| Records |
Author  |
Ben-Shlomo, G.; Plummer, C.; Barrie, K.; Brooks, D. |
| Title |
Characterization of the normal dark adaptation curve of the horse |
Type |
Journal Article |
| Year |
2012 |
Publication |
Veterinary Ophthalmology |
Abbreviated Journal |
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| Volume |
15 |
Issue |
1 |
Pages |
42-45 |
| Keywords |
adaptation; curve; dark; electroretinography; equine; scotopic |
| Abstract |
Objective The goal of this work is to study the dark adaptation curve of the normal horse electroretinogram (ERG). Procedures The electroretinographic responses were recorded from six healthy female ponies using a contact lens electrode and a mini-Ganzfeld electroretinographic unit. The horses were sedated intravenously with detomidine, an auriculopalpebral nerve block was then performed, and the pupil was fully dilated. The ERG was recorded in response to a low intensity light stimulus (30 mcd.s/m2) that was given at times (T) T = 5, 10, 15, 20, 25, 30, 40, 50, and 60 min of dark adaptation. Off-line analysis of the ERG was then performed. Results Mean b-wave amplitude of the full-field ERG increased continuously from 5 to 25 min of dark adaptation. The b-wave amplitude peaked at T = 25, however, there was no statistical significance between T = 20 and T = 25. The b-wave amplitude then remained elevated with no significant changes until the end of the study at T = 60 (P > 0.49). The b-wave implicit time increased continuously between T = 5 and T = 20, then gradually decreased until T = 60. No distinct a-wave was observed during the testing time. Conclusions Evaluation of horse rod function or combined rod/cone function by means of full-field ERG should be performed after a minimum 20 min of dark adaptation. |
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| Publisher |
Blackwell Publishing Ltd |
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| ISSN |
1463-5224 |
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Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
5626 |
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| Author |
Hurn, S.D.; Turner, A.G. |
| Title |
Ophthalmic examination findings of Thoroughbred racehorses in Australia |
Type |
Journal Article |
| Year |
2006 |
Publication |
Veterinary Ophthalmology |
Abbreviated Journal |
Vet Ophthalmol |
| Volume |
9 |
Issue |
2 |
Pages |
95-100 |
| Keywords |
Animals; Cataract/epidemiology/veterinary; Diagnostic Techniques, Ophthalmological/veterinary; Eye Diseases/diagnosis/epidemiology/*veterinary; Female; Horse Diseases/diagnosis/*epidemiology; Horses; Male; Prevalence; Victoria/epidemiology |
| Abstract |
OBJECTIVE: To record the prevalence and document the types of eye disease in population of Thoroughbred racehorses in Victoria, Australia. DESIGN: Prospective study. ANIMALS: Two hundred four Thoroughbred racehorses. PROCEDURE: All horses and both eyes were examined at four metropolitan and two country racing stable complexes. Ophthalmic exam was performed following dark adaptation with a transilluminator, biomicroscope, and direct ophthalmoscope. Intraocular pressures were measured when indicated. Both pupils were dilated with tropicamide when indicated. RESULTS: One hundred eighty-two (89.2%) flat-racing and 22 (10.8%) jump-racing (hurdle or steeple) horses were examined. Age range: 2-9 years (mean 3.7 years, median 3); 97 (47.5%) male-neuter, 74 (36. 3%) female, 33 (16.2%) male. Potential vision-threatening eye disease was present in 15 (7.4%) different horses: complete lenticular cataracts 3, posterior lens luxation and cataract 1, large peripapillary 'butterfly' inactive lesions 3, large peripapillary 'butterfly' active lesions 2, peripapillary focal inactive 'bullet hole' chorioretinal lesions (> 20) 5, optic nerve atrophy 1. Non-vision threatening eye disease was present in 117 (57.4%) different horses, involving one or more ocular structures: lower eyelid scars 3; periocular fibropapillomatous disease 1; third eyelid squamous cell carcinoma 1; corneal scars 6; corneal band opacity 2; anterior iris synechia 1; developmental cataracts 36 (17.2%); peripapillary focal inactive 'bullet hole' chorioretinal lesions (< 20) 103 (50.0%); linear peripapillary hyperpigmentation bands 16 (7.9%). Unusual variations of normal ocular anatomy and colobomata was recorded in 11 (5.4%) different horses: granular iridica hypoplasia 3, granular iridica hyperplasia 2, multilobular granular iridica cyst 1, microcornea 1, hyaloid remnant 1, rotated optic nerve head 1, coloboma of the lens 1, atypical coloboma of the retina 1. CONCLUSIONS: This survey demonstrates that the prevalence of vision-threatening eye disease in racing horses may be greater than previously perceived, and highlights the importance of ocular examination within any routine physical examination of horses. |
| Address |
All Animal Eye Services, Mount Waverley, Victoria, Australia. sdhurn@bigpond.com |
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English |
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| ISSN |
1463-5216 |
ISBN |
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| Notes |
PMID:16497233 |
Approved |
no |
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Equine Behaviour @ team @ |
Serial |
3766 |
| Permanent link to this record |
