How do Dog's Eyes Handle Extremes of Light?

[arealhuman]

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I was out walking with our dog in the snow and sun recently, and it was very bright and it got me to thinking how dog's eyes handle extremes of light. For example, bright sunlight, turning a light on inside when it's dark, and so on. I've noticed Jimmy will squint in bright light, but he never seems bothered by going from total darkness to a lit room. Do changes like this make them uncomfortable?

 

[Violet Turner]

What an interesting question, i had a quick re-search as I'm not 100% sure and its been a long time since i did anatomy of a dog etc. Dog eyes also have the ability to “re-use” existing light to improve their vision in low-light environments. Many mammals, including cats and dogs, have a layer of highly reflective cells behind the retina that reflects back any light the eye captures. The tapetum lucidum enhances the light-gathering efficiency of your dog’s eyes by nearly 40 percent and accounts for that eerie eye-glow you see at night. From Night Vision to Television, An In-Depth Look at What Dogs Can See

 

[Josie]

Very interesting question! Don’t have any answers though...

 

[JudyN]

I think dogs can see better than us in the dark but not as well as cats can - this is something I looked up when OH and I disagreed over whether we should leave the light on in the kitchen when he was eating.

 

[Nanny71]

I used to leave a plug in night light for Dudley. I still take one with us to use on holiday as he is in a strange place and may not find his water bowl at night

 

[JoanneF]

I used to leave a plug in night light for Dudley. I still take one with us to use on holiday as he is in a strange place and may not find his water bowl at night

I do too but it's as much to help me find the 'water bowl' in the dark lol

 

[leashedForLife]

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unless a dog has congenitally-abnormal eyes, an infection or inflammation, or a serious nutritional deficiency, moving from dim or moderate light to bright sunlight shouldn't bother their eyes.
There are, however, many many potential k9 eye-defects, including "collie eye", micro-opthalmia [tiny eyes], the various congenital eye-defects caused by DOUBLE MERLE matings [breeding merle dam to merle stud], albinism, abnormal irises, & more.

Dog vision is considerably different from human vision - being primates, color is important to us [the contrast of ripe fruit against green foliage in particular], so we have lots & lots of CONES for color vision, & can see deep jewel tones as well as a wide range of pastels, plus a decent range of greys.
Dogs don't care much about color, they care about MOVEMENT, so they have many-more rods than they do cones; they see an incredible range of greys, plus of course black & white, but they see jewel tones in much-less saturated color; their version of peacock blue or schoolbus yellow is almost pastel. // Dogs are also red / green color blind, so while that red Kong on the green lawn pops visually for us, for dogs, by contrast, there's no contrast - it's just 2 slightly different shades of grey.
Dogs see blue & yellow very well, so a dog-friendly Kong color would be sky-blue, or sunshine yellow [which this is not - it's more butternut-squash, but the yellow disappears into the ash-white background], not brick or tomato red.

Dogs can see MUCH better in low-light than humans can - not only b/c of their tapetum magnifying the available light once it's inside the eye, but b/c of their eye anatomy: all those rods! Wow.
So while we can see a million-plus discernible colors in a wide spectrum of shades, plus we see jewel tones, dark colors, & pastels, dogs see thousands of discernible shades of grey, varying in brightness [how much light they reflect, vs absorb] & saturation. When U combine their ability to see many shades of grey, & to see with decent focus in very dim light, *plus* their eyes selectively react to -movement- rather than static objects, even at a considerable distance, dogs have a massive built-in advantage, visually, in dim light.

Dogs also have acute hearing that goes well beyond the human audio-spectrum, into both ultrasound & infrasound - ultrasonic includes bat-calls & mouse vocalizations, including the 'song' of male mice broadcasting for females, the shrieks of running compressors on refrigeration units, the high-pitched hum of fluorescent lights, & the whine of a booby-trap wire reacting to a breeze blowing over it.
Infrasonic sounds are very deep-pitched; to us, they're inaudible - "pictured' in a sonograph, they make widely spaced peaks, & humans feel them rather than hear them. Examples of infrasound are elephant rumbles & deep calls, & distant thunder - dogs can hear thunder about 10-miles away. // The long, wide waves of infrasound travel long, long distances - elephants can communicate over enormous areas, & some elephant calls can travel over 50-miles. Many species of the great whales use infrasonic calls, & some of these calls can travel literally around the world, as water propagates sound-waves so much better than air.
Add their acute sense of smell, & dogs' ability to detect things we cannot see, smell, or hear is phenomenal - that's why dogs are so helpful to soldiers & police on night patrol, when highly-visual humans are relatively blind, & 24 / 7, we're pretty deaf & unbelievably nose-blind, when compared to dogs.

- terry

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[arealhuman]

I need to rephrase my question - how comfortable is it for a dog going from (almost) complete darkness to bright light? So imagine it's night time and it's dark, you turn on your bright light in the room and your dog starts looking around, eyes wide open. Does this sudden changes of extremes hurt their eyes like it would ours?

 

[leashedForLife]

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in a word? - No.

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[Biker John]

I do tend to wonder if dogs think we humans have magic powers, after all as soon as we go into a dark room it instantly becomes light.