Olfaction evaluation in dogs with sudden acquired retinal degeneration syndrome.

PURPOSE: To evaluate olfaction in dogs with sudden acquired retinal degeneration syndrome (SARDS) compared with sighted dogs and blind dogs without SARDS as control groups. ANIMALS STUDIED: Forty client-owned dogs. PROCEDURE: Olfactory threshold testing was performed on three groups: SARDS, sighted, and blind/non-SARDS using eugenol as the test odorant. The olfactory threshold was determined when subjects indicated the detection of a specific eugenol concentration with behavioral responses. Olfactory threshold, age, body weight, and environmental room factors were evaluated. RESULTS: Sixteen dogs with SARDS, 12 sighted dogs, and 12 blind/non-SARDS dogs demonstrated mean olfactory threshold pen numbers of 2.8 (SD = 1.4), 13.8 (SD = 1.4), and 13.4 (SD = 1.1), respectively, which correspond to actual mean concentrations of 0.017 g/mL, 1.7 × 10-13 g/mL and 4.26 × 10-13 g/mL, respectively. Dogs with SARDS had significantly poorer olfactory threshold scores compared with the two control groups (p < .001), with no difference between the control groups (p = .5). Age, weight, and room environment did not differ between the three groups. CONCLUSIONS: Dogs with SARDS have severely decreased olfaction capabilities compared with sighted dogs and blind/non-SARDS dogs. This finding supports the suspicion that SARDS is a systemic disease causing blindness, endocrinopathy, and hyposmia. Since the molecular pathways are similar in photoreceptors, olfactory receptors, and steroidogenesis with all using G-protein coupled receptors in the cell membrane, the cause of SARDS may exist at the G-protein associated interactions with intracellular cyclic nucleotides. Further investigations into G-protein coupled receptors pathway and canine olfactory receptor genes in SARDS patients may be valuable in revealing the cause of SARDS.

Sulcus intraocular lens implantation in 17 dogs using a modified ab externo technique.

OBJECTIVE: To describe a modified ab externo method of sulcus intraocular lens (IOL) fixation and report outcomes of eyes treated with this approach. PROCEDURES: Records of patients with lens instability or luxation that underwent a lensectomy and sulcus IOL implantation from January 2004 to December 2020 were reviewed. RESULTS: Nineteen eyes of 17 dogs had a sulcus IOL placed via a modified ab externo approach. The median follow-up time was 546 days (range 29-3387 days). Eight eyes (42.1%) developed POH. A total of six eyes (31.6%) developed glaucoma and required medical management long term to control IOP. The IOL position was satisfactory in most cases. Nine eyes developed superficial corneal ulcers within 4 weeks following surgery, all of which healed without complication. At the time of the last follow-up, 17 eyes were visual (89.5%). CONCLUSIONS: The technique described represents a potentially less technically challenging option for sulcus IOL implantation. The success rate and complications are similar to previously described approaches.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Ocular findings in cats with blastomycosis: 19 cases (1978-2019).

OBJECTIVE: To document ocular findings in cats with blastomycosis. ANIMALS: 35 cats with blastomycosis. PROCEDURES: Medical records from 1978 through 2019 were reviewed to identify cats with confirmed Blastomyces infection. Cats were grouped as having or not having ocular involvement. Clinical signs, histopathologic findings, and response to treatment were evaluated. RESULTS: 21 of the 35 (60%) cats with confirmed blastomycosis had ocular abnormalities. Two of 21 cats with ocular abnormalities also had systemic hypertension and were excluded. Of the remaining 19 cats, 15 (79%) had bilateral ocular signs. Ten (53%) cats had inflammatory ocular lesions, and 9 (47%) had neuro-ophthalmic abnormalities. Six of the 19 (32%) cats appeared to be completely blind, and 5 (26%) appeared to be unilaterally blind. For the 10 cats with inflammatory ocular lesions, the most common lesions were anterior uveitis (9/20 eyes), active chorioretinitis (6/20 eyes), and retinal detachment (4/20 eyes). For the 9 cats with neuro-ophthalmic abnormalities, the most common abnormalities were a negative menace or tracking response (10/18 eyes) and negative pupillary light response (4/18 eyes). CLINICAL RELEVANCE: Results suggested that ocular involvement is common in cats with blastomycosis and that both inflammatory lesions and neuro-ophthalmic abnormalities can be seen. Blastomycosis should be considered in the differential diagnosis for cats with anterior uveitis, posterior segment inflammation, or neuro-ophthalmic abnormalities, and a complete ophthalmic examination should be performed in all cats with confirmed or suspected blastomycosis.

