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.

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.

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.

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.

Comparison of the rebound tonometer (TonoVet) with the applanation tonometer (TonoPen XL) in normal Eurasian Eagle owls (Bubo bubo).

OBJECTIVE: To examine the feasibility and accuracy of a handheld rebound tonometer, TonoVet, and to compare the intraocular pressure (IOP) readings of the TonoVet with those of an applanation tonometer, TonoPen XL, in normal Eurasian Eagle owls. ANIMALS STUDIED: Ten clinically normal Eurasian Eagle owls (20 eyes). PROCEDURES: Complete ocular examinations, using slit-lamp biomicroscopy and indirect ophthalmoscopy, were conducted on each raptor. The IOP was measured bilaterally using a rebound tonometer followed by a topical anesthetic agent after 1 min. The TonoPen XL tonometer was applied in both eyes 30 s following topical anesthesia. RESULTS: The mean +/- SD IOP obtained by rebound tonometer was 10.45 +/- 1.64 mmHg (range 7-14 mmHg), and by applanation tonometer was 9.35 +/- 1.81 mmHg (range 6-12 mmHg). There was a significant difference (P = 0.001) in the IOP obtained from both tonometers. The linear regression equation describing the relationship between both devices was y = 0.669x + 4.194 (x = TonoPen XL and y = TonoVet). The determination coefficient (r(2)) was r(2) = 0.550. CONCLUSIONS: The results suggest that readings from the rebound tonometer significantly overestimated those from the applanation tonometer and that the rebound tonometer was tolerated well because of the rapid and minimal stress-inducing method of tonometry in the Eurasian Eagle owls, even without topical anesthesia. Further studies comparing TonoVet with manometric measurements may be necessary to employ rebound tonometer for routine clinical use in Eurasian Eagle owls.

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.

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.