Evaluating malformations of the lacrimal drainage system in brachycephalic dog breeds: A comparative computed tomography analysis

Simplified medial canthoplasty: Technique and early postoperative complications in 601 dogs (1180 eyes)

PURPOSE

To present a novel modified medial canthoplasty (MCP) technique, the application in 601 dogs (1180 eyes), and a review of the early postoperative complications related to the technique.

INTRODUCTION

Macroblepharon and nasal entropion is a common presentation in many brachycephalic dog breeds promoting chronic keratitis. The previously described MCP techniques limit the medial shortening of the eyelids to the location of the lacrimal puncta. A novel technique was developed allowing for a more extensive eyelid shortening nasally.

METHODS

The modification of the here described technique includes the longitudinal splitting of the lacrimal canaliculi allowing for an extensive shortening of the lids beyond the lacrimal puncta. Records of 601 dogs which underwent the modified MCP were reviewed regarding breed, indications for surgery, follow-up, and early postoperative surgical complications. Descriptive statistics were applied.

RESULTS

Six hundred one dogs (1180 eyes) were included in this study. Twenty-four different breeds underwent the simplified MCP with the Pug (n = 403) being the most represented breed. Indications were macropalpebral fissure, medial entropion, pigmentary keratitis, trichiasis by haired caruncle, strabismus after globe prolapse, and facial nerve paralysis. The overall complication rate was 1.01% (12/1180) and consisted of wound dehiscence 0.59% (7/1180), corneal ulceration caused by suture material 0.25% (3/1180), and wound infection (2/1180). None of the 601 operated dogs developed serious complications related to the surgical technique.

CONCLUSIONS

The simplified MCP is a novel technique with a very low complication rate.

A transconjunctival surgical technique for dacryocystotomy in dogs with foreign body-induced dacryocystitis

PURPOSE

The purpose of this study is to describe a simplified, less invasive dacryocystotomy technique that allows for complete inspection of the canine lacrimal sac and to retrospectively evaluate this surgical technique in a larger series of dogs. The anatomical background of the canine nasolacrimal system is described as a basis for the surgical technique.

METHODS

Records of dogs from 2003 to 2023 which were diagnosed with dacryocystitis due to presumed foreign body and underwent surgical exploration and removal of foreign bodies within the lacrimal sac using this technique were reviewed. Postoperative treatment and outcome were evaluated.

RESULTS

Records of 48 dogs were included. A foreign body was discovered during the surgery or upon retrieval of the catheter in 85% of cases (41/48). An indwelling catheter was placed in 83% of cases (40/48) for a median of 21 days. At the last recheck, the nasolacrimal duct was patent in 87% of the cases (41/47). The median follow-up time was 34 days (3-1255 days). The most commonly affected breeds were Golden retrievers (11) and dachshunds (8). The following complications occurred: two dogs removed or partly removed the catheter themselves (day 7, day 14), and one dog showed marked irritation at the catheter site which had to be removed by day 10.

CONCLUSIONS

The transconjunctival dacryocystotomy technique is simple and less invasive than other described techniques with a successful long-term outcome in the majority of cases.

The Anatomy of the Stomatognathic System in Different Skull Types in Dogs

The anatomy of the stomatognathic system is important for both clinical evaluations and surgical approaches in all animal species. The aim of this study was to describe the innervation and vascularization of the stomatognathic system of the dog. Twelve dogs without a history of disease or cranial malformation were used: 4 brachycephalic, 4 mesocephalic, and 4 dolichocephalic. The dogs were dissected, and arteries, veins, and nerves related to the masticatory and swallowing components were identified. The distribution pattern of these structures in the 3 different skull types were observed. The entire blood supply of the stomatognathic system is derived from the external carotid artery, which originates from the common carotid artery, and terminates as it branches into the superficial temporal and maxillary arteries. The other main branches of the common carotid artery are the occipital, cranial laryngeal, ascending pharyngeal, lingual, facial, caudal auricular, and parotid arteries. Blood drainage was achieved via the external jugular vein, which originates from the union of the linguofacial and maxillary veins. Brachycephalic dogs had blood vessels with greater sinuosity (more deviations) when compared to dolichocephalic and mesocephalic dogs. The stomatognathic system innervation of brachycephalic skull dogs showed differences in the distribution of the facial nerve in the labial commissure and maxillary and mandibular regions. The cranial conformation of dogs demonstrated anatomical variations of the vascular and neural structures of the stomatognathic system. This data may be useful to improve clinical practice, surgical planning, and interpretation of clinical dysfunctions.

