Clinical and pathological characterization of ophthalmic disease in a canine model of mucopolysaccharidosis type I.

Mucopolysaccharidosis type I (MPS I) is a rare lysosomal storage disease caused by α-L-iduronidase enzyme deficiency, resulting in glycosaminoglycan (GAG) accumulation in various cell types, including ocular tissues. Ocular manifestations in humans are common with significant pathological changes including corneal opacification, retinopathy, optic nerve swelling and atrophy, and glaucoma. Available treatments for MPS I are suboptimal and there is limited to no effect in treating the ocular disease. The goal of this study was to characterize the clinical and pathological features of ocular disease in a line of MPS I affected dogs, including changes not previously reported. A total of 22 dogs were studied; 12 MPS I were affected and 10 were unaffected. A subset of each underwent complete ophthalmic examination including slit lamp biomicroscopy, indirect ophthalmoscopy, rebound tonometry, and ultrasonic pachymetry. Globes were evaluated microscopically for morphological changes and GAG accumulation. Clinical corneal abnormalities in affected dogs included edema, neovascularization, fibrosis, and marked stromal thickening. Intraocular pressures were within reference interval for affected and unaffected dogs. Microscopically, vacuolated cells containing alcian blue positive inclusions were detected within the corneal stroma, iris, ciliary body, sclera, and optic nerve meninges of affected dogs. Ganglioside accumulation was identified by luxol fast blue staining in rare retinal ganglion cells. Increased lysosomal integral membrane protein-2 expression was demonstrated within the retina of affected animals when compared to unaffected controls. Results of this study further characterize ocular pathology in the canine model of MPS I and provide foundational data for future therapeutic efficacy studies.

Interleukin-6 and lactate dehydrogenase expression in a novel ex vivo rocking model of equine corneal epithelial wound healing.

PURPOSE: To establish a physiologically relevant ex vivo model of equine corneal epithelial wound healing. METHODS: Fourteen equine corneas were randomly assigned to one of two groups: wounded (n = 8) or unwounded (n = 6) controls. In the wounded group, the axial corneal epithelium was removed by applying a 6 mm filter paper disk soaked in 1N-NaOH for 60 s. Corneas were subsequently cultured using an air-liquid interface model. Evaluation of corneal healing was performed daily, and culture medium was collected. Corneas were randomly assigned to undergo processing via histopathology and RNAscope in situ hybridization for interleukin-6 (IL-6) and alpha-smooth muscle actin (αSMA) expression at T24, T48, and T72 h after wounding. Media of the cultured corneas were evaluated for the presence of lactate dehydrogenase (LDH) by a colorimetric assay. RESULTS: The ulcerated area of the wounded corneas decreased over time and all corneas healed within 72 h. Histologically, normal corneal architecture was observed including healthy epithelium (in areas other than the ulcerated ones), minimal stromal edema, intact endothelium, and Descemet's membrane. IL-6 expression was increased in wounded corneas compared with unwounded controls. LDH expression was elevated for both wounded and unwounded corneas at T24 but decreased substantially and was not detected at T48 in media from wounded and unwounded corneas, respectively. No αSMA expression was detected from either wounded or unwounded corneas. CONCLUSIONS: The equine air-liquid interface, ex vivo, corneal epithelial wound healing model is effective and physiologically relevant. This model can be used in future studies evaluating various corneal therapies.

Estimation of intraocular pressure in normal canine eyes utilizing the newly introduced TonoVet Plus and TonoPen Avia, and their comparison to the established TonoVet.

