J Vet Sci.  2007 Dec;8(4):409-414. 10.4142/jvs.2007.8.4.409.

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

• Yu HA
• Jeong MB
• Park SA
• Kim WT
• Kim SE
• Chae JM
• Yi NY
• Seo KM

• KMID: 1106222
• DOI: http://doi.org/10.4142/jvs.2007.8.4.409

Abstract

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/m2 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 occured 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.

Keyword

dark adaptation time; electroretinography; Miniature Schnauzer dogs

MeSH Terms

Animals
Dark Adaptation/*physiology
Dogs/*physiology
Electroretinography/*veterinary
Male
Retina/*physiology
Time Factors

Figure

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  Fig. 1 A conscious Miniature Schnauzer dog is positioned on the table, and the head and light stimulator (LED-electrode) is stabilized by the assistant's hand (A). A contact lens, cushioned with 0.3% hydroxypropyl methylcellulose, is applied on the cornea. A ground subdermal electrode is placed on the external occipital protuberance and a reference electrode about 2 cm caudal to the lateral canthus of the tested eye (B).

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  Fig. 2 Influence of dark-adaptation time on the amplitudes of a-waves in conscious Miniature Schnauzer dogs. a, b : A different superscript on the error bars indicates a statistically significant difference (p < 0.05).

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  Fig. 3 Influence of dark adaptation time on the implicit times of a-wave in the conscious Miniature Schnauzer dogs. a: The same superscript on the error bars indicates no statistical difference (p < 0.05).

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  Fig. 4 Influence of dark adaptation time on the amplitudes of the b-wave in conscious Miniature Schnauzer dogs. a, b, c : A different superscript on the error bars indicates a significant statistical difference (p < 0.05).

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  Fig. 5 Influence of dark-adaptation time on the implicit times of the b-wave in conscious Miniature Schnauzer dogs. a, b, c : A different superscript on the error bars indicates a significant statistical difference (p < 0.05).

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  Fig. 6 The graph represents the waveforms of the ERG in relation to dark adaptation times (1, 10, 20, 30, 40, 50, and 60 min) at a white light intensity of 2.5 cd·s/m2 in Miniature Schnauzer dogs. The light stimulus is given at the beginning of each recording. A) 1:1 min of dark adaptation time; 2:10 min of dark adaptation time; 3:20 min of dark adaptation time B) 4:30 min of dark adaptation time; 5:40 min of dark adaptation time; 6:50 min of dark adaptation time; 7:60 min of dark adaptation time.

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