Histologic comparison of canine skin biopsies collected using monopolar electrosurgery, CO2 laser, radiowave radiosurgery, skin biopsy punch, and scalpel

OBJECTIVE: To compare the histologic appearance of canine skin biopsies collected by use of a scalpel, skin biopsy punch, monopolar electrosurgery, CO2 laser, and radio wave radiosurgery in fully rectified wave form (RWRS). STUDY DESIGN: Experimental, randomized design. ANIMALS: Healthy adult grayhounds (n=4). METHODS: Skin biopsies were collected using 5 techniques. Cut margins of biopsy specimens and adjacent peripheral skin were evaluated using light microscopy to compare penetration of the dermis by tissue carbonization (char). RESULTS: No char occurred in skin specimens collected by biopsy punch and scalpel. Char penetration occurred in all specimens collected by electrosurgery, CO2 laser, and RWRS. Mean char penetration in skin biopsies collected by RWRS (0.158 mm) was significantly less than for monopolar electrosurgery (0.223 mm) and CO2 laser (0.215 mm). Mean char penetration in adjacent peripheral skin surrounding biopsies collected by RWRS (0.171 mm) was significantly less than monopolar electrosurgery (0.255 mm) but not less than CO2 laser (0.215 mm, P<.07). CONCLUSIONS: RWRS (blended waves in cut-coagulate mode) caused less lateral thermal damage to canine skin biopsies than monopolar electrosurgery and CO2 laser and less lateral thermal injury to peripheral skin than monopolar electrosurgery. CLINICAL RELEVANCE: Excision of canine skin biopsies with heat-generating devices may not allow reliable histologic interpretation, particularly when assessing margins of small biopsy specimens. RWRS may be less traumatic to canine skin than monopolar electrosurgery and CO2 laser when used to make incisions.     

Histologic comparison of skin biopsy specimens collected by use of carbon dioxide or 810-nm diode lasers from dogs

OBJECTIVE: To compare histologic artifacts caused by carbon dioxide (CO2) or 810-nm diode surgical lasers used to obtain small biopsy specimens of skin from healthy dogs. DESIGN: Prospective study. ANIMALS: 4 dogs. PROCEDURE: 21 skin biopsy specimens were collected from each dog. Three biopsy specimens were obtained with a CO2 or an 810-nm diode laser at 3 operating settings each, and 3 biopsy specimens were obtained with a 6-mm biopsy punch instrument (controls). After processing, biopsy specimens were examined for artifacts related to laser-tissue interactions. Microscopically visible char was measured from the lateral edge of each specimen obtained with a laser. RESULTS: There were no significant differences among mean char distances in biopsy specimens obtained with the CO2 laser at various settings. Mean char distance was significantly greater in all skin biopsy specimens obtained with the diode laser, compared with those obtained with the CO2 laser. Mean char distance was significantly greater in biopsy specimens obtained with the 810-nm diode laser at high power, compared with biopsy specimens obtained with the 810-nm diode laser at low power. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the CO2 laser caused less thermal injury at margins of skin biopsy specimens; therefore, if a surgical laser is used for removal of cutaneous masses or to obtain skin biopsy specimens, use of the CO2 laser is recommended. Veterinarians performing a biopsy by using a surgical laser should be aware that laser-induced artifacts may render small biopsy specimens useless for providing accurate histologic diagnosis.     

Thermal injury and wound healing of the endometrium subsequent to minimally invasive transendoscopic use of Nd:YAG-laser-and electrosurgery in horses

