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Objective To describe ophthalmic abnormalities secondary to periocular and ocular snakebite in dogs. Animal Studied Retrospective review of medical records from dogs presenting to the Small Animal Hospital at University of Florida following snakebites to the face (2012–2014). Two groups were identified: periocular bites (PB) and ocular bites (OB). Results Records from eleven dogs matched the search criteria and were included in the study (PB=9, 81.8%; OB=2, 18.2%). Both OB cases involved the cornea. Facial edema, blepharospasm, chemosis, and conjunctival hyperemia occurred in all cases (100%). Hemorrhage from the eyelids occurred in eight cases (72.7%; PB=7, OB=1). Subconjunctival hemorrhage occurred in seven cases (63.6%; PB=6, OB=1). Third eyelid laceration and nictitans gland prolapse occurred in 1 case each (9%; PB=1). Lagophthalmia was present in three cases (27.3%; PB=3), with secondary corneal ulcer in two cases (18.2%; PB=2). Corneal ulcer due to direct corneal bite occurred in two cases (18.2%—partial thickness with melting 1 and full thickness 1). Uveitis was present in 6 cases (54.5%; PB=4, OB=2), with flare and miosis in 4 cases (36.4%; PB=2, OB=2). Hyphema, fibrin in anterior chamber, and cataract occurred in one case (9%; OB=1). Vision loss occurred in two cases (18.2%; PB=2), secondary to retinal degeneration (PB=1) and amaurosis (PB=1). Mean follow-up time was 7 weeks (range: 3 days–11 months). Most clinical signs had resolved by last examination. Conclusions Periocular symptoms were more commonly observed than ocular alterations, regardless of bite location. Appropriate supportive therapy should be instituted according to clinical signs.

Objective To evaluate effects of Coherin™ on intraocular pressure (IOP), pupil size (PS), and heart rate (HR) in glaucomatous Beagles in single-dose studies in a pilot study. Materials and methods Intraocular pressure, PS, and HR were measured in eight glaucomatous Beagles. One randomly chosen eye received single 50 μL doses of differing concentrations of Coherin™ (treated eye) or vehicle (placebo-treated eye), and the fellow eye served as the untreated control. After the first measurements, a single dose of either Coherin™ or sterile water vehicle was instilled in the drug and placebo eyes, respectively. Results The mean ± SEM diurnal changes in IOP after 0.005%, 0.01%, 0.2%, 0.284%, 1%, 2%, and 4% topical Coherin™ once daily were 7.6 ± 3.2 mmHg, 15.5 ± 5.3 mmHg, 11.2 ± 4.4 mmHg, 11.8 ± 4.4 mmHg, 19.1 ± 3.8 mmHg, 5.0 ± 1.8 mmHg, and 8.8 ± 2.8 mmHg, respectively. The declines in IOP were significantly different (P

Objective To evaluate the changes in intraocular pressure (IOP) and pupil size in 12 Beagles with inherited glaucoma after instillations of 0.033, 0.0033, 0.001, 0.00033, and 0.0001% travoprost (Travatan®-Alcon Laboratories, Inc., Ft Worth, TX, USA) in multiple single-dose studies. Procedures Intraocular pressure and pupil diameter (PD) measurements were obtained at 9 am, 12 pm, 3 pm, and 9 am the following day (24 h) in two groups of six glaucoma dogs. After 7 days, the vehicle or concentration was repeated in the contralateral eye of the same animals. Results Concentrations of 0.00033, 0.001, and 0.0033% travoprost significantly lowered IOP and PD, but the 0.0001% concentration provided limited IOP changes, although PD changes were still significant. This suggests travoprost is effective in the dog to lower IOP and reduce pupil size at concentrations starting between 0.0001 and 0.00033%. Conclusions The dose response for travoprost in the glaucomatous Beagle indicates this model is highly sensitive to this group of drugs, even at concentrations as low as 0.00033% (1/12 the commercially available concentration).

