Schirmer tear test-1 with open or closed eyelids: An evaluation in brachycephalic and nonbrachycephalic dogs.

PURPOSE: Assess aqueous tear production when measured with the dogs' eyelids open or closed. METHODS: Thirty healthy dogs (15 Shih Tzus, 15 Labrador retrievers) were recruited. With the order of testing randomized for each dog, two sessions (separated by 30 min) of STT-1 testing were performed with the dogs' eyelids closed or open. Schirmer strip wetness (every 10 s for 60 s) and number of time(s) the strip dislodged during testing were recorded in each eye. Preferred STT-1 method was surveyed via a global Listserv of the veterinary ophthalmology community. RESULTS: STT-1 values were significantly higher in closed versus open eyes in Shih Tzus (18.6 ± 2.7 mm/min vs. 16.3 ± 2.5 mm/min; p = .002) and Labrador retrievers (21.6 ± 2.9 mm/min vs. 17.8 ± 3.2 mm/min, p < .001), findings that were also significant at times <60 s for either breed (p ≤ .004). Schirmer strips dislodged from six dogs with open eyelids and no dogs with closed eyelids. Maximal STT-1 difference with closed versus open eyelids was 13 mm/min in Labrador retrievers and 7 mm/min in Shih Tzus. Survey results from 275 veterinarians showed STT-1 performed with "closed eyelids" (38.5%), "open eyelids" (26.9%), or "never paid attention, sometimes closed, sometimes open" (34.6%). CONCLUSIONS: Eyelids status (closed or open) during STT-1 testing had a significant impact on aqueous tear secretion in brachycephalic and nonbrachycephalic dogs, highlighting the importance of consistency when repeating STT-1 in a canine patient. STT-1 differences are likely due to sustained reflex tearing throughout the test duration when the dogs' eyelids are closed.

Systemic absorption and gastrointestinal adverse effects from topical ketorolac and diclofenac ophthalmic solutions in healthy dogs.

OBJECTIVE: To investigate systemic absorption and gastrointestinal (GI) adverse effects of topical ketorolac 0.5% and diclofenac 0.1% ophthalmic solutions. ANIMALS: 11 healthy purpose-bred Beagles. METHODS: Dogs were randomly assigned to receive either ketorolac (n = 6) or diclofenac (5), 1 drop in both eyes 4 times daily for 28 days. Upper GI endoscopy was performed on days 0 and 29 with mucosal lesion scores (0 to 7) assigned to each region evaluated. Plasma samples were collected on days 14, 21, and 28 for measurement of diclofenac and ketorolac using high-performance liquid chromatography-mass spectrometry. RESULTS: GI erosions and/or ulcers developed in all ketorolac-treated dogs and 1 of 5 diclofenac-treated dogs. Post-treatment mucosal lesion score for the antrum was higher in the ketorolac group than in the diclofenac group (P = .006) but not significantly different for any other region. Post-treatment antral mucosal lesion scores were significantly related to plasma ketorolac concentrations (P < .001). Ketorolac and diclofenac were detected in the plasma at all time points (median ketorolac day 14, 191 ng/mL; day 21, 173.5 ng/mL; and day 28, 179.5 ng/mL; and median diclofenac day 14, 21.1 ng/mL; day 21, 20.6 ng/mL; day 28, 27.5 ng/mL). Vomiting and decreased appetite events were observed uncommonly and were not significantly different between treatment groups. CLINICAL RELEVANCE: GI ulceration and erosion developed after ophthalmic administration of ketorolac and diclofenac, with higher plasma concentrations and more severe GI lesions associated with ketorolac. Clients should be alerted to this potential risk with ophthalmic use and informed to watch for systemic clinical signs that would warrant veterinary reevaluation.

Using a smartphone-based digital fundus camera for screening of retinal and optic nerve diseases in veterinary medicine: A preliminary investigation.