Transendoscopic thermal preparation techniques like laser- or electrosurgery have proved to be most reliable for minimal invasive intrauterine surgery during operative hysteroscopy in mares. To determine the effect of Nd:YAG laser surgery on the endometrium and the complete uterine wall compared with electrosurgery, standard lesions were obtained by transendoscopic monopolar electrosurgery (loop electrode, cutting blade) and Nd:YAG laser surgery (contact, bare fibre, 25 Watt, exposure time four seconds, non contact, 80 Watt, exposure time four seconds) in five healthy mares on days d 0, 7, 14, 18 and 21. The gross effects were controlled endoscopically before the consecutive lesions were set. Following the last diathermic endometrial irritation, hysterectomy was performed under general anaesthesia. Recovery of the mares was uneventful. Specimens from the lesions were collected after dis-section of the uterus, fixed in formalin, routinely embedded and stained with H. E. for histological evaluation. The different energy forms caused tissue alterations of comparable quality but differing in degree. Most intensive peripheral hyperemia and tissue edema occurred on postoperative days three to seven. Non contact laser irradiation initiated maximal amount of fibrinous exudate. Lesions created with a loop electrode were superficial only and did only affect the endometrium. Preparation with an electrosurgical cutting blade or a laser bare fibre resulted in craterlike lesions lined by carbonisation and did involve deeper layers of the myometrium. The lesions caused by non contact laser irradiation affected all layers of the uterine wall. Three weeks postoperatively, reepithelization of the luminal epithelium was completed. The depth of thermal injury and coagulative necrosis, inflammatory reactions and scar formation was greater in lesions created by laser application compared with those set with a loop electrode at power densities comparable to those usually achieved at hysteroscopic surgery. The results suggest that an electrosurgical loop designed for operative hysteroscopy may be a reliable tool for diathermic resection of pathological endometrial structures like uterine cysts characterized by minimal thermal injuries and a short period of reconvalescence. Non contact laser irradiation may result in deep thermal injuries with the risk of delayed uterine perforation but may be profitable for treatment of partly intramural structures like an intramural leiomyoma.     

Evaluation of EnSeal®, an adaptive bipolar electrosurgical tissue-sealing device

Relatively few, and inconsistent, data are available in the literature about the properties of EnSeal?, an electrosurgical tissue-sealing device. For this reason, we conducted control safety tests on experimental pigs. The mean burst pressure of sealed vessels (2-7 mm in diameter) proved to be 873.89 ± 120.57 mmHg (n = 60). Surface temperature increased to 69.25 ± 0.98 °C in average (n = 22). The mean diameter of the collateral microscopic thermal injury zone was found to be 0.28 ± 0.04 mm, and it did not show significant differences among the groups of tissues studied (n = 183). During our studies, the device worked reliably and met the relevant requirements in all cases. It can be established that EnSeal? enables high-safety clinical interventions at high blood pressure values, in different tissues and even at sites adjacent to heat-sensitive tissues, and thus it paves the way for new operative solutions in both human and veterinary surgery. In our opinion, the discrepancies between data reported in the literature arise from differences in the design of studies and in the designated limit values. To ensure standardisation, we recommend the use of the nitroblue-tetrazolium chloride/lactate dehydrogenase (NBTC/LDH) enzyme histochemical technique for studying thermal injury induced by the different performance levels and application times of devices operating with electromagnetic energy.     

Neodymium:yttrium aluminum garnet surgical laser versus bipolar electrocoagulation for laparoscopic ovariectomy in dogs

OBJECTIVE: To compare use of neodymium:yttrium aluminum garnet (Nd:YAG) surgical laser and bipolar electrocoagulation (BEC) for laparoscopic ovariectomy (OVE) in dogs. STUDY DESIGN: Prospective clinical trial. ANIMALS: Female dogs (n=72). METHODS: Laparoscopic OVE by Nd:YAG laser (600 microm optical fiber, contact mode) in 36 dogs was compared with laparoscopic OVE by bipolar electro-coagulating grasping forceps. Dogs were paired (laser, electrocoagulation) matched for breed, age, body weight, obesity, and number of heat cycles. Duration of predetermined surgery times and total surgical time were compared between groups. Occurrence of intra- and postoperative complications and their effect on surgical duration were evaluated. RESULTS: Laser surgery resulted in a higher incidence of intraoperative mesovarial bleeding (12 times; 9 dogs) compared with electrosurgery (4 times; 3 dogs). Use of laser caused a 2 minute delay for transection of the left ovary compared with electrosurgery. Postoperative complication rates and convalescence were similar for both groups. CONCLUSIONS: BEC reduced surgical time and intraoperative mesovarial bleeding compared with laser resection. CLINICAL RELEVANCE: Although the laser was effective for laparoscopic OVE, bipolar electrosurgical laparoscopic OVE remained the method of choice.     

