It is accepted that onychectomy in cats is a controversial and painful procedure.1–3 Attempts have been made to address these concerns not only with pharmacologic remedies but also in developing different surgical techniques (ie, laser onychectomy and tendonectomy). In fact, recent evidence suggests that in the early postoperative period, cats that have unilateral onychectomy are more reluctant to use their operated limb because of pain than are dogs recovering from surgery for a torn cranial cruciate ligament and medial meniscus4,5 because dogs had a smaller decrease in PVF 24 hours after surgery than did cats after onychectomy. It has also been determined that 12 days after unilateral onychectomy in cats, GRFs have not returned to preoperative values.4 However, in the long term, this lameness does resolve.1
An important component of evaluating a pharmaceutical or surgical technique with regards to quality of analgesia in veterinary medicine is patient assessment. The use of pain scales is widely accepted in human medicine and has been used for the evaluation of pain in cats.2,6–11 Some of the pitfalls of using pain scales in veterinary medicine are that the patient cannot verbally communicate, an observer is required to estimate the level of pain, and the evaluation process is subjective and dependent on observer experience.7,10 Several studies2,7,8,10,12–14 have attempted to use weight bearing, behavioral responses (ie, vocalization or posture), lameness, or response to palpation of the feet as an indication of pain. Nonetheless, with the exception of studies in which a palpometer was used to squeeze the paw2 and in which a thermal threshold device was used to assess antinociception,15,16 these assessments have some degree of subjectivity. In addition, the use of physiologic values (ie, heart rate, respiratory rate, temperature, and appetite), β-endorphin concentrations, and serum cortisol concentrations, although objective, have yielded inconsistent results in cats7,10,17,18 and correlate poorly with behavioral measures of pain in dogs.14,19 Pressure platform gait analysis, similar to force platform gait analysis, is an objective, accurate means of assessing normal and pathologic changes in gait and has recently been used in assessing limb function and pain in dogs and cats.1,4,5,20–22,a
Three major surgical techniques have been described for feline onychectomy: scalpel excision, guillotine-style shearing, and CO2 laser excision.9,23–26,b One of the major incentives toward development of laser onychectomy is the suggestion that it decreases the amount of postoperative pain and is associated with a lower rate of complications.9,25,27–30,b Although there are numerous claims in the veterinary literature of the ability of the CO2 laser to reduce postoperative pain, compared with other forms of onychectomy, such reports25,27 appear largely anecdotal.
The objective of this prospective study was to compare limb function as determined by use of pressure platform gait analysis, as an indication of discomfort, in cats after scalpel and laser onychectomy. Our null hypothesis was that there would be no significant difference in limb function between cats undergoing scalpel versus laser onychectomy.
Peak vertical force
Ground reaction force
Lascelles BDX, Findley K, Correa M, et al. Kinetic evaluation in normal cats using a pressure sensing walkway (abstr). Vet Surg 2005;34:E15.
Lapham B, Levy J, Hardie E, et al. Evaluation of laser onychectomy in the cat (abstr), in Proceedings. 19th Annu Meet Soc Laser Med 1999;73.
Vetrap, 3M Animal Care Products, Saint Paul, Minn.
AccuVet LX-20SP, AccuVet Laser Surgery, Norwood, Mass.
Torbugesic, Fort Dodge Animal Health, Fort Dodge, Iowa.
Tekscan Inc, South Boston, Mass.
Latitude CPx personal laptop, Dell Computer Corp, Round Rock, Tex.
I-scan, version 4.20, South Boston, Mass.
Vet-50 electronic scale, Detecto-Cardinal Scale, Webb City, Mo.
JMP, version 5.1.1, SAS Institute Inc, Cary, NC.
Romans CW, Conzemius MG, Horstman CL, et al. Use of pressure platform gait analysis in cats with and without bilateral onychectomy. Am J Vet Res 2004;65:1276–1278.
Carroll GL, Howe LB, Slater MR, et al. Evaluation of analgesia provided by postoperative administration of butorphanol to cats undergoing onychectomy. J Am Vet Med Assoc 1998;213:246–250.
Patronek GJ. Assessment of claims of short- and long-term complications associated with onychectomy in cats. J Am Vet Med Assoc 2001;219:932–937.
Romans CW, Gordon WJ, Robinson DA, et al. Effect of postoperative analgesic protocol on limb function following onychectomy in cats. J Am Vet Med Assoc 2005;227:89–93.
Horstman CL, Conzemius MG, Evans RB, et al. Assessing the efficacy of perioperative oral carprofen after cranial cruciate surgery using noninvasive, objective pressure platform gait analysis. Vet Surg 2004;33:286–292.
Grint NJ, Murison PJ, Coe RJ, et al. Assessment of the influence of surgical technique on postoperative pain and wound tenderness in cats following ovariohysterectomy. J Feline Med Surg 2006;8:15–21.
Gellasch KL, Kruse-Elliott KT, Osmond CS, et al. Comparison of transdermal administration of fentanyl versus intramuscular administration of butorphanol for analgesia after onychectomy in cats. J Am Vet Med Assoc 2002;220:1020–1024.
Carroll GL, Howe LB, Peterson KD. Analgesic efficacy of preoperative administration of meloxicam or butorphanol in onychectomized cats. J Am Vet Med Assoc 2005;226:913–919.
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Cambridge AJ, Tobias KM, Newberry RC, et al. Subjective and objective measurements of postoperative pain in cats. J Am Vet Med Assoc 2000;217:685–690.
Dobbins S, Brown NO, Shover FS. Comparison of the effects of buprenorphine, oxymorphone hydrochloride, and ketoprofen for postoperative analgesia after onychectomy or onychectomy and sterilization in cats. J Am Anim Hosp Assoc 2002;38:507–514.
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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.
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Smith JD, Allen SW, Quandt JE. Changes in cortisol concentration in response to stress and postoperative pain in clientowned cats and correlation with objective clinical variables. Am J Vet Res 1999;60:432–436.
Conzemius MG, Hill CM, Sammarco JL, et al. Correlation between subjective and objective measures used to determine severity of postoperative pain in dogs. J Am Vet Med Assoc 1997;210:1619–1622.
Besancon MF, Conzemius MG, Derrick TR, et al. Comparison of vertical forces in normal greyhounds between force platform and pressure walkway measurement systems. Vet Comp Orthop Traumatol 2003;16:153–157.
Besancon MF, Conzemius MG, Evans RB, et al. Distribution of vertical forces in the pads of Greyhounds and Labrador Retrievers during walking. Am J Vet Res 2004;65:1497–1501.
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Jankowski AJ, Brown DC, Duval J, et al. Comparison of effects of elective tenectomy or onychectomy in cats. J Am Vet Med Assoc 1998;213:370–373.
Yeon SC, Flanders JA, Scarlett JM, et al. Attitudes of owners regarding tendonectomy and onychectomy in cats. J Am Vet Med Assoc 2001;218:43–47.
Franks NJ, Boothe HW, Taylor L, et al. Evaluation of transdermal fentanyl patches for analgesia in cats undergoing onychectomy. J Am Vet Med Assoc 2000;217:1013–1020.
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Rizzo LB, Ritchey JW, Higbee RG, et al. Histologic comparison of skin biopsy specimens collected by use of carbon dioxide or 810-nm diode lasers from dogs. J Am Vet Med Assoc 2004;225:1562–1566.
Mison MB, Steficek B, Lavagnino M, et al. Comparison of the effects of the CO2 surgical laser and conventional surgical techniques on healing and wound tensile strength of skin flaps in the dog. Vet Surg 2003;32:153–160.
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