Studies Pertaining to Declawing (Annotated)

Adapted from Patronek, Studies Pertaining to Onychectomy, 2001

Additional studies not cited in the original noted in color; additions and comments by Jean Hofve, DVM

Study	No. Cats	Time	Relevant Outcomes	Description of Study, Sample and Major Findings	Comments
Benson et al., 1991	18		Post-operative plasma catecholamine levels	Randomized experiment. 24 cats were randomized to either no surgery, or onychectomy with intravenous morphine, xylazine, or salicylate. Onychectomy was associated with increased postoperative plasma catecholamines that were decreased by morphine and xylazine but not saline.	The conclusion was that pain is very hard to detect and quantify in cats, and that pain in animals is frequently treated inadequately.
Bennett, Houpt and Erb, 1988	25	2 years	Reason for declawing, desirable and undesirable behaviors up to two years post surgery	Retrospective survey of a sample of 25 intact and 25 declawed cats in private practice and a medical record review of 24 cats from a behavior referral service in a teaching hospital. Similar proportions of intact and declawed cats were reported biting and house soiling. Reported that 1 (4%) cat began to defecate out of box and 3 (12%) began to bite after onychectomy. 60/217 (27.6%) private practice cats were simultaneously declawed. A larger proportion of cats in the referral population were declawed.	Major reason for declaw: damage to furniture (not stated whether this was a current or merely potential problem) 16% developed behavior problems; 27.6% were declawed as a package deal. More declawed (55%) than intact (45%) cats were referred to the vet teaching hospital for behavior problems.
Borchelt and Voith, 1987	252		Aggressive behavior	Retrospective survey of 887 cat owners from private practices. Clients were asked to fill out a survey on the incidence of aggressive behaviors in their cats. Similar proportions (60/252, 23.8%) of declawed vs. (168/613, 27.4%) intact cats bit family members; 2.3% of each seriously enough for medical attention	Declawed cats were slightly more likely to bite.
Carroll et al., 1998	63	72 hrs	Pain, lameness appetite and personality, 24, 48, and 72 hrs post surgery	Randomized controlled trial in a teaching hospital, DVM student surgeons. Post-operative analgesia evaluated in 63 cats undergoing elective onychectomy. 42 received butorphanol postoperatively and orally for two days after surgery. Post-operative analgesia and recovery scores better in butorphanol treated group. Owner-reported appetite and lameness scores were better in the butorphanol treated group on day 1; no differences were observed in owner evaluations by day 2.	Only half of cats being declawed at a teaching hospital received any pain medication at all.
Cambridge et al., 2000	6 & 6	36 hrs	Pain, endorphins, vital signs up to 36 hrs post-surgery	Randomized controlled trial in a teaching hospital. Temperature, pulse, respiration, pain, plasma ß-endorphins, and cortisol were assessed in six cats admitted for elective onychectomy, six for elective tendonectomy and compared with six bandaged, non-surgical controls. Only visual analogue scores for pain and response to palpation scores differed significantly between control and surgical groups.	Only half of cats being declawed received pain medication. The conclusion was that pain is very hard to detect and quantify in cats.
Chomel et al. 2004			Bartonella and other zoonotic infections	Bartonella (“cat scratch disease”) is primarily vector-borne (fleas and biting flies).	Cat scratches rarely result in Bartonella infection.
Clancy et al. 2003	183		Survey of indoor vs outdoor cats	There was no significant (P = 0.3) difference in outdoor access with regard to onychectomy status. Outdoor access was given to 9 of 29 (31%) declawed cats and 63 of 154 (41%) nondeclawed cats.	Owners of declawed cats let them roam outdoors at the same rate as non-declawed cats.
Cooper et al. 2005	2		New complication of declaw noted	Two cats presented with bilateral flexor tendon contracture following onychectomy. This previously unreported complication proved to be painful and debilitating. Deep digital flexor tenectomy successfully resolved the problem. Twelve months after surgery, the first cat remains free of complications. The second cat recovered full limb function, but died of unrelated causes.	First published report of tendon contracture after declaw (at 3 and 6 months post-op), although authors suggest that prior cases may have been categorized in earlier studies as “lameness.”
