Ovariectomy (OVE) is an effective and safe method for routine neutering of female dogs and is not associated with an increased risk of complications when compared to traditional ovariohysterectomy (OVH) (1,22).

Laparoscopic OVE (Lap-OVE) has several advantages over traditional open surgery including rapid recovery, reduced trauma, less hemorrhage, and excellent visualization (12). The extent of adhesions after open surgery is significantly higher than with laparoscopy due to the longer incision, application of suture material, and increased manipulation resulting in more trauma and hemorrhage (26).

Lap-OVE has been widely described in dogs (2,5-7,12). In human and veterinary surgery, there has been interest in reducing the number and size of portals used with the goal of improving patient recovery (8,16). Lap-OVE with two cannulas, rather than one, resulted in shorter surgical times without increasing the severity of postoperative pain (3). In small dogs, Lap-OVE using 3-mm and 5-mm portals has been reported, but there are no reports on Lap-OVE using two 3-mm portal sites. Also, following the removal of both ovaries, the peritoneum and skin are typically closed with a simple interrupted suture pattern (13).

In this study, we evaluated the feasibility of a novel technique for Lap-OVE in small dogs using two 3-mm portal sites. In addition, we aimed for a sutureless surgery by not needing a larger incision for ovary extraction.

Animals

Client-owned sexually intact female dogs (n = 6) brought to Kangwon National University were enrolled in the study. Dogs were considered for inclusion if they were healthy and weighed up to 10 kg. Lap-OVE was performed in young dogs (under 2.5 years) to decrease the incidence of mammary gland tumor (28). Owners completed a standard questionnaire about the dog (number of heat-cycles, date of last heat, presence of pseudopregnancy, general health, diet, and vaccination status). Dogs with diseases of the reproductive tract and mammary gland or systemic diseases were excluded from this study.

Preoperative preparation

All dogs had food withheld for 12 hours before surgery. To increase laparoscopic working space, an oral antifoaming agent (25 mg, PO; Gasocol suspension; TAEJOON PHARM Co.) was administered to the dogs for gas clearance (21). Ultrasonographic examination was performed in all dogs to evaluate the status of reproductive system and measure the length and height of the ovary in longitudinal section (4). The middle finger of a size M Sterling Nitrile Powder-Free Exam Glove (Kimberly-Clark; Texas, USA) was cut at its base and sterilized with ethylene oxide gas preoperatively.

Surgical procedure

Each dog was premedicated with butorphanol (0.2 mg/kg, IV; Butophan injection; Myungmoon Pharm Co.) and midazolam (0.2 mg/kg, IV; Vascam; Hana Pharmaceutical Co. Ltd.). Preoperatively, cefazolin (25 mg/kg, IV; Cefazol; Hankook Korus Pharm Co.) and meloxicam (0.1 mg/kg, IV; Metacam Solution; Boehringer Ingelheim) were administered. In all dogs, anesthesia was induced with propofol (6 mg/ kg, IV; Provive; Myungmoon Pharm Co.). General anesthesia was maintained with isoflurane (Terrell TM; Piramal Critical Care) in 100% oxygen through an endotracheal tube in a circle rebreathing system. Each dog was positioned in dorsal recumbency on a tilting table. The ventral abdominal area was clipped and aseptically prepared.

Using the Veress needle technique, the abdomen was insufflated with carbon dioxide (CO₂) with a pressure of 8 mmHg. Incision length (approximately 2 mm length) was made smaller than the outer diameter of the cannula and was marked with a surgical pen. The first 3.5-mm trocar was inserted 1 cm cranial to the umbilicus using a blind technique. A second 3.9-mm trocar was placed 2 cm caudal to the umbilicus. The cannula was introduced with a pyramidal tip trocar (Karl Storz; Tuttlingen, Germany) in all cases. A 3-mm HOPKINS^® II Straight Forward Telescope 0º (Karl Storz; Tuttlingen, Germany) was introduced into the cranial cannula and a 3-mm laparoscopic grasping forceps (Karl Storz; Tuttlingen, Germany) into the caudal cannula. A routine exploratory laparoscopy was performed, and anomalies of the abdominal organs were recorded. The operating table was tilted 30° on either the right or the left side to ease exposure of the left and right ovary, respectively. The ovary was pulled to the abdominal wall using laparoscopic grasping forceps. A polyamide monofilament transabdominal suspension suture attached to a round atraumatic needle was placed at the level of the proper ovarian ligament and held outside the abdomen by mosquito forceps. Using a 3-mm TAKE-APART^® Bipolar Coagulation Forceps (Karl Storz; Tuttlingen, Germany) and 3-mm laparoscopic scissors (Karl Storz; Tuttlingen, Germany), the proper ligament, mesovarium, and suspensory ligament were progressively sealed and transected (Fig. 1) (8).

