Evisceration with implantation of an intrascleral silicone prosthesis in dogs: A retrospective study of 107 cases (2010-2019).

OBJECTIVE: To retrospectively analyze the preoperative clinical characteristics and surgical outcomes of evisceration with implantation of an intrascleral silicone prosthesis (EIISP) procedures in dogs and evaluate whether brachycephalic dogs are more prone than non-brachycephalic dogs to develop postoperative complications after EIISP. ANIMAL STUDIED: Ninety-One dogs (19 of which were brachycephalic) were included. PROCEDURES: Medical records from 2010 to 2019 were reviewed. Signalment, reason for EIISP, postoperative complications, follow-up time, and postoperative eye appearance were analyzed. RESULTS: The most frequently represented breeds were French Bulldog [11/91 (12%) dogs], Jack Russell Terrier [6/91 (7%)], and Shih Tzu [6/91 (7%)]. Brachycephalic dogs were statistically younger than non-brachycephalic dogs at the time of EIISP (p = 1.61 × 10-5 ). Uncontrolled glaucoma was the most common reason for EIISP in both groups. Short-term complications (from D0 to D15) seen in 7/91 (8%) dogs included epithelial corneal ulcers (n = 3), keratoconjunctivitis sicca (KCS) (n = 2), and prosthesis extrusion (n = 2). Long-term complications seen in 26/91 (29%) dogs included KCS (n = 11), epithelial corneal ulcers (n = 7), stromal ulcers (n = 3), entropion (n = 4), and prosthesis extrusion (n = 1). Extrusion of the prosthesis occurred twice in eyes that had undergone diode laser transscleral cyclophotocoagulation. The risk of postoperative complications was not significantly different between brachycephalic and non-brachycephalic dogs (p = .3). CONCLUSIONS: Brachycephalic status in dogs does not appear to influence the risk of complications from EIISP. Nevertheless, the present study is a reminder that EIISP focuses on esthetics, and considering the possible complications associated with it, it does not provide a benefit to the patient compared to enucleation.

Investigation of ocular surface parameters in dogs with different cephalic conformations using veterinary ocular surface analyzer (OSA-VET).

OBJECTIVE: To compare ocular surface parameters in dogs with different cephalic conformations and evaluate correlations among tests. ANIMALS STUDIED: Sixty-eight privately owned dogs. PROCEDURES: The study categorized canine eyes into three groups based on the craniofacial ratio (CFR): brachycephaly (≤0.52), mesocephaly (>0.52 to <0.67), and dolichocephaly (≥0.67). All eyes were examined using an ocular surface analyzer (OSA-VET) to determine lipid layer thickness (LLT) of the tear film, tear meniscus height (TMH), non-invasive tear breakup time (NIBUT), and meibomian gland loss rate of the lower eyelids (MGLRL). Schirmer tear test 1 (STT-1) and tear film breakup time (TBUT) were also performed. Statistical analyses involved one-way ANOVA, Kruskal-Wallis H test, post hoc Holm-Sidak test, and Pearson correlation coefficient. RESULTS: While STT-1 showed no significant difference among dog groups, brachycephalic dogs had significantly lower values in TBUT, NIBUT, and LLT, and a higher TMH, compared to mesocephalic and dolichocephalic dogs. Additionally, brachycephalic dogs exhibited a significantly higher MGLRL than dolichocephalic dogs. Correlations among tests were generally weak to moderate (r < .6) except for a strong correlation between CFR and LLT (r = .641, p < .001), and between TBUT and NIBUT (r = .899, p < .001). CONCLUSIONS: Brachycephalic morphology predisposes dogs to a significantly thinner lipid layer and diminished tear film stability, likely due to factors such as impaired meibomian gland function and increased ocular exposure compared to other cephalic conformations, thereby increasing their risk of keratoconjunctivitis sicca (KCS). OSA-VET shows a valuable tool to provide more comprehensive and precise diagnosis for canine ocular surface disorders.

Risk factors for corneal conjunctival grafting failure in dogs at four referral centers in the southern United States (203 patients): 2015-2021.

