Canine Solar Eclipse Blindness




Canine solar eclipse blindness is a rarity among dogs but one we should be aware of. In the United States on Monday, August 21, 2017, the Great American Eclipse 2017 began. At 8:46 AM PT, the total solar eclipse started in Oregon; by 5:04 PM ET it ended in South Carolina, forming a 67-mile-wide path.

With much anticipation, the total solar eclipse was viewed by thousands upon thousands of excited viewers. And … many of these people had their dogs with them. Scientists and veterinarians have found that dogs can be blinded or develop vision problems if they are not cared for properly when viewing such exciting phenomenon. Others say not. In this article, we approached it as a yes, the solar eclipse may cause visual problems if your dog’s eyes are not protected adequately.

Nebraska researchers in Kearney studying animal behavior from eclipse

A Nebraska study in Kearney NE, with researchers Dustin Ranglack and Nate Bickford, researched the effects of a solar eclipse on animals. According to the Associated Press, they hope to find out whether animals can sense the approaching alignment of the Earth, Moon and Sun before the eclipse becomes visible.

Currently, the researchers are gathering information on six red-tail hawks that are wearing GPS devices for a long-term university project at the University of Nebraska at Kearney. This global positioning equipment for existing research will gather information on the effects of a solar eclipse on animals.

The data was gathered one week ahead of the solar eclipse and one week after the solar eclipse for future studies.

canine solar eclipse blindness

Image provided by NASA

 

Five stages of the total solar eclipse

A complete total solar eclipse consists of five phases:
• Partial eclipse begins – this is when the Moon becomes visible over the Sun’s disk.
• Total eclipse begins – the entire disk of the Sun is covered by the Moon.
• Totality and maximum eclipse – the Moon completely covers the disk of the Sun. The only thing visible is the Sun’s corona. Halfway through the time of totality is the maximum point of eclipse.
• Total eclipse ends – the Moon begins to move away, and the Sun reappears.
• Partial eclipse ends – the Moon stops overlapping the Sun’s disk and the eclipse ends.

 

Eclipse retinopathy in dogs

Canine solar eclipse blindness due to solar retinopathy involves the lens of the dog’s eyes. Dogs normally do not stare into the sun. But when your dog, or even yourself, just happens to glance or stare into the sun, it would be like using a magnifying glass to focus on the sun’s rays. In other words, your eye will scorch if not protected.

This causes eclipse or solar retinopathy damage to develop in the retina, located in the back of the eyeball. This damage can be (1) immediate and permanent, (2) immediate and reversible, or (3) delayed and progressive. Eclipse retinopathy causes pathological (diseased) changes in the retina after looking directly into the sun. It is seen frequently after an eclipse of the sun. If you think there has been visual damage, take your pet to the vet immediately. It is better to be safe than sorry.

Signs of canine eclipse retinopathy

• Bad vision – reduced visual acuity
• Blind spots – central scotomas
• Chromatopsia -disruption or tinting of color perception
• Metamorphosia – disruption or distortion of shape perception
• Photophobia – light sensitivity

Age-related macular degeneration in older dogs

Scientists think that eclipse retinopathy contributes to age-related macular degeneration in older people and in older dogs. It is thought to be a common cause of progressive blindness. Unfortunately, there is no effective medical treatment for it. Occasionally, vision will recover after sun damage occurs, but not canine solar eclipse blindness is unpredictable at best.

Different from snow blindness, eclipse retinopathy does not require a true burn caused by heat. The eye retina is exposed to direct sun for less time and experiences less temperature increase than would normally cause a burn. The burn from a solar eclipse is mostly caused by a photochemical damage.

Photochemical damage of the retina

A Sweden study in Stockholm, located in the Department of Vitreoretinal Diseases at the Saint Erik’s Eye Hospital and Karolinska Institution, was titled “Photochemical Damage of the Retina.” According to this study, visual perception occurs when radiation reaches the retina. The radiation has a wavelength between 400 and 760 nm. Over time, the retina has evolved to capture photons efficiently, allowing it to initiate visual transduction. However, the retina is vulnerable to damage by light.

Because scientists are aware of it, they know to look for photochemical damage. This is because it can cause retinal damage within the intensity range of natural light. Photochemical lesions are in the outer layers of the central region of the retina. Two classes of photochemical damage are recognized:

• Class I damage – characterized by the rhodopsin actin spectrum, mediated by visual pigments. The primary lesions are in the photoreceptors.
• Class II damage – general confined to the retinal pigment epithelium (the pigmented cell layer outside the neurosensory retina that nourishes the retinal visual cells).

The rhodopsin action spectrum in the Class I damage peaks in a short wavelength region, converting light into an electrical signal. Rhodopsin, referred to as visual purple, is found in a wide range of organisms from vertebrates to bacteria. It is a biological pigment found in the rods of the retina. It also provides the basis for the concept of “blue light hazard” … the potential for a photochemical inducing retinal injury. If it develops, it has resulted from electromagnetic radiation exposure at wavelengths between 400 and 500 nm.

 

dog with sunglasses in a colored hammock

Figure 2 – Microsoft Word/Pickit Free Images

Children have an increased risk of eclipse retinopathy. A child’s eye lens is clear and crystalline. It does not block UV rays or and infrared light like in adults. If staring is done repeatedly before and after totality, eye damage will occur in young children.

So far, we see that those who are susceptible to damaged eyes from a solar eclipse are older people, older dogs, children and young puppies, young kittens, and so on. The advantage that animals have over people is that they do not stare directly into the sun as people do. Which is when the damage occurs to the retina. However, there is no guarantee it will not happen.

Viewing the solar eclipse in a safe manner

The only safe time to look directly into the solar eclipse is during totality. This is during the 2-1/2 minutes or so when the Sun is completely blocked by the Moon. Any time before or after totality when the Sun is visible, is when eye damage will occur.

The most dramatic stage of a total solar eclipse is when the Moon covers the disk of the Sun, leaving the Sun’s corona visible. It is during this time that temperatures drop, the sky becomes as dark as night, and birds and animals become quiet. And it is the time to watch for canine solar eclipse blindness developing.

If you or your dog have damaged eyes due to the eclipse
• STOP looking directly at the sun.
• Go indoors, preferably into a dark room
• Rest your eyes.
• Follow up later with an eye specialist.
• Test retinopathy now.
• Remember that canine solar eclipse blindness may have developed!

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