The effect of postoperative oral antibiotic therapy on the incidence of postoperative endophthalmitis after phacoemulsification surgery in dogs: 368 eyes (1997-2010).

PURPOSE: To assess the effectiveness of postoperative administration of oral antibiotics at reducing the incidence of endophthalmitis following phacoemulsification cataract extraction in dogs. METHODS: Medical records of the University of Tennessee College of Veterinary Medicine were reviewed for cases having undergone phacoemulsification and divided according to whether or not they had received oral antibiotics postoperatively. Records were then evaluated for a diagnosis of endophthalmitis and incidence rates between the group receiving postoperative oral antibiotics and the group not receiving postoperative oral antibiotics were compared. RESULTS: A total of 215 patients (368 eyes) were identified by the search. One-hundred twelve patients (197 eyes) were treated with oral antibiotics postoperatively. One-hundred and three patients (171 eyes) were not treated with oral antibiotics postoperatively. Three cases of endophthalmitis were identified, with one in the antibiotic-treated group and two in the non-antibiotic treated group (P > 0.05, Fisher's exact test). CONCLUSIONS: The overall incidence of endophthalmitis at the University of Tennessee from 1997-2010 was 0.82%. The rate of post-phacoemulsification endophthalmitis was unaffected by the postoperative administration of oral antibiotics.

Comparison of antimicrobial resistance patterns in dogs with bacterial keratitis presented to a veterinary teaching hospital over two multi-year time periods (1993-2003 and 2013-2019) in the Southeastern United States.

OBJECTIVE: To report clinical characteristics of dogs with bacterial keratitis, identify the most common bacterial isolates within this population, characterize the bacterial isolates' antimicrobial resistance patterns, and compare those resistance patterns to previously reported resistance patterns. ANIMAL STUDIED: Dogs diagnosed with bacterial keratitis between 2013 and 2019. PROCEDURES: Data pertaining to breed; Schirmer tear test I results; use of cyclosporine, tacrolimus, or corticosteroids at time of ulcer diagnosis; bacterial genus or species isolated; and resistance to selected antimicrobials as measured by Kirby-Bauer disk diffusion were collected. Resistance patterns were compared to those reported by Tolar et al. (2006). RESULTS: One hundred seventy bacterial isolates were cultured from 138 eyes from 130 dogs. Of these dogs, 45% were brachycephalic, 62% had STT <15 mm/min, and 28% were receiving a corticosteroid at the time of examination. The most common isolates were Staphylococcus pseudintermedius (31%), ß-hemolytic Streptococcus spp. (28%), and Pseudomonas aeruginosa (18%). Compared to the 1993-2003 study period, there were significant increases in resistance to cephalothin and polymyxin B among S. pseudintermedius isolates. ß-hemolytic Streptococcus spp. and P. aeruginosa isolates had no significant changes in resistance to the tested antimicrobials. CONCLUSION: Isolates of S. pseudintermedius, ß-hemolytic Streptococcus spp., and P. aeruginosa had minimal changes in resistance between the two study periods. In this population, monotherapy with ciprofloxacin or combination therapy of tobramycin and a first-generation cephalosporin continue to be appropriate for use in cases of suspected bacterial keratitis while awaiting results of susceptibility testing.

Retrobulbar and Tongue Base Pyogranulomatous Myositis Resulting in Strabismus in a Dog: Case Report.