Objective The gene (myocilin: MYOC) has been attributed to be involved in over 6% of inherited types of human glaucoma, the highest correlation for any gene to date. This study determines myocilin protein levels in the aqueous humor (AH) of normal laboratory quality, genetic carrier (offspring of normal laboratory quality and POAG Beagles), and primary open angle glaucoma (POAG) Beagles. Materials and methods Eighteen dogs were used and classified as either normal, carrier or having mild, moderate or advanced POAG. A 0.1-mL sample of AH was drawn from the anterior chamber of each dog in the study and frozen on dry ice. A modified Coomassie stain and Western blot, using a polyclonal rabbit antihuman myocilin antibody (Santa Cruz Biotechnologies, Santa Cruz, CA), was run on each sample to compare the myocilin levels. A purified human trabecular meshwork excreted myocilin protein sample was used as a control (Alcon Research Laboratories, Fort Worth, TX) and its band/densitometry measurement was defined as one unit of myocilin for comparisons. Results Comparisons of AH myocilin levels differed among normal laboratory quality, genetic carrier, and POAG Beagles at different stages of the disease. In the normal laboratory, Beagles the AH myocilin measured 0.817 ± 0.075 units (mean ± SEM); in the carrier Beagles the AH myocilin was 3.117 ± 0.290 units. As POAG progressed, myocilin protein levels also increased to 6.097 ± 0.810, 8.844 ± 1.079, and 17.228 ± 1.198 units in the early, moderate, and advanced forms, respectively. Overall comparisons between normal, carrier and all POAG Beagles combined showed significant differences (P

Objective To evaluate the visual outcome of three techniques of corneal transplantation surgery in treating severe inflammatory keratopathies in the horse. Design Retrospective medical records study. Animals studied Medical records of 206 horses that received corneal transplantation surgery at the University of Florida Veterinary Medical Center from 1993 to 2007 were reviewed. Procedure Data collected from the medical records included signalment, types of ocular lesions, type of transplant surgery performed, length of follow-up, complications, and visual outcomes. Results Full thickness penetrating keratoplasty (PK) was performed in 86 horses for melting ulcers, iris prolapse/descemetoceles, and medically nonresponsive full thickness stromal abscesses (SA). Posterior lamellar keratoplasty (PLK) and deep lamellar endothelial keratoplasty (DLEK) are split thickness penetrating keratoplasties that were utilized for medically nonresponsive deep stromal abscesses (DSA) in 54 and 66 eyes, respectively. The most common postoperative surgical complication was graft rejection and varying degrees of graft opacification. Wound dehiscence and aqueous humor leakage was also a common postoperative problem. A positive visual outcome was achieved for PK, PLK, and DLEK in 77.9%, 98.1%, and 89.4%, respectively. Conclusions Corneal transplantation is a tectonically viable surgery in the horse with an overall success rate of 88.5% in maintaining vision when treating vascularized and infected corneal disease in the horse.

Soft tissue often displays marked age-associated stiffening. This study aims to investigate how age affects scleral biomechanical properties in a canine glaucoma model with ADAMTS10 mutation, whose extracellular matrix is concomitantly influenced by the mutation and an increased mechanical load from an early age. Biomechanical data was acquired from ADAMTS10-mutant dogs (n = 10, 21 to 131 months) and normal dogs (n = 5, 69 to 113 months). Infusion testing was first performed in the whole globes to measure ocular rigidity. After infusion experiments, the corneas were immediately trephined to prepare scleral shells that were mounted on a pressurization chamber to measure strains in the posterior sclera using an inflation testing protocol. Dynamic viscoelastic mechanical testing was then performed on dissected posterior scleral strips and the data were combined with those reported earlier by our group from the same animal model (Palko et al, IOVS 2013). The association between age and scleral biomechanical properties was evaluated using multivariate linear regression. The relationships between scleral properties and the mean and last measured intraocular pressure (IOP) were also evaluated. Our results showed that age was positively associated with complex modulus (p

