avoids palpation | 1 | |
Turns head or vocalizes | 2 | |
Tries to fee or reacts aggressively | 3 |
Pain score was calculated as the sum of the scores for the 6 variables evaluated; potential scores ranged from 0 to 18. Dogs with a score ranging from 1 to 5 were considered to have signs of discomfort, dogs with a score ranging from 6 to 10 were considered to have moderate pain, and dogs with a score ranging from 11 to 18 were considered to have severe pain.
Signs that were assessed included alterations in respiratory rate or depth, whimpering, standing with an arched back, maintaining a guarded position, nervousness or signs of depression, lack of appetite, and looking at, biting, or licking the wound.