A seven-year-old female spayed Australian Shepherd was presented for a 3-day history of left eye ventromedial strabismus, episcleral injection, protrusion of the third eyelid, miosis, and enophthalmia. Magnetic Resonance Imaging (MRI) identified lesions in the left medial pterygoid muscle and left tongue base. Cytology and histopathology revealed pyogranulomatous inflammation with rod-shaped bacteria and pyogranulomatous myositis, respectively. One month of oral antibiotics resolved both lesions. Repeat MRI showed a mild decrease in size of the left medial pterygoid muscle consistent with fibrosis. Clinically, residual, positional ventral strabismus remained upon dorsal neck extension, but all other ophthalmic abnormalities resolved. To the authors' knowledge, this is the first report of pyogranulomatous myositis causing this constellation of clinical signs and of repeat imaging depicting resolution of these lesions with therapy.

Efficacy of long-term topical flurbiprofen in limiting lens capsule opacities following phacoemulsification in dogs.

OBJECTIVE: To assess lens capsule opacity (LCO) following phacoemulsification in dogs receiving long-term topical ophthalmic flurbiprofen sodium 0.03%. ANIMAL STUDIED: Twenty-five client owned dogs undergoing phacoemulsification surgery for either diabetic or nondiabetic cataracts. METHODS: Prospective, randomized, masked clinical study assessing two groups of dogs for twelve months following phacoemulsification. All dogs underwent a complete eye examination and were photographed at each visit, beginning three weeks post-surgery, and repeated at 2, 3, 6, and 12 months post-surgery. Post-operative treatment protocols were similar for both groups, except that Group F received topical flurbiprofen once daily for 12 months and Group A received artificial tears once daily for 12 months. Digital photographs were analyzed for LCO using a subjective grading scale (0-4). The change in capsular opacities from 3 weeks to 12 months post-surgery was evaluated for each dog, and the groups were compared. RESULTS: There were 25 dogs evaluated post-phacoemulsification at each designated time point of the study. There were 12 dogs in Group A and 13 dogs in Group F. There was no significant statistical difference in LCO score between Groups A and F at baseline (3 weeks post-surgery), 6 months post-surgery, or 12 months post-surgery. Scores did not change significantly from baseline to 12 months within or between groups. CONCLUSIONS: Topical ophthalmic flurbiprofen sodium 0.03% solution applied once daily for 12 months following phacoemulsification does not appear to lead to a decrease in LCO formation as compared to artificial tears control.

Tear film concentrations of topically applied 0.5% oxytetracycline ointment in normal canine eyes.

OBJECTIVE: To determine the tear film levels of oxytetracycline in normal canine eyes after application of the ophthalmic ointment, Terramycin™ (0.5% oxytetracycline, polymyxin B sulfate), to guide appropriate treatment frequency. ANIMALS STUDIED: Ten research beagles. PROCEDURES: Ten research beagles with confirmed normal eyes were administered 0.02 mL of Terramycin™ ophthalmic ointment onto the dorsal bulbar conjunctival surface of the right eye. Tear samples were collected via dye-less Schirmer tear strips at 2, 4, 6, 8, and 12 hours post-administration. The sample for each timepoint was collected on a separate day, and concentrations of oxytetracycline were determined using high-performance liquid chromatography (HPLC). RESULTS: There was a semi-logarithmic decline in the median tear concentration of oxytetracycline. The median (2.5th and 97.5th percentiles) tear concentrations of oxytetracycline at 2, 4, 6, 8, and 12 hours were 43.5 µg/mL (11.1-302.2 µg/mL), 28.7 µg/mL (8.04-113.7 µg/mL), 16.1 µg/mL (4.96-37.7 µg/mL), 9.2 µg/mL (4.52-28.1 µg/mL), and 6.11 µg/mL (4.36-26.7 µg/mL), respectively. Mean (±SD) drug recovery via HPLC was 88% (±7.5%). CONCLUSIONS: Ophthalmic Terramycin™ achieves a substantially higher tear level than the MIC for common bacterial corneal pathogens up to 12 hours post-administration in normal eyes. Anti-collagenolytic tear levels were not achieved at the timepoints evaluated or with the manufacturer-prescribed dosing frequency. HPLC can be used to analyze tear concentrations of ophthalmic ointment formulations.

