A Look at the Canine Eye - Simply For Dogs
Canine Eye

A Look at the Canine Eye

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Medically Reviewed by Veterinarian Angela Dwyer, DVM on July 09, 2018

When you look into your dog’s sweet eyes, you just have to melt, right? They really are windows to the soul. But have you ever wondered what exactly makes your dog’s eyes different from your own? Let’s take a closer look at the canine eye.

What Makes Up the Canine Eye?

Generally speaking, dogs have the same sort of eyes as other mammals, but there are some differences that have evolved over the eons. Essentially, a canine eye is a sphere, with two chambers that are filled with fluid. The lens separates these chambers, and works to focus beams of light onto the retina, which is the rear portion of the eye. The outer structure is the cornea, which serves two purposes – to assist the lens in delivering light to the retina, and also to protect the eye.

The dark center in your dog’s eye is the pupil, and the colored area around the pupil is the iris. The white part of the eye is called the sclera. Usually, the iris is brown, but some dogs have blue eyes. In other cases, a dog might have one blue and one brown eye – this is called heterochromia.

Dogs have an upper and a lower eyelid, as well as a third eyelid located toward the bottom of the eye, between the lower lid and the eyeball. It’s believed that the purpose of the third eyelid is to protect the eyeball, and to assist in flushing out foreign particles.

The muscles that surround the dog’s eyeballs are called orbicularis oculi. They work to move the eyes in various directions.

The Function of the Canine Eye

I don’t know about you, but my night vision isn’t all that good. Come to think of it, I don’t think I’ve ever heard anyone claim that they have outstanding night vision. This is because our eyes simply aren’t built for good night vision. We’ve evolved in such a way as to be naturally active during the daylight hours, so night vision isn’t essential for our survival as a species.

Dogs, on the other hand have great night vision, because they evolved as predators that were naturally more active at dusk and dawn. Their eyes are also better equipped for detecting movement than ours.

A lot of people think that dogs only see in black and white, but that’s not true. They’re not able to perceive color quite as well as humans, but they do see color – mainly shades of blue, violet and yellow. They don’t see red, orange and green very well, though.

Canine Eye Structure

The canine eye also differs from the human eye in other ways. The lens and corneal area of the canine eye are larger, and this is largely what enables dogs to see better in the dark. A dog’s night vision is also enhanced by the tapetum, which is a reflective surface located behind the retina. This is also what causes your dog’s eyes to appear to glow in the dark, when exposed to a beam of light.

The retina of the canine eye is similar to that of a human in that it is comprised of rods and cones. Rods are the structures that enable the eye to perceive motion and work in low light. Cones are what control the ability to identify colors, and function in higher light levels. The canine eye has a higher proportion of rods to cones than the human eye, and this is another reason why a dog’s night vision is so much better than a human’s. As well, the human eye has three types of cones as opposed to the two types in the canine eye, which is why we’re able to see more colors.

When you look at your dog’s eyes, you’ll see that they’re set farther apart than your own. This means that your dog has far better peripheral vision than you do, but his depth perception isn’t as good.

It was once believed that dogs were essentially myopic (nearsighted), but this has been disproven thanks to advances in eye examination techniques. We now know that dogs have fairly normal vision, although there are some breeds that are prone to myopia – Schnauzers, Rottweilers and German Shepherds, for instance, are often not the best “sight” dogs.

Your Dog’s Other Senses

As humans age, they sometimes develop cataracts. This is a hardening of the eye’s lens, which impedes its ability to deliver light to the retina. Dogs can also develop cataracts. Fortunately, there have been advances in canine eye surgery that can correct the condition. One treatment would be removing the cataracts. Another would involve the use of prosthetic lenses to correct the loss of vision.

Humans rely a great deal on their ability to see, although it’s well known that other senses frequently become heightened when a person’s vision is compromised. This is true also of dogs that are losing their eyesight. However, even dogs with perfect eyesight rely less on visual perception than they do on other senses. As an example, a dog can hear sound frequencies that humans cannot. Dogs also have a much better sense of smell than humans, because they have approximately 300,000,000 scent receptors in their noses, as opposed to our comparatively paltry 6,000,000.

A dog’s sense of balance is also far superior to our own. How do we know this? Well, consider how well you get around in the dark. If you’re anything like me (and like most other humans), you probably stumble around and feel disoriented. Dogs don’t. The nerve endings along a dog’s spine, in the joints, and even in the pads of the feet are constantly sending information to the dog’s brain, helping him to maintain his sense of balance.

So, there’s a lot more than just the canine eye at work when it comes to helping your best buddy “see.”

A Holistic Approach to the Canine Eye

Now you know how the canine eye works. Holistic health practitioners take it further, though, believing that your dog’s eyes can indicate any number of conditions, not all of which are directly related to the eye. Conventional health practitioners know, of course, that humans and other animals that are afflicted with liver disease will often display a yellowish tinge to the whites of their eyes. Holistic practitioners know this too, but they also believe that there are other ways in which the eyes can serve to identify various illnesses.