Curcio et al. 2006	20	168 hours (7 days)	Evaluation of butorphanol vs. bupivicane nerve block	To evaluate signs of postoperative pain and complications after forelimb onychectomy in cats receiving buprenorphine alone or with bupivacaine administered as a 4-point regional nerve block.	Bupivacaine nerve blocks did not decrease discomfort or complication scores in cats undergoing forelimb onychectomy.
Dobbins et al. 2002	68		Comparison of analgesics	Compared buprenorphine, carprofen, oxymorphone and ketoprofen in 68 cats: 20 onychectomy alone; 20 onychectomy and neuter; 28 onychectomy and spay. Buprenorphine demonstrated the highest efficacy with the lowest cumulative pain scores and serum cortisol levels.	Buprenorphine had the best efficacy.
Franks et al., 2000	45	40 hrs	Recovery, vital signs, pain, and lameness, up to 40 hours post-onychectomy	Randomized controlled trial in a teaching hospital, DVM student surgeons. Cats undergoing elective onychectomy were randomly assigned to be treated with transdermal fentanyl patches or butorphanol. Cats treated with fentanyl patches had better recovery scores at two of four evaluation times, lower sedation scores at two of eight evaluation times, and lower pain scores at six of eight evaluation times. There were no differences in forelimb pressure between the groups, but there were differences between pre and postoperative values.	Test of pain meds for declawing. Lameness scores varied pre- and post-surgery for individual cats though not between groups.
Gaynor J. 2005			Chronic pain syndrome of onychectomy	Feline patients who have had onychectomy (declaw) may experience chronic pain. Owners of such cats usually report one of several concerns, the most common of which is fear that the cat is still in pain, especially in the fore paws, because it seems to walk very lightly on those feet, as if walking on nails or glass. Another common concern is behavioral changes, which may include decreased activity, decreased appetite, or increased aggression. The inciting cause for these presentations within days to months to years is usually the lack of adequate acute pain control in the immediate postoperative period.	Chronic pain in declawed cats acknowledged; author suggests that it may not be noticed for long periods. Increased aggression may be one result. Options given for prevention and treatment.
Gellasch et al., 2002	22	48 hrs.	Comparison of fentanyl patch vs butorphanol	Our data did not reveal a difference in pain relief between administration of TDF and butorphanol. Plasma cortisol concentrations were not different between groups. Fentanyl appeared to provide equivalent analgesia to butorphanol in cats undergoing onychectomy. The primary advantage of using a TDF patch is that repeated injections are not required.	Butorphanol given q4h for 12 hours only. Assessment by cortisol measurement and pain scores.
Gordon-Evans, 2005	n/a		Pain management options for post-declaw analgesia	Interpreting behavior in cats to assess pain has been notoriously difficult. And interpreting objective physiological parameters has not been consistent because of confounding factors such as stress or drug effects. Additionally, veterinarians perform several different onychectomy techniques at very different skill levels. And because of the ethical considerations that surround this procedure, providing both the owner and the cat with effective perioperative and postoperative analgesic options is critical. In this article, we offer guidance on what drug or combination of drugs to use, concentrating mainly on postoperative analgesia.	According to this (relatively recent) study, 14 million cats per year get declawed. Inconsistency in surgical skills noted. Good review of pain management options.
Greenfield, et al. 2004	n/a		Skills needed by new grads for small animal practice	The present study was designed to obtain input from private veterinary practitioners from around the United States concerning the skills and knowledge new graduates should have and the procedures they should be able to perform when entering small animal practice.	Onychectomy ranked #14, ahead of cystocentesis, FNA, bandaging, biopsy, and CPR, and was estimated to be used 1 or more times per week in general practice.