OBJECTIVE: To report risk factors associated with conjunctival graft failure in dogs at four referral specialty centers. PROCEDURES: Records of 203 dogs (229 eyes) undergoing conjunctival graft repair of ulcerative keratitis at four hospitals from 2015 to 2021 were reviewed. Success was defined as full graft integration with globe retention at the last postoperative evaluation; vision status was reported separately. Factors assessed included patient signalment, ophthalmic examination findings, surgical factors, and follow-up information. RESULTS: Conjunctival graft failure occurred in 11% (25/229) of eyes and was significantly associated with ulcer depth, with corneal perforations having increased odds of graft failure compared with descemetoceles (odds ratio [OR] = 3.22, 95% confidence interval [CI] 1.11-9.32; p = .03) and stromal ulcers (OR = 10.89 [95% CI 1.38-86.18], p = .02). Brachycephalic dogs were significantly more likely than non-brachycephalic dogs to experience graft failure (OR = 5.02 [95% CI 1.42-17.74], p < .01). Surgery on the opposite eye relative to surgeon handedness was significantly associated with an increased risk of graft failure (OR 4.28 [95% CI 1.53-11.94], p < .01). The use of 7-0 and 8-0 suture versus 9-0 (p = .03) and the use of a combined simple continuous and interrupted pattern (p = .03) were significantly associated with an increased risk of graft failure. At the last follow-up, (median 61.5 days), 87% of dogs were visual. CONCLUSIONS: Corneal perforations, surgery on the opposite eye relative to surgeon handedness, suture size and pattern, and brachycephalic conformation were significantly associated with an increased risk of graft failure in this study. These characteristics can be considered when determining prognosis for ulcerative keratitis requiring surgical intervention.

Treatment outcome of spontaneous chronic corneal epithelial defects in brachycephalic dogs comparing Boxers and non-Boxers: A retrospective multicenter study of 420 dogs.

OBJECTIVE: To compare characteristics and treatment outcomes of spontaneous chronic corneal epithelial defects (SCCEDs) in brachycephalic non-Boxers and Boxers. We hypothesized that brachycephalic non-Boxers develop SCCEDs at a younger age and develop complications more frequently than Boxers. ANIMALS STUDIED: Retrospective review of medical records of brachycephalic dogs treated for SCCEDs between January 2018 and December 2022 in multiple ophthalmology referral centers in the UK. PROCEDURE: Data recorded included breed, age, time of onset, treatment prior to referral, treatment at referral, time to heal, need for further procedures, and complications. RESULTS: A total of 464 SCCEDs in 420 dogs were included composed of 173 Boxers with 200 SCCEDs and 247 brachycephalic non-Boxer dogs with 264 SCCEDs. Boxers were significantly older (median 8.2, range 4.5-12.7 years) than brachycephalic non-Boxers (median 7.2, range 1.6-15.9 years) (p < .001). The first treatment (cotton-tipped applicator [CTA] debridement, diamond burr debridement, superficial keratectomy, grid keratotomy, punctate keratotomy, or combinations of these) selected was significantly different between groups (p < .001). Healing, excluding cases addressed by CTA debridement, following the first procedure was significantly more successful in Boxers (p = .049). Excluding cases addressed by CTA debridement, 9.6% of SCCEDs in Boxers (20/200) and 13.4% (32/239) of non-Boxers required more than one procedure. In the non-Boxer group, 9.5% (25/264) developed complications, contrasting with 4% (8/200) in the Boxer group. Non-Boxers were more likely to develop complications after the first treatment (p = .006). CONCLUSION: Non-Boxer brachycephalic dogs develop SCCEDs younger than Boxers. This study suggests SCCEDs in brachycephalic non-Boxers may be less likely to heal following one mechanical treatment and are more likely to develop complications.

Evaluation of photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) in feline infectious keratitis-patient demographics, treatment protocols, risk factors, and treatment outcome: a retrospective study.