In Chinese medicine, for instance, it’s believed that the appearance of the eye can be used to identify disease in virtually any organ. This is because the eyes reveal the animal’s Shen, or spirit. If the eyes are bright and lively, then the source of life (the Jing) is in good shape. If the eyes are dull or red, then there’s a problem with one or more of the internal organs.

Iridology is another type of alternative medicine. As you might gather from the name, this is a technique in which the iris of the eye is examined. It is believed that a disease of the internal organs will manifest as a change in the shape or color of the part of the iris that corresponds to the affected organ.

Natural Care for the Canine Eye

I’m a big believer in modern veterinary medicine, but having said that, much of the time natural care can be equally effective when it comes to the canine eye. Remember, though, that preventing eye problems is invariably better than treating them once they’ve occurred, and that there will be times when you’ll simply have to see your veterinarian.

The following are some natural methods you can use to keep your dog’s eyes healthy.

1. Make Sure Your Dog Gets Plenty of Exercise

Exercise is vital for any number of reasons – to prevent or correct weight gain, ensure good joint mobility, and keep your dog stimulated both physically and mentally, to name just a few benefits. It also works to flush out toxins throughout all the structures of the body, including the eyes.

2. Provide a Good Diet

Toxins are also flushed out of your dog’s system via dietary antioxidants. You’ll find plenty of B, C and E vitamins and other antioxidants in leafy, green vegetables, carrots, egg yolks and pumpkin. Unless your dog is on a corn-free diet due to allergies, you can also mix some corn in with his food. The main nutrient when it comes to your dog’s eyes is simply water – if your dog isn’t properly hydrated, the membranes can dry out and cause irritation and other problems.

3. Look After Your Dog’s Immune System

Holistic practitioners believe that many health issues can be traced back to an immune system that’s out of balance. The things that can adversely affect your dog’s immune system are essentially the same that can cause your own immune system to become unbalanced – artificial flavors and preservatives in food, stress, herbicides and pesticides.

It’s easy enough to avoid herbicides and pesticides, but perhaps a bit more difficult to make sure that your dog’s food is additive-free. One thing that can usually be easily dealt with in your dog, though, is stress. If your dog is depressed (perhaps due to a change in the family structure, or the death of another pet) or angry because he’s been left home alone too much, there are measures you can take.

In What Happens to Your Dog When You Divorce, I talked about the importance of easing your dog through the transition, and offered some suggestions as to how it can be done. So, if you’re in the middle of a breakup, or even if your relationship with your significant other is just going through a rough patch and you think that your dog is troubled, I think that’s a post worth reading.

If you’re not at home much, you might consider enrolling your buddy in doggie daycare, or hiring a pet-sitter. For depression, look to what’s going on in your own life that might be making your dog depressed, and take measures to ease the conflict. You can also consider aromatherapy for either condition in order to get your dog’s immune system back into balance.

4. Do an Eye Massage

You can help improve circulation to the canine eye by doing an eye massage. Using your fingertips, make gentle circular motions starting at the corner of the eye and moving around the bony areas. Be sure to be gentle – you don’t want your dog to feel poked and prodded, because if he does, he could move suddenly and you might inadvertently cause an injury.

Most dogs will also appreciate a general body massage.

These are some things you can do to encourage good canine eye health. Now, let’s talk about natural and conventional treatments for eye disorders.

Treating Canine Eye Problems

I am fortunate in having a wonderful veterinarian who takes a holistic approach when possible, but who is also highly skilled in conventional veterinary medicine. I rely so much on Stephen’s advice that I often tell him, “Just do what you’d do if Janice and Leroy were your own dogs.” As my dogs age, for instance, I know that I can trust Stephen with any age-related issues.

Cataracts could be one such issue. The holistic approach would be to try to prevent cataracts using good nutrition, ensuring that your dog’s immune system is in balance, etc. If Janice or Leroy should develop cataracts, I’m confident that Stephen would know when a holistic treatment would be best, and when conventional surgery would be the better approach. I let him guide me because his knowledge is so much greater than my own.

I think this is the best course of action for most dog parents. I know a few people, though, who invariably insist on alternative treatments. But sometimes, there just isn’t an alternative treatment – as an example, if your dog ends up being poked in the eye with a stick, no amount of massage or nutrition or herbal therapy is going to help. The dog is going to need conventional treatment.

The problem with taking an “alternative medicine” approach to canine eye issues is that they don’t work as quickly as conventional medical treatments. The flip side is that conventional treatments usually focus more on simple treatment, without giving overly much consideration to the cause. So, what alternative treatments are best? Here are a few.

1. Acupuncture

Acupuncture has its origins in Chinese medicine, which sees the eyes as connected to the liver. It’s been used over the centuries to treat eye conditions like irritations, conjunctivitis and keratitis.