Figure 1. Ovary resection procedure. (A) Two 3-mm midline portals and veress needle (arrowhead) were inserted. (B) Ovary (arrowhead) and proper ovarian ligament (dotted line) suspended at the body wall using 1-0 blue nylon needle. (C) Ovarian pedicle (dashed line) and suspensory ligaments (dotted line) were cauterized using a 3-mm bipolar forceps. (D) Ovary was dissected free by transecting the cauterized ovarian pedicle and suspensory ligament (dashed line) and proper ligament (dotted line). CrC, cranial cannula; CdC, caudal cannula; U, uterus.

After both ovaries were transected, the Silicone Leaflet Valve (Karl Storz; Tuttlingen, Germany) of the caudal cannula was removed. To facilitate the glove retrieval bag passing through the caudal cannula, the prepared glove was reversed and inserted into the abdominal cavity using a Knot Pusher (Arthrex; Florida, USA) as an applicator. The inserted glove was placed on the spleen. The Silicone Leaflet Valve of the caudal cannula was closed. A CO₂ insufflation tube was connected to the cranial cannula and pneumoperitoneum was re-established. The transected ovary was grasped with the laparoscopic grasping forceps and released from the transabdominal suture. Both ovaries were placed in the glove and the mouth of the glove was pulled out of the port through the caudal cannula with the laparoscopic grasping forceps. With the mouth of the glove opened outside, the ovary was grasped with Adison-Brown tissue forceps and fragmented using iris scissors. The same morcellation and extraction procedure was repeated on the other ovary. Following removal of the ovaries, the incision length was measured and 3M VetbondTM (3M; Minnesota, USA) was used to close the peritoneum and skin of the cranial and caudal portal sites (Fig. 2).

Figure 2. Glove retrieval bag insertion and Ovary extraction procedure. (A) Finger part of nitrile glove was cut at its base and reversed. (B) Prepared glove was inserted to the abdominal cavity through caudal port by using Knot Pusher as an applicator (white asterisk). (C) Endoscopic view of glove retrieval bag insertion procedure. (D) Resected ovary (arrowheads) was placed in a glove retrieval bag through mouth of glove retrieval bag (black dashed line). (E) Pull out the mouth of glove retrieval bag through the caudal port with laparoscopic atraumatic grasper. (F) Endoscopic view of procedure (E). (G) The mouth of glove retrieval bag was widely opened to outside and attached to skin by using mosquito forceps. (H) Ovary was morcellated with iris scissors and extracted with Adson-Brown tissue forceps. (I) Cranial and caudal wound length were measured. (J) Skin was closed by using a tissue adhesive. G, glove.

Postoperative management

Transpore^TM White (3M; Minnesota, USA) was applied to the surgical wound site and a pressure bandage was applied. All dogs were sent home the same day as surgery. The owners were questioned regarding the dog’s appetite and any abnormality or discomfort noted postoperatively.