A Review of Clinical Outcomes, Owner Understanding and Satisfaction following Medial Canthoplasty in Brachycephalic Dogs in a UK Referral Setting (2016-2021)

Brachycephalic breeds have increased in popularity despite growing awareness of their predisposition to a wide range of conformation-related diseases. The extreme facial conformation of many popular brachycephalic breeds compromises their ocular surface health, increasing the risk of painful corneal ulceration. Medial canthoplasty (MC) is a surgical procedure to address ocular abnormalities in brachycephalic dogs, which are collectively referred to as brachycephalic ocular syndrome (BOS). This study retrospectively reviewed the records of dogs recommended MC at a referral hospital between 2016 and 2021. A questionnaire was designed to identify owners' perceptions pre- and post-operatively. From 271 brachycephalic dogs recommended MC, 43.5% (118/271) underwent surgery and 72.0% (85/118) were Pugs. The majority of dogs (73.7%, 87/118) that underwent surgery had current or historical corneal ulceration. Follow-up was available in 104 dogs, of which 5.7% (6/104) had corneal ulceration post-operatively. Sixty-four owners completed the questionnaire and reported post-operative corneal ulceration in 12.5% of dogs (8/64), reduced ocular discharge (70.8%, 34/48), reduced ocular irritation (67.7%, 21/31) and less periocular cleaning (52.5%, 32/61). Owners were satisfied with the clinical (85.9%, 55/64) and cosmetic (87.5%, 56/64) outcome. In conclusion, MC has high clinical relevance for the surgical management of BOS, restoring functional conformation and improving the quality of life of affected dogs.

Novel findings on the anatomy of medial canthus in dogs

PURPOSE

Severe entropion of the medial canthus results in ocular surface diseases and tear staining syndrome. However, detailed anatomical structures of the medial canthus and lacrimal ducts in dogs are poorly understood. We aimed to understand the anatomical structures of the medial canthus by analyzing the distances from the medial palpebral commissure to the superior lacrimal punctum (DSP) and to the inferior lacrimal punctum (DIP) and by histological examinations of the medial canthal anatomy.

METHODS

Dogs that underwent modified medial canthoplasty (MMC) between April 2017 and March 2021 were studied. As a reference, non-brachycephalic dogs that underwent other surgeries were also examined. DSP and DIP were measured preoperatively in all dogs in both the non-everted and everted positions. Histological examinations of the medial canthal anatomy were performed in four eyes isolated from beagles.

RESULTS

The ratios of DIP to DSP (mean ± SD) at the non-everted and everted positions in 242 MMC eyes of 126 dogs were 2.05 ± 0.46 and 1.05 ± 0.13, respectively (p < .01). The ratios of everted to non-everted positions for DIP and DSP were 0.98 ± 0.21 and 1.93 ± 0.49, respectively (p < .01). Histological findings indicated that the orbicularis oculi muscle (OOM) circumjacent lacrimal canaliculus transformed into collagen fibers and were attached to the lacrimal bone.

CONCLUSIONS

Histological studies revealed that the OOM circumjacent lacrimal canaliculus transformed into collagen fibers and these collagen fibers may be related to the difference between DSP and DIP.

Tear film breakup time and Schirmer tear test in normal dogs: Effects of age, sex, reproductive status, skull type, and nasolacrimal duct patency

OBJECTIVE

The present study aimed to determine the effects of age, sex, reproductive status, skull type, and nasolacrimal duct (NLD) patency on tear production and tear film breakup time (TBUT) in normal dogs.

ANIMALS STUDIED

The ophthalmic data of 82 healthy adult dogs were evaluated in this study.

PROCEDURES

Age, sex, breed, and reproductive status were recorded. Schirmer tear test (STT) and TBUT were assessed in all dogs, and interferometry was available for the selected dogs. The Jones test was used to evaluate NLD patency. The cephalic index (CI) was calculated for each dog (skull width/skull length ×100).

RESULTS

Mean (SD) values for the STT results for the right (OD) and left (OS) eyes were 20.6 (2.7) and 20.2 (2.7) mm/min, respectively. Mean (SD) TBUT values for OD and OS were 6.5 (2.5) and 6.1 (2.3) mm/min in all dogs, respectively. Sex and reproductive status had no significant effect on STT and TBUT (P_[OU]  > 0.05). Skull type significantly affected TBUT in both eyes (P_(OD)  = 0.01, P_(OS)  = 0.003), but had no effect on STT (P_[OU]  > 0.3). Age had no correlation with STT and TBUT in either eye (P_[OU]  > 0.05). STT and TBUT had no correlation in either eye (P_[OU]  > 0.2). NLD patency had no significant effect on STT or TBUT (P_[OU]  > 0.1).

CONCLUSIONS

The results of this study showed lower TBUT values in brachycephalic breeds than in non-brachycephalic breeds. A compensatory increase in STT values was observed in dogs with low TBUT values.