Content continues after advertisement

Onychectomy & Tendonectomy

Susanna Hinkle Schwartz, DVM, Cincinnati Animal Referral and Emergency Center, Cincinnati, Ohio

Orthopedics

|March 2011|Peer Reviewed

Sign in to Print/View PDF

Onychectomy & Tendonectomy

Profile - Definition

  • Onychectomy is a very controversial and emotional issue.
  • This article will not debate the ethics of onychectomy, but will provide information to decrease short- and long-term postoperative complications.

Signalment

  • Approximately 14.4 million1 cats undergo onychectomy each year; approximately 45% of owned cats are declawed.2
  • Onychectomy usually involves the front paws of indoor felines (6 months to 3 years of age).
  • Approximately 50% of cats are declawed at the time of ovariohysterectomy/castration.2

Indications

  • Scratching furniture and people
  • Other indications include paronychia (onychomycosis, follicular infection) or nail bed neoplasms (squamous cell carcinoma, melanoma, soft tissue sarcoma, osteosarcoma, mast cell tumors)3,4

Related Article: Analgesia for Declaw Patients

Medications

Preoperative Pain Management

  • Premedication 20 minutes prior to induction has been demonstrated to minimize stress, decrease dose of other anesthetic medications, and lessen postoperative pain.5
  • Common premedication protocols include:
    • Hydromorphone and diazepam (0.05–0.2 mg/kg each) or
    • Buprenorphine (0.01 mg/kg) and acepromazine (0.1 mg/kg) or
    • Buprenorphine (0.01 mg/kg) and diazepam (0.05–0.2 mg/kg).5
  • Cats are usually induced with:
    • Thiopental sodium (8–13 mg/kg) or
    • Propofol (2–4 mg/kg) or
    • Ketamine (5.5 mg/kg)/diazepam(0.275 mg/kg).5
  • Anesthesia is usually maintained with iso­flurane or sevoflurane in oxygen.
  • Preoperative meloxicam (0.3 mg/kg SC) given to cats 15 minutes after premedication and before anesthesia has been shown to result in improved analgesia for 24 hours without clinically relevant adverse effects.6 I use only a preoperative dose of meloxicam at 0.1 mg/kg SC or PO due to the new warning labels on Meloxicam (boehringer-ingelheim.com; see Extra-Label Use of Meloxicam on page 98 of the November issue for more information).
  • A bupivacaine 4-point ring nerve block of the radial, ulnar, and median nerves can aid in perioperative analgesia (1 mg/kg of a 0.75% solution7 or 0.1–0.2 mL/site of 0.5% bupivacaine, with a total dose not to exceed 5 mg/kg4).
  • A study performed by Curcio, et al, revealed no difference in discomfort or complication scores between control limbs and limbs receiving nerve blocks.7 In my opinion, a 4-point ring nerve block is minimally invasive and may contribute to multimodal pain management, with cats exhibiting less post­operative pain.

Related Article:Feline Onychectomy Complications: Prevention & Management

Sites for nerve blocks to the feline forepaw
(A) Extend the carpus and palpate the superficial digital flexor tendon along the palmar aspect of the paw. Block the median nerve with 0.15 mL bupivacaine just medial to the superficial digital flexor tendon. Similarly, block the palmar branches of the ulnar nerve along the lateral superficial digital flexor tendon.
(B) Block dorsal digital nerves II to V by inserting the needle from lateral to medial just distal to the carpus. Inject 0.2 mL of bupivacaine as the needle is withdrawn. Block dorsal digital nerve I at the articulation between metacarpal I and II with 0.1 mL of bupivacaine.

Reprinted from Fossum’s Small Animal Surgery, 3rd ed. Fossum TW, Hedlund CS, Hulse DA—Philadelphia: Mosby, 2007, Figure 18-44, with permission.

Postoperative Pain Management

  • While the patient is hospitalized, IV, IM, or SC injections of butorphanol, hydromorphone, oxymorphone, or buprenorphine are often administered.
  • In addition, the following medications, administered through routes other than injection, also provide postoperative analgesia:
    • Buprenorphine: 0.01 to 0.02 mg/kg PO sublingual Q 6 to 8 H8
    • Butorphanol: 0.5 to 1 mg/kg PO Q 6 to 8 H8
    • Fentanyl patches: 25 mcg patch applied transdermally8,9
  • Many studies show that cats are lame after surgery; analgesic medications should be dispensed to owners when the cat is discharged from the hospital.