Comparison of Nd:YAG surgical laser and Remorgida bipolar electrosurgery forceps for canine laparoscopic ovariectomy

Objective— To investigate and compare technique, surgical time, and complications of canine laparoscopic ovariectomy using Nd:YAG surgical laser and Remorgida bipolar electrosurgery forceps.
Study Design— Randomized, prospective clinical trial.
Animals— Female dogs (n=40) for elective ovariectomy.
Methods— Dogs had bilateral ovariectomy with one ovary randomly assigned to removal by use of Nd:YAG surgical laser with a 600 μm optical fiber in contact mode and the other ovary to removal by use of a Remorgida forceps (featuring bipolar electrocoagulation with simultaneous sharp resection). Duration of predetermined surgery intervals and complications were compared between techniques. Additionally, the effects of several intraoperative variables on surgical time were evaluated.
Results— Ovariectomy by use of Remorgida forceps required significantly less time than laser ovariectomy but intraoperative hemorrhage was not reduced. Surgical time was significantly increased in obese dogs, depending on the amount of fat in the ovarian ligament. Intraoperative hemorrhage had no significant influence on surgical time.
Conclusion— Both ovariectomy techniques were effective but the Remorgida forceps can be used as a relatively inexpensive, stand-alone device that decreases surgical time compared with Nd:YAG laser ovariectomy.
Clinical Relevance— Novel techniques, such as laser and combined bipolar electrosurgical and cutting forceps aim to reduce surgery duration, complication rates and recovery time in laparoscopic surgery.     

An alternative pathway electrosurgical unit injury in a dog

Objective: To report esophageal perforation, caused by alternative current pathway from the use of a monopolar electrosurgery unit (ESU), during routine orthopedic surgery in a dog. Study Design: Clinical report. Animals: Two‐year‐old male Labrador retriever. Methods: Medial meniscectomy and lateral suture stabilization were performed on a healthy Labrador retriever with a ruptured cranial cruciate ligament. Monopolar electrosurgery was used during the procedure for hemostasis and tissue dissection. Anesthetic monitoring was augmented with an esophageal electrocardiogram (ECG) probe. The day after surgery, the dog appeared dehydrated. After intravenous fluid therapy, respiratory distress was noted and thoracic radiography and contrast fluoroscopy revealed an esophageal perforation. Results: Exploratory surgery was planned to repair the defect. Cardiac arrest occurred after induction. Gross necropsy findings and histopathologic examination revealed lesions consistent with thermal necrosis of the esophagus and myocardial degeneration. An internal investigation of this medical device accident revealed that multiple factors may have contributed to the injury. Conclusions: An alternative current pathway from the monopolar ESU to the esophageal ECG probe resulted in a full‐thickness esophageal thermal injury and cardiac failure.     

Diode laser and endoscopic laser surgery.

Two functionally important differences exist between the diode laser and the carbon dioxide (CO2) laser (used more commonly in small animal surgery). Diode laser energy is delivered through a quartz fiber instead of being reflected through an articulated arm or waveguide. Quartz fibers are generally more flexible and resilient than waveguides and can be inserted through an endoscope for minimally invasive procedures. Laser-tissue interaction is the other significant difference. The CO2 laser is completely absorbed by water, which limits the effect to visible tissue. The diode wavelength is minimally absorbed by water and may affect tissue as deep as 10 mm below the surface in the free-beam mode. With proper respect for the tissue effect, these differences can be used to the advantage of the patient.     

Comparison of the carbon dioxide laser and the radiofrequency unit for feline onychectomies

This study compared the collateral tissue damage and incisional bridging with granulation tissue via histopathological examination following feline onychectomy performed by radiofrequency (RF) and carbon dioxide (CO(2)) laser. Two cats were euthanized, and their digits were harvested for histopathological evaluation on days 1, 3, and 7 post-onychectomy. Each digit was evaluated for total lesion width, total necrosis width, and degree of edema, hemorrhage, and inflammation. This study found few significant differences in collateral tissue damage between RF and CO(2) laser, but more incisional bridging by granulation tissue was noted with RF for feline onychectomies. These results indicate that RF for feline onychectomy is a reasonable alternative to CO(2) laser in regard to collateral tissue damage and bridging of the incision by granulation tissue. In addition, RF is not accompanied by the strict safety considerations and initial expense of acquisition of a CO(2) laser.     