PURPOSE: To evaluate the IOP values obtained from normal canine eyes, by means of the TonoVet Plus (TVP) and TonoPen Avia (TPA), and compare them to an established tonometer, the TonoVet (TV). METHODS: Tonometry was performed bilaterally in 50 healthy dogs, age 1-11 years. The rebound tonometers (TV and TVP) were used first (in a random order), and then, one drop of tetracaine hydrochloride was applied to each eye, and approximately one minute later the IOP was estimated using the TPA. The mean ± standard deviation (SD) was calculated for each tonometer and a paired Student's t test was used to compare the IOP values between tonometers. A P value ≤ .05 was considered significant. The agreement between tonometers was assessed by a Bland-Altman plot. RESULTS: The mean ± SD (range) IOP values were 15.0 ± 3.2 mm Hg (7-22), 19.2 ± 3.1 mm Hg (11-25), and 12.8 ± 2.9 mm Hg (6-19), for the TV, TVP, and TPA, respectively. The IOP values obtained by each tonometer were significantly different compared to the other two (P < .0001). There was a good agreement with fixed bias between all tonometers. CONCLUSIONS: The average IOP values of the TVP were significantly higher than those of the TV, which were significantly higher than those of the TPA, in normal canine eyes. Knowing the normal IOP values for these tonometers and the bias between them will help the clinician with the interpretation of IOP values obtained by these devices and compare between them.

Novel use of a combination of extracellular matrices for wound healing following resection of a large inferior eyelid mass in a miniature Hereford.

CASE DESCRIPTION: A 9-month-old miniature Hereford heifer was evaluated for a mass on the right inferior eyelid that had progressed in size over 3 months. CLINICAL FINDINGS: Physical examination revealed a firm, ulcerated, pedunculated mass on the right inferior eyelid that extended from the medial quarter to beyond the lateral canthus of the eye. The base of the mass measured 7.4 × 6.7 cm, and the dorsal margin of the base of the mass was approximately 3 mm ventral to the inferior eyelid margin. Histologic evaluation of incisional biopsy specimens from the mass was consistent with fibrosarcoma. TREATMENT AND OUTCOME: The mass was surgically resected with care taken to preserve the eyelid margin. The resulting 10 × 8.5-cm surgical wound was treated with adjunct CO2 laser therapy and closed by primary closure at its medial and central aspects and placement of a 4.6 × 2.6-cm lyophilized equine amnion multilayer graft and 2 sheets of 4-ply porcine small intestinal submucosa at its lateral aspect. The grafts were kept moist by alternating topical antimicrobial and artificial tear ointments for 3 weeks. The wound healed without complications, resulting in a functional and aesthetically pleasing outcome despite the development of moderate ectropion at the lateral aspect of the inferior eyelid. CLINICAL RELEVANCE: Results suggested that a combination of extracellular matrix scaffolds may be an alternative to extensive skin flaps for management of large dermal wounds, particularly wounds resulting from blepharoplasty where preservation of an eyelid margin is desired.

Soft Contact Lens with Embedded Microtubes for Sustained and Self-Adaptive Drug Delivery for Glaucoma Treatment.

Because of the physiological and anatomical constraints of the eye, ophthalmic drug delivery is challenging. When applied topically, less than 1% of administered ophthalmic drugs reach the aqueous humor. The delivery of a drug within an efficient therapeutic concentration, to the required site of action, for an extended period of time, is complicated. Herein, a novel type of contact lens device, with embedded microtubes as drug containers, is reported. This device can provide a simple, noninvasive, extended drug release up to 45 days with higher bioavailability and lower risk for adverse effects. Another unique feature of the device is the release of drug triggered by stretching of the contact lens, indicating the possibility for achieving a self-adaptive drug release device for treating glaucoma patients.

Electrolyte composition of tears in normal dogs and its comparison to serum and plasma.

PURPOSE: The dog is an important animal model for tear dysfunction diseases, however to-date the electrolyte composition of the dog's tears is unknown. The aim of this study was to analyze the electrolyte content of canine tears and compare it to serum and plasma. METHODS: Tear samples were collected from 18 eyes of 9 dogs. Blood for serum was collected in tubes with no anticoagulants; plasma was obtained by using two different anticoagulants: Citrate-Phosphate-Dextrose (CPD) and heparin. The electrolytes were measured in all samples, analyzed, and compared. RESULTS: Most of the electrolyte values in tears were statistically different (P < 0.05) from electrolyte values in serum and plasma. Potassium and chloride values were significantly higher in tears compared to serum and plasma, while calcium and phosphate values were significantly lower. Sodium values in tears were higher than in serum and heparinized-plasma, but lower than CPD-plasma. Bicarbonate values were lower in tears compared to serum and heparinized plasma, but was not statistically different than CPD-plasma. While magnesium values were lower in tears compared to serum and heparinized-plasma, the difference was not statistically different. CONCLUSIONS: Herein, we report for the first time the electrolyte composition of the canine tears and its comparison to serum and plasma.