Related Article: Chronic Pain Syndrome Feline Onychectomy

 Laser Onychectomy

A surgical laser may be used to cut the skin and soft tissues of the distal interphalangeal joint. Differences in discomfort and complications between groups of cats on which onychectomy was performed with the blade technique as opposed to carbon dioxide laser were not clinically relevant and were observed only 1 day after surgery.3

In this study, cats in the laser onychectomy group had improved limb function immediately after surgery compared to those in the blade onychectomy group,7 but the improved peak vertical force for the laser group was only observed on days 1 and 2 postoperatively, and was equal between groups by day 3. Holmberg and Brisson found that patients experienced discomfort at 10 days after onychectomy by either laser or blade, but laser onychectomy was associated with less lameness during the first 7 days after surgery.10

Advantages

  • Tourniquet unnecessary, as the laser vaporizes the tissue and seals the blood vessels and lymphatics11
  • Avoids tourniquet placement complications (neuropraxia of the radial nerve, tissue ischemia, muscle damage)
  • Bandages not absolutely necessary, although some surgeons place for 24 hours after surgery
  • Tissue necrosis subsequent to improper bandage placement does not occur1

Disadvantages

  • Procedure takes longer to complete11
  • Safety issues (eg, inhalation of irritating and noxious smoke, laser-induced combustion, and eye and skin burns)12
  • High cost of purchasing and maintaining laser and smoke evacuation systems
  • No studies evaluating long-term complications

Surgery

The 2 main surgical options to prevent scratching are tendonectomy and onychectomy.

Tendonectomy
Tendonectomy severs the deep digital flexor tendon to prevent the cat from flexing and extending the third phalanx. After tendonectomy, the claw remains retracted, but the nail continues to grow. Tendonectomy may be less painful than ony­­chectomy,13 but the owner must trim the cat’s nails. There are conflicting results of studies regarding owner satisfaction with tendonectomy versus onychectomy, and there may also be more complications after tendonectomy than onychectomy.14,15

  • Scrub the feet with a 2% chlorhexidine gluconate solution and saline (0.9% NaCl) or isopropyl alcohol; place the cat in lateral or dorsal recumbency.
  • Place a tourniquet distal to the elbow to minimize radial, median, and ulnar nerve damage.
  • Make a small incision on the palmar surface between the second and third phalanx.
  • Dissect under the shiny white tendon with mosquito hemostats or small scissors; transect and remove approximately 5 mm of the tendon.
  • Close the skin edges with tissue adhesive or sutures.

Onychectomy
Onychectomy involves removing the third phalanx either using a blade, guillotine-type nail clipper, or surgical laser (see Laser Onychectomy) to cut the supporting soft tissues.

The key to humane onychectomy is pre- and postoperative pain management, nerve blocks, tourniquet application below the elbow, careful soft tissue incisions, and being sure not to cut the pads.

Blade Onychectomy

  • Aseptic preparation is required for blade onychectomy.
  • Place a penrose drain tourniquet distal to the elbow joint.
  • Apply a towel clamp or hemostat to the claw; pull it forward to expose the cuticle-like skin around the nail bed.
  • Make a circumferential incision at the distal interphalangeal joint using an 11 or 15 blade (the most common blades for this procedure).
  • After the skin is incised, transect the common digital extensor tendon and dorsal ligaments.
  • Pass the blade around the contour of the third phalanx to transect the collateral ligaments, followed by the deep digital flexor tendon.
  • Incise the remaining soft tissues and joint capsule.
  • Take care to avoid cutting the digital paw pads as this is thought to result in increased pain.
  • Remove the entire third phalanx to prevent nail or bone regrowth.
  • Apply a few drops of surgical skin glue between the skin and squeeze closed, or place cruciate sutures (3–0, monofilament absorbable) taking care to avoid the digital pads.
  • Most surgeons bandage the paws after blade onychectomy.

Guillotine-Type Onychectomy

  • A guillotine-type nail clipper (Resco nail shears, teclausa.com/resco) can also be used to perform onychectomy. Aseptic preparation is required for this procedure.
  • Trim the nails to ease nail clipper placement and pass the digit through the nail clipper.
  • Grasp the claw with a towel clamp or hemostat and extend the claw.
  • Place the blade at the dorsal joint surface, then lift the claw to deviate the flexor process ventrally. The curved portion of the nail clipper is typically seated in the dorsal joint space between P2 and P3. Apply the blade of the nail clipper to the ventral surface, using the blade to push the distal edge of the digital pad proximally.
  • Be sure the digital pad is not in the blade and close the blade.
  • Inspect the third phalanx to ensure that the entire palmar process is removed. Typically, a small fragment of the flexor process of P3, the point at which the digital flexors attach, remains. The key issue is to ensure that the ungual crest (location of germinal tissue) has been completely removed to prevent nail regrowth.
  • Remove any remaining bone with a scalpel blade or scissors.
  • Close and bandage as in the blade declaw technique.4
  • Short-term complications are more common with the blade technique, but long-term complications are more common with guillotine-type nail clipper technique.4
  • A surgical laser may also be used to cut the skin and soft tissues of the distal interphalangeal joint.