Synovial regeneration in the equine carpus after arthroscopic mechanical or carbon dioxide laser synovectomy

OBJECTIVE: To compare synovial regeneration in the equine carpus after mechanical or CO(2) laser synovectomy. STUDY DESIGN: Arthroscopic partial synovectomy was performed in the radiocarpal and intercarpal joints. SAMPLE POPULATION: Twelve horses, 3 to 6 years of age, were randomly divided into 3 groups. METHODS: The antebrachiocarpal and intercarpal joints in each horse were randomly assigned a treatment such that each horse had one joint treated as a control (arthroscopic lavage), one in which a mechanical or CO(2) laser partial dorsal carpal synovectomy was performed, and one in which a combination of the mechanical and laser techniques was performed. The groups were euthanized for collection of specimens, respectively, at 1, 3, and 6 months postoperatively. The synovial membrane was evaluated grossly, histologically, and by transmission and scanning electron microscopes (TEM and SEM). RESULTS: The synovial villi failed to regenerate in all groups. At 1 month, the intimal cell layer was incomplete and the surface was still granulating. At 3 months, intimal regeneration was complete but more mature in the CO(2) laser synovectomy groups than in the mechanical synovectomy groups. Intimal regeneration was complete in all groups at 6 months. The subintima was replaced with fibrous tissue that separated the original subintimal vascular bed from the regenerated synovial surface. The CO(2) laser required preliminary training to operate effectively, and the air environment altered the intraoperative evaluation of the synovectomy site. CONCLUSIONS: Villous regeneration does not occur in horses after surgical synovectomy. All synovial membranes healed with a fibrous subintima and less populated intima. The CO(2) laser is capable of performing a more superficial synovectomy than that achieved with mechanical synovectomy using a motorized arthroscopic synovial resector. CLINICAL RELEVANCE: Mechanical or CO(2) laser synovectomy may be performed in the horse; however, additional evaluation is needed to determine the physiological significance of the lack of villus regeneration in this species. A combination of the resection techniques is not advised because of the increased risk of full-thickness capsular defects.     

A histopathological comparison of two techniques for soft palate resection in normal dogs

Eighteen dogs were used to compare histopathological findings following excision of the soft palate using either a bipolar sealing device or a carbon dioxide laser. Histopathological comparisons were done at 48 and 96 hours after soft palate resection. Mean depths of tissue injury at 96 hours were 3.5 and 3.33 mm for bipolar sealing device and carbon dioxide laser, respectively. Control of hemorrhage was excellent in all dogs, and none of the dogs developed signs of respiratory compromise after soft palate resection. Using the bipolar sealing device for soft palate resection was significantly faster than using the carbon dioxide laser, although both techniques were fast.     

Effects of buprenorphine, carprofen and saline on thermal and mechanical nociceptive thresholds in cats

OBJECTIVE: To evaluate a prototype pressure stimulus device for use in the cat and to compare with a known thermal threshold device. ANIMALS: Eight healthy adult cats weighing between 3.0 and 4.9 kg. METHODS: Pressure stimulation was given via a plastic bracelet taped around the forearm. Three 2.4 mm diameter ball bearings, in a 10-mm triangle, were advanced against the craniolateral surface of the antebrachium by manual inflation of a modified blood pressure bladder. Pressure in the cuff was recorded at the end point (leg shake and head turn). Thermal threshold was also tested. Stimuli were stopped if they reached 55 degrees C or 450 mmHg without response. After four pressure and thermal threshold baselines, each cat received SC buprenorphine 0.01 mg kg(-1), carprofen 4 mg kg(-1) or saline 0.3 mL in a three period cross-over study with a 1-week interval. The investigator was blinded to the treatment. Measurements were made at 0.25. 0.5, 0.75, 1, 2, 3, 4, 6, 8, and 24 hours after injection. Data were analyzed by using ANOVA. RESULTS: There were no significant changes in thermal or pressure threshold after administration of saline or carprofen, but thermal threshold increased from 60 minutes until 8 hours after administration of buprenorphine (p < 0.05). The maximum increase in threshold from baseline (DeltaT(max)) was 3.5 +/- 3.1 degrees C at 2 hours. Pressure threshold increased 2 hours after administration of buprenorphine (p < 0.05) when the increase in threshold above baseline (DeltaP(max)) was 162 +/- 189 mmHg. CONCLUSIONS AND CLINICAL RELEVANCE: This pressure device resulted in thresholds that were affected by analgesic treatment in a similar manner but to a lesser degree than the thermal method. Pressure stimulation may be a useful additional method for analgesic studies in cats.     