Fluorophotometric Assessment of Tear Volume and Turnover Rate in Healthy Dogs and Cats.

Purpose: The study establishes normative data of tear volume (TV) and tear turnover rate (TTR) in healthy dogs and cats, 2 species commonly used for translational research in ophthalmology. Methods: Thirty-six dogs and 24 cats were enrolled, encompassing a variety of breeds with diverse skull conformations (brachycephalic, mesocephalic, and dolichocephalic). Two microliters of 10% fluorescein were instilled onto the upper bulbar conjunctiva of both eyes, followed by tear collection with 2-µL capillary tubes at 0, 2, 4, 6, 10, 15, and 20 min. Fluorescein concentrations were measured with a computerized scanning ocular fluorophotometer. The TV and TTR were estimated based upon nonlinear mixed-effects analysis of fluorescein decay curves. Results: In dogs, median (interquartile range) TV, basal TTR (bTTR), and reflex TTR (rTTR) were 65.3 µL (42.3-87.9), 12.2%/min (3.7-22.1), and 50.0%/min (25.9-172.3), respectively. In cats, median (interquartile range) TV, bTTR, and rTTR were 32.1 µL (29.5-39.9), 10.9%/min (3.0-23.7), and 50.0%/min (28.4-89.4), respectively. Body weight (r = 0.44) and age (r = 0.30) were positively correlated (P ≤ 0.019) with TV in dogs. Age was negatively correlated (P ≤ 0.018) with TTR in dogs (r = -0.33) and cats (r = -0.24). However, TV and TTR were not associated with skull conformation in either species. Conclusions: Dogs have greater TV than cats but similar basal and rTTR. Tear parameters were impacted by body weight and age, but not by skull conformation. In both clinical and research settings, successive lacrimal tests should be spaced by ≥10 min to provide sufficient time for the tear film to replenish, as bTTR is ∼11%/min-12%/min in both species.

MicroPulse™ transscleral cyclophotocoagulation in the treatment of canine glaucoma: Preliminary results (12 dogs).

OBJECTIVE: To describe the clinical application and effect of MicroPulse™ transscleral cyclophotocoagulation (MP-TSCPC) in dogs with glaucoma. ANIMALS STUDIED: Twelve dogs with primary (n = 8) or secondary (n = 4) glaucoma, aged 2-13 years (mean ± SD, 7.2 ± 3.8 years). PROCEDURES: MP-TSCPC was performed under sedation or general anesthesia. Laser duty cycle was 31.3%, laser power varied from 2000-2800 mW, and each hemisphere was treated for 90-180 seconds. The probe was applied to each quadrant in a "sweeping motion," sparing the 3 and 9 o'clock positions. RESULTS: The number of MP-TSCPC procedures per eye varied from 1 to 3 (1.4 ± 0.7). Intraocular pressure (IOP) was controlled (<25 mm Hg) in 11/12 dogs (92%) within 1-15 days post-operatively. The IOP control at 1 month and the duration between repeated procedures were significantly greater in eyes treated with high energy laser (2800 mW) compared to 2000-2500 mW. Long-term follow-up (315.3 ± 100.7 days) showed controlled IOP in 5/12 (42%) and vision retention in 4/8 (50%) dogs. In unsuccessful cases, loss of IOP control or vision loss occurred within 3-245 days (109.1 ± 93.7 days) and 28-261 days (114 ± 101.6 days), respectively, resulting in a salvage procedure in 6 dogs. Complications were as follows: corneal hypoesthesia (92%), anterior uveitis (67%), post-operative ocular hypertension (50%), neurotrophic corneal ulcer (25%), keratoconjunctivitis sicca (8%), and rubeosis iridis (8%). CONCLUSIONS: MP-TSCPC is a viable tool for managing canine glaucoma, although further studies are required to improve the long-term effect and reduce the complication rate.

