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by gsdlvr2 on 28 March 2008 - 01:03
The reason I asked about water is because even at sea level water and the reflection off of it can have a similar effect to the high altitudes on eyes. True of an ocean or large body of water.
Sorry about your dog. Wish she the outlook was better.
by hodie on 28 March 2008 - 02:03
Many of you have some misconceptions about UV light. Perhaps this will help:
Ultraviolet, or UV, radiation makes up part of what is called the electromagnetic spectrum (EM) of light. The human eye can see wavelengths of light that are in the color portion of the EM spectrum. Light with wavelengths shorter and more energy intensive than the human eye can see is called ultraviolet light. The UV spectrum of light can be further broken down into UV-A, UV-B, and UV-C but for simplicities sake, we will forget that for now.
UV light is contained in the range of wavelengths that is produced by the sun. Only a small portion reaches the surface of the earth. Most UV light is absorbed by the ozone layer that protects the Earth. Some is reflected back into space. It is important to understand that sunlight is received as direct rays and as diffuse light. Diffuse light is light which has been scattered by the atmosphere and is sometimes referred to as skyshine (as opposed to moonshine LOL - just kidding). The sky is blue because air molecules scatter the shorter wavelength blue light. UV light is scattered even more than blue light. So we actually receive more UV radiation from this skyshine than from direct sunshine! Just think about how it is possible to get sunburned at the beach on a cloudy day when there is no direct sunshine from the sun. Also the reflection of ultraviolet radiation from the surface of water is about twice as great as from a field of grass, but only one-fourth as much as from freshly fallen snow. One receives about eight times the amount of UV radiation from a snow-covered field as opposed to a field of grass. The glass in our homes, offices, and automobiles prevents the passage of most ultraviolet rays. But outside, certain surfaces like water, snow, concrete etc. reflect a lot of UV all around, including into our eye and onto our skin.
How much UV radiation reaches the earth's surface varies greatly depending on the time of year or season, time of day, weather conditions, type of surface, altitude, and latitude. It is important to note that at higher altitudes more UV radiation, between 4-5% for every 1000 feet ascended, can reach the earth's surface. So for those of us at higher altitudes, we naturally have anywhere from 40-50 % more UV, but that can be even more dramatic an increase if there is snow cover etc. But it is incorrect to assume that at lower altitudes one is not getting any UV exposure.
We know that UV-C radiation damages DNA in skin. It is highly likely that eventually some genes will be found in the German Shepherd Dog that are damaged in one way or another and that then are expressed by the development of the disease. It is just like how human eyes are also damaged by such light, but we get cataracts.....
by Darcy on 28 March 2008 - 03:03
Thank you for some of the science behind this Hodie. Anything about the eye structure that makes this happen in the dogs eyes vs humans getting cataracts?
Do you know has this been a long stnading problem with German Shepherds or a more recent problem?
Darcy
by GoZags on 28 March 2008 - 04:03
Thanks for the great topic. We adopted our 5 year old GSD a few weeks ago from a cousin who was moving and couldn’t keep him. He was diagnosed with pannus last year and was prescribed prednisolone drops. He lived in AZ and I’m sure spent time watching the kids swim in the pool, so the UV probably played a part. As a coincidence, I did check his online pedigree and saw Eiko V kirschental, but it is way back on the 6th generation. Glad I found this message board. Thanks for the great information.
by DenWolf on 28 March 2008 - 04:03
Pannus is more prevalent at high altitudes. It is seen in other breeds as well. I live in Colorado, at about 6,000 ft. We have more sunny days here than any other state except Arizona. UV is pretty strong, and gets worse the higher you go. Air is very dry almost all year.
I have a male GSD who developed Pannus at about 7-8 years of age. He was born at sea level, but moved here at 1 year of age. The eye specialist has me treat with cortisone and special compunded cyclosporin drops. It works well, but the Pannus lingers. It always worsens if he is out on sunny days in the warm part of the day. The specialist said if he were brought to sea level, it would go away.
Last winter, I took him to Florida for 6 weeks. The pannus completely vanished after about a week there, but returned fairly quickly after we returned to Colorado in the spring.
This dog has produced about 50-60 puppies, and only one has ever developed the condition, and it lives in Colorado as well.
Interesting thing that I remember.. this dog developed the disease within 6 months of being sprayed directly into his eyes at very close range by a skunk.. Since it is immune related, I wonder if one day there will link something to skunk-spray and bacteria that may trigger this in certain predisposed dogs...
(Remember that doctors didn't believe stomach ulcers were caused by bacteria until late last century. )
Just an observation!
Bottom line, I don't believe this is a simple genetic trait that you can test for and weed out of breeding animals..
No Kirshental either.
by ziegenfarm on 28 March 2008 - 05:03
the elevation here is 1211. no large bodies of water within 5 miles. we do get a fair amount of snow in the winter time and humidity is fairly high year 'round.
pjp
by hodie on 28 March 2008 - 14:03
Humidity has nothing to do with this. Genetics, altitude and latitude do. If one is at a higher altitude, you get more UV radiation. If you are at a lower latitude, meaning closer to the equator, you get more UV radiation. If you are around surfaces that reflect you receive more UV radiation.
The current treatment usually is eye drops using prednisolone acetate and/or cyclosporin. There is a surgery available where some of the scar tissue can be removed, but how effective it is, and how much it helps long term since the underlying pathology is not resolved, is unclear. If not treated, and in some cases, even if treated, the dog will be blinded. But even blind dogs can do well.
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