Histological evaluation of the equine larynx after unilateral laser-assisted ventriculocordectomy

REASONS FOR PERFORMING STUDY: Trans-endoscopic laser surgery, such as unilateral laser-assisted ventriculocordectomy (LVC), has gained popularity in the treatment of RLN because a laryngotomy incision or general anaesthesia are not required. However, removal of the vocal fold and ventricle takes considerable laser energy and could cause collateral tissue damage, including injury to the adjacent laryngeal cartilages. OBJECTIVES: To document the histological effects of laser surgery on laryngeal tissues in horses that have undergone LVC for the treatment of laryngeal hemiplegia (LH). METHODS: Six horses were used: 4 with experimentally induced LH that had subsequently undergone LVC 6 months prior to euthanasia; and, 2 horses were used as controls. One of the control horses with naturally occurring LH was used to study the effect of neuropathy alone, whereas the other was subjected to euthanasia immediately following LVC to evaluate the acute effect of laser surgery. Using a band saw, each larynx was sectioned transversely at 5 mm intervals and evaluated histologically. RESULTS: Acutely, LVC caused thermal damage to adjacent soft tissues but did not affect the histology of the laryngeal cartilages. Six months after LVC, laryngeal cartilages were histologically normal and there was squamous metaplasia of the repaired laryngeal mucosa, resulting in restitution of the mucosal integrity. CONCLUSIONS: Using a diode laser in contact fashion at 20 W, LVC can be used to remove the laryngeal vocal fold and ventricle without causing laryngeal cartilage damage. POTENTIAL RELEVANCE: Laryngeal chondritis is an unlikely consequence of LVC.     

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

OBJECTIVE: To determine if CO(2) laser was superior to conventional surgical techniques (CST) for creation of skin flaps in dogs as determined by hemostasis, wound healing, and wound tensile strength. STUDY DESIGN: In-vivo model ANIMALS: Six large, mixed-breed dogs. METHODS: On each dog's trunk, 3 pairs of identical, dorsally based, pedicled skin flaps were created and sutured back into position. Based on a Latin Square design, flaps on one side were created with a CO(2) laser and on the other side by CST. Intraoperative hemorrhage was measured by weighing sponges used to absorb blood. On days 7, 10, and 14, specimens from the flap-skin junction and the central portion of each pair of flaps were collected. Specimens were subjected to tensile strength testing and histologic examination to evaluate wound healing. RESULTS: Mean (+/- standard error of mean [SEM]) hemorrhage was significantly less (P =.02) with CO(2) laser (4.70 +/- 1.37 g) than CST (10.82 +/- 1.37 g). Wound tensile strength (N/m(2)) after CST (0.49 +/- 0.049) was significantly greater (P =.01) than with CO(2) laser (0.17 +/- 0.049). Laser incisions had partial necrosis of the wound edges and a more extensive inflammatory response; however, healing of the wound beds were similar regardless of technique. CONCLUSIONS: The CO(2) laser provided better intraoperative hemostasis than CST. However, overall healing and increase in tensile strength of the skin-flap junction of the flaps created by the laser may be delayed during the first few weeks of wound healing. CLINICAL RELEVANCE: Skin flaps used to repair large skin defects in dogs can be created and elevated with a CO(2) laser. In areas of increased skin mobility or tension, skin flaps created with CO(2) laser may be more susceptible to complications such as dehiscence, and care should be taken to minimize these complications.     

A self-contained culture platform using carbon dioxide produced from a chemical reaction supports mouse blastocyst development in vitro

Elevated CO(2) is required for in vitro embryo culture to maintain proper media pH and to supply embryo metabolic pathways. As an alternative to current approaches using gas cylinders, we examined use of a chemical reaction to supply CO(2). A closed culture system was constructed and chemicals added to generate CO(2), which was then supplied to developing embryos. This system was shown to provide a stable pH (7.2-7.4) over 4 days of use. One-cell mouse embryos were cultured in the device and no difference in blastocyst formation or cell number was apparent between embryos grown in a closed system with CO(2) supplied by a chemical reaction or positive controls grown in a an open system in a CO(2) incubator. This approach provides a highly purified, inexpensive, and easily obtainable gas source and offers potential for development of new, self-contained culture platforms.     

Femoral neuropathy in a dog with iliopsoas muscle injury

OBJECTIVE: To report femoral nerve dysfunction caused by focal iliopsoas muscle injury and treated by performing tenectomy of the muscle insertion. STUDY DESIGN: Case report. ANIMALS: A 4-year-old, castrated male, English Mastiff. RESULTS: Iliopsoas muscle injury caused femoral nerve deficits and severe pain. Focal injury was not detected by ultrasonography or computed tomography but was visible on magnetic resonance (MRI) images. Tenectomy of the insertion of the iliopsoas muscle relieved signs of pain. CONCLUSIONS: Femoral nerve dysfunction may occur with iliopsoas muscle injury. CLINICAL RELEVANCE: Iliopsoas muscle injury should be considered in patients with hip pain and MRI is a useful test for diagnosis. Tenectomy may be indicated for relief of chronic iliopsoas muscle pain.     

