A Retrospective study on the association between vitreous degeneration and cataract in dogs.

OBJECTIVE: This study was performed to evaluate the relationship between cataract and vitreous degeneration on ultrasonography (VDU) in dogs. MATERIALS AND METHODS: Medical records of dogs were retrospectively reviewed. The dogs presented at the Veterinary Medical Teaching Hospital of Seoul National University from January 2009 to December 2011 for ocular ultrasonography to investigate the suitability of the patient for cataract surgery. A total of 97 dogs (179 eyes) were included in this study. Data collected included age, gender, ophthalmic examination, and ultrasonographic examination. Cataract was classified into five grades by ophthalmic examination (0: normal, 1: incipient, 2: immature, 3: mature, and 4: hypermature). VDU was classified into 4 grades (0: no degeneration, 1: mild vitreous degeneration, 2: moderate vitreous degeneration, and 3: marked vitreous degeneration). RESULTS: The mean rank of VDU grades increased with the progression of cataracts, and statistical significant differences were shown between cataracts grade 0 and 2 (P = 0.010), between 0 and 3 (P < 0.001), between 0 and 4 (P = 0.010), between 1 and 3 (P = 0.03), between 1 and 4 (P = 0.02), and between 2 and 4 (P = 0.04). There were no significant differences in age and gender according to the cataract grades. There was no statistical significant difference in the mean rank of VDU grades between cataractous eyes with lens-induced uveitis (LIU) and those without LIU. CONCLUSIONS: The results indicated that increased VDU was associated with more severe cataract grades in dogs.

Accuracy of intraocular pressure measurements in dogs using two different tonometers and plano therapeutic soft contact lenses.

OBJECTIVE: To compare and evaluate the accuracy of intraocular pressure (IOP) measured through a therapeutic contact lens, using applanation (TonoPen XL(®)) and rebound (TonoVet(®)) tonometers in enucleated dog eyes. ANIMALS STUDIED: A total of 30 enucleated eyes from 15 beagle dogs. PROCEDURES: To measure accurate IOP, the anterior chamber of each enucleated eye was cannulated with two 26-gauge needles and two polyethylene tubes were connected vertically to an adjustable reservoir bag of normal saline and a pressure transducer. IOP was measured by the TonoPen XL(®) followed by the TonoVet(®) without a contact lens. After a contact lens was applied to the cornea, IOP was re-measured in the same order. Three consecutive IOP measurements were performed using both tonometers. RESULTS: Without the contact lens, the IOP values obtained by both tonometers correlated well according to the regression analysis (TonoVet(®): γ(2) = 0.98, TonoPen XL(®): γ(2) = 0.97, P < 0.001). The TonoPen XL(®) consistently underestimated values as transducer IOP increased; however, IOP values measured with the TonoPen XL(®) were in close agreement and were less variable than those determined with the TonoVet(®) when a contact lens was applied to the cornea. Bland-Altman analysis was used to determine the lower and upper limits of agreement (TonoVet(®): -29.7 and +21.1 mmHg, TonoPen XL(®): -3.9 and +3.6 mmHg) between the two devices. CONCLUSIONS: This study suggests that the TonoPen XL(®) is a useful tonometer for dogs wearing therapeutic contact lenses, and importantly, contact lenses would not need to be removed prior to IOP measurement.

Comparison of two electroretinography systems used in dogs: the HMsERG and the RETIport.

The purpose of the study was to compare two different electroretinography (ERG) instruments used on the same animal in a laboratory setting. Retinal function in both eyes of 12 healthy miniature schnauzers was evaluated under general anesthesia. Scotopic and photopic ERGs were recorded by the HMsERG and the RETIport using the Dog Standard Protocol recommended by the European College of Veterinary Ophthalmologists (ECVO). The waveforms of the ERGs obtained by the two ERG units were similar to those described in previous studies. The 90% reference ranges using the multiple of medians (MoM) showed that the changes in ERG parameters obtained by the HMsERG unit were very similar to those of the RETIport for most ERG responses, except for a few. The results demonstrate that the two ERG systems are comparable for evaluating retinal function in dogs. Further, the results also show that it is necessary to establish ERG system-specific limits of normality in each laboratory or clinic in order to obtain a correct diagnosis, for example by using a graphical representation of the 90% reference range.