OBJECTIVES: To describe patient demographics and treatment protocols in a population of feline patients undergoing photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) as an adjunctive treatment for infectious keratitis. Furthermore, to determine the proportion of PACK-CXL treatment success in the population studied, explore risk factors for treatment failure, and provide recommendations for future PACK-CXL clinical studies. MATERIALS AND METHODS: Records from four veterinary ophthalmology practices were reviewed to identify eligible patients and extract data. Recorded variables included patient-related factors, ocular examination findings, PACK-CXL protocol parameters, and treatment outcome. RESULTS: Records for 153 cats (154 eyes) were included. Median age in the treatment success group was 8 years (interquartile range (IQR) 4-12), with a median ulcer depth of 30% (IQR 30-40). Median age in the treatment failure group was 10.5 years (IQR 4.75-12) with a median ulcer depth of 45.9% (IQR 30-75). Persian cats were the most represented brachycephalic breed (52 out of 64 cats). Modified PACK-CXL protocols were used, including fast energy delivery (134 eyes), and increased fluence (52 eyes). The overall proportion of success was 88% (95% CI 84-93), which was variable between clinics. Eighty-two of 89 mesocephalic cat eyes (92%), and 54 of 65 brachycephalic cat eyes (83%) were classified as treatment successes. CONCLUSIONS: PACK-CXL appeared to be a useful, adjunctive therapeutic modality for the treatment of infectious keratitis in the feline patient population presented here. Brachycephalic cats, older cats, and those with deeper ulcers may be at increased risk for treatment failure.

The Shih Tzu eye: Ophthalmic findings of 1000 eyes.

PURPOSE: To evaluate the frequency of ophthalmic disorders in Shih Tzus. ANIMALS: Five hundred client-owned Shih Tzu dogs (1000 eyes). PROCEDURES: Medical records of 500 Shih Tzu dogs were reviewed and ophthalmic examination data were collected and analyzed. RESULTS: In total, out of 1000 eyes, 964 (96.4%; OD: 480 eyes, OS: 484 eyes) had at least one ophthalmic abnormality, and only 36 eyes (3.6%; OD: 20 eyes, OS: 16 eyes) were diagnosed as normal. A total of 1375 individual ophthalmic abnormalities were observed in 964 diseased eyes. Fifty-nine different unique diagnoses were made in the study population, and only three conditions [medial canthal entropion (10.4% of eyes; bilateral in 10.2% of dogs), caruncular trichiasis (21.1% of eyes; bilateral in 20.2% of dogs), and reduced tear film breakup time (17.6% of eyes; bilateral in 17.4% of dogs)] affected 49.1% of the eyes. CONCLUSION AND CLINICAL RELEVANCE: Findings suggested that the most prevalent disorders for the Shih Tzus were hairy caruncle, reduced TBUT, medial canthal entropion, keratoconjunctivitis sicca, pigmentary keratitis, lagophthalmos, and mature cataract.

Comparative evaluation of corneal and limbal epithelial thickness in brachycephalic dogs with and without corneal diseases using spectral domain optical coherence tomography.

OBJECTIVE: To evaluate alterations in epithelial thickness during corneal degeneration, corneal pigmentation, and additional features observed through spectral-domain optical coherence tomography (SD-OCT) in brachycephalic dogs. ANIMALS AND PROCEDURES: The study used 55 eyes from 49 brachycephalic dogs that underwent OCT-containing ophthalmic examinations. The examined eyes were classified into corneal degeneration, corneal pigmentation, and normal groups according to corneal lesions. For each eye, corneal epithelial thickness (CET) in the central cornea and maximum limbal epithelial thickness (maxLET) in 4 quadrants of limbus (superior, inferior, nasal, and temporal) were measured from OCT images. Additional abnormal findings on OCT images, including irregular epithelium, subepithelial hyperreflectivity, and conjunctivochalasis, were also recorded. RESULTS: The corneal degeneration group had significantly thinner nasal and temporal maxLETs than that of the normal group (p < .001). In the central corneal OCT image of the corneal degeneration group, an irregular epithelium was observed in 70.6% and subepithelial hyperreflectivity in 82.4%, both of which were significantly higher than the normal group (p < .001). In a comparative analysis, the nasal, temporal, and inferior maxLETs were significantly thinner in the corneal pigmentation group than those in the normal group (p < .001, p < .001, and p = .01, respectively). CONCLUSIONS: Morphological changes in the limbal epithelium were observed in dogs with corneal degeneration and corneal pigmentation. LET reduction could be associated with their pathogenesis and would be valuable as an additional parameter for corneal diseases.