Laparoscopic ovariectomy using sequential electrocoagulation and sharp transection of the equine mesovarium

OBJECTIVE: To describe in horses and ponies a laparoscopic ovariectomy technique facilitated by electrosurgical instrumentation. STUDY DESIGN: Elective ovariectomy was performed in 23 mares using laparoscopic electrosurgical instrumentation. ANIMALS OR SAMPLE POPULATION: Twenty-three mares (13 horses, 10 ponies), aged from 2 to 21 years and weighing 90 to 545 kg. METHODS: Food was withheld for a minimum of 12 hours. Mares were sedated with detomidine hydrochloride (0.02 to 0.03 mg/kg) or xylazine hydrochloride (0.5 to 1.0 mg/kg). Excluding the pony mares, all other mares were restrained in stocks. Portal sites in the paralumbar fossa region were desensitized with 2% mepivacaine. Abdominal insufflation was achieved through a teat cannula positioned in the ventral abdomen or a Verres-type needle placed through the paralumbar fossa. After trocar and laparoscope insertion, the ipsilateral ovary and mesovarium were identified, and the mesovarium, tubal membrane, and proper ligament were infiltrated with 2% mepivacaine. The mesovarium was coagulated using bipolar or monopolar electrosurgical forceps and transected sequentially from cranial to caudal until the ovary was completely freed and then removed. The contralateral ovary was removed in a similar fashion through the opposite paralumbar fossa. RESULTS: Bipolar and monopolar electrosurgical forceps were easy to use and provided adequate coagulation of vessels within the mesovarium. Two mares were euthanatized after the procedure for unrelated reasons. One mare had mild signs of colic 24 hours after ovariectomy. In 1 pony mare, the incision used to remove one ovary dehisced on the 5th postoperative day and was allowed to heal by second-intention. No long-term complications had occurred in 11 horses and 10 ponies, 6 to 24 months after surgery. CONCLUSION: Laparoscopic ovariectomy and hemostasis of the mesovarium can be easily accomplished using electrosurgical instrumentation. CLINICAL RELEVANCE: Standing laparoscopic ovariectomy, using electrosurgical instrumentation, is an effective and safe technique to provide hemostasis of the mesovarium in mares.     

Evaluation of a technique using the carbon dioxide laser for the treatment of aural hematomas

A new technique using the carbon dioxide (CO2) laser for the treatment of aural hematomas is described. The laser is used to make an incision into the hematoma to allow for evacuation of the blood, and then multiple, small incisions are made over the surface of the hematoma to stimulate adhesions between the tissue layers. The CO2 laser was used in this fashion to treat 10 aural hematomas in eight dogs. Follow-up ranged from 1 to 23 months. Owners evaluated the cosmetic results following CO2 laser surgery as excellent in three ears, good in five ears, and fair in two ears. Hematomas were resolved in all 10 cases, although two cases developed serosanguineous fluid accumulation that required percutaneous drainage in one case and a second laser procedure in the other case.     

Use of carbon dioxide laser for onychectomy in cats

OBJECTIVE: To compare postoperative signs of discomfort and complications associated with use of CO2 laser for onychectomy with those of the scalpel technique in cats. DESIGN: Prospective, randomized, masked clinical trial. ANIMALS: 20 client-owned cats. PROCEDURE: Forelimb feet (right, left) were randomly assigned to laser and scalpel treatment groups. Signs of discomfort (lameness and signs of pain) and complications (hemorrhage, swelling, and discharge) were assessed on days 0, 1, and 7. Surgeries were performed by 1 experienced surgeon. Evaluations were performed by 2 individuals without knowledge of treatment group. Signs of discomfort and complications were scored on scales of 0 to 8 and 0 to 9, respectively. RESULTS: Onychectomy did not result in high discomfort or complication scores 1 day after surgery, regardless of technique used, although the laser-treated group had significantly lower scores for signs of discomfort and complications. Seven days after surgery, significant differences were not detected between groups for signs of discomfort or complications. CONCLUSIONS AND CLINICAL RELEVANCE: The CO2 laser can be an excellent tool for onychectomy in cats, with excellent hemostasis and minimal postoperative discomfort and complications. 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.