Evaluation of microbial contamination of canine plasma eyedropper bottles following clinical use in canine patients.

OBJECTIVE: To investigate microbial contamination of canine plasma eye drops when used clinically and to compare the effect of two different eyedropper bottles on contamination rate. METHODS: Forty-six bottles containing plasma were randomly dispensed for use on 42 dogs with ulcerative keratitis. Of these, 23 were standard eyedropper bottles and 23 were Novelia® bottles designed to prevent contamination. After use for up to 2 weeks, samples for bacterial culture were obtained from a drop of plasma, the bottle tip, the plasma inside the bottle, and the corneal surface. Fungal culture was performed from a drop of plasma. RESULTS: The overall microbial contamination rate was 17.4% (8/46 bottles); however, only one bottle had growth from the plasma inside the bottle. There was a lower contamination rate of Novelia® bottles (3/23 = 13.0%) compared to standard bottles (5/23 = 21.7%), but this difference was not statistically significant (P = .57). There were also no significant differences in contamination rate of bottles used greater than 7 days compared to less than or equal to 7 days, or in bottles used greater than 4 times daily compared to 4 times daily or less. Three corneal samples (6.5%) had bacterial growth, but none matched contamination from the bottles. CONCLUSIONS: Novelia® bottles may decrease contamination of plasma eye drops used clinically. However, while microbial contamination of plasma bottles was documented, no clinically relevant complications were observed. This study supports safe use of plasma eye drops for up to 2 weeks when refrigerated and dispensed from either Novelia® or standard eyedropper bottles.

Canine oral mucosa evaluation as a potential autograft tissue for the treatment of unresponsive keratoconjunctivitis sicca.

PURPOSE: Labial mucosa transplantation for the treatment of canine keratoconjunctivitis sicca (KCS) has been reported recently. Postoperative alleviation of clinical signs was noted and assumed to be the result of labial salivary glands providing lubrication to the ocular tissue. The aim of this study was to evaluate the presence of minor salivary glands (MSG) in the canine oral mucosa. METHODS: Oral mucosal biopsies were collected from six dogs that died (n = 1) or were euthanized (n = 5) for reasons unrelated to this study. The breeds included were two Doberman Pinschers, one Labrador Retriever, one Portuguese Water Dog, one German Shepherd Dog, and one mixed canine. Three were spayed females, and three were castrated males with the median age of 9 years (range, 6-13 years). Samples were obtained by an 8-mm punch biopsy at the following locations of the canine oral cavity: upper rostral labial mucosa at midline, lower rostral labial mucosa at midline, upper labial mucosa near the commissure, lower labial mucosa near the commissure, and buccal mucosa approximately 1 cm caudal to the commissure. Samples were routinely processed with hematoxylin and eosin, and periodic acid-Schiff stains. Samples were evaluated by light microscopy. RESULTS: At the selected locations, no MSG or other secreting cells were detected. CONCLUSIONS: Minor salivary glands are not associated with alleviation of canine KCS symptoms following labial mucosa transplantation. Further studies are needed to determine the mechanism leading to the transient improvement of KCS symptoms in canine patients following labial mucosa transplantation.

The post-natal development of intraocular pressure in normal domestic cats (Felis catus) and in feline congenital glaucoma.