Follow-Up

Patient Monitoring

  • Remove bandages 12 to 24 hours after declaw. If bleeding persists, replace bandages for an additional 1 to 3 days.
  • Instruct owners to use shredded paper rather than cat litter and restrict exercise for 1 to 2 weeks after surgery.
  • Recheck 2 weeks postoperatively to assess the declaw site and remove sutures if present.

Complications

  • The most common short-term postoperative complications are hemorrhage, pain, and soft tissue swelling.
  • The most common long-term postoperative complications are claw regrowth, protrusion
  • of the second phalanx, incisional dehiscence/infection/draining tract, and persistent lameness.
  • Uncommon long-term complications include radial nerve paralysis from tourniquet use; tissue necrosis from improper bandage placement; and rarely, cystitis,and asthma.1

In General

In my opinion, onychectomy is an appropriate surgery when performed correctly. The key is to complete the procedure in the most humane way possible, including preoperative pain medication; nerve blocks; tourniquet application below the elbow; careful soft tissue incisions, being sure not to cut the pads; and appropriate postoperative pain management. Laser is an appropriate method of performing onychectomy but has not been proven superior to the blade or guillotine-type nail clipper technique.

TX at a Glance

  • First, attempt to prevent scratching through behavioral training with positive reinforcement. Encourage owners to use scratching posts and nonsurgical treatments, such as Soft Paws (softpaws.com) vinyl caps (placed every 6 to 8 weeks; the cat's nails will still need to be trimmed on a regular basis).
  • Surgical options include onychectomy and tendonectomy.

ONYCHECTOMY & TENDONECTOMY • Susanna Hinkle Schwartz

References

1. Assessment of claims of short- and long-term complications associated with onychectomy in cats. Patronek GJ. JAVMA 219:932-937, 2001.
2. Dynamics of the dog and cat populations in a community. Patronek GJ, Beck AM, Glickman LT. JAVMA 210:637-642, 1997.
3. Use of carbon dioxide laser for onychectomy in cats. Mison MB, Bohart GH, Walshaw R, et al. JAVMA 221:651-653, 2002.
4. Surgery of the footpads and digits. Fossum TW. In Fossum TW (ed) Small Animal Surgery, 3rd ed—St. Louis: Mosby, 2002, p 202.
5. Drugs used for preanesthetic medications. Muir WW, Hubbell JA, Skarda RT, et al. In Schrefer JA (ed): Handbook of Veterinary Anesthesia, 3rd ed—St. Louis: Mosby, 2000, pp 19-40, 314-331.
6. Analgesic efficacy of preoperative administration of meloxicam or butorphanol in onychectomized cats. Carroll GL, Howe LB, Peterson KD. JAVMA 226:913-919, 2005.
7. Evaluation of postoperative pain and complications after forelimb onychectomy in cats receiving buprenorphine alone or with bupivacaine administered as a four-point regional nerve block. Curcio K, Bidwell LA, Bohart GV, et al. JAVMA 228:65-68, 2006.
8. Plumb’s Veterinary Drug Handbook, 6th ed—Stockholm WI: Blackwell, 2008, pp 112-114, 116-119, 379-382.
9. Effect of postoperative analgesic protocol on limb function following onychectomy in cats. Romans CW, Gordon WJ, Robinson DA, et al. JAVMA 227:89-93, 2005.
10. A prospective comparison of postoperative morbidity associated with the use of scalpel blades and lasers for onychectomy in cats. Holmbers DL, Brisson BA. Can Vet J 47:162-163, 2006.
11. Evaluation of short-term limb function following unilateral carbon dioxide laser or scalpel onychectomy in cats. Robinson DA, Romans CW, Gordon-Evans WJ, et al. JAVMA 230:353-358, 2007.
12. The basics of surgical lasers. Bartels KE. Western Veterinary Conference 2009.
13. Deep digital flexor tendonectomy: An alternative to amputation onychectomy for declawing cats. Rife JN. JAAHA 24:73-76, 1998.
14. Attitudes of owners regarding tendonectomy and onychectomy in cats. Yeon SC, Flanders JA, Scarlett JM, et al. JAVMA 218:43-47, 2001.
15. Comparison of effects of elective tenectomy or onychectomy in cats. Jankowski AJ, Brown DC, Duval J, et al. JAVMA 213:370-373, 1998.

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Clinician's Brief may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.

Podcasts

Clinician's Brief:
The Podcast

Listen as host Alyssa Watson, DVM, talks with the authors of your favorite Clinician’s Brief articles. Dig deeper and explore the conversations behind the content here.
Clinician's Brief provides relevant diagnostic and treatment information for small animal practitioners. It has been ranked the #1 most essential publication by small animal veterinarians for 9 years.*

*2007-2017 PERQ and Essential Media Studies

© Educational Concepts, L.L.C. dba Brief Media ™ All Rights Reserved. Privacy Policy (Updated 05/08/2018) Acceptable Use Policy (Updated 11/22/2021)