Effect of central corneal thickness on intraocular pressure with the rebound tonometer and the applanation tonometer in normal dogs.

OBJECTIVE: To evaluate the effect of central corneal thickness (CCT) on the measurement of intraocular pressure (IOP) with the rebound (TonoVet(®)) and applanation (TonoPen XL(®)) tonometers in beagle dogs. ANIMAL STUDIED: Both eyes of 60 clinically normal dogs were used. PROCEDURES: The IOP was measured by the TonoVet(®), followed by the TonoPen XL(®) in half of the dogs, while the other half was measured in the reverse order. All CCT measurements were performed 10 min after the use of the second tonometer. RESULTS: The mean IOP value measured by the TonoVet(®) (16.9 ± 3.7 mmHg) was significantly higher than the TonoPen XL(®) (11.6 ± 2.7 mmHg; P < 0.001). The IOP values obtained by both tonometers were correlated in the regression analysis (γ(2) = 0.4393, P < 0.001). Bland-Altman analysis showed that the lower and upper limits of agreement between the two devices were -0.1 and +10.8 mmHg, respectively. The mean CCT was 549.7 ± 51.0 µm. There was a correlation between the IOP values obtained by the two tonometers and CCT readings in the regression analysis (TonoVet(®) : P = 0.002, TonoPen XL(®) : P = 0.035). The regression equation demonstrated that for every 100 µm increase in CCT, there was an elevation of 1 and 2 mmHg in IOP measured by the TonoPen XL(®) and TonoVet(®), respectively. CONCLUSIONS: The IOP obtained by the TonoVet(®) and TonoPen XL(®) would be affected by variations in the CCT. Therefore, the CCT should be considered when interpreting IOP values measured by tonometers in dogs.

Comparison of the effects of three different combinations of general anesthetics on the electroretinogram of dogs.

The objective of this study is to compare the effects of three different anesthetic combinations on the electroretinogram in the same animals under similar laboratory conditions. Thiopental-isoflurane (TI), medetomidine-ketamine (MK), and xylazine-ketamine (XK) were used on each of 12 healthy miniature schnauzer dogs (MS) with a period of at least 3 weeks in between subsequent anesthesia protocols, using the Dog Standard Protocol. The scotopic ERGs consisted of scotopic low stimulus strength (S) responses designated S1, S2, S3, S4, and S5, at 1, 5, 10, 15, and 20 min after dark adaptation, respectively, and scotopic standard stimulus strength (S-ST) responses. The photopic ERGs consisted of a photopic single flash (P) response and 31 Hz flicker (P-FL) responses. For S-ST (2.5 cd s/m(2)), the amplitude of the a-wave using TI was significantly lower than that using MK (adjusted P = 0.05) and XK (adjusted P = 0.03), and the implicit time of the a-wave was significantly shorter than that using MK (adjusted P = 0.04). For P (2.5 cd s/m(2)), the amplitude of the b-wave using XK was significantly higher than that using MK (adjusted P = 0.01). The implicit times of the b-wave using TI was significantly longer and shorter than that of MK for S1, S2 and P-FL and for S4 and S-ST, respectively, and than that of XK for S2 and P-FL and for S5 and S-ST, respectively. The results of the present study showed that TI affected both the amplitude and the implicit time of the a-wave for S-ST and the implicit time of the b-wave relatively more so than was the case when using XK or MK. Therefore, it appears that either XK or MK could be advantageous to use rather than TI for clinical studies.

Comparison of orbital prosthesis motility following enucleation or evisceration with sclerotomy with or without a motility coupling post in dogs.