Measured data

Data recorded included breed, body weight, age, and body condition score (BCS). Body condition score ranged from 1 (thin) to 5 (obese) (9). Fat score of the ovarian pedicle (FSOP; 0 = no fat; 1 = small amount of fat; 2 = moderate amount of fat; and 3 = large amount of fat) was also recorded (29). Length and height of the ovary was measured in longitudinal section using ultrasonography (4). Total surgical time (TST)—first skin incision to surgical wound closure—was measured using a stopwatch and recorded video. The following new stages of this surgery were recorded: Glove retrieval bag insertion time (GIT) – from Silicone Leaflet Valve opened to closed; Ovary insertion time (OIT) – from mouth of glove retrieval bag opened to both ovaries inserted; Ovary extraction time (OET) – mouth of glove retrieval bag opened outside to both ovaries extracted. The incision lengths of the cranial and caudal portal sites were measured. Major and minor intraoperative and postoperative complications were recorded. The data were summarized as mean ± standard deviation (SD).

Six dogs with normal health status were included in this study. Breeds were mixed (n = 2), Poodle (n = 1), Dachshund (n = 1), Bichon Frise (n = 2). For all dogs, mean ± SD body weight was 5.1 ± 1.4 kg (range: 3.0 to 7.2 kg). The mean ± SD age was 15.3 ± 5.4 months (range: 8 to 23 months). Body condition score was 4.0 ± 1.3 (range: 2 to 5). FSOP was moderate amount of fat (2.0 ± 1.3). Longitudinal length and height (mm) of the left ovary were 11.9 ± 3.8 and 5.9 ± 1.9, respectively. Longitudinal length and height (mm) of the right ovary were 11.1 ± 3.4 and 5.3 ± 0.7, respectively. TST was 61.9 ± 2.7 min (range: 56.9 to 64.3 min). The time needed for GIT was 0.8 ± 0.1 min (range: 0.7 to 0.9 min), OIT was 4.2 ± 0.7 min (range: 3.2 to 5.2 min) and OET was 16.6 ± 0.8 min (range: 15.2 to 17.5 min). Mean surgical wound length was 4.3 ± 0.4 mm (range: 4.0 to 5.0 mm) in the cranial portal sites and 4.8 ± 0.4 mm (range: 4.5 to 5.5 mm) in the caudal portal sites (Table 1).

Table 1 . Clinical data of 6 dogs undergoing a 3-mm 2 port laparoscopic ovariectomy.

No.	Breed	Cannula size (mm)		Wound length (mm)		Ovary size (mm)		Body weight (kg)	BCS	FSOP	TST (minute)	GIT (minute)	OIT (minute)	OET (minute)	Additional incision and complication
		Cr.	Cd.	Cr.	Cd.	Left (L x H)	Right (L x H)
1	Mix	3.5	3.9	5	4.5	8.8 x 4.2	7.3 x 5.1	3	3	0	62.9	0.7	3.8	15.2	No
2	Poodle	3.5	3.9	4	4.5	9.6 x 5.1	8.1 x 5.6	4.5	4	2	61	0.7	3.2	16.1	No
3	Dachshund	3.5	3.9	4	5	8.3 x 4.4	9.2 x 4.3	3.6	2	1	63.9	0.8	4.0	16.3	No
4	Bichon	3.5	3.9	4.5	5.5	11.9 x 8.5	11.7 x 5.7	6	5	3	62.1	0.8	4.0	17.0	No
5	Bichon	3.5	3.9	4.1	4.5	15.6 x 8.1	14.1 x 6.3	6.2	5	3	56.9	0.9	5.2	17.2	No
6	Mix	3.5	3.9	4.3	4.8	17.5 x 4.9	15.8 x 4.7	7.2	5	3	64.3	0.8	5.0	17.5	No
	Mean (SD)	-	-	4.3 (0.4)	4.8 (0.4)	11.9 (3.8) x 5.9 (1.9)	11.1 (3.4) x 5.3 (0.7)	5.1 (1.4)	4 (1.3)	2 (1.3)	61.9 (2.7)	0.8 (0.1)	4.2 (0.7)	16.6 (0.8)	-

Lap-OVE was possible in all dogs using two 3-mm portal sites. In all cases, the glove was inserted smoothly through the caudal cannula without tearing. Additional skin and peritoneal incision enlargement was avoided in all dogs. The ovary morcellation and extraction technique was utilized in all dogs. After the ovary extraction procedure was completed, the cranial and caudal portal sites were closed with tissue adhesive in all dogs. No intraoperative and postoperative complications occurred.