Hellyer, 2002	n/a		Discussion of pain management	The current state of pain management in dogs and cats is uneven at best, ranging from the excellent use of pain control techniques by some veterinarians to the complete disregard of pain control by others. Over the last decade, incredible gains have been made in our understanding and treatment of pain in animals, yet it is estimated that few animals under veterinary care receive adequate pain control. Considering what is currently known about pain and the resources available to veterinarians, an important question remains: Why do so many dogs and cats suffer needlessly? This article will provide a brief overview of some of the exciting advances that have occurred in the treatment of pain in dogs and cats as well as some of the existing barriers that hinder the treatment of pain by veterinarians.	Discusses lack of consistency in pain management from one vet to the next; and vets’ attitudes about it. Author indicates that, overall, adequate pain control is the exception rather than the rule.
Holmberg, et al. 2006	9	10 days	Compare laser to scalpel technique	This study compared patient discomfort for 10 d following feline onychectomies performed using a CO2 surgical laser versus a scalpel blade. Both techniques appeared to result in discomfort of a similar duration, although the laser caused significantly less lameness than blade excision during the first 7 d.	No difference in lameness between laser and scalpel beyond the first couple of days after surgery.
Jankowski et al., 1998	24	180 days	Short and long term complications, owner satisfaction in tendonectomy vs. onychectomy	Prospective clinical study using teaching hospital and private practice clients. 13/18 of the elective onychectomies were performed by DVM student surgeons. 4/17 (24%) cats had short-term postoperative complications including, two hemorrhage, one infection, and one change in behavior. Mean and median days until walking normally were 6.3 and 7 days, respectively, range 1–21 days. One cat did not walk normally for 180 days. Sixteen (88.9%) owners were satisfied.	High complication rate (24%) blamed on student surgeons. Owner satisfaction with tendonectomy lower than with declaw. Cites literature that says up to half of declawed cats suffer complications. (Cites Martinez, Tobias, Lin, Benson) Two tendonectomized cats were later declawed. 24/38 cats were declawed along with spaying or neutering (63%). 6/38 (16%) cats were given post-op pain meds.
Landsberg, 1991	276		Owner satisfaction, short and long term complications	Retrospective written survey of private practice clients. 70% of cats were declawed between 0.5 and 12 months of age, and 69% at the time of neutering. 266 (96%) owners had a positive attitude towards declawing. Primary reason (86%) was household damage, and second (29%) was to reduce injuries to people. Owners reported that 94 (34%) cats had discomfort post-surgically, primarily tenderness (78%). 157/233 (67%) recovered fully within three days, and 96% within two weeks. Cats done > age 1 yr had more post-surgical discomfort; 102/246 (41%) were still allowed outdoors. One (0.4%) cat had difficulty bearing weight for at least four months, and another (0.4%) developed a house soiling problem. Ten (4%) reported a possible increase in biting or harder biting, but these owners still remained positive about the surgery.	70% cats were declawed at less than 1 year of age; ~70% of those were declawed at the same time as spaying/neutering. Many medical and behavioral complications noted; 34% were obviously painful post-op; 33% were still painful more than 3 days post-op. Older cats were more painful. 11 cats (4%) developed or had worsened behavior problems post-op. Only 4% of owners stated that they would not have kept the cat if not declawed (compared to veterinarians’ estimates of 10-70% of clients likely to relinquish.)
Landsberg, 1991	N/A		Veterinarians’ attitudes, estimated complication	Retrospective mail survey of veterinarians. 320/400 returned questionnaires. 196/250 (78.4%) did not advocate declawing and only did it on request. 104/221(47%) veterinarians’ recollections indicated no problems, 55 (24.9%) reported nail regrowth, and 22 (9.9%) reported additional long term problems. Out of an estimated total of 120,000 cats declawed, this was extrapolated to a complication rate of 1/6,000 cats.	Memory-based survey. 22% of surveyed veterinarians actively advocated declawing, though most (78%) would declaw on request. 34.8% of vets reported long-term complications. “Extrapolated” complication rate far lower than found in actual post-op studies.
Lascelles, et al. 2004	6		Evaluation of butorphanol for pain control after declawing	Concluded that butorphanol provided only 90 minutes of analgesia no matter how much was given	Butorphanol is a poor choice for declaw analgesia.