Addition of a metoclopramide constant rate infusion to prevent ptyalism, regurgitation and vomiting in brachycephalic dogs undergoing spinal surgery.

OBJECTIVE: To assess whether adding metoclopramide to a protocol of maropitant and pantoprazole would reduce incidence of ptyalism, vomiting and regurgitation in brachycephalic dogs undergoing thoracolumbar spinal surgery. STUDY DESIGN: Randomized blinded controlled trial. ANIMALS: A total of 43 brachycephalic dogs undergoing thoracolumbar spinal surgery. METHODS: In addition to a standardized anaesthetic regimen, dogs were randomized to be administered either a 2 mg kg-1 day-1 metoclopramide constant rate infusion (CRI) or a saline solution at an equivalent infusion rate, started after anaesthetic induction and discontinued 5 hours after tracheal extubation. The presence of vomiting, regurgitation and pytalism, and short form of the Glasgow Composite Pain Scale pain scores were assessed by a blinded observer hourly for 4 hours, starting 1 hour postextubation. RESULTS: Regurgitation occurred in six dogs postoperatively; three dogs were in the placebo group and three in the metoclopramide group. The odds ratio (OR) of regurgitation after surgery did not differ between groups [OR: 0.76, 95% confidence interval (CI): 0.13-4.3, p = 0.76]. The odds of observing ptyalism at 3 and 4 hours was approximately 15 times less than 1 hour postoperatively (both OR: 15.4, 95% CI: 1.8-130.7, p = 0.012) and did not differ based on the addition of metoclopramide (OR: 0.73, 95% CI: 0.07-8.0, p = 0.79). The odds of observing pain did not change over time and did not differ based on the addition of metoclopramide (OR: 0.71, 95% CI: 0.12-4.2, p = 0.71). Vomiting did not occur during the study (0.0%, 95% CI: 0.0-8.2%). No adverse effects were observed during the study period in either group. CONCLUSIONS AND CLINICAL RELEVANCE: The addition of a metoclopramide CRI to maropitant and pantoprazole did not result in a significant reduction in ptyalism or regurgitation in brachycephalic dogs undergoing thoracolumbar spinal surgery.

Computer tomography measurements of the airway and thoracic cavity do not provide support for bronchial conformation as a predisposing factor of left cranial lung lobe torsion in pugs.

The objective of this retrospective clinical study was to determine if airway or thoracic cavity measurements in pugs, particularly the left cranial lung lobe, were significantly different from brachycephalic and mesocephalic control. Thoracic computed tomographic studies of 10 pugs, French bulldogs (FB), and Jack Russell Terriers (JRT) were analyzed. Thoracic height: width ratio (H:W), cross-sectional areas of the left mainstem bronchus (CSA LMB), left cranial lung lobe bronchus (CSA LCrBr), left caudal lung lobe bronchus (CSA LCauBr), CSA LCrBr relative to length (CSA LCrBr/length) and CSA LCauBr/length were measured and adjusted to body weight (/kg). CSA LMB/kg, CSA LCauBr/length/kg, and CSA LCrBr/length /kg were smaller in pugs and FB compared with JRT (P < .05), but no differences were found between pugs and FB. Cross-sectional areas of left cranial lung lobe bronchus /kg and CSA LCauBr/kg were smaller in pugs than JRT (P < .05), but no differences were found between pugs and FB or FB and JRT. No difference was found in thoracic H:W between any breeds. This demonstrated that pugs and FB had significantly narrower bronchi CSA/lengths ratios compared with JRT, but this was not limited to the LCBr. Airway measurements were not significantly different between brachycephalic breeds; therefore, the pugs' predisposition to left cranial lung lobe torsion cannot be solely explained by narrower lower airways.

A correlation of computed tomographic esophageal hiatal cross-sectional surface area between brachycephalic and nonbrachycephalic cats.