2. Herbal Remedies

Herbs can be used both internally, because of the antioxidants, vitamins and minerals they contain. They can also be applied directly to the eyes, but please keep in mind that this isn’t usually a “DIY” thing. It would be great if you could just go online and identify the types of herbs that can be applied to your dog’s eyes for various conditions, but there’s a lot of misinformation out there, and even, unfortunately, some “bad actors” who think it’s amusing to recommend treatments that could harm your dog. It’s always best to consult your vet before using herbal remedies.

3. Chiropractic Treatments

It might seem odd to think that a chiropractic adjustment would help the canine eye, but a lot of dog owners swear by them. When you think about it, humans often use chiropractic treatments to treat issues that would seem to have nothing to do with the spine. In fact, I even have a friend who insists that after trying to quit smoking for years, she finally got it right with the help of regular chiropractic adjustments.

Usually, if you go this route for treating canine eye problems, the worst case scenario is that you’ll be out money, and the condition won’t improve. If you think it’s worth a try, though, ask your vet to recommend a practitioner who is skilled in chiropractic treatments for dogs.

Now, let’s go a bit deeper, and talk about specific conditions and how they might be treated naturally.

Treatments for Canine Eye Disorders

I know I keep stressing this, but I think it’s worth mentioning again that alternative treatments might not always be best for canine eye problems. I always follow my vet’s advice.

Keep in mind, too, that when you use natural treatments to treat canine eye problems, you should proceed from a position of regularly examining your dog’s eyes and keeping them clean. Then, if you see symptoms, see your vet. A natural remedy might be appropriate, or it might not.

With that said, here are some common conditions along with how they can be treated.

1. Irritations

An eye irritation can be due to any number of things – a foreign object lodged in the eye, irritation due to chemicals like herbicides, pesticides or smoke, or pollen or dust entering the eye.

Signs of eye irritation include redness, scratching, rubbing, swollen tissues and runny eyes. If it’s just one eye that’s affected it’s most likely a foreign object. If it’s both eyes, then most likely it’s an irritant. In rare cases, it could be due to disease.

Sometimes, simply rinsing out the eyes with water will ease the condition. If the irritation persists, though, it could be that the cornea has been harmed, in which case you will need to see your vet in order to find out the extent of the damage and to determine a proper treatment.

2. Keratitis and Conjunctivitis

Karatitis is inflammation in the cornea, whereas conjunctivitis is inflammation in the membrane. Either condition could mean an eye disease, or one that’s more generalized. The symptoms are pretty much identical to those that occur with the introduction of irritants into the eyes, and can also be caused by viral, bacterial or fungal infections.

Herbal medications can be effective. An infusion of calendula, chamomile, elder flowers or Oregon grape root can be very helpful. If herbal treatments don’t lead to improvement, though, see your vet.

3. Cataracts

I know I keep going back to cataracts. That’s because today, dogs are living longer, and the likelihood of developing this condition is increasing proportionally. It usually takes a number of years for cataracts to develop.

Depending on the age of your dog, you might choose not to have cataracts treated. They hardly ever cause complete blindness. If treatment is warranted, herbal treatments could involve bilberry, eyebright, and other herbs that are rich in antioxidants.

Acupuncture is also believed to improve blood circulation to the eye area, which could slow the development of cataracts.

If total blindness seems likely, your vet will likely recommend surgery to remove the cataracts.

4. Dry Eyes

Dry eyes can be related to immunological conditions like diabetes, arthritis and lupus. Various medications like antihistamines and gastrointestinal medications are also believed to be linked to dry eyes.

Symptoms of dry eyes include redness, itching, watery eyes, and pain. The condition is diagnosed by using a strip of paper on the lower lid to determine the level of tear production – this is known as a Shirmer test.

Conventional treatment for dry eyes in dogs is the same as it is for humans – artificial tears. If you and your vet think that an herbal remedy will get the job done, there is a preparation known as Similsan eye drops that might be equally effective. These eye drops contain euphrasia, apis and sabadilla.

When dealing with dry eyes, antioxidants are again important. So is ensuring that your dog is properly hydrated. If the condition is related to arthritis, then you can also use glucosamine and chondroitin. The jury is out on the effectiveness of these supplements, with some veterinarians recommending them and others condemning them as useless. I can offer anecdotal evidence in favor, though. My aging Boxer, Gloria, was far less troubled by arthritis pain once I began administering glucosamine and chondroitin on the advice of my then-vet, Dr. Kim.

These are just a few of the canine eye problems that can be treated using alternative medicine, conventional medicine, or a combination of the two.

The Final Word

The canine eye is an amazing structure, no less amazing than the human eye. It is a bit different, though. When it comes to some functions, canine eyes work better than human eyes. In others, not so much.

In one very important way, though, canine eyes and human eyes are the same – they need to be cared for. You know the importance of regular eye exams, and looking after your ocular health. You wouldn’t “experiment” with your own eyesight, so please, don’t do it with your dog. It’s great to want to go with natural treatments if possible, but listen to your vet in the same way that you would your own eye doctor. Most vets are very open to holistic eye care, but if conventional medicine is the better treatment, don’t try to second-guess. After all, you want to be looking into bright, loving, healthy eyes for many years to come.

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