Objective The purpose of this study was to evaluate the effectiveness of postoperative beta-irradiation with strontium-90 as an adjunctive treatment to superficial keratectomy and permanent bulbar conjunctival graft for removal of equine corneolimbal squamous cell carcinoma (SCC), in decreasing recurrence rate. Study The retrospective case study included 38 horses diagnosed and treated for SCC of the eye that involved the limbus and/or cornea. The patients were treated between 1990 and 2002, with strontium-90 irradiation immediately after corneal and conjunctival graft surgery. Recurrence was defined as the postoperative and postirradiation regrowth of SCC in the same site and globe that was previously treated. Results The Appaloosa was the most commonly represented breed and horses that had more than one base coat color represented the majority of the cases (53%). The coat colors of white, chestnut/sorrel and gray were the most commonly represented colors of the horses treated. Eight horses (21%) could not be assessed for tumor recurrence due to lack of two or more post-treatment examinations, and another horse was enucleated 6 days postoperatively due to progressive corneal ulceration. Twenty-four horses (63% of the entire study population; 83% of the followed cases) had a mean ± SD of 1754 ± 1319 days without tumor recurrence, ranging from 14 days to 5110 days. Five horses (13% of the entire study population; 17% of the assessed horses) had tumor recurrence at a mean ± SD of 449 ± 339 days with a range of 29 days to 900 days. For the five recurrences, treatment included local excision (n = 1), enucleation (n = 2), and additional strontium-90 therapy (n = 3). Conclusions The combination of superficial keratectomy, β-irradiation and permanent bulbar conjunctival grafts for limbal, corneal or corneolimbal SCC in horses is effective in at least 83% of the horses. Recurrence occurred in about 17% of the horses. Multiple biannual re-examinations are recommended to observe for tumor recurrence.

Objective To determine whether the combination multiple-dose dorzolamide–timolol administered topically has any greater effects on the reduction of intraocular pressure, pupil size, and heart rate in dogs with glaucoma than do either timolol or dorzolamide alone. Procedure Applanation tonometry, pupil size, and heart rate measurements were made at 7 a.m., 1 p.m., and 7 p.m. daily of 12 laboratory Beagles with inherited primary open-angle glaucoma during each active phase of this study. Timolol 0.5% was administered first twice daily for 4 consecutive days. Dorzolamide 2.0% was administered next three times daily for 4 consecutive days. The fixed combination of the two (timolol 0.5% and dorzolamide 2.0%) was administered twice daily for 4 consecutive days during the final week of the study. Between administration of each drug, a withdrawal period of at least 10 days was instituted. Statistical comparisons between the effects of the three drugs were performed. Results Intraocular pressure (IOP) was decreased with the administration of all three drugs: timolol alone, dorzolamide alone, and the combination of the two decreased IOP after 1 day of treatment 2.83 ± 0.70 mmHg, 6.47 ± 0.32 mmHg, and 6.56 ± 0.37 mmHg, respectively. After 4 days of treatment, the IOP decreased even further: timolol alone, dorzolamide alone, and the combination of the two decreased IOP 3.75 ± 0.88 mmHg, 7.50 ± 0.29 mmHg, and 8.42 ± 0.58 mmHg, respectively. Heart rate was significantly decreased with timolol (−11.9 ± 2.0 bpm) and the combination preparation (−8.6 + 2.4 bpm), but not with dorzolamide (−3.7 ± 1.8 bpm) alone. Pupil size was significantly decreased with timolol (−1.42 + 0.40 mm) and the combination preparation (−1.3 + 0.33 mm), but not with dorzolamide (0.97 ± 0.36 mm) alone. Conclusions The combination dorzolamide–timolol appears to be more effective at reducing intraocular pressure in glaucomatous dogs than is either timolol or dorzolamide alone.

A 9-week-old miniature mule foal presented to the Veterinary Medical Teaching Hospital for acute blindness, ataxia, and depression following an overdose of an over-the-counter ivermectin-based de-worming medication. Ophthalmic examination and electrodiagnostic evaluation eliminated outer retinal abnormalities as the primary cause of the bilateral blindness, implicating instead a central neurologic effect of the drug. With symptomatic and supportive care, the foal recovered fully and regained its vision.