Intraocular pressure (IOP) is the most consistent risk factor for progressive vision loss in glaucoma. Cats with recessively inherited feline congenital glaucoma (FCG) exhibit elevated IOP with gradual, painless progression of glaucoma similar to humans and are studied as a model of glaucoma in humans and animals. Here, post-natal development of IOP was characterized in normal domestic cats and in cats with FCG caused by a homozygous LTBP2 mutation. Rebound tonometry (TonoVet®, ICare Oy, Finland) was used to measure IOP non-invasively, 2-3 times weekly in 63 FCG and 33 normal kittens, of both sexes, from eyelid opening until 3-6 months of age. IOPs in the left and right eyes of both FCG and normal kittens were compared by paired t-test and linear regression. One-way ANOVA and Tukey-Kramer post-tests were used to compare IOP of cats grouped by age and disease status. A p-value <0.05 was considered significant. In the second week of life, mean IOP was 7.16 mmHg (SD = 1.3) in normal kittens and 8.72 mmHg (SD = 1.4) in kittens with FCG. Mean IOP at age 10 weeks was significantly higher in FCG (19.8 mmHg; 95% CI = 17.7, 21.9  mmHg) than in normal kittens (13.2 mmHg; 95% CI = 11.9, 14.5  mmHg). At 3 months of age, IOP in normal cats reached adult values while IOP in FCG cats continued to increase through at least six months of age. These results provide ranges for normal IOP values in young kittens and confirm that IOP is significantly higher than normal by 10wks of age in this spontaneous feline glaucoma model.

The Equine Fundus.

Fundus is an anatomic term referring to the portion of an organ opposite from its opening, and the fundus of the eye is the back portion of the posterior segment of the globe, including the optic nerve, retina, and choroid. Clinically, the fundus can be visualized by direct or indirect ophthalmoscopy. Understanding the normal anatomy and appearance of the equine fundus is crucial for differentiating normal variations from abnormalities. This article reviews the normal anatomy and appearance of the equine fundus and discusses basic and advanced examination techniques. It also discusses common findings in the equine fundus and their interpretation.

Schirmer tear test I in dogs: results comparing placement in the ventral vs. dorsal conjunctival fornix.

OBJECTIVE: To compare Schirmer tear test I (STT I) values obtained from placement of tear strips in the ventral and dorsal conjunctival fornices in dogs. PROCEDURE: Schirmer tear test I was performed on each eye of 16 clinically normal dogs (32 eyes) in a crossover study. Initial tear strip placement site was randomized for each eye. Alternative placement site measurements were obtained after 1 week. RESULTS: The mean (± standard deviation, SD) STT I for dorsal and ventral conjunctival fornices was 20.44 (±4.46) mm/min and 23.56 (±3.98) mm/min, respectively. STT I values obtained from the ventral conjunctival fornix were significantly greater than those obtained from the dorsal conjunctival fornix (P = 0.004). CONCLUSIONS: Schirmer tear test I values were significantly greater with tear strips placed in the ventral conjunctival fornix.

Bioavailability and biochemical effects of diclofenac sodium 0.1% ophthalmic solution in the domestic chicken (Gallus gallus domesticus).

OBJECTIVE: To determine if topical ophthalmic diclofenac sodium 0.1% solution alters renal parameters in the domestic chicken, and to determine if the drug is detectable in plasma after topical ophthalmic administration. ANIMALS: Thirty healthy domestic chickens. PROCEDURES: Over 7 days, six birds were treated unilaterally with one drop of artificial tear solution (group 1), 12 birds were treated unilaterally (group 2) and 12 bilaterally (group 3) with diclofenac sodium 0.1% ophthalmic solution. Treatments were provided every 12 h in all groups. Pre- and post-treatment plasma samples from all birds were evaluated for changes in albumin, total protein, and uric acid. Post-treatment samples of all birds, collected 15 min post-administration, were analyzed by high-performance liquid chromatography with mass spectrometry for diclofenac sodium detection. A randomly selected renal sample from each group was submitted for histopathologic review. RESULTS: Changes in pre- and post-treatment plasma albumin were significant (P < 0.05) in groups 2 and 3, but not for group 1. Pre- and post-treatment changes in total protein and uric acid were not significant for any group. Diclofenac sodium was not detectable (limit of detection = 0.10 ng/mL) in plasma samples from birds in group 1. Post-treatment concentration of diclofenac in group 3 was statistically greater than group 2 (P = 0.0008). Histopathologic changes did not identify diclofenac-induced acute renal tubular necrosis. CONCLUSIONS: Ophthalmic diclofenac sodium 0.1% administered topically every 12 h in one or both eyes for 7 days is detectable in systemic circulation in the domestic chicken, but does not cause overt significant changes in plasma uric acid or total protein.