In humans and dogs, especially brachycephalics, enlargement of the esophageal hiatus and insufficiency have been correlated with decreased lower esophageal sphincter pressure and increased frequency of gastroesophageal reflux. In cats, it has been suggested that gastroesophageal reflux occurs frequently with upper airway obstruction, including brachycephalics. Therefore, the purpose of the study was to determine whether the esophageal hiatal cross-sectional surface area (EH-CSA) differs between brachycephalic and nonbrachycephalic cats. Clinical records and CT images of cats that underwent thoracic, abdominal, and entire skull CT at multiple centers between January 2015 and September 2022 were retrospectively reviewed. Esophageal hiatal parameters (EH-CSA, EH-long axis diameter, and EH-short axis diameter) and craniometric indices (cranial index, skull index, and facial index) were measured by using multiplanar reconstruction, and the correlation of craniometry with EH-CSA was investigated. Ninety-eight cats (group 1: 42 brachycephalic cats and group 2: 56 nonbrachycephalic cats) were included. Esophageal hiatal cross-sectional surface area in brachycephalic cats was significantly larger than that in nonbrachycephalic cats. The EH-CSA significantly increased with the craniometric indices tending to increase with brachycephalism. The present study contributes to the veterinary literature by providing the EH-CSA as anatomical evidence that could likely correlate to gastroesophageal reflux predisposition in brachycephalic cats.

Evaluation of measurements for tracheal hypoplasia in French bulldogs.

Tracheal narrowing may increase airflow resistance, resulting in clinical manifestations associated with brachycephalic obstructive airway syndrome (BOAS). When diagnosing tracheal hypoplasia, established values are based on measurements established for English bulldogs or non-specific "bulldog" breeds. The objective of this study was to investigate tracheal diameter ratios in French bulldogs to gain a better understanding of what would constitute tracheal hypoplasia in this breed. A retrospective observational analysis was conducted to measure the right lateral thoracic radiographs of 139 French bulldogs to investigate tracheal diameter ratios. Pulmonary disease was observed in 55/139 dogs. The mean TD:Ti for healthy French bulldogs was 0.15 (±0.02), and the mean TD:ML was 0.32 (±0.07). 44/84 dogs had a TD:Ti < 0.15 (±0.02), and 37/65 dogs had a TD:ML < 0.32 (±0.07). At least one thoracic vertebral anomaly was observed in 131/139 of evaluated French bulldogs, and sternal malformations were observed in 42/139 dogs. TD:ML showed an excellent interclass correlation between observers (ICCinter 0.9562). The listed covariables were compared for statistical significance when measuring relative tracheal ratios, and none were found. There was a statistically significant relationship between TD:Ti and sex. An objective value for tracheal hypoplasia in French bulldogs has previously not been established. The mean TD:Ti described for French bulldogs in this study is higher than that previously described in other "bulldog" populations. The mean TD:ML is similar to previously reported for non-brachycephalic and non-bulldog brachycephalic small breed dogs. The correlative relationship between TD:Ti and TD:ML was statistically significant but weak.

Computed tomographic characteristics of anatomical variations of external and internal jugular veins in dogs.

The external jugular vein (EJV) has been commonly used for clinical procedures in veterinary medicine, while the internal jugular vein (IJV) has been used mainly for research. Limited literature regarding anatomical variants in both EJV and IJV is available. The objectives of this descriptive retrospective study were to identify the number of dogs with variations of the jugular veins in canine patients undergoing CT of the head and neck and characterize these variations. Of 1000 dogs, 193 dogs (19.3%) had anatomical variations. Six types of anatomical variations were identified. The most common Type I was the absence of the linguofacial vein (72.0%, n = 139), with the lingual, facial, and maxillary veins entering the EJV at a common branching point. Type II described a variable course of the EJV and IJV, which in some dogs resulted in the absence of the EJV (14.0%, n = 27). Type III was a variable anastomotic loop formed by the linguofacial or maxillary vein cranial or at the junction of the EJV (4.2%, n = 8). In Type IV, the EJV was either suspected to be aplastic or markedly reduced in diameter compared with the contralateral side just distal to its formation (3.6%, n = 7). Type V was found in only six dogs (3.1%) with unilateral differences in the diameter of the IJV. Six of 193 dogs had a combination of more than one variation (Type VI, 3.1%). Type I was significantly observed more frequently in meso- and dolichocephalic breeds. Type II was significantly observed more frequently in brachycephalic breeds.

Radiographic determination of the tracheal indices at caudal cervical, thoracic-inlet, and intra-thoracic trachea in non-bulldog brachycephalic breeds without evidence of cardiorespiratory disease.