Levy et al., 1999 (Abstract)	20	48 hours	Bleeding, pain, healing, behavior, plasma cortisol, urine cortisol:creatinine ratios up to 24 hours after surgery	Clinical trial. 40 cats were assigned to either non-surgical control (20) or onychectomy via laser (10) or blade.(10) Complication rates, behavioral changes, plasma cortisol, and urine cortisol:creatinine ratios were evaluated up to 48 hours post-surgery. Complication rates were generally higher for the laser declaw group in the first two days, but were equivalent thereafter. Negative behavioral changes were more pronounced in the blade declaw group for two days, with less play and willingness to use their paws. Blood and urine cortisol were increased more in the blade declaw group for 24 hours.	Assessment of laser declawing; pain was worse from laser than scalpel in immediate post-op period (only tracked for 48 hours).
Lin et al., 1993	27	2 wks	Plasma catecholamine levels	Randomized experiment. 27 cats were randomly assigned to one of four anesthetic regimens involving a dissociative/tranquilizer combination plus either butorphanol or oxymorphone. Onychectomy performed on one forefoot without analgesics, and catecholamine levels were measured. Protocol was repeated the following week using the other forefoot, plus cats received either butorphanol or oxymorphone. Addition of butorphanol decreased norepinephrine levels immediately after surgery; oxymorphone resulted in lower epinephrine values four hours after surgery.	Each of 16 adult purpose-bred cats (weighing up to 13 lbs.) was declawed only on one paw. The conclusion was that pain is very hard to detect and quantify in cats.
Martinez et al., 1993	167	6 mo.	Complications seven days and six months post-surgery	Prospective clinical study in a teaching hospital, DVM student surgeons. Two techniques for onychectomy and two adhesives for wound closure were compared. 167/252 (66%) cats returned for both one week and six-month clinician rechecks. Lameness occurred more frequently in cats with disarticulation amputation (14/87, 16%) than in cats with bony amputation (4/80, 5%), possibly due to greater soft tissue trauma. Dehiscence occurred in 22% and 12% of cats, respectively. Lameness resolved within six months.	Compared 2 techniques for declawing. Claw regrowth was seen in 1 cat at 6 months post-op (case reports indicate that regrowth can occur more up to 15 years later). 19% incidence of lameness; 34% wound dehiscence.
Mison et al. 2002	20	7 days	Compare laser to scalpel technique	Differences in discomfort and complications between groups treated via scalpel versus CO2 laser were not clinically relevant and were only observed 1 day after surgery.	There were big differences between treatment groups on day 1 but author states they “did not seem relevant.”
Morgan and Houpt, 1989	24		Behavior problems and owner attitudes	Cross sectional internet survey, convenience sample of 60 owners; 24/ 122 (19.6%) cats were declawed. Complication rates after declawing were not reported. Declawed cats showed more jumping on tables (~75%) than intact cats (~53%) and more house soiling (~25%) than intact cats (~15%) but this latter difference was not significant. Twenty percent of all respondents reacted negatively to the question about declawing.	In The Domestic Cat: The Biology of Its Behavior, lack of ability to climb vs. the cat’s strong instinct to climb may account for the increase in jumping on tables and counters. Mentions that in 1998 the Canadian Veterinary Association stated that behavior problems may increase and recommended against declawing.
Patronek et al., 1996	476		Behavior problems, risk of relinquishment	Case-control study of owned and relinquished cats involving a random digit dial survey of cat owners. Prevalence of declawing was 45% (476/1056) in the owned cat population. In the univariate analysis, declawed cats were at decreased risk of relinquishment compared to non-declawed cats (OR=0.63; 95% CI 0.45-0.87). After adjustment in a multivariate model, declawed cats were at an increased risk of relinquishment (OR=1.89;1.00-3.58); this reversal made the effect of declawing difficult to interpret. Among 218 cats relinquished to a shelter, more (44/84; 52.4%) declawed cats than non-declawed cats (39/134; 29.1%) were reported by owners to have inappropriate elimination (p=0.022).	Odds of being relinquish for declawed cats almost double that of intact cats (odds ratio 1:89 to 1.00, range 1:00 — equal odds — up to 3.58–almost 4 times as likely).Inappropriate elimination was twice as common in declawed (52.4%) as intact cats (29.1%).