Effect of attentional focus levels on spontaneous eyeblink rate in horses.

OBJECTIVE: Spontaneous eyeblink rate (SEBR) is inversely proportional to the level of attentional focus in humans. The objective of this study was to evaluate the effects of attentional focus on SEBR in horses. PROCEDURES: Twenty client-owned horses (2.5-23 years of age, five mares, 15 geldings) were evaluated. A GoPro HERO5 Session™ video recorder was attached to the halter and directed toward the eyes. Horses were acclimated for two hours before study commencement. Horses were filmed in five scenarios requiring different levels of attention: alone in a stall ("stall"), stall with an observer ("person"), standing in an arena ("stand"), walking in an arena ("walk"), and trotting in arena ("trot"). Each of the five scenarios was filmed for ten minutes. Video recordings were reviewed, and SEBR (incomplete, complete, and total blinks) was measured for both eyes in each scenario. RESULTS: The median (25%,75%) total SEBRs (blinks/min) were as follows: STALL: OD-16.6 (12.4, 24.3), OS-18.8 (11.5, 26.9); PERSON: OD-17.7 (14.6, 24.2), OS-17.4 (13.9, 24.4); STAND: OD-18.7 (15.1, 24.4), OS-19.4 (16.2, 24.7); WALK: OD-40.1 (34.1, 44.8), OS-40.6 (33.8, 44.7); and TROT: OD-39.7 (30.3, 44.6), OS-39.4 (28.6, 45.0). The total SEBRs at walk and trot were significantly greater than SEBR in stationary scenarios. CONCLUSIONS: Despite requiring increased levels of attentional focus, activities involving motion caused increased SEBR in horses. We hypothesize the need for additional tear distribution due to tear evaporation (associated with air movement over the corneas) prevailed over the level of attentional focus to increase the SEBR.

Long-term outcome of phacoemulsification in raptors-A retrospective study (1999-2014).

OBJECTIVE: To determine long-term outcome of phacoemulsification in raptors at the University of Tennessee Veterinary Medical Center. ANIMALS STUDIED: Seven nonreleasable diurnal raptors including, four bald eagles (Haliaeetus leucocephalus), two red-tailed hawks (Buteo jamaicensis), and one peregrine falcon (Falco peregrinus) that had undergone phacoemulsification. All birds showed behavioral changes attributable to visual deficits prior to surgery. PROCEDURES: All birds underwent phacoemulsification for cataracts. Four underwent bilateral phacoemulsification, and three had unilateral surgery. Due to a low sample size, statistics were not done. RESULTS: Six raptors (nine eyes) had long-term follow-up (median 75 months, range 28 to 105 months). Seven of these eyes (78%) were visual at last examination. Of those visual eyes, two developed mild to moderate posterior synechiae, four had mild to moderate capsular opacities, and one developed a lipid keratopathy. The remaining two eyes with long-term follow-up were from the same red-tailed hawk. Both eyes developed fibropupillary membranes that were blinding. One eye was pseudophakic, and the other was aphakic and also developed a rhegmatogenous retinal detachment. Another bald eagle was euthanized two months after surgery due to refractory glaucoma; one eye was pseudophakic. CONCLUSIONS: Phacoemulsification is a viable treatment for captive raptors with cataracts. The most severe complications occurred relatively soon after surgery. Captive raptors appear to adapt well to aphakia.

Migration of retrobulbar wooden foreign body between diagnostic imaging and surgical extraction in a German shepherd dog.

A 2-year-old, male castrated German shepherd dog was presented to the University of Tennessee Veterinary Medical Center (UTVMC) with periorbital swelling and conjunctival mucopurulent discharge 2 days following removal of a twig from the medial canthus by the owner. Diagnostic imaging was pursued due to the suspicion of a retrobulbar foreign body (FB). A cylindrical FB approximately 3.0 cm in length and 1.0 cm in diameter with concentric rings, suspected to be wooden material, was identified on computed tomography (CT) imaging. An attempt to remove the FB via a stab incision using ultrasound guidance was unsuccessful, and postmanipulation ultrasound confirmed the FB position was unchanged. An exploratory orbitotomy was performed, using the acquired CT images for guidance in locating the FB; however, the FB was not present at the predicted site. The CT imaging was repeated and showed that the FB had migrated rostrally approximately 3.0 cm, compared to the originally acquired study and its same location during attempted ultrasound-guided removal. A combination of CT-guided needle placement and contrast injection was then used with repeat imaging in an attempt to better localize the FB and its soft tissue tract. The dog was taken back into the operating room, and the wooden FB was successfully removed.