BACKGROUND: Congenital tracheal hypoplasia is a component of airway syndrome affecting a wide variety of brachycephalic dog breeds. Several radiographic procedures were utilized to assess vertical tracheal diameter (VTD) in dogs. The objective of this study was to calculate the tracheal indices at the caudal cervical, thoracic-inlet, and intra-thoracic tracheal regions on the right lateral thoracic radiograph to further establish a screening protocol for diagnosis of tracheal hypoplasia in non-bulldog brachycephalic breeds. Dogs without clinical or radiographic evidence of tracheal, respiratory, or cardiovascular abnormalities were investigated. The absolute and average VTDs were normalized by manubrium length (ML), thoracic-inlet distance (Ti-D), and proximal 3rd rib width (PR3-W). Manubrium-tracheal index (M-TI), thoracic inlet-tracheal index (Ti-TI), and proximal R3-tracheal score (PR3-TS) were calculated. Correlations between averaged VTD and each of the normalizing parameters (ML, Ti-D, and PR3-W), and between M-TI and each of the previously established procedures (Ti-TI and PR3-TS) were determined. RESULTS: Eighty healthy subjects met the inclusion criteria for the study. There were significant differences (P ≤ 0.0001) among the means of absolute and normalized VTDs at the 3 tracheal levels. The smallest VTD was identified at the thoracic inlet. The average tracheal diameter showed a better correlation with ML (rs=0.81, P < 0.0001) compared to Ti-D and PR3-W. There was a strong correlation (rs=0.83, P < 0.0001) between the averaged M-TI and Ti-TI. CONCLUSION: Radiographic M-TI could be an alternative to traditional procedures to assess the tracheal lumen in non-bulldog brachycephalic dogs. M-TI < 0.39, < 0.30, or < 0.34 at caudal cervical, thoracic inlet, or intrathoracic trachea, respectively, may indicate tracheal hypoplasia in non-bulldog brachycephalic breeds. Screening of tracheal diameter using M-TI should be recommended. However, further investigation of non-bulldog brachycephalic breeds with cardiac and/or respiratory disease is indicated.

That brachycephalic look: Infant-like facial appearance in short-muzzled dog breeds.

Brachycephalic dog breeds are highly popular, yet their conformation-related disorders represent a major welfare concern. It has been suggested that the current popularity of such breeds can be explained by their cute, infant-like facial appearances. The concept of 'kindchenschema' refers to the observation that certain physical features of infant humans and other animals can automatically stimulate positive and nurturant feelings in adult observers. But the proposal that brachycephalic dogs possess heightened 'kindchenschema' facial features, even into adulthood, has never been formally investigated. Here, we hypothesised that relative muzzle shortening across a range of breeds would be associated with known 'kindchenschema' facial features, including a relatively larger forehead, larger eyes and smaller nose. Relative fronto-facial feature sizes in exemplar photographs of adult dogs from 42 popular breeds were measured and associated with existing data on the relative muzzle length and height-at-withers of the same breeds. Our results show that, in adulthood, shorter-muzzled breeds have relatively larger (taller) foreheads and relatively larger eyes (i.e. area of exposed eyeball relative to overall face area) than longer-muzzled breeds, and that this effect is independent of breed size. In sum, brachycephalic dog breeds do show exaggeration of some, but not all, known fronto-facial 'kindchenschema' features, and this may well contribute to their apparently cute appearance and to their current popularity as companion animals. We conclude that the challenge of addressing conformation-related disorders in companion dogs needs to take account of the cute, 'kindchenschema' looks that many owners are likely to be attracted to.

Comparison of habitual physical activity in French Bulldogs, Pugs and normocephalic dogs by accelerometry.