BACKGROUND: Ophthalmoscopy is a valuable tool in clinical practice. We report the use of a novel smartphone-based handheld device for visualisation and photo-documentation of the ocular fundus in veterinary medicine. METHODS: Selected veterinary patients of a referral ophthalmology service were included if one or both eyes had clear ocular media, allowing for examination of the fundus. Following pharmacological mydriasis, fundic images were obtained with a handheld fundus camera (Volk VistaView). For comparison, the fundus of a subset of animals was also imaged with a veterinary-specific fundus camera (Optomed Smartscope VET2). RESULTS: The large field of view achieved by the Volk VistaView allowed for rapid and thorough observation of the ocular fundus in animals, providing a tool to visualise and record common pathologies of the posterior segment. Captured fundic images were sometimes overexposed, with the tapetal fundus artificially appearing hyperreflective when using the Volk VistaView camera, a finding that was less frequent when activating a 'veterinary mode' that reduced the sensitivity of the camera's sensor. The Volk VistaView compared well with the Optomed Smartscope VET2. LIMITATION: The main study limitation was the small sample size. CONCLUSIONS: The Volk VistaView camera was easy to use and provided good-quality fundic images in veterinary patients with healthy or diseased eyes, offering a wide field of view that was ideal for screening purposes.

Marginal resection and infracyanine green-mediated photodynamic therapy in the management of feline eyelid squamous cell carcinoma: Two cases.

OBJECTIVE: Describe the presenting features, surgical procedure, and clinical outcomes of two cats managed with marginal resection and photodynamic therapy (PDT) for eyelid squamous cell carcinoma (SCC). ANIMALS STUDIED: A 12-year-old female spayed domestic shorthair cat (case 1) and a 10-year-old female spayed domestic shorthair cat (case 2). PROCEDURES: Following marginal resection of the eyelid neoplasm, hemostasis was achieved using a handheld cautery unit then 1 mL of infracyanine green was injected into the surgical wound bed. Photodynamic therapy was performed using an 810 nm diode laser in two consecutive steps: (i) six cycles at 500 mW for 30 s per cycle, using a rapid movement; then (ii) one (case 1) or two cycles (case 2) of 30 s at 2000 mW, using a slow deliberate movement to effect (charred surface). RESULTS: Histopathology was consistent with SCC resected with incomplete margins in both cats. Follow-up duration was 416 and 161 days in case 1 and case 2, respectively. Consecutive exams and photo-documentation (in clinic or by owners) showed appropriate healing of the lower eyelid, with a smooth lid margin, and no evidence of tumor regrowth or ocular irritation. Subtle trichiasis was noted in case 1 on day 185, but not at the last follow-up. CONCLUSIONS AND CLINICAL RELEVANCE: Marginal resection followed by PDT may be a valid alternative to complete surgical resection of periocular SCC in cats. The procedure was easy to perform, post-operative recovery was uncomplicated, and neither cat developed recurrent disease during the follow-up period.

Increased drug concentration and repeated eye drop administration as strategies to optimize topical drug delivery: A fluorophotometric study in healthy dogs.

OBJECTIVES: Determine tear film kinetics with different fluorescein concentrations and repeated eye drop administration at various time intervals. ANIMALS STUDIED: Six healthy Beagles. PROCEDURES: Six experiments were conducted on separate days: single eye drop administration (control) or two separate eye drops administered at 30 s, 1, 2, 5, and 10 min intervals. For each experiment, one eye received 0.3% fluorescein solution while the other eye received 1% fluorescein solution, and tear fluid was collected with capillary tubes at 0, 1, 5, 10, 20, 30, 40, 50, 60, 90, 120, and 180 min. Fluorescein concentrations were measured using automated fluorophotometry. RESULTS: Compared with 0.3% solution, eyes receiving 1% fluorescein solution had significantly higher tear film concentrations (p ≤ .046) and the area-under-the-fluorescein-time curve was twofold greater (p = .005). Compared with control: (i) Tear film concentrations were significantly higher for up to 20 min when repeating administration 30 s to 5 min after the first drop (p ≤ .006); (ii) The highest increase in area-under-the-curve was obtained with 2 and 5 min intervals for 0.3% (+109%-130%) and 1% solutions (+153%-157%); (iii) The highest increase in median precorneal retention time (defined as tear film concentration < 5% from baseline values) was obtained with 5 min intervals for 0.3% (55 min vs. 15 min in control) and 2-5 min intervals for 1% solutions (50 min vs. 25 min in control). CONCLUSIONS: Drug delivery to the ocular surface can be enhanced by using more concentrated formulations and/or by repeating eye drop administration 2-5 min after the first dose.