OBJECTIVE: To evaluate motility of silicone orbital implants and corneoscleral prostheses, with and without use of a motility coupling post (MCP) in dogs. ANIMALS STUDIED: Eighteen mixed-breed dogs. PROCEDURES: The motility of an orbital silicone implant and corneoscleral prosthesis after enucleation (n = 6), evisceration (n = 6), or use of a MCP with evisceration (n = 6) in dogs were compared. One eye from each dog had surgery whereas the opposite eye was used as a control. Clinical evaluations were performed three times a week. Histopathology of the orbital tissues was performed 8 and 12 weeks after surgery. RESULTS: Implant motility in dogs with evisceration (vertical movement [VM] 8.04 +/- 2.13; horizontal movement [HM] 11 +/- 3.05) and evisceration with MCP (VM 9.61 +/- 1.59); HM was significantly greater than the enucleation group (VM 0.51 +/- 0.5; HM 1.22 +/- 0.68) (P < 0.01). Prosthetic motility in dogs with evisceration with MCP was significantly greater than in dogs with evisceration; dogs with evisceration had significantly greater motility than dogs with enucleation (P < 0.01). No postoperative complications were observed in any of the groups. No significant abnormalities were noted on histopathology. CONCLUSIONS: MCP placement in silicone orbital implants significantly enhanced the prosthetic motility in dogs. This study supports the use of MCP in silicone orbital implants to enhance corneoscleral prosthesis motility and cosmetics in dogs.

Clinical manifestations of cataracts in small breed dogs.

OBJECTIVE: To determine the incidence, etiology, and concurrent ophthalmic findings in small breed dogs that presented with cataracts. ANIMAL STUDIED: Five hundred and sixty-one small breed dogs (942 eyes) were presented to the Veterinary Medical Teaching Hospital of Seoul National University between July 2002 and December 2007 with cataract. PROCEDURE: The medical records of small breed dogs with cataract were reviewed. The reason for presentation, cataract duration, bilaterality, breed, gender, age, vision, etiology, stage of cataract development, concurrent ophthalmic findings, IOP, ocular ultrasonography findings, and scotopic electroretinography (ERG) findings were investigated. RESULTS: The most frequently presented breeds were the Miniature/Toy Poodle (n = 112, 20.0%), Yorkshire Terrier (n = 110, 19.6%), and Shih Tzu (n = 95, 16.9%). The Miniature/Toy Poodle showed a significantly higher odds ratio for cataract formation (2.6). The proportion of female cataract patients was significantly higher than that of male cataract patients in the overall population (P < 0.05). The Miniature/Toy Poodles had significantly higher numbers of females affected with cataract (P < 0.01). The mean age for cataract formation was 8.3 +/- 3.9 years. The mean age at onset in the Miniature/Toy Poodle and Yorkshire Terrier was significantly higher, whereas that in the Miniature Schnauzer group was significantly lower (P < 0.0001). Clinical signs related to lens induced uveitis had a tendency to increase with cataract progression (P < 0.05). There were no significant differences in the b-wave amplitude for mixed rod cone response by stage (P = 0.137). CONCLUSIONS: Small breed dogs with cataracts had characteristics with regard to age of onset and gender distribution, depending on the breed.

Evaluation of the mydriatic effect of intracameral lidocaine hydrochloride injection in eyes of clinically normal dogs.

OBJECTIVE-To evaluate the mydriatic effect of intracameral injection of preservative-free 1% and 2% lidocaine hydrochloride solutions and determine the onset and duration of mydriasis according to the concentration and volume of lidocaine administered in healthy dogs. ANIMALS-5 healthy adult Beagles weighing 7 to 10 kg, with no apparent ocular disease. PROCEDURES-A double-blind randomized 9-session crossover trial was designed. Both eyes were assigned to 9 treatments with a minimum 7-day washout period between treatments: 0.1, 0.2, and 0.3 mL of 2% lidocaine solution; 0.1, 0.2, and 0.3 mL of 1% lidocaine solution; and 0.1, 0.2, and 0.3 mL of balanced salt solution. Dogs were anesthetized, and the allocated treatment was injected intracamerally after aspiration of the same volume of aqueous humor from the anterior chamber of each eye. Two perpendicular pupil diameters were measured. Intraocular pressure, heart rate, respiratory rate, ECG readings, and end-tidal partial pressure of CO(2) were monitored. RESULTS-Intracameral injection of 1% or 2% lidocaine solutions in volumes of 0.1 to 0.3 mL induced a significant degree of mydriasis, and the effect was maintained for 74 to 142 minutes. Lidocaine injection had no significant effect on intraocular pressure, heart rate, respiratory rate, ECG readings, or end-tidal partial pressure of CO(2). CONCLUSIONS AND CLINICAL RELEVANCE-Intracameral lidocaine injection in healthy dogs induced mydriasis, the timing of which was affected by concentration and volume of lidocaine. This technique could serve as an alternative to topically administered mydriatics for intraocular surgery in dogs.