Brachycephalic obstructive airway syndrome (BOAS) is a major welfare concern in flat-faced dog breeds. As BOAS causes respiratory difficulties and exercise intolerance, it can reduce dogs' daily quality of life (QOL). However, evaluation of QOL in dogs is difficult, and many owners perceive BOAS signs as 'normal' for the breed. Accelerometers that measure frequency, duration and intensity of activities can offer an objective way of evaluating dogs' daily activity and thereby deliver potential insights into QOL. The aim of this study was to assess habitual physical activity of 48 brachycephalic and 23 non-brachycephalic dogs using accelerometers. The accelerometers were used for one week and owners filled in a questionnaire regarding their dog's well-being and activities. Veterinary-assessed BOAS grading for brachycephalic dogs was determined. Compared with controls, more severely affected French Bulldogs and Pugs had significantly lower total activity counts and spent less time in high activity. In Pugs, mildly affected dogs were also less active, but age can be a contributing factor here, as older age decreased activity in Pugs and controls showed a wider age range. In French Bulldogs, those dogs with no or mild signs of BOAS did not differ from controls regarding their daily activity. In conclusion, accelerometers were easy to use for objective measurement of daily activity in bracycephalic dogs, although a degree of discomfort due to the collar was reported. Results showed that BOAS signs were associated with decreased habitual physical activity. These findings emphasise the importance of actions taken to reduce incidence of BOAS in brachycephalic breeds.

Retrospective investigation of perioperative risk factors for immediate postoperative corneal erosions in dogs undergoing phacoemulsification.

OBJECTIVE: To characterize the incidence, contributing risk factors, and healing characteristics of immediate postoperative corneal erosions (IPCE) in dogs undergoing routine phacoemulsification. ANIMALS STUDIED: Medical records of 313 canine eyes (159 dogs) undergoing routine phacoemulsification surgery. PROCEDURES: Medical records of dogs undergoing planned cataract surgery at UW Veterinary Care were retrospectively reviewed. Patient-related variables including age, skull conformation, diabetes status, and cataract stage at the time of surgery were recorded. Intraoperative variables per eye were also recorded including surgical technique, surgeon expertise level, average phacoemulsification power, and phacoemulsification time. Diagnosis of IPCE ≤ 24 h after completion of surgery and time to IPCE healing were recorded where follow-up data were available. RESULTS: Immediate postoperative corneal erosions were observed in 48/313 (15.3%) operated eyes. The presence of diabetes mellitus or brachycephalic skull conformation, preoperative Schirmer tear test (STT) value, surgical technique and surgeon experience level, phacoemulsification time, and absolute phacoemulsification time were not statistically significant risk factors for IPCE. Average phacoemulsification power was associated with IPCE (RR 1.52, p = .001). Time to IPCE healing was similar in diabetic and non-diabetic dogs (median [IQR] 8 [6-11] days and 8 [6-15] days, respectively). Diabetes mellitus, brachycephaly, and phacoemulsification parameters were not associated with IPCE healing at 7 or 14 days postoperatively. CONCLUSIONS: Higher average phacoemulsification power may be associated with the development of IPCE in canine eyes. The presence of diabetes mellitus or brachycephaly are not risk factors for the development of IPCE, nor are they factors that influence IPCE healing.

Ocular surface physiology and aqueous tear secretion in cats of diverse cephalic conformations.

OBJECTIVE: To describe normative ocular surface and aqueous tear testing data for cats of various cephalic conformation. ANIMALS STUDIED: Fifty-three healthy adult cats (11 British Shorthair, 11 Burmese, 10 Devon Rex, 10 Scottish Fold, and 11 Sphynx). PROCEDURES: Blink rate, corneal tactile sensation (CTS), and Schirmer tear test with or without topical anesthesia (STT-1, STT-2) and with nasolacrimal stimulation (NL-STT1, NL-STT2) were assessed. Palpebral fissure length (PFL) and skull morphology were measured, and cephalic index (CI) and craniofacial ratio (CFR) calculated. RESULTS: Mean ± SD test results were as follows: blink rate (5.0 ± 2.3 blinks/min), CTS (3.2 ± 0.7 cm), STT-1 (11.2 ± 4.3 mm/min), STT-2 (6.7 ± 3.6 mm/min), NL-STT1 (13.4 ± 5.7 mm/min), NL-STT2 (13.5 ± 5.2 mm/min), and PFL (2.0 ± 0.2 cm). Corneal sensitivity did not differ significantly among breeds (p = .152) but was negatively correlated with body weight (r = -.32, p = .019). STT-1 significantly differed among breeds (p < .001) and was lowest in Sphynx cats (8.7 ± 4.3 mm/min). A positive correlation was detected between STT-1 values at 30 and 60 s (r = .98; p < .001). The nasolacrimal reflex significantly increased STT in anesthetized and unanesthetized eyes (approximately +100% and +20%, respectively; p ≤ .002). STT-1 tended to be higher in intact versus neutered cats (p = .062). Age did not impact any test result (p ≥ .085). CONCLUSIONS: Normative data described here serve as a baseline for future studies assessing ocular surface disease in multiple feline breeds. Unlike dogs, brachycephalic cats did not have lower CTS or STT-1 than non-brachycephalic cats.