Patronek, 1995	476		Survey of dog and cat populations	Found that 45% of 1,056 cats in a single community were declawed.	This actual count of 45% is a much larger number than other estimates have suggested.
Pollari and Bonnett, 1996	534	13 mo.	Prevalence of complications of elective surgeries	Computer records of short-term complications (within three weeks) of all elective surgeries performed at five private practices over 5–13 months. 450/851 (52.9%) feline sterilizations had onychectomy performed at the same time. Recording of complications in the computerized records was inconsistent.	Concluded that records are inaccurate, and computerized records are even worse than paper records. Complication rate for declaw alone was 2/50 (4%).
Pollari et al., 1996	146		Prevalence of complications of elective surgeries	Computerized abstracts of medical records and sub-sample of written medical records at a teaching hospital. 287/1313 (21.8%) of cats sterilized were simultaneously declawed. Complications detected for 2/146 (1.4%) cats that underwent elective onychectomy alone during prior eight yrs. Specific complications were not reported.	All elective procedures performed on cats over 8 years of age were declaws. Simultaneous s/n and declaw frequently performed.
Ringwood, et al. 2000	1		Ring block technique	How to improve anesthesia for a cat undergoing declaw surgery using local nerve blocks	A variety of surgical techniques for declawing have been described, all of which result in substantial signs of pain in cats.
Robinson et al. 2007	20	12 days	Compare laser to scalpel technique	To evaluate short-term postoperative forelimb function after scalpel and laser. All cats were treated with butorphanol tartratee (0.4 mg/kg, IM) prior to discontinuation of anesthesia and every 4 hours for the first 24 hours following surgery.Relevance—Cats had improved limb function immediately after unilateral laser onychectomy, compared with onychectomy with a scalpel, tourniquet, and bandage. This improved limb function may result from decreased pain during the 48 hours following unilateral laser onychectomy.	Despite being roundly criticized by Hornstein et al. in JAVMA for using inadequate analgesia in their 2005 study, and despite their own study showing the need for long-term (12+ days) of analgesia, in their next study the same researchers again provided totally inadequate analgesia and were again criticized in JAVMA, this time by Hofve.
Romans et al. 2004	26	6 mo.	To determine vertical forces in cats that had or had not undergone bilateral forelimb onychectomy.	Gait analysis was successfully performed in cats with a pressure platform walkway. The absence of differences in PVF and VI between the 2 groups of cats suggests that bilateral forelimb onychectomy did not result in altered vertical forces measured more than 6 months after surgery in cats.	Vertical forces were similar in non-declawed cats and cats declawed more than 6 months earlier. More weght on forelimbs in both groups at 6 months than immediate post-op period.
Romans,et al. 2005	27	12 days	Assessment of analgesia on post-operative limb function	To evaluate the analgesic effects of topical administration of bupivacaine, IM administration of butorphanol, and transdermal administration of fentanyl in cats undergoing onychectomy. Results suggest that limb function following onychectomy is significantly better in cats treated with fentanyl transdermally or butorphanol IM than in cats treated with bupivacaine topically. Regardless of the analgesic regimen, limb function was still significantly reduced 12 days after surgery, suggesting that long-term analgesic treatment is needed for cats undergoing onychectomy.	Although they didn’t follow their own advice in the next study, the authors recommended pain management for at least 12 days post-op. In practice, Very few cats receive pain meds for more than 3 days.
Smith et al. 1996	50		Assessment of post-op pain and correlation with clinical indicators	Cats that did not receive analgesics had higher cortisol concentration than did cats without surgery and cats that received butorphanol after surgery. Systolic blood pressure measured by ultrasonic Doppler was found to be predictive of cortisol concentration, using a multiple linear regression model. CONCLUSIONS: Cortisol concentration increased in response to surgical stress and pain, and this increase was diminished by use of butorphanol. CLINICAL RELEVANCE: Systolic blood pressure was the best clinical predictor of postoperative pain.	An attempt to find an objective indicator for post-op pain using declawing as the pain-producing procedure. Study used butorphanol, later shown to be a poor choice for pain in cats. Found that blood pressure was the most reliable indicator.