Standard and modified glabellar flap for medial canthus reconstruction following mass removal in three dogs and two cats.

PURPOSE: To describe the surgical technique and clinical outcomes of the glabellar flap and its modification for the reconstruction of the medial canthus following resection of tumors in three dogs and two cats. METHODS: Three dogs (7-, 7-, and 12.5-year-old mixed breeds) and two cats (10- and 14-year-old Domestic shorthair) presented with a 7-13 mm tumor affecting the eyelid and/or conjunctiva in the medial canthal region. Following en bloc mass excision, an inverted V-shaped skin incision was made in the glabellar region (i.e., the area between the eyebrows in humans). The apex of the inverted V-shaped flap was rotated in three cases, whereas a horizontal sliding movement was performed in the other two cases to better cover the surgical wound. The surgical flap was then trimmed to fit the surgical wound and sutured in place in two layers (subcutaneous and cutaneous). RESULTS: Tumors were diagnosed as mast cell tumors (n = 3), amelanotic conjunctival melanoma (n = 1), and apocrine ductal adenoma (n = 1). No recurrence was noted in a follow-up time of 146 ± 84 days. Satisfactory cosmetic outcome with normal eyelids closure was achieved in all cases. Mild trichiasis was present in all patients and mild epiphora was noted in 2/5 patients, but there were no associated clinical signs such as discomfort or keratitis. CONCLUSIONS: The glabellar flap was easy to perform and provided a good outcome in terms of cosmetic, eyelid function, and corneal health. Postoperative complications from trichiasis appear to be minimized by the presence of the third eyelid in this region.

Accuracy of data in abstracts of veterinary ophthalmology research articles published in peer-reviewed journals.

OBJECTIVE: Assess the accuracy of abstracts in published veterinary ophthalmology articles. PROCEDURES: Abstracts and contents of 204 original research articles in veterinary ophthalmology published in seven peer-reviewed journals between 2016-2020 were reviewed. Abstracts were considered inconsistent if they contained data that were either missing from or inconsistent with corresponding data in the article's body. Each abstract was graded between 0 (inaccurate) to 3 (accurate), and each inconsistency was subjectively classified as minor or major. The influence of selected variables was assessed: journal, impact factor, year of publication, number of words in abstract, study type (prospective/retrospective), and characteristics of the corresponding author [institution (academia/private practice), country of domicile (native/non-native English), number of publications]. RESULTS: Most abstracts were accurate, with 1%, 4%, 9% and 86% receiving a score of 0, 1, 2 and 3, respectively. When detected, most inconsistencies were considered minor (77%). Although not statistically significant (p ≥ .130), the proportion of articles with a perfect score (=3) was higher in prospective (88%) vs. retrospective (81%) studies, academia (88%) vs. private practice (78%), and studies from corresponding authors domiciled in English (89%) vs. non-English (83%) speaking countries. A significant but very weak (r = -0.15 to -0.19; p ≤ .034) negative correlation was found between accuracy score and number of words, as well as 1-year and 5-year impact factors. CONCLUSIONS: Although relatively uncommon, data in abstracts that are inconsistent or missing from the article's body do occur in veterinary ophthalmology articles, and could adversely influence a reader's interpretation of study findings.

Symblepharon in kittens: a retrospective study of 40 kittens and 54 eyes (2002-2022).

