MATERIALS AND METHODS

Study area: The present study was carried out in the Veterinary Teaching Hospital, Department of Surgery, Anesthesiology and Radiology, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt, from 1 March, 2019-1 June, 2019.

Ethics: The present study was approved by The National Ethical Committee of Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt, according to The OIE standards for use of animals in research.

Experimental animals: The present study was conducted on five (n = 5) clinically healthy, adult mongrel dogs of both sexes (2 males and 3 non-pregnant, non-lactating females). Their weights ranged between 12-15 kg body weight (BW) and ages from 1-2 years old. The dogs were housed individually in standard cages with food and water ad libitum.

Surgical procedure: Dogs were premedicated by administration of xylazine-ketamine combination, mixed in the same syringe at doses of 1 mg kg^–1 xylazine 2% (Xyla-Ject, ADWIA Co., SAE, Egypt) and 2 mg kg^–1 ketamine 5% (Ketamine, Sigma-tec Pharmaceutical Industries, SAE, Egypt). Anaesthesia then was maintained by continuous infusion of 1 mg kg^–1 h^–1 xylazine 2% and 10 mg kg^–1 h^–1 ketamine 5%¹⁹.

The animal was maintained in the right lateral recumbency. The area below the base of the ear extending along the caudal border of the vertical ramus of the mandible and the wing of the atlas and neck area were prepared for aseptic surgery and draped except for the surgical site.

A V-shaped skin incision was made below the base of the ear and extends downward for 6-7 cm (Fig. 1a). Dissections was started from the point of the V-shaped incision upward to dissect the skin from the underlining tissues and then the V-shaped skin fold was reflected dorsally (Fig. 1b). Carefully, the subcutaneous tissue and fascia over the gland were dissected until the lobulation of the gland through its capsule was identified (Fig. 1c).

Dissection of the gland was started upside down, the dorsal border, the cranial border, the medial aspect of the gland and then the posterior border (Fig. 1d). Severed blood vessels during the process of the dissection were ligated by 3-0polygelactin 910. After removal of the gland, the site of operation was checked for any points of hemorrhages. The resultant dead space was occupied by a sterile piece of gelatin sponge (Equispon, Equimedical BV, The Netherlands) of suitable size and shape (triangular) (Fig. 2a). The fascia was closed over the gelatin sponge piece by 3-0 polyglactin 910 in a simple continuous manner (Fig. 2b). The V-shaped incision then was closed into two layers, the subcutaneous tissue in a continuous manner using 3-0 polyglactin 910 and the skin was closed in a simple interrupted manner using 3-0 polyglactin 910 (Fig. 2c).

All dogs were administered intramuscular (IM) cephalexin monohydrate 25 mg kg^–1 (1000 mg ampoules, Rameda Pharmaceuticals, SAE, Egypt), once daily for 5 successive days and Ketofan 2 mg kg^–1 (2 mL ampoule containing 100 mg ketoprofen, Amriya Pharm. Ind., Alexandria- Egypt), once daily for 3 successive days postoperatively for control of infection and postoperative pain, respectively.

Elizabethan collars were applied for dogs to prevent the animals from biting or scratching at the wound region until healing of the wounds.

Dogs were kept under clinical observation for 3 months. The dogs were examined daily till removing of skin stitches (10-12 days postoperatively) for the presence of any swellings, exudates from the site of operation, presence of infection, patency of stitches or any other complications.

Fig. 1(a-d):

(a) V-shaped skin incision, (b) Dissection and reflection of the V-shaped skin fold over the parotid gland, (c) Dissection of the subcutaneous and fascia over the parotid gland and (d) Excision of the parotid gland

Fig. 2(a-c):

(a) Sterile sponge of gelatin in the dead space after excision of the parotid gland, (b) Closure of the fascia over the gelatin sponge and (c) Closure of the V-shaped skin incision

RESULTS

No deaths or severe complications were recorded intraoperatively or postoperatively in dogs. The V-shaped skin incision achieved a reliable and satisfactory exposure to the parotid gland during its excision. There was no need to use wound dilators. The dissection of the fascia over the fine capsule of the parotid gland revealed the lobulation of the gland and subsequently, its borderlines, which made the resection of the gland from the surrounding tissues, went easier, safer and less traumatized.

The dead space left after the excision of the parotid gland was relatively large. The wounds were closed without leaving a drain space and healing was achieved by the first intention in all dogs.

The symptoms of facial nerve function disorder were not detected during the postoperative clinical examination in the dogs. Postoperative hemorrhages, abscessation, seroma or wound dehiscence were not recorded between the dogs.

DISCUSSION

The current study added new trends on the parotidectomy technique in dogs, by which the technique may be easier and safer as well as, minimize the postoperative complications that were recorded in many literatures^{8, 11, 17, 18}.

Surgical removal of the parotid gland represents a great challenging due to its association with vital structures. The ventral angle of the gland is usually tunneled by the internal maxillary vein. From under its rostral border, emerge the palpebral, auriculotemporal and the dorsal and ventral buccal nerves. The parotid lymph node usually lies mostly on the part under the rostral border near the ventral angle. The rostral auricular artery and vein and the transverse facial artery run under or along the rostral border of the parotid gland. The caudal border is circled by branches of the intermediate auricular blood vessels, however, some of these structures may run through the gland. The deep surface of the parotid gland is related to the facial nerve and its terminal branches. The deep portion of the gland is also related to the maxillary and superficial temporal arteries. The internal maxillary vein is related to the parotid gland at a more ventral and superficial level than the maxillary nerves and arteries^3,15,17.

The dissection of the facia over the gland capsule of the parotid revealed its lobulation and identified its borderlines that made the excision of the gland went easier and less traumatizing to the surrounding structures resulting in less postoperative surgical complications. This may be the cause that there were no recorded cases of facial nerve paralysis in the present study, on the contrary to the results recorded by Dunning¹⁸, Trumpatori et al.⁷, Guthrie and Hardie¹¹ and Proot et al.¹⁷.

Seromas, postoperative hemorrhages, wound dehiscence as well as, abscessation were recorded as postoperative complications following the parotidectomy in dogs¹⁷. Such complications were not reported in the present study. This may be attributed to the use of the sterile gelatin sponge in the dead space following the parotidectomy, which potentially prevented the formation of exudate or transudate, enabled the wound to be closed completely without the need to leave a drain space, other than its hemostatic effect.

CONCLUSION

The skin incision over the parotid gland on V-shape and revealing the gland lobulation made the parotidectomy procedure easier, safer and less traumatized to related structures. The use of the gelatin sponge in the dead space prevented exudate or transudate formation and enabled the wounds to heal by the first intention. These new trends may minimize parotidectomy related postoperative complications and improve surgical outcomes in dogs.

SIGNIFICANCE STATEMENT

This study addressed new trends in parotidectomy technique that can be beneficial for canine patients. This study will help the researchers and practitioners to cover the critical areas of this technique achieving better surgical outcomes and less postoperative complications.