Combination auriculopalpebral nerve block and local anesthesia for placement of a nictitating membrane-to-superotemporal bulbar conjunctiva flap in dogs.

The purpose of this study was to evaluate the efficacy of combined local anesthesia in dogs undergoing nictitating membrane (NM)-to-superotemporal bulbar conjunctiva flap construction. Medical records of 47 dogs that had received local anesthesia for NM-to-superotemporal bulbar conjunctiva flap were reviewed. Combined local anesthetic technique included auriculopalpebral nerve block, topical anesthesia of the eye, and infiltration anesthesia of the superotemporal bulbar conjunctiva and palpebral surface of the NM. Forty-two (89.3%) dogs complied with the anesthetic procedures and underwent NM flap without general anesthesia or sedation. No complications were related to the combined local anesthesia. Combined local anesthesia for NM-to-superotemporal bulbar conjunctiva flap may be a time- and cost-effective method that produces both analgesia of the surgical site and akinesia of the eyelid.

Effects of stimulus intensity for electroretinogram in conscious Miniature Schnauzers.

The aim of this study was to determine the most effective light intensity for flash electroretinogram (ERG) examination in conscious dogs using ERG equipment with a contact lens electrode with a built-in LED light source. ERG was performed on the bilateral eyes of ten clinically healthy Miniature Schnauzers at 6 different intensities (0.025, 0.079, 0.25, 0.79, 2.5 and 7.9 cd.s/m2) after dark adaptation for 20 min. With the increase in stimulus intensity, the most significant increase in a and b-wave amplitudes were observed at 2.5 cd.s/m2 (p<0.05). As the intensity of light was increased, the implicit times of both waves significantly decreased. Therefore, the most effective intensity of stimulus was 2.5 cd.s/m2 in the conscious Miniature Schnauzers. This suggests that this procedure would be applicable for evaluation of retinal function in conscious dogs, especially in high-risk patients.

The determination of dark adaptation time using electroretinography in conscious miniature Schnauzer dogs.

The optimal dark adaptation time of electroretinograms (ERG's) performed on conscious dogs were determined using a commercially available ERG unit with a contact lens electrode and a built-in light source (LED-electrode). The ERG recordings were performed on nine healthy Miniature Schnauzer dogs. The bilateral ERG's at seven different dark adaptation times at an intensity of 2.5 cd.s/m(2) was performed. Signal averaging (4 flashes of light stimuli) was adopted to reduce electrophysiologic noise. As the dark adaptation time increased, a significant increase in the mean a-wave amplitudes was observed in comparison to base-line levels up to 10 min (p < 0.05). Thereafter, no significant differences in amplitude occurred over the dark adaptation time. Moreover, at this time the mean amplitude was 60.30 +/- 18.47 microV. However, no significant changes were observed for the implicit times of the a-wave. The implicit times and amplitude of the b-wave increased significantly up to 20 min of dark adaptation (p < 0.05). Beyond this time, the mean b-wave amplitudes was 132.92 +/- 17.79 microV. The results of the present study demonstrate that, the optimal dark adaptation time when performing ERG's, should be at least 20 min in conscious Miniature Schnauzer dogs.

Study on the ophthalmic diseases in ICR mice and BALB/c mice.