OBJECTIVES: The aim of this study was to retrospectively evaluate the signalment, treatment, surgical technique and outcomes for feline symblepharon. METHODS: A retrospective medical record review and standardized grading of clinical descriptions and photographs was undertaken. RESULTS: Forty kittens (54 eyes) aged 3-46 weeks had symblepharon of five types in various combinations: eyelid deformation (24 kittens; 32 eyes); ankyloblepharon (four kittens; four eyes); conjunctiva-to-conjunctiva (11 kittens; 12 eyes); third eyelid-to-conjunctiva (24 kittens; 29 eyes); and corneoconjunctival adhesions (14 kittens; 16 eyes). At initial presentation, 23 (43%) eyes were affected by one type of symblepharon, 25 (46%) eyes by two types and six (11%) eyes by three types; 11 (20%) corneas were ulcerated. Twenty-four (44%) eyes of 18 (45%) kittens were managed medically. Surgery was performed under general anesthesia/sedation (30 occasions) or topical anesthesia (21 occasions) on 30 (56%) eyes of 22 kittens; 12 eyes (40%) underwent multiple surgeries. Four techniques were commonly employed: separation of conjunctival-to-conjunctival adhesions ± eyelid margins (14 eyes); resection of third eyelid adhesions ± temporary tacking of the third eyelid (modified Arlt's pterygium technique; 18 eyes); en bloc resection of the third eyelid (two eyes); and separation of corneoconjunctival adhesions (14 eyes). Median duration of follow-up was 55 days (range 1-1051). Median symblepharon grade in kittens treated surgically improved for all types except corneoconjunctival symblepharon. Median symblepharon grade in kittens receiving medical management remained the same or improved. Corneoconjunctival symblepharon opacity decreased for eyes treated surgically but increased for eyes treated medically. Three eyes were enucleated due to complications of corneoconjunctival symblepharon. At final presentation, symblepharon persisted in 46 (85%) eyes; however, menace response was evident in 13/16 eyes and dazzle reflex in 23/23 eyes. CONCLUSIONS AND RELEVANCE: Symblepharon is a heterogeneous group of conditions with diverse anatomic involvement, clinical appearance and impact, optimal treatment and prognosis for vision.

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.

A review of diagnostic tests for qualitative and quantitative tear film deficiency in dogs.

Dry eye disease (DED) is a complex multifactorial condition caused by loss of ocular surface homeostasis from quantitative and/or qualitative tear film deficiency. Schirmer tear test (STT) is often the only diagnostic test used to assess for DED in veterinary practice. STT is invaluable in the diagnosis and monitoring of quantitative tear film deficiency (i.e., keratoconjunctivitis sicca); however, it is not sufficient to optimize therapy and fully recognize other contributing factors for the disturbance in ocular surface homeostasis. The present work reviews diagnostic tests for assessing aqueous tear production in veterinary medicine, as well as the quality of tears, corneal epithelial barrier integrity, and the lacrimal functional unit.

The pandemic of ocular surface disease in brachycephalic dogs: The brachycephalic ocular syndrome.

Brachycephalic dog breeds are popular around the world, yet many brachycephalic dogs are affected by numerous health problems, including several head-related diseases that are directly linked to their conformation. In addition to the well-recognized disorders associated with the respiratory system (brachycephalic obstructive airway syndrome, i.e., BOAS), brachycephalic dogs have a concerningly high prevalence of ocular surface disorders that can cause chronic discomfort, loss of the globe, and/or require long-term, daily therapy. This review offers a summary of the physiological and anatomical features of brachycephalic ocular syndrome (BOS) that predispose brachycephalic dogs to develop ocular surface disease, followed by a concise description of common ocular diseases associated with BOS. It ends with an overview of evidence-based guidelines and animal welfare legislation that some in the veterinary community have already implemented but that requires a wider, international effort in order to reduce the prevalence of BOS-associated disorders and improve the ocular health of affected dogs.

An eye on the Shih Tzu dog: Ophthalmic examination findings and ocular surface diagnostics.

OBJECTIVE: To characterize the ocular surface parameters and determine the prevalence of ocular pathology in Shih Tzu dogs. ANIMAL STUDIED: Fifty Shih Tzu dogs (28 male, 22 female). PROCEDURES: Each dog underwent a complete ophthalmic examination (recording any pathology) and a series of diagnostics, allowing for a 10 min-interval between tests: intraocular pressure (IOP), blink rate, palpebral fissure length (PFL), corneal tactile sensation (CTS), Schirmer tear test and nasolacrimal reflex without (STT-1, NL-STT1) and with topical anesthesia (STT-2, NL-STT2), tear ferning, strip meniscometry test (SMT), tear film breakup time (TFBUT), and punctate fluorescein staining (PFS) of the cornea. RESULTS: Mean ± SD test values were as follows: IOP (17.9 ± 3.7 mmHg), blink rate (2.4 ± 1.4 blinks/min), PFL (23.8 ± 1.8 mm), CTS (1.8 ± 0.7 cm), STT-1 (22.0 ± 5.5 mm/min), NL-STT1 (24.2 ± 4.7 mm/min), STT-2 (16.9 ± 6.5 mm/min), NL-STT2 (18.5 ± 7.5 mm/min), SMT (7.5 ± 3.5 mm/5 s), TFBUT (5.3 ± 2.4 s), tear ferning (1.3 ± 0.7), and PFS (1.6 ± 0.6). PFL was significantly greater in male vs. female Shih Tzus (p< .001). Age was negatively correlated with TFBUT results (r = -0.31, p = .027). Lagophthalmos was observed in 82% eyes. Ocular surface pathology was common, including adnexal abnormalities (100% eyes with caruncular trichiasis and medial lower lid entropion) and corneal opacification (27% pigmentation, 20% fibrosis, 12% neovascularization). CONCLUSIONS: Qualitative tear film deficiency (low TFBUT), along with several anatomical abnormalities that promote ocular irritation and reduce globe protection, together help explain the concerningly high prevalence of ocular surface disease in the Shih Tzu breed. Prophylactic measures (e.g., medial canthoplasty, topical lubrication) could be considered to improve ocular health in Shih Tzus.