Effect of topical ophthalmic latanoprost 0.005% solution alone and in combination with diclofenac 0.1% solution in healthy horses: a pilot study.

OBJECTIVE: To evaluate the effect of topical ophthalmic 0.005% latanoprost alone and in combination with 0.1% diclofenac on healthy horses. ANIMALS STUDIED: Twelve healthy adult horses. PROCEDURES: A randomized, masked crossover design was used with horses divided into three groups for once daily treatment in one randomly selected eye. For arm 1 of the study, Group D (n = 3) received 0.1% diclofenac, Group L (n = 3) received 0.005% latanoprost, and Group DL (n = 6) received 0.005% latanoprost and 0.2 ml of 0.1% diclofenac. For arm 2 of the study, horses from Group D and L were placed into Group DL and horses from Group DL were placed into either Group D or L. Evaluations of intraocular pressure (IOP), vertical pupil diameter, aqueous flare, conjunctival hyperemia, epiphora, blepharospasm, and blepharoedema were performed 4 times daily on days 1 and 2 (baseline), days 3 to 7 (arm 1 treatment), days 8 to 11 (washout), days 12 to 16 (arm 2 treatment), and days 17 and 18 (return to baseline). RESULTS: During the treatment period, significant reduction in IOP and vertical pupil diameter occurred in treated eyes of Groups L and DL, but not Group D. These variables did not differ significantly between Groups L and DL. Blepharospasm, blepharoedema, epiphora, and conjunctival hyperemia scores were significantly higher in Group L than in Groups D and DL. CONCLUSIONS: Latanoprost reduced IOP in healthy horses and signs of drug-induced discomfort were mitigated by concurrent use of diclofenac.

A vet with a vision.

When he learned what being a veterinarian meant, Gil Ben-Shlomo felt that the career had been invented especially for him. He has since specialised, and is now professor of ophthalmology at Iowa State University.

Corneal fibrosarcoma in a cat.

PURPOSE: To present the clinicopathologic features of a Domestic Short-haired cat with spontaneous, intermediate-grade corneal fibrosarcoma, possibly secondary to chronic corneal irritation associated with a corneal sequestrum. METHODS: A 12-year-old, spayed female Domestic Short-haired cat was evaluated for a slowly growing, pink, exophytic mass affecting the left cornea. The cat had presented 6 years previously for bilateral brown corneal sequestra, as well as 3 years previously for a small pale growth on the left cornea hypothesized to be an epithelial inclusion cyst and a corneal ulcer affecting the right eye. Incisional biopsy of the corneal mass indicated intermediate-grade corneal fibrosarcoma within the corneal stroma. Owing to the potential for malignant behavior, the left globe was enucleated. Routine systemic staging was performed prior to surgery with no evidence of metastasis. RESULTS: Definitive diagnosis of corneal fibrosarcoma was made through histopathologic examination of the incisional biopsy. There was an elevated mitotic index, indicating an intermediate-grade phenotype. Histopathology of the enucleated globe substantiated the initial findings, and complete tumor resection was confirmed. Subjacent to the corneal fibrosarcoma, there was a region of necrotic tissue suggestive of a corneal sequestrum. Six months after diagnosis and enucleation, the patient remained healthy with no signs of local spread or distant metastasis. CONCLUSIONS: To the authors' knowledge, this is the first documented case of a corneal fibrosarcoma in a cat.

Hypokalemia and suspected renal tubular acidosis associated with topical carbonic anhydrase inhibitor therapy in a cat.