Objective To evaluate effects of lacrimal punctal plugs positioned in either the upper, lower, or combination of upper and lower lacrimal canaliculi on plug retention and tolerance; tear production, as measured by the Schirmer tear test; and the dilution of fluorescein within the tear film in normal dogs. Material and methods Lacrimal punctal plugs were positioned in the lower, upper, or combination of lower and upper plugs in six laboratory-quality Beagles under topical anesthesia. Retention of plugs was evaluated daily from 8 to 23 days by visual inspection and slit-lamp biomicroscopy. Schirmer tear tests (STT 1 without topical anesthesia) were performed at 48-h intervals. Dilution of fluorescein was determined at 5- and 45-min post-fluorescein instillations once weekly. Results Lacrimal punctal plugs of 0.4 and 0.6 mm in diameter were retained for 14 (lower plugs: 100%) and 23 days (75%), and for the upper plugs at 8 days less often (75%), and were infrequently locally nonirritating. Combination of lower and upper plugs seemed to adversely affect retention of either plug. When loss of the plugs occurred, a next larger size plug was necessary suggesting some stretching of the lacrimal canaliculi occurred. Pre- and postplug placement STT results indicated no change with lower and combination lacrimal punctal plugs, but decreased levels following upper lacrimal punctal plugs. Tear fluorescein levels at 5 and 45 min in control eye (no punctum plugs) were 3.39% and 0.14%, respectively. With lower, upper, and the combination of lower and upper lacrimal puncta plugs, tear fluorescein levels at 45 min were higher than the controls (lower: 0.76%; upper: 0.45%, and combination 0.56%). Conclusion Lacrimal punctal silicone plugs are retained for 8–23 days in the lower, upper, and combined lower and upper canaliculi at high rates. Effects on STT levels appear limited. Fluorescein within the tear film persists longer with all different positioned lacrimal punctum plugs than in the control eyes.

Objective To determine the prevalence of secondary glaucomas in dogs associated with cataract formation, lens luxation or displacement, cataract surgery, uveitis, hyphema and intraocular neoplasia. Methods Information was obtained from the Veterinary Medical Data Base (VMDB) from all veterinary medical teaching hospitals in North America from March 1964 to March 2003. Secondary glaucomas were diagnosed at the same examination or after the primary diagnosis was made, and included those associated with cataract formation, lens luxation, cataract surgery, uveitis of unknown cause, hyphema of unknown cause, and intraocular neoplasia. The data were evaluated by decade, breed, gender and age of presentation. Results A total of 1 592 831 dogs were presented, and 9695 canine secondary glaucomas. Secondary glaucoma associated with cataract formation represented 81% of all the canine secondary glaucomas. Breeds (n = 7890 dogs) predisposed to secondary glaucoma and cataracts had an overall prevalence of 0.5%, but nearly 20% of all the cataractous dogs developed secondary glaucoma in at least one eye. For the years 1994–2003, these breeds included the American Cocker Spaniel; Boston Terrier; Toy, Miniature and Standard Poodle; English Springer Spaniel; Bichon Frise; and Labrador Retriever. The other forms of secondary glaucoma occurred less frequently, and included those glaucomas with lens luxation or displacement (779 dogs; 12.0%), postcataract surgery (528 dogs; 5.1%), with uveitis from unknown cause (399 dogs; 7.1%), with hyphema from unknown cause (117 dogs; 7.3%), and with intraocular neoplasia (19 dogs; 3.5%). The risk of the secondary glaucomas from 1984 to 2002 was highest after the intracapsular lens extraction (ICLE), less in the extracapsular technique (ECLE), and lowest for the phacoemulsification/phacofragmentation method. Conclusion Prevalence of the canine secondary glaucomas ranges from 0.25% (1964–1973), 0.46% (1974–1983), 0.79% (1984–1993), to 0.80% (1994–2003) and are as frequent as the primary or breed-related glaucomas during these same time periods.

A periocular nodular sarcoid of the right upper and lower eyelids was diagnosed in an 11-year-old Thoroughbred mare. Computed tomography scan revealed the extent of the tumor. The mass was surgically debulked under general anesthesia, and the affected periocular region was injected intralesionally with Bacillus of Calmette and Guerin (BCG). An emulsion of cell wall fractions was used, which has been modified to reduce the toxic and allergic effect, but retain the antitumor activity. In total, five injections were performed at 2-week intervals. At follow-up 7 months after the last BCG injection, the tumor was completely resolved. Two years after the last treatment, the horse remains tumor-free.