Blink patterns and kinematics of eyelid motion in ophthalmologically normal horses.

OBJECTIVE To describe qualitative blinking patterns and determine quantitative kinematic variables of eyelid motion in ophthalmologically normal horses. ANIMALS 10 adult mares. PROCEDURES High-resolution videography was used to film blinking behavior. Videotapes were analyzed for mean blink rate, number of complete versus incomplete blinks, number of unilateral versus bilateral blinks, and subjective descriptions of blinking patterns. One complete blink for each horse was analyzed with image-analysis software to determine the area of corneal coverage as a function of time during the blink and to calculate eyelid velocity and acceleration during the blink. RESULTS Mean ± SD blink rate was 18.9 ± 5.5 blinks/min. Blinks were categorized as minimal incomplete (29.7 ± 15.6%), moderate incomplete (33.5 ± 5.9%), complete (30.8 ± 13.1%), and complete squeeze (6.0 ± 2.8%); 22.6 ± 9.0% of the blinks were unilateral, and 77.3 ± 9.1% were bilateral. Mean area of exposed cornea at blink initiation was 5.89 ± 1.02 cm2. Mean blink duration was 0.478 seconds. Eyelid closure was approximately twice as rapid as eyelid opening (0.162 and 0.316 seconds, respectively). Deduced maximum velocity of eyelid closure and opening was -16.5 and 7.40 cm/s, respectively. Deduced maximum acceleration of eyelid closure and opening was -406.0 and -49.7 cm/s2, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Kinematic variables of ophthalmologically normal horses were similar to values reported for humans. Horses had a greater percentage of complete squeeze blinks, which could increase tear film stability. Blinking kinematics can be assessed as potential causes of idiopathic keratopathies in horses.

Phacoemulsification outcomes in Boston terriers as compared to non-Boston terriers: a retrospective study (2002-2015).

OBJECTIVES: To compare visual outcome and cause of blindness between two groups of dogs undergoing phacoemulsification. ANIMALS STUDIED: Study population consisted of 35 Boston terriers (BT; 70 eyes) and 77 non-Boston terriers (NBT; 154 eyes) that underwent bilateral phacoemulsification surgery. PROCEDURES: Medical records were reviewed to determine visual outcome, complications leading to blindness and follow-up. A Kaplan-Meier survival curve was used to estimate surgical success at 1 and 2 years postoperatively. RESULTS: Eleven of 35 BT developed known vision loss, with 12 of 70 (17.1%) eyes becoming blind within one year of surgery, and 17 of 77 NBT developed known vision loss, with 19 of 154 (12.3%) eyes becoming blind within 1 year of surgery. No further vision loss was reported among those BT with a 2-year follow-up. In the NBT group, seven additional dogs, a total of 24 of 77 NBT developed vision loss, with a known total of 31 of 154 (20.1%) eyes becoming blind within two years of surgery. These results were not significantly different. The overall surgical success in both groups based on individual eyes was estimated to be between 80 and 90% at 1 year postsurgery and between 65 and 80% at 2 years postsurgery. Glaucoma was the leading cause of vision loss in both groups. CONCLUSIONS: There was no significant difference in visual outcomes between a group of BT and a group of NBT undergoing bilateral phacoemulsification at the University of Tennessee between 2002 and 2015. Glaucoma was the leading cause of vision loss in both groups.

Tear film osmolality and electrolyte composition in healthy horses.