Assessment of corneal and limbal epithelial thickness by spectral-domain optical coherence tomography in brachycephalic and non-brachycephalic dogs.

OBJECTIVE: To investigate the variance in corneal epithelial thickness (CET) and limbal epithelial thickness (LET) according to the age and skull type by using spectral-domain optical coherence tomography (SD-OCT) in normal dogs. ANIMALS AND PROCEDURES: This study used an eye each from 46 dogs (24 brachycephalic and 22 non-brachycephalic dogs) assessed to have clear corneas. Each dog was classified according to age into groups 1 (0-5 years), 2 (6-10 years), and 3 (>11 years). OCT imaging was performed on the central cornea for CET and perpendicular to the quadrant of the limbus for LET. The average of the maximum LET (maxLET) value was measured in four eye quadrants. RESULTS: Corneal epithelial thickness was not significantly different according to age in brachycephalic and non-brachycephalic dogs. Visualization of the limbal invagination was better when the maxLET was thick. Nasal and temporal maxLETs were significantly thicker than superior and inferior maxLETs in non-brachycephalic dogs. In brachycephalic dogs, there was a significant decrease in nasal maxLET with age (rs  = -0.489, p = .015). Significant differences between brachycephalic and non-brachycephalic dogs were observed in nasal maxLET (p = .024) and temporal maxLET (p = .011). CONCLUSIONS: Invagination was better visualized in the nasal and temporal limbal quadrants of non-brachycephalic dogs compared with brachycephalic dogs, and the maxLETs of the regions were thicker than those of the brachycephalic dogs. CET and LET measurements using SD-OCT can help in clinical assessment and research on ocular surface diseases in 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.

Epidemiology and clinical significance of canine distichiasis: A retrospective study of 291 cases.

OBJECTIVE: To describe the epidemiological factors and clinical significance of canine distichiasis. ANIMALS STUDIED: Two hundred and ninety-one client-owned dogs. METHODS: Retrospective study of medical records for canine patients diagnosed with distichiasis between 2010 and 2019 in an ophthalmology specialty practice. The breed, sex, skull conformation, coat type, age at the time of diagnosis, reason for presentation, clinical examination findings, and affected eyelid(s) were reviewed. RESULTS: The prevalence of distichiasis was 5.5% (95% confidence interval (CI): 4.9-6.1) in the population of dogs presented to an ophthalmology specialty practice. The breeds with the highest prevalence were English bulldogs (35.2%, 95% CI: 26.7-43.7) and American cocker spaniels (19.4%, 95% CI: 8.3-30.5). The prevalence was significantly higher in brachycephalic dogs (11.9%, 95% CI: 9.8-14.0) than in non-brachycephalic dogs (4.6%, 95% CI: 4.0-5.3) and in short-haired dogs (8.2%, 95% CI: 6.8-9.6) than in dogs with other coat types (5.3%, 95% CI: 4.5-6.1). Most dogs were affected bilaterally (63.6%, 95% CI: 58.0-69.1). Among dogs with clinical signs, 39.0% (95% CI: 26.5-51.4) exhibited corneal ulceration, including superficial ulcers (28.8%, 95% CI: 17.3-40.4) and deep stromal ulcers (10.2%, 95% CI: 2.5-17.8). Distichiasis was non-irritating in 85.0% (95% CI: 80.6-89.4) of affected dogs. CONCLUSION: This study reports the largest cohort of canine distichiasis to date. In a large proportion of dogs, distichiasis was a non-irritating condition. However, brachycephalic breeds, especially English bulldogs, were the most frequently and severely affected.