Role of Inflammation in Canine Primary Glaucoma.

Primary glaucoma is a painful, progressive, and blinding disease reported in many canine breeds, characterized by intraocular pressure (IOP) elevation in the absence of antecedent intraocular disease. Clinical observations of dogs with primary glaucoma suggest that many affected eyes develop concurrent intraocular inflammation in addition to elevated IOP. In this work, we summarize the current knowledge that relates inflammation to primary glaucoma in dogs, reviewing studies focused on genetics, physiology, histopathology, bioanalysis of ocular fluids, therapeutics, and clinical outcomes of glaucomatous patients. Through disruption of the blood-aqueous and blood-retinal barriers, pigment dispersion, and biochemical changes to the aqueous humor and tear film, the pathogenesis of canine primary glaucoma appears to involve inflammatory changes to various extents and with various consequences from the front to the back of the eye. Among others, inflammation further impacts IOP by reducing aqueous humor outflow at the level of the iridocorneal angle and accelerates vision loss by promoting neuronal degeneration. As such, the vicious cycle of ocular inflammation and IOP elevation might warrant the use of anti-inflammatory medications as a core component of the treatment regime for dogs with primary glaucoma, either therapeutically (i.e., actively glaucomatous eye) or prophylactically in the yet unaffected contralateral eye.

Incidence of concurrent systemic injuries with traumatic proptosis and its effect on outcome - 100 dogs.

Objective: To evaluate the incidence of concurrent systemic injuries in dogs with traumatic ocular proptosis and their effect on survival to discharge. Additionally, to evaluate for associations between the type of trauma, each presenting vital signs, minimum laboratory database findings including packed cell volume, total solids, plasma glucose and lactate concentrations, and the diagnosis of concurrent systemic injury and survival. Design: Retrospective study between the years 2017 and 2022. Setting: One university teaching hospital and one large, private practice. Animals: One hundred dogs presenting to the hospital with a diagnosis of traumatic ocular proptosis. Measurements and main results: Medical records were retrospectively reviewed; signalment, breed, sex, age, weight, date of presentation, type of trauma sustained, time from trauma to presentation, vitals on presentation, and minimum laboratory database findings including packed cell volume (PCV), total solids (TS), plasma glucose concentration, and plasma lactate concentration were recorded. A modified animal trauma triage (ATT) score was retrospectively calculated. A total of 17 dogs (17%) had concurrent systemic injury. Compared to dogs without systemic injuries, dogs with systemic injuries had a significantly lower body temperature [median 101.1F (38.3C) vs. 101.6F (38.6C); P = 0.008], significantly higher plasma glucose concentrations (125 mg/dL, 6.9 mmol/L vs. 112 mg/dL, 6.2 mmol/L; P = 0.012) and approaching statistical significance, lower PCV values (median 40 vs. 46%; P = 0.051). Conclusions: Dogs presenting with traumatic ocular proptosis do present with concurrent systemic, non-ocular injuries; however, these concurrent injuries do not seem to be associated with survival to discharge.

Impact of multi-drug resistance on clinical outcomes of dogs with corneal ulcers infected with Staphylococcus pseudintermedius.