OBJECTIVE: To describe the occurrence of hypokalemia, metabolic acidosis, and suspected renal tubular acidosis associated with the administration of topical ophthalmic carbonic anhydrase inhibitor (CAI) in a cat. CASE SUMMARY: A 2-year-old, 5.3 kg, male, castrated, domestic short-haired cat developed hyporexia 6 weeks after starting topical ophthalmic dorzolamide 2% therapy for treatment of ocular hypertension. Two weeks later, the cat was evaluated for severe weakness, cervical ventroflexion, and anorexia. Plasma electrolyte and acid-base measurement revealed hypokalemia (K+ = 2.9 mmol/L; reference interval 3.8-5.4 mmol/L) and metabolic acidosis (plasma HCO3- = 9.8 mmol/L; reference interval 15-23 mmol/L) in the presence of a urine pH of 7.5 (reference interval 6.5-7.5). The pH abnormalities were consistent with a renal tubular acidosis. Clinical and biochemical abnormalities resolved with short-term supportive care, potassium supplementation, and discontinuation of dorzolamide therapy. NEW OR UNIQUE INFORMATION PROVIDED: This is the first report of hypokalemia and metabolic acidosis associated with topical CAI therapy in a cat.

Anticoagulant rodenticide toxicity in six dogs presenting for ocular disease.

OBJECTIVE: To describe cases of suspected anticoagulant rodenticide toxicity manifesting with predominantly ocular signs. MATERIALS AND METHODS: Six canine cases that presented to veterinary referral hospitals for ocular abnormalities and were diagnosed with suspected or confirmed anticoagulant rodenticide ingestion were reviewed for commonalities in presentation and outcome. RESULTS: Five dogs had unilateral ocular signs and one dog had bilateral manifestations. Signs included subconjunctival hemorrhage, exophthalmos, and commonly orbital pain without other significant physical examination findings. Prothrombin time was measured in 5 of 6 dogs and was prolonged in all. Partial thromboplastin time was measured in 4 of 6 dogs and was prolonged in all. Complete blood cell count and serum chemistry profiles demonstrated mild, if any, abnormalities. Five dogs had known anticoagulant rodenticide exposure, and rodenticide ingestion was suspected in 1 additional case based on clinical signs, clinical pathologic abnormalities, and response to treatment. Five of 6 cases were hospitalized overnight for plasma transfusions along with oral or injectable vitamin K1 , and all dogs were treated with oral vitamin K1 for 30 days. All dogs experienced complete resolution of clinical signs within 6 weeks of initiating treatment. CONCLUSIONS: Anticoagulant rodenticide toxicity can present with predominantly ocular manifestations. Rodenticide ingestion should be considered in dogs with unilateral or bilateral subconjunctival hemorrhage, exophthalmos, and orbital pain.

Comparison of two- and three-times-daily topical ophthalmic application of 0.005% latanoprost solution in clinically normal dogs.

OBJECTIVE: To determine whether 2- or 3-times-daily application of topical ophthalmic 0.005% latanoprost solution is more effective at lowering intraocular pressure (IOP) in clinically normal dogs. ANIMALS: 9 clinically normal dogs. PROCEDURES: For each dog, I drop of latanoprost 0.005% solution was applied to 1 eye every 8 or 12 hours each day for 5 days; the contralateral eye received topical ophthalmic treatment with 1 drop of saline (0.9% NaCl) solution at the times of latanoprost application. Ocular examinations of both eyes were performed every 6 hours starting 48 hours prior to and ending 42 hours after the treatment period. Following a 5-week washout interval, the procedures were repeated but the previously latanoprost-treated eye of each dog received latanoprost application at the alternate frequency. RESULTS: Mean ± SD IOP reduction in the latanoprost-treated eyes was 31 ± 6.9% with 2-times-daily application and 33 ± 8.2% with 3-times-daily application. A 2-way repeated-measures ANOVA revealed significant differences in IOP with contributions by treatment (2 or 3 times daily), time of day (diurnal variation), and individual dog. The maximum mean daily IOP reduction in latanoprost-treated eyes was detected on day 3 of latanoprost treatment in each group. Eyes treated 3 times daily had significantly smaller pupil diameter and greater conjunctival hyperemia than eyes treated 2 times daily. CONCLUSIONS AND CLINICAL RELEVANCE: The clinical importance of the ocular hypotensive effects of 3-times-daily topical ophthalmic application of 0.005% latanoprost solution in dogs with glaucoma warrants investigation.