OBJECTIVE: To evaluate the tear film osmolality and electrolyte composition in healthy horses. ANIMALS: 15 healthy adult horses. PROCEDURES: Each horse was manually restrained, and an ophthalmic examination, which included slit-lamp biomicroscopy, indirect ophthalmoscopy, and a Schirmer tear test, was performed. Tear samples were collected from both eyes with microcapillary tubes 3 times at 5-minute intervals. The tear samples for each horse were pooled, and the osmolality and electrolyte concentrations were measured. The mean (SD) was calculated for each variable to establish preliminary guidelines for tear film osmolality and electrolyte composition in healthy horses. RESULTS: The mean (SD) tear film osmolality was 283.51 (9.33) mmol/kg, and the mean (SD) sodium, potassium, magnesium, and calcium concentrations were 134.75 (10), 16.3 (5.77), 3.48 (1.97), and 1.06 (0.42) mmol/L, respectively. The sodium concentration in the tear film was similar to that in serum, whereas the potassium concentration in the tear film was approximately 4.75 times that of serum. CONCLUSIONS AND CLINICAL RELEVANCE: Results provided preliminary guidelines with which tear samples obtained from horses with keratopathies can be compared. Measurement of tear film osmolality in these horses was easy and noninvasive. The tear film concentration of divalent cations was greater than expected and was higher than the divalent cation concentrations in the tear films of rabbits and humans. These data may be clinically useful for the diagnosis and monitoring of hyperosmolar ocular surface disease in horses.

Biometry, keratometry, and calculation of intraocular lens power for the bald eagle (Haliaeetus leucocephalus).

OBJECTIVE: To document intraocular measurements and predict intraocular lens (IOL) power specific to the bald eagle. ANIMALS STUDIED: Eleven adult, captive bald eagles. PROCEDURES: Axial globe length (AGL), anterior chamber depth (ACD), crystalline lens thickness (CLT), and the distance from the cornea to the posterior lens capsule (CPLC) were measured in eight adult bald eagles using B-mode with vector A-mode ultrasound. Keratometry was done on four eagles. Two estimates for postoperative anterior chamber depth (PACD) were obtained from four aphakic eyes from three eagles by measuring from the apex of the anterior cornea to the center of an imaginary line that would connect the remaining edges of the anterior lens capsule across the capsulorhexis (PACD1) and from the apex of the anterior cornea to halfway between the anterior and posterior lens capsule (PACD2). IOL strength was predicted using the Colenbrander, Binkhorst, and Fyodorov theoretical formulas. RESULTS: Mean ± SD biometry for phakic eyes was AGL = 26.57 ± 0.45 mm, ACD = 4.45 ± 0.18 mm, CLT = 5.49 ± 0.14 mm, and CPLC = 10.00 ± 0.33 mm. Mean predicted PACD1 was 6.1 ± 0.66 mm, and PACD2 was 6.4 ± 0.70 mm. Mean horizontal and vertical corneal refractive power was 39.91 ± 0.43 diopters (D) and 40.02 ± 0.08 D, respectively. Calculated IOL power ranged from +16.4 to 17.4 D. CONCLUSIONS: Calculations using ultrasonographic biometry, keratometry, and theoretical IOL formulas suggest that the strength of an IOL necessary to return an aphakic bald eagle to emmetropia is between +16.4 and +17.4 D.

Flash electroretinography in the bald eagle (Haliaeetus leucocephalus).

Photopic and scotopic flash electroretinograms (fERGs) were done on 12 adult captive anesthetized bald eagles (Haliaeetus leucocephalus) following a complete ophthalmic exam. The b-wave amplitude in the bald eagle exceeds that seen in other species when using a similar protocol. This data may be used clinically as a reference for bald eagles undergoing fERG evaluation for retinal disease or as a preoperative screening tool before phacoemulsification.

Two time point versus 4 time point data acquisition in aqueous humor flow rate determinations by fluorophotometry.