Objective To determine the prevalence of the breed-related glaucomas in pure-bred dogs presented to the veterinary medical teaching hospitals in North America that participate in the Veterinary Medical Data Base (VMDB). Materials and methods In this retrospective study, age of first diagnosis, breed, and gender data for all breeds of dogs were collected from the VMDB with the clinical diagnosis of primary glaucoma (glaucoma-NOS) at 5–10 year intervals from 1964 to 2002. The prevalence for each breed (affected dogs compared to all dogs of each breed), any changes over the 38 years, and any gender differences for these glaucomas were determined. Results The prevalence of the primary breed-related glaucomas has gradually increased from 0.29% (1964–1973); 0.46% (1974–1983); 0.76% (1984–1993); to 0.89% (1994–2002). Breeds that consistently featured among the highest 10 for glaucoma prevalence from four different periods (1964 to 2002) included American Cocker Spaniel, Basset Hound, Wire Fox Terrier, and Boston Terrier. During the last observation period (1994–2002), 22 different breeds had 1% or higher prevalence of the glaucomas. The highest prevalence of glaucomas in 1994–2002 by breed included: American Cocker Spaniel (5.52%); Basset Hound (5.44%); Chow Chow (4.70%); Shar-Pei (4.40%); Boston Terrier (2.88%); Wire Fox Terrier (2.28%); Norwegian ElkHound (1.98%); Siberian Husky (1.88%); Cairn Terrier (1.82%); and Miniature Poodle (1.68%). A predominance of females with glaucoma occurred in the American Cocker Spaniel, Basset Hound, Cairn Terrier, Chow Chow, English Cocker Spaniel, Samoyed, and perhaps the Siberian Husky, and a predominance of males in the Australian Cattle dog and St Bernard. Age affected the time for first presentation of the glaucomas in the pure-bred dog. In the majority of breeds the glaucomas were presented for initial diagnosis in dogs between 4 and 10 years of age. Conclusion Breed-related glaucomas in pure-bred dogs are frequently presented to the veterinary medical teaching hospitals in North America. The prevalence of the breed-related glaucomas in the dog appears similar to humans, and in some breeds exceeds that in humans. In many breeds the high prevalence of the glaucomas suggests a genetic basis.

Bilateral hypertensive retinopathy and choroidopathy with bullous retinal detachment was diagnosed in a 17-year-old, female spayed Domestic Short-haired cat. The underlying cause of the systemic hypertension could not be determined. The blood pressure was lowered successfully with the oral application of the L-type calcium channel blocker amlodipine besylate. The cat subsequently regained vision. The improvement in retinal function was documented using electroretinography.

OBJECTIVE To evaluate the effect of a single dose of topical 1% tropicamide on tear production as measured by the Schirmer tear test (STT) in the normal dog and cat. MATERIAL AND METHODS Twenty-eight dogs and 32 cats received 50 micro l : l of 1% tropicamide in one eye and the opposite eye served as the control. STTs were performed immediately before instillation of tropicamide and then at 1, 4, 8 and 24 h post drug instillation. STT results were compared between the control and treated eyes at the different times. RESULTS Aqueous tear production in dogs, measured by STT, was not significantly reduced. The mean +/- SEM STTs for the baseline time for control and tropicamide-treated eyes were 19.9 +/- 0.8 and 20.3 +/- 0.8 mm wetting/min, respectively. For the control eyes, the subsequent mean +/- SEM STT levels were 20.3 +/- 0.9 (1 h), 21.1 +/- 0.8 (4 h), 20.1 +/- 0.9 (8 h), and 18.7 +/- 0.7 (24 h). For the tropicamide-treated eyes, the subsequent mean +/- SEM STT levels were 19.4 +/- 0.9 (1 h), 19.3 +/- 0.9 (4 h), 20.0 +/- 0.9 (8 h), and 18.4 +/- 0.8 (24 h). Aqueous tear production of both eyes was significantly reduced in cats at 1 h but returned to baseline by 4 h post tropicamide instillation. The mean +/- SEM STT levels for the baseline time in cats for control and tropicamide-treated eyes were 14.9 +/- 0.8 and 14.7 +/- 0.8 mm wetting/min, respectively. Subsequent mean +/- SEM STT levels for the control eyes were 6.4 +/- 1.1 (1 h), 11.9 +/- 1.0 (4 h), 13.9 +/- 0.8 (8 h), and 16.4 +/- 1.0 (24 h). For the tropicamide-treated eyes, the subsequent mean +/- SEM STT levels were 5.3 +/- 0.8 (1 h), 10.2 +/- 0.8 (4 h), 14.7 +/- 1.0 (8 h), and 16.6 +/- 1.0 (24 h). CONCLUSION Single dose 1% tropicamide does not significantly lower tear production rates, as measured by the STT, in normal dogs. However, in normal cats single doses of 1% tropicamide in one eye cause significant reductions in tear production of both eyes at 1 h that recovered to baseline levels by 4 h.