Objective: Compare characteristics and clinical outcomes of dogs with infectious keratitis from Staphylococcus pseudintermedius considered to be multidrug-resistant (MDR) or not. Procedures: Staphylococcus pseudintermedius isolated as the primary pathogen from canine patients with ulcerative keratitis were considered MDR if resistant to at least one agent in three or more classes of antibiotics. Medical records were reviewed for history, patients' characteristics, clinical appearance, therapeutic interventions, and clinical outcomes. Results: Twenty-eight dogs (28 eyes) were included. Compared to non-MDR cases, MDR diagnosis was significantly more common in dogs with recent (≤30 days) anesthesia (7/15 vs. 1/13, P = 0.038) and more common in non-brachycephalic dogs (8/15 vs. 2/13, P = 0.055). Clinical appearance (ulcer size/depth, anterior chamber reaction, etc.) did not differ significantly between groups (P ≥ 0.055). Median (range) time to re-epithelialization was longer in MDR vs. non-MDR eyes [29 (10-47) vs. 22 (7-42) days] but the difference was not significant (P = 0.301). Follow-up time was significantly longer in dogs with MDR keratitis [47 (29-590) vs. 29 (13-148) days, P = 0.009]. No other significant differences were noted between MDR and non-MDR eyes in regard to time for ulcer stabilization [4 (1-17) days vs. 4 (1-12), P = 0.699], number of eyes requiring surgical stabilization (7/15 vs. 7/13, P = 0.246) or enucleation (1/15 vs. 2/13, P = 1.000), success in maintaining globe (14/15 vs. 11/13, P = 0.583) or success in maintaining vision (12/15 vs. 10/13, P = 1.000). Conclusions: MDR infections may prolong corneal healing time but did not appear to affect overall clinical outcomes in dogs with bacterial keratitis. Further research is warranted in a larger canine population and other bacterial species.

Culture and characterization of canine and feline corneal epithelial organoids: A new tool for the study and treatment of corneal diseases.

In this study, we isolated and cultured canine and feline 3D corneal organoids. Samples derived from corneal limbal epithelium from one canine and one feline patient were obtained by enucleation after euthanasia. Stem cell isolation and organoid culture were performed by culturing organoids in Matrigel. Organoids were subsequently embedded in paraffin for further characterization. The expression of key corneal epithelial and stromal cell markers in canine and feline organoids was evaluated at the mRNA level by RNA-ISH and at the protein level by immunofluorescence (IF) and immunohistochemistry (IHC), while histochemical analysis was performed on both tissues and organoids using periodic-acid Schiff (PAS), Sirius Red, Gomori's Trichrome, and Colloidal Iron stains. IF showed consistent expression of AQP1 within canine and feline organoids and tissues. P63 was present in canine tissues, canine organoids, and feline tissues, but not in feline organoids. Results from IHC staining further confirmed the primarily epithelial origin of the organoids. Canine and feline 3D corneal organoids can successfully be cultured and maintained and express epithelial and stem cell progenitor markers typical of the cornea. This novel in vitro model can be used in veterinary ophthalmology disease modeling, corneal drug testing, and regenerative medicine.

Kinetics and minimal inhibitory concentrations of ceftiofur in tear film following extended-release parenteral administration (Excede®) in dogs.

Purpose: Describe the pharmacokinetics of extended-release parenteral ceftiofur (Excede®) in canine tear film and compare these concentrations to minimal inhibitory concentrations (MICs) of ceftiofur against common ocular pathogens in dogs. Method: Six dogs of various breeds were enrolled. Disruption of blood-tear barrier was achieved with histamine-induced conjunctivitis to ensure clinical relevance of the results. Each dog received a single subcutaneous injection of 5 mg/kg Excede®, followed by tear collection with Schirmer strips at times 0, 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36, 48, 72, 96, 120, 144, 168, 192, 216 and 240 h. Drug quantification was performed with liquid chromatography-mass spectrometry. MICs were determined for Staphylococcus pseudintermedius, Streptococcus canis and Pseudomonas aeruginosa by assessing bacterial growth (n = 10 per bacterial species) in the presence of ceftiofur at increasing concentrations. Results: Blood-tear barrier breakdown provided tear film concentrations of ceftiofur 3.2-28.9-fold higher than in the contralateral healthy eye (n = 1 dog, pilot experiment). In all six dogs, ceftiofur concentrations in tears varied from 2.3 to 637.5 ng/mL and were detectable up to 10 days (240 h) after subcutaneous injection. However, tear levels always remained below MICs for common ocular isolates (≥640 ng/mL). Conclusions: Ceftiofur reached the tear compartment (for up to 10 days) after a single parenteral injection, however tear concentrations were extremely variable and too low to be effective against common bacterial pathogens in dogs. Further studies with different ceftiofur dosage or other long-acting injectable antibiotics are warranted.