The use of small-diameter portal sites (3-mm and 5-mm) has previously been described for Lap-OVE in small dogs (13). Minimally invasive surgery reduces surgical trauma and improves postoperative rehabilitation; thus, the reduction of port size and number have been key objectives in veterinary medicine (3,8,24,27). Our study is the first to describe Lap-OVE in small dogs using two 3-mm portal sites (3.5 and 3.9-mm cannula).

Enlargement of the peritoneal incision was needed in the previous study because extraction of the ovaries was not possible through the 3-mm portal sites. Enlarging the portal site goes against the concept of minimal access surgery (25). Also, there is a risk of inadvertent, temporary loss of the ovary in the abdominal cavity during ovary extraction (3). In the current study, by using our novel techniques and the nitrile glove retrieval bag, additional incision was avoided in all dogs.

Small dogs weighing less than 10 kg were included in this study. To avoid residual ovarian syndrome, ovary resection was performed including the surrounding tissues of ovary. Therefore, the size of the tissue inserted into the glove was larger than the size of the ovary. The exact size of the ovaries is dependent on the body mass of the dog and the estrous cycle stage (4). In general, the average size of an ovary in a 11 kg dog is 15 mm long, 7 mm wide, and 5 mm thick (10). The diameter of the mouth of the glove used in this study is approximately 19 mm. Considering the diameter of the mouth of the glove retrieval bag and the average size of an ovary, we conclude that laparoscopic ovary extraction using our glove retrieval bag method is feasible in dogs under 10 kg.

In a previous study, a 5-mm portal site was used to remove ovaries from the abdomen (5,13). However, only 3-mm portal sites were used in this study, and since an ovary cannot fit through a 3-mm portal site (5), manual morcellation was performed in a glove retrieval bag to facilitate ovary removal. Most commercially available retrieval bags require 10- to 12-mm cannulas for introduction into the body cavity. The use of a glove finger as a retrieval bag allows introduction through a 3-mm cannula and extraction of the ovary contained within a durable closed pouch, thus reducing the risk of content spillage during extraction (11). In this study, the middle finger of an M size nitrile glove was used as a retrieval bag. When using a larger glove size, there was a problem with the glove tearing during the glove insertion procedure. Moreover, direct insertion of the glove retrieval bag through the caudal incision site resulted in peritoneal incision enlargement and glove tearing in a pilot study. Needless to say, it is essential to be able to insert the glove through a 3-mm caudal cannula without the glove tearing. Friction between the glove and the cannula’s inner layer, in addition to the small diameter size, contributes to the difficulty of passing the glove retrieval bag through the 3-mm caudal cannula. The smooth inner surface of the nitrile glove, along with using a twisting motion with the applicator, enables it to pass more easily.

Commercially available retrieval bags have a rigid rim that maintains a large opening, greatly facilitating the insertion of tissue (11). A glove retrieval bag does not have a rigid rim; therefore, the mouth of the glove retrieval bag is closed when it is placed into the abdominal cavity. To insert the ovary into the glove, the mouth of the glove retrieval bag has to be opened. If our study had used a 3-port Lap-OVE technique, we could have grabbed one side of the glove with a grasper and used another grasper to open the mouth of the glove retrieval bag. Because we used a 2-port Lap-OVE technique in this study, an alternative method was needed to open the mouth of the glove retrieval bag. By changing the CO₂ insufflation tube connection from the Verres needle to the cranial cannula, insufflation pressure could be directed toward the mouth of the glove retrieval bag to open it.

In contrast to commercial retrieval bags, a glove retrieval bag has no rigid delivery system. Therefore, the inserted glove retrieval bag is placed on a spleen surface. After the mouth of the glove retrieval bag was opened using CO₂ pressure, the transected ovaries were grasped and inserted into the glove retrieval bag one by one. When the ovary was placed in front of the mouth of the glove retrieval bag, a hit and push motion in the direction of the glove pouch using the laparoscopic grasping forceps helped the ovary slip into the glove retrieval bag.