In pharmaceutical companies and research institutes, many toxicity tests are performed with laboratory animals. This study was performed to produce reference data for eye toxicity tests and to investigate the ophthalmic diseases of 408 ICR mice and 119 BALB/c mice, which are commonly used as subjects in toxicity tests. The experimental animals without clinical disorders were selected regardless of sex. The ophthalmic diseases were examined by using special ophthalmic instruments: direct ophthalmoscope, indirect ophthalmoscope, slit-lamp biomicroscope and focal illuminator. The most prevalent ocular variation within normal limits was hyaloid vessel remnant (ICR mice, 28.2%; BALB/c mice, 31.9%) and the incidence gradually decreased with age. The ocular diseases found in ICR mice were retinal degeneration (9.8%), corneal scar (4.2%), focal cataract (2.2%), anisocoria (1.2%), corneal ulcer (0.2%) and uveitis (0.2%). In BALB/c mice, corneal scar (9.2%), focal cataract (1.7%) and corneal ulcer (0.8%) were the ocular diseases found.

Phacoemulsification and acryl foldable intraocular lens implantation in dogs: 32 cases.

This study evaluated the surgical outcome and complications of phacoemulsification and the implantation of an acryl foldable intraocular lens (IOL) with a squared edge in dogs with cataracts. Thirty-two eyes from 26 dogs were examined. The mean follow up period was 75.9 days ranging from 23 to 226 days. The complications after phacoemulsification were posterior capsular opacity (PCO) around the IOL (n = 11), ocular hypertension (n = 4), focal posterior synechia (n = 4), hyphema (n = 3) and corneal ulcer (n = 2). The complications associated with the IOL were decenteration of the optic (n = 2) and ventral haptic displacement (n = 1). Most cases of PCO were found only around the margin of the IOL, and all eyes had vision during the observation period. In conclusion, the implantation of an acryl-foldable lens with a squared edge at the time of phacoemulsification is an effective method for preserving the central visual field of dogs with cataract.

Malignant ocular melanoma in a dog.

A mongrel male dog of three years old was referred to the Seoul National University Veterinary Teaching Hospital following a one month history of glaucoma. On ophthalmic examination, hyphema, glaucoma, uveitis, iridal mass, and loss of vision were noted in the right eye. Ultrasonography and computed tomography revealed a mass with involvement of the entire uvea. Radiographic evaluation did not reveal any evidence of distant metastasis. The right eye was surgically removed because of the high likelihood of neoplasia. A histologic diagnosis of malignant uveal melanoma was made.

Medial canthoplasty for epiphora in dogs: a retrospective study of 23 cases.

The medical records of 23 dogs that underwent medial canthoplasty for treatment of epiphora were reviewed. The most prevalent breed encountered was the shih tzu. Other affected breeds included the Pekingese, Maltese, toy poodle, and pug. All dogs had epiphora associated with medial canthal trichiasis and/or entropion. Other ocular abnormalities included conjunctivitis, keratitis, pigmentary keratitis, corneal ulceration, globe prolapse, and nasal fold trichiasis. After medial canthoplasty, the epiphora resolved in all dogs.

A Case of oculocutaneous albinism in a Maltese.

A 4-month-old female maltese dog was admitted to Veterinary Medical Teaching Hospital of Seoul National University for evaluation of abnormal color of bilateral irises. This patient had the photophobia in the light and exhibited the complete absence of pigment resulting in white hair, pink muzzle, eyelids and foot-pads. Central zone of the irises were yellow in color influenced by tapetal reflex, and peripheral zone were pale blue. The iridal capillaries were transparented on the irises. Ophthalmoscopic examination revealed a yellow tapetal fundus but no pigment in the nontapetal fundus.

Reverse effects of tetraarsenic oxide on the angiogenesis induced by nerve growth factor in the rat cornea.

To compare the antiangiogenic effects of tetraarsenic oxide (As4O6) with those of diarsenic oxide (As2O3) in the rat cornea, rat cornea micropocket assay was conducted to induce angiogenesis by implantation of the pellet contained 1.0 ng of nerve growth factor (NGF). Ten of thirty eyes of Sprague-Dawley rats were randomly assigned to one of three groups, namely, control group (no medication), As2O3 group (50 mg/kg As2O3, PO, s.i.d.), and As4O6 group (50 mg/kg As4O6, PO, s.i.d.). After implantation, the number of new vessels, vessel length and clock hour of neovascularization were examined under the microscope from day 3 to day 7. The area of neovascularization was calculated using a mathematical formula. Although new vessels in control and As2O3 groups were first noticed at day 3, whereas those of As4O6 group were first observed on day 5. The number, length, clock hour of neovascularization and areas of the vessels in As4O6 group showed more significant inhibition than those of control and As2O3 groups from day 5 (P<0.05). However, there were no differences in all parameters between control group and As2O3 group during the entire study period. These results showed that As4O6 had antiangiogenic effects on the new vessels induced by NGF in the rat cornea.