Objective To measure changes in the ocular and orbital blood flow velocities by color Doppler imaging (CDI) in beagles with primary open angle glaucoma as the disease progressed from early to advanced stages. Methods CDI measurements were performed periodically on 13 glaucomatous Beagles during the nontreated mild, moderate and advanced stages of POAG over the course of 4 years. CDI was performed with the dogs lightly anesthetized (butorphanol 0.1 mg/kg IV, acepromazine maleate 0.02 mg/kg IV, and atropine sulfate 0.05 mg/kg) while the CD transducer was placed directly on the cornea anesthetized with 0.5% tetracaine hydrochloride. Intraocular pressure (IOP) by pneumatonography or TonoPen XL, heart rate and mean arterial blood pressure were measured at the beginning, middle and end of each study. The ophthalmic vessels examined included: external ophthalmic arteries and veins, long and short posterior ciliary arteries, anterior ciliary arteries and veins, primary retinal arteries, and vortex veins. Recordings of each vessel included peak systolic velocity (PSV), end diastolic velocity (EDV) and time averaged velocity (TAV), and when possible the resistive index (RI) and pulsatility index (PI) were computed. Results CDI abnormalities were present before intraocular pressure exceeded the normal range. As the animals aged, and the glaucoma progressed with higher levels of IOP, significant changes occurred in nearly all vessels, and generally included a major increase in RI (P

The objective of this study was to evaluate the changes in intraocular pressure (IOP) in glaucomatous dogs after instillations of 0.2% brimonidine once, twice and three times daily in single day studies, and after twice and three times daily for 4 days in multiple dose studies. We studied eight Beagles with inherited primary open angle glaucoma. Applanation tonometry (IOP), pupil size (PS) and heart rate (HR) measurements were obtained at 8 am, 10 am, 1 pm, 3 pm and 5 pm. The studies were divided into: eight glaucoma dogs and five of the eight dogs that demonstrated greater response to 0.2% brimonidine. Single-dose drug studies are divided into placebo (0.5% methylcellulose), 0.2% brimonidine administered once daily (8 am); twice daily (8 am and noon); and three times daily (8 am, noon and 5 pm). The 5-day multiple-dose studies included: day 1, no drug; and 4 days, 0.2% brimonidine instillations either twice daily (8 am and 2 pm) or three times daily (8 am, 2 pm and 9 pm). Statistical comparisons between drug groups included control (nondrug) and treated (placebo/0.2% brimonidine) eyes for both single- and multiple-dose studies. The mean +/- SEM diurnal decrease in IOP in the eight glaucomatous Beagles for the control and placebo eyes were 3.4 +/- 4.7 and 5.4 +/- 2.8 mmHg, respectively. The mean +/- SEM diurnal decrease in IOP after 0.2% brimonidine once, twice and three times daily was 6.4 +/- 3.5, 8.0 +/- 6.1 and 9.8 +/- 8.1 mmHg, respectively; this trend was not significant statistically. Significant miosis occurred starting 2 h postinstillations, and the resultant mean +/- SD pupil size was 2.7 +/- 0.3 mm. A significant decrease in heart rate also occurred (12%). In the five most responsive dogs the changes in PS and HR during these studies were similar to the larger group, but significant decreases in IOP occurred at most measurement times. In the multiple-dose study with 0.2% brimonidine twice daily the mean +/- SEM decrease in IOP for day 1 to day 4 was 5.0 +/- 1.3, 5.7 +/- 1.3, 1.4 +/- 3.3 and 4.9 +/- 1.3 mmHg, respectively. When 0.2% brimonidine was instilled three times daily the mean +/- SEM diurnal IOP decrease was from day 1 to day 4 and was 0.75 +/- 1.3, 2.4 +/- 1.5, 1.2 +/- 2.7 and 1.4 +/- 1.8 mmHg, respectively. The mean change in pupil diameter was 1.3 +/- 0.5 mm. Decrease in HR averaged 22%. In the same single-dose studies with the five most responsive dogs, PS and HR were similar, but the decreases in IOP were significant at more measurement intervals. We conclude that 0.2% brimonidine produces a decrease in IOP in dogs, a statistically significant miosis, and a reduced heart rate (12-22%). However, because of the limited drug-induced ocular hypotension, brimonidine should be combined with other drugs when used for the glaucomas in the dog.