Effect of topical nitric oxide donors 0.03% nitroglycerin and 0.1% hydralazine on intraocular pressure in healthy canine eyes.

OBJECTIVE: To investigate the potential intraocular pressure (IOP)-lowering effects of nitric oxide (NO)-donating compounds in healthy canine eyes METHODS: A total of 79 dogs were divided into 3 groups in a masked, controlled and randomised study. Group N (n = 26) was administered 0.03% nitroglycerin in one eye and vehicle-control in the other, Group H (n = 26) was administered 0.1% hydralazine in one eye and vehicle-control in the other, while Group C (n = 27) received vehicle-control in both eyes (control group). Following eye drop administration, IOP was measured in both eyes at selected times (10-250 min), along with monitoring of heart rate and signs of ocular discomfort. Data was analysed with repeated measures mixed model and one-way ANOVA RESULTS: IOP was significantly reduced over the 4-h period with 0.03% nitroglycerin (p < 0.0001) but not 0.1% hydralazine (p = 0.520) when compared to contralateral vehicle-controlled eyes. IOP was reduced by up to 12% with 0.03% nitroglycerin from 10 to 70 min post-treatment; however, differences in IOP at individual time points were not statistically significant for either drug (p ≥ 0.133) as compared to contralateral vehicle-control eyes. No treatment group significantly affected heart rate (compared to Group C), and both treatment groups appeared well tolerated CONCLUSIONS: Both compounds were well-tolerated in healthy dogs. Nitroglycerin mildly reduced IOP in canine eyes, and further investigations are warranted in healthy and diseased states (e.g. glaucoma, ocular hypertension).

Prevalence and characteristics of ocular diseases in Sphynx cats: A retrospective assessment (2012-2021) and comparison with non-Sphynx cats.

PURPOSE: To describe the prevalence of ocular diseases in Sphynx cats, and compare disease characteristics with other feline breeds. METHODS: Medical records of Sphynx cats presented to an ophthalmology referral center between 1/2012 and 4/2021 were examined. Cats of other breeds examined during the same period served as controls. RESULTS: One hundred ten Sphynx cats were examined during the study period, diagnosed with corneal sequestrum (n = 42 cats), lower eyelid entropion (n = 25), presumed herpetic keratoconjunctivitis (n = 19), conjunctivitis (n = 7), corneal ulcers (n = 6), nasolacrimal duct atresia/obstruction (n = 6), corneal dystrophy (n = 3), eosinophilic keratitis (n = 2), uveitis (n = 2), non-ulcerative keratitis (n = 1), and cataract (n = 1). Corneal sequestrum was significantly more common in Sphynx versus non-Sphynx cats (odds ratio = 8.0, 95% CI = 5.3-12.2, p < .001), and age of diagnosis was significantly younger in Sphynx cats (2.0 ± 1.5 years vs. 5.9 ± 4.0 years, p < .001). Corneal sequestrum recurrence was noted in 19.4% Sphynx eyes and 6.4% non-Sphynx eyes undergoing surgery (p = .015). Lower eyelid entropion-most often bilateral (80%)-was significantly more common in Sphynx versus non-Sphynx cats (odds ratio = 4.1, 95% CI = 2.3-7.1, p < .001), and age of diagnosis was significantly younger in Sphynx cats (0.9 ± 1.4 years vs. 3.5 ± 3.3 years, p < .005). CONCLUSIONS: Corneal sequestrum and entropion were overrepresented and diagnosed at an earlier age in Sphynx cats when compared with the general feline population. Given the high prevalence, early age of onset, and relatively high recurrence of corneal sequestrum in Sphynx cats, further studies are warranted to better understand etiopathogenesis and preferred therapies.