One factor that influenced the surgical procedures was the amount of fat covering the ovarian pedicle. The fat made it difficult to identify the ovarian vasculature, so sealing the ovarian pedicle was a more difficult and time-consuming procedure than expected (15). FSOP was significantly increased in obese dogs, hence obesity had a significant effect on surgery duration (29). In this study, case no. 6 had the longest total surgery time because of the higher BCS and FSOP scores compared to the other cases.

The mean total surgical time (61.9 min) is longer than the 45 min reported previously (13). By using a glove as a retrieval bag, new surgical stages (GIT, OIT, OET) were added. Of these times, OET was a major factor in prolonging the mean TST. The ovary being resected along with the surrounding tissues, and the manual morcellation of both ovaries, made the OET longer. In contrast to the previous study; however, postoperative management was not required in this study. Considering that time was not spent on postoperative management, the mean total surgical time of this study is an acceptable level.

This study used the same-size cranial cannula size (3.5-mm) as the previous study. The mean surgical wound length for the cranial cannula was 4.3 mm, which is shorter than the 4.8 mm of the previous study. The mean caudal surgical wound length was 4.8 mm (range: 4.5 to 5.5 mm), which is shorter than the 7.1 mm (13) and 9 mm previously reported (5). Because a smaller (3.9-mm) caudal cannula was used in this study, the mean surgical wound length in the caudal cannula was shorter than in the previous study. It is important to minimize the size of portal sites for sutureless Lap-OVE; the incision length was made smaller than the outer diameter of the cannula and marked by surgical pen. Using the Modified Hasson technique, makes it difficult to fit the cannula sheath tightly to the abdominal wall without extending the size of the portal (5,13). Thus, the Veress Needle Technique was used for insufflation, and the first cannula was introduced with a pyramidal tip trocar to minimize the portal site size. After the laparoscope was inserted, the second cannula was introduced under direct laparoscopic observation to minimize the risk of injury (11).

Suture material has the potential to delay wound healing and cause discomfort. Rapid tissue union, painless treatment, and bactericidal effects are not achievable with either absorbable or nonabsorbable sutures. Tissue adhesives made of N-butyl-cyanoacrylate, with antibacterial properties mainly against Gram positive microorganisms, have been developed and successfully used to close skin lacerations in numerous cases. Also, N-butyl-cyanoacrylate is suitable for closure of the peritoneal defect and contribute to the prevention of chronic postoperative pain (20). Additionally, tissue adhesive provides sufficient mechanical support for the wound with no need for suture removal (17,23). In the previous study, suture material was needed to close the surgical wounds because a 5-mm portal site was used for Lap-OVE. However, tissue adhesive was used for wound closure in cases of 3-mm portal sites (13). In our study, there was no need to suture because only 3-mm portal sites were used.

Several reports have identified the development of pyometra and mammary gland carcinoma in captive tiger. For nonbreeding female tigers, OVH or OVE is recommended to reduce the occurrence of these diseases. Wild animals are returned to an outdoor environment after surgical procedures; surgical wounds cannot be cleaned, protected with a bandage, or closely monitored; and sutures cannot be removed due to personnel safety concerns (14,18). For these reasons, sutureless Lap-OVE could be an appropriate surgical option for aggressive patients or wild animals.

In human laparoscopic surgery, morcellation is a technique used to retrieve solid tissue from the abdominal cavity. A morcellator is an important instrument for tissue removal in myomectomy or splenectomy and works by using a sharp cylindrical blade to cut the tissue into small strips (19). However, commercially available morcellator sizes are 10 mm, 12 mm, and 15 mm. In the future, the application of a smaller-sized morcellator in veterinary laparoscopic surgery would facilitate ovariectomy, as well as various other abdominal surgeries, through small cannulas.

In conclusion, Lap-OVE in small dogs was accomplished using two 3-mm portal sites with our novel techniques and a nitrile glove retrieval bag. Additionally, sutureless surgery was achieved because of the small cannula and incision sizes. Therefore, Lap-OVE using two 3-mm portal sites is an acceptable procedure and a surgical option for ovariectomy in small dogs.

The authors have no conflicting interests.