Swiderski, 2002	n/a			Onychectomy and its alternatives are often sought by owners to provide permanent alleviation of scratching behaviors in cats. These alternatives include behavioral modification, nail caps, and deep digital flexor tendonectomy. Although surgical options are commonly performed, they are controversial and have potential complications. Our role as veterinarians is to educate clients to allow them to make the best decision for themselves and their pets. The purpose of this article is to provide an objective review of the positive and negative aspects of onychectomy, describe and discuss alternatives to onychectomy, and review the specific surgical techniques.	There are many non-surgical, humane alternatives to declawing.
Tobias, 1994	163	54 d; 96 mo.	Prevalence of post-operative complications, pain, behavior problems	Retrospective review of medical records at a teaching hospital, DVM student surgeons. 163 medical records of cats undergoing elective onychectomy reviewed for post-operative complications. Follow-up was by exam and phone. Early complication rate 82.5% for blade and 51.5% for shear onychectomy. 61 cats were painful 1-42 days post-operatively (median two days) and 43 cats showed lameness that persisted from 1-54 days. Long term follow up was done for 121/163 cats; one cat showed prolonged lameness (96 months). High complication rate attributed to student surgeons.	50% of cats had one or more medical complications immediately after surgery while still in the hospital; 19.8% developed complications after release.
Tobias, et al., 2006	52		Efficacy of pain relievers	Evaluated 4 pain management techniques. The conclusion was that butorphanol was a poor choice that provided reliable pain relief for, at best, 2 hours.	Butorphanol ineffective for pain control.
Wagner, 2000			Survey of analgesia and anesthesia in private practice	For onychectomy: No analgesia (88, 30%), some analgesia (205, 70%); of those who used any analgesia, 141 (69%) used butorphanol, 10 used morphine, 16 used meperidine, 16 used ketoprofen, and 29 used other drugs (aspirin, flunixin, etodolac, buprenorphine, meperidine, oxymorphone, fentanyl, fentanyl patch, codeine and acetominophen, medetomidine, corticosteroids, diazepam, and acepromazine [also bupivacaine and lidocaine for cat onychectomy]).	Survey found that 30% used no pain meds at all; and of the other 70%, the majority used butorphanol (now known to be a poor choice). NOTE: since I know Dr. Wagner, I emailed her and asked if she thinks that the situation is better now. She said that pain management is now routinely taught in vet schools. She believes there has been significant improvement in analgesia over the years; however, there have not been any more recent surveys to prove it.
Winkler et al., 1997	18		Pain in the immediate post-operative period	Clinical trial in a teaching hospital, DVM student surgeons. 18 cats that underwent elective onychectomy were alternately assigned to treatment groups and evaluated blindly to determine if wound irrigation with bupivicaine decreased pain in immediate post-op period. Bupivicaine treated patients had higher pain scores than saline treated controls at two hrs but not three hours post-op.	No realistic pain management was provided for any cat, and the experimental treatment with bupivicaine actually seemed to make pain worse immediately post-op.
Yeon et al., 2001	39	2 mo. to 5 yr	Recovery, short and long term complications, owner attitudes	Retrospective phone follow-up of teaching hospital clients, DVM student surgeons. 39/98 owners whose cats underwent elective onychectomy or tendonectomy were contacted two months to five years (median 11.5 months) after surgery. 17 (44%) of declawed cats returned to normal within three days, 35 (90%) within two weeks. 31 (80%) had more than one medical complication. 13 (33%) developed at least one behavior problem. 6 (15.4%) would not use the litter box and 7 (17.9%) had an increase in biting habits or intensity. 34 (87%) owners had a positive attitude and 2 (5.1%) had a negative attitude towards declawing.	Longest-term study to date, survey indicated that 80% of cats experienced medical complications, and less than half had returned to “normal” within 3 days. 33% developed behavior problems after surgery (18% biting and 15% house-soiling)

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