Effect of intratesticular injection of xylazine/ketamine combination on canine castration.

This study was performed to compare the effect of intratesticular (IT) injection of xylazine/ketamine combination for canine castration with those of intramuscular (IM) or intravenous (IV) injection. Xylazine and ketamine was administered simultaneously via intratesticularly (IT group), intramuscularly (IM group) or intravenously (IV group) at doses of 2 and 10 mg/kg, respectively. Pain response at the time of injection, mean induction time, mean arousal time, mean walking time and cardiopulmonary function during anesthesia were monitored after the xylazine and ketamine administration. In IV and IM groups, heart rates were significantly decreased 30 and 45 min after xylazine and ketamine administration, respectively (p < 0.05). Respiratory rates were significantly decreased in the IV group (p < 0.05). In the IT group, there was no significant changes in heart and respiratory rates. The occurrence of cardiac arrhythmias was less severe in IT group compared with those in IM and IV groups. The route of administration did not affect rectal temperature. Mean induction time was significantly (p < 0.05) longer in IT group than in IM and IV groups. On the contrary, mean arousal time and mean walking time were shortened in IT group. Clinical signs related to pain response at the time of injection and vomiting were less observed in IT group than in IM group, and head shaking was less shown in IT group than in IM and IV groups during recovery period. These results indicated that intratesticular injection of xylazine/ketamine for castration has several advantages such as less inhibition of cardiopulmonary function and fast recovery from anesthesia without severe complications, and would be an effective anesthetic method for castration in small animal practice.

Surgical removal of stones in the stomach of a tiger shovelnose catfish.

A seven months old, tiger shovelnose catfish was referred to the veterinary medical teaching hospital of the college of veterinary medicine, Konkuk university because of suspecting a foreign body in the stomach. By physical and radiologic examinations, the catfish revealed abdominal enlargement, vomiting, inactivity and radiopaque foreign bodies in the stomach. Under general anesthesia with dilute isoflurane solution, celiotomy was performed. Stomach was atonic, and three foreign bodies were palpated in the stomach. In this process, three stones came out through mouth. Abdominal muscles were closed with a simple continuous suture pattern, and skin was closed with a simple mattress suture pattern. Sutured site was covered with glue and mucous taken from allogenic skin. On the second day after surgery, the patient recovered to normal condition, showing increased appetite and activity.

Clinical and electroretinographic findings of progressive retinal atrophy in miniature schnauzer dogs of South Korea.

The purpose of the study was to describe the clinical and electroretinographic features of clinical cases of progressive retinal atrophy (PRA) in miniature schnauzer (MS) of South Korea. Sixty-six MS (14 normal and 52 affected) were included. All animals underwent routine ocular examinations. Electroretinogram (ERG) was recorded in the 14 normal and 15 affected dogs. For normal dogs, the mean age ± SD was 4.1 ± 2.4 years (1 to 9 years), and there were no ocular abnormalities on the basis of ocular examinations and ERG results. For the PRA-affected dogs, it was shown that the mean age ± SD was 4.3 ± 1.1 years (2 to 7 years), and 44 dogs (84.6%) were 3 to 5 years old. Most of the PRA-affected dogs had abnormal menace responses (98.1%) and pupillary light reflexes (PLRs, 88.5%); some dogs showed normal menace response (1.9%) and PLRs (11.5%). Ophthalmoscopic abnormalities in the affected group included one or more of the following changes: hyperreflectivity and discoloration of the tapetal area, attenuation of retinal vessels, depigmentation in non-tapetal area and optic disc atrophy. ERG in the affected dogs showed non-recordable responses in all cases tested with clinical signs of PRA. The present study showed that PRA in MS was mainly observed between the age of 3 to 5 years. ERG revealed abnormal rod and cone responses in affected dogs at the ages studied.