PURPOSE: To establish the validity of a fluorophotometric protocol based on 2 time points to facilitate aqueous humor flow rate calculations in minimally cooperative species. MATERIALS AND METHODS: A standard canine fluorophotometry protocol was followed in 6 dogs. Fluorescein concentrations were obtained at 4 time points: 5, 6, 7, and 8 hours after topical application of 3 drops of 10% fluorescein. At the 5- and 8-hour time points, each animal was scanned 4 times. Fluorophotometric parameters were calculated using: (1) the first 5-hour scan, the 6- and 7-hour scans, and the first 8-hour scan (ie, the "4 pt method"); and (2) using only the average of the 4 scans obtained at 5 hours and the average of the 4 scans obtained at 8 hours (ie, the "2 pt method"). Parameters calculated using each method were compared using paired t tests. RESULTS: There were no statistically significant differences between the 2 methods of parameter acquisition (P>0.05 for all parameters). CONCLUSIONS: When fluorophotometric aqueous humor flow rate calculations are needed in species for which acquisition of fluorescein concentrations at >2 time points is difficult, using data obtained at 2 widely spaced points provides reasonably accurate estimates of flow rate provided multiple scans are performed at each of those 2 time points.

Normal ocular parameters and characterization of ophthalmic lesions in a group of captive bald eagles (Haliaeetus leucocephalus).

Sixteen adult captive bald eagles (Haliaeetus leucocephalus) underwent a complete bilateral ocular examination to assess normal ocular parameters and describe ophthalmic lesions. Tear production was measured with the Schirmer tear test 1 and intraocular pressure was measured with applanation tonometry. The menace response was normal bilaterally in 13 of 16 eagles. Two birds had normal menace responses despite having fundic lesions, and 2 birds with an inconsistent or absent menace response did not have appreciable ophthalmic lesions. Mean (SD) tear production was 14 +/- 2 mm/min (range, 8-19 mm/min). Mean intraocular pressure was 21.5 +/- 1.7 mm Hg (range, 15-26 mm Hg). At least 1 ocular lesion was present in 50% of examined eyes. Cataracts, the most common lesion observed, were present in 8 eyes of 5 birds. Three of 4 known geriatric birds were or had been affected with bilateral cataracts. Overall, ocular lesions are common in captive bald eagles, and cataracts appear to be more prevalent in geriatric bald eagles. An obvious positive menace response is present in most visual birds but may be absent in some eagles that are either normal or that do not have appreciable ophthalmic lesions. Applanation tonometry and the Schirmer tear test 1 can be performed easily on adult bald eagles and provide reproducible results.

Effects of a topically applied 2% delta-9-tetrahydrocannabinol ophthalmic solution on intraocular pressure and aqueous humor flow rate in clinically normal dogs.

OBJECTIVE: To determine the effects of topically applied 2% delta-9-tetrahydrocannabinol (THC) ophthalmic solution on aqueous humor flow rate (AHFR) and intraocular pressure (IOP) in clinically normal dogs. ANIMALS: 21 clinically normal dogs. PROCEDURES: A randomized longitudinal crossover design was used. Following acquisition of baseline IOP (morning and evening) and AHFR (afternoon only) data, dogs were randomly assigned to 2 treatment groups and received 1 drop of either 2% THC solution or a control treatment (olive oil vehicle) to 1 randomly selected eye every 12 hours for 9 doses. The IOPs and AHFRs were reassessed after the final treatment. Following a washout period of ≥ 7 days, dogs were administered the alternate treatment in the same eye, and measurements were repeated. RESULTS: Mean ± SD IOPs in the morning were 15.86 ± 2.48 mm Hg at baseline, 12.54 ± 3.18 mm Hg after THC treatment, and 13.88 ± 3.28 mm Hg after control treatment. Mean ± SD IOPs in the evening were 13.69 ± 3.36 mm Hg at baseline, 11.69 ± 3.94 mm Hg after THC treatment, and 12.13 ± 2.99 mm Hg after control treatment. Mean IOPs were significantly decreased from baseline after administration of THC solution but not the control treatment. Changes in IOP varied substantially among individual dogs. Mean ± SD AHFRs were not significantly different from baseline for either treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Topical application of 2% THC ophthalmic solution resulted in moderate reduction of mean IOP in clinically normal dogs. Further research is needed to determine efficacy in dogs with glaucoma.