The Eyes Have It

By David Ramey | https://www.doctorramey.com/

I was recently asked to write something about horse eyes (I'm happy to respond to such requests, by the way). I think that eyes are really cool, so here goes.

From a medical standpoint, eyes are their own little world. And, honestly, I think that it would be a little irresponsible of me to try to write all about the medical problems that can affect horse eyes because, frankly, I don't think that it's a very good idea to try to treat such an important structure as an eye without consulting your veterinarian. Of course, not all eye problems are serious problems, but if you see your horse holding his eye shut, or if the cornea (the surface of the eye) is cloudy, or if you see blood, or excessive tearing, then you should call your veterinarian immediately.

Now, that said, the eyes of the horse are unique in several ways. So, here are a few things about normal horse eyes that you maybe did not know. Fun stuff to talk about around the barn.

The surface membrane of the eye – the cornea – provides a clear, protective layer for the eye. Clear, of course, so that the horse can see through it. It's clear because it has water in it. However, it doesn't have as much water in it as it can hold – in fact, keeping the right amount of water in the cornea is an important part of the function of cells of the cornea. There is even a word for keeping the right amount of water in the cornea: deturgescence.

Ever see an injured eye? In many cases, the eye that has been injured turns a bluish color There is a reason for that. It is because the injury to the eye causes the cornea to swell. And when it swells, the clearness of the cornea is lost: it turns blue. So, if you are going out to see your horse, and you see that his eye is blue, call your veterinarian. The cornea is swollen, and there is something wrong. Horses are mostly colorblind. They aren't completely colorblind –just mostly Horses can see blue and green, but not red. To a horse, red, and related colors, appear mostly green (like red-green colorblindness in people).

If you are painting jumps for a horse, you might want to take this into consideration. If the jumps and the color of the ground are only a few shades different from each other, the horse will have a harder time distinguishing between the rail and the ground. In fact, there have even been studies to show that horses are less likely to knock down a rail if a jump is painted with two or more contrasting colors, as opposed to one color. So, in addition to multi-colored jumps being prettier, they are probably safer, too. And keep mind that horses do not distinguish colors very well the next time you hear someone tell you about their horse being afraid of a particular color. In fact, most horses can't tell that there is much of a difference.

Horses actually have pretty good vision. Most studies suggest that horses don't see as well as people, but they see better than dogs, cats, and rats. (Imagine doing visual acuity studies on a rat. There truly is a job for most everyone.) There is actually a part of the eye where vision cells are concentrated, which explains why horses often tilt their heads to look at things; they're trying to get the objects into the best area of vision to see them more clearly.

Horses are very sensitive to detecting motion, too. Of course, horses are prey animals, so they need to be able to quickly detect when a predator is moving in. Unfortunately, the area where motion if first seen – at the edges of the eye, in the peripheral vision field – is where vision is the poorest. And that is why horses often spook if they see something moving – they can detect the motion, and, who knows, it may be coming to eat them!

Horse eyes are really big, and they see a lot. In fact, horse eyes are one of the largest eyes of any mammal. They are set on the sides of the horse's head, which allows the horse to see in an almost 360 degree circle (almost – they can't see directly behind themselves, so you should never come up from behind a horse and surprise him).

They may see a lot, but their depth perception is pretty bad. There is a trade-off for the wide field of vision. Because the horse's eyes are set so far apart, they mostly use one eye to see anything, and that is mostly in front of the horse's face. And because they usually use one eye, they don't have very good depth perception. And that is why you often see horses arching their necks, or moving their heads up and down, when confronted with an object that they don't recognize – they're trying to get the best view of the object.

Horses cannot see two things clearly at the same time. At one time, I heard that horses had the amazing ability to see two things at the same time. That is, they could be down on the ground grazing, and see the grass clearly, and, at the same time, see clearly in the distance (to look for predators, or, people coming to catch them, I supposed). This was supposed to be due to what was described as a “ ramp retina”. But it turns out that the ramp retina does not exist. When a horse needs to see distant objects, he picks his nose up to use the part of his visual field where both eyes are in play – down the nose.

What is that black stuff coming out of my horse's eye? That is called the corpora nigra (black body, in Latin). It sticks out from the top of the iris. It looks like a bunch of black globs. I have had three emergency calls on them over the years, too. But they are normal. Nobody is completely sure why it looks like the inside of the horse's eye is exploding, but some people thing that it is a sunblocker for the pupil (the slit in the iris that lets light back into the eye). Don't worry.

How come my horse's eyes glow in the dark when I shine a light on them? That's the tapetum (ta – PEE – tum). It is a layer of tissue at the back of the horse's eye, that reflects light and enables the horse (and cat, and dog, and deer, for example) to see better at night. So there you go – some tidbits about the horse's eye. Eyes (all eyes – not just horse eyes) are absolutely fascinating. They are like their own little self-contained world. And not all eyes are alike, for example, they are quite different from human eyes.

Of course, if you think that your horse has an eye problem (squinting, draining, swelling of the eyelids, etc.), it is best to get your veterinarian out to see it as soon as possible. As interesting as eyes are, they are also too important to mess around with.

ABOUT DAVID RAMEY, DVM:

Dr Ramey began veterinary practice in 1984, in the Los Angeles area of southern California. He has been providing outstanding care to horses in southern California ever since. He specializes in the care and treatment of pleasure and performance horses. His clients particularly value his no nonsense approach, focused on providing services instead of selling products, his compassion for horses, and his ethical approach to the practice of veterinary medicine.

Dr Ramey believes that compassionate care involves providing therapies for which there is good scientific evidence of effectiveness. It is not compassionate to simply offer to sell someone the latest unproven therapeutic nostrum, nor is it kind to the horse to simply pull out therapies and give them a try, just because it is something to do. True com-passion – for horse and horse owner –involves adhering to high ethical standards, and high standards of scientific evidence in choosing therapies.

Spring Feeding Tips

With Dr. Nettie Liburt of Buckeye Nutrition

By Lisa Kiley | https://www.cashmans.com/

Spring is just around the corner and soon we will be enjoying nicer, longer days and hopefully some anticipated extra time in the barn with our horses. While this is a great time to do some spring cleaning around the barn and prepare for the season ahead with our horses, from scheduling trail rides to planning for upcoming shows, it is also a great time to think about your horse's nutrition. Changing seasons have an impact on our horses needs and it is important to take some time to evaluate your feeding program to make sure it is working well or see if some adjustments need to be made.

Dr Nettie Liburt is the Senior Equine Nutrition Manager at Buckeye Nutrition, and she has some great tips for what to think about when it comes to feeding your horse this spring.

There are often two main issues that come to mind when thinking about our horses – horses that may need to gain weight and those that might need to lose a little. In the spring, these issues can be magnified because we are dealing with fluctuations in temperature and pastures that are producing grass quickly. Dr. Liburt advised that monitoring horses through the winter is important for keeping track of any weight fluctuations. Checking under blankets and regular grooming sessions are a good start, but she also recommends getting in the habit of snapping a photo of your horse about once a month and using a weigh tape to get a real sense of any changes that are going on. While we might think that we would be able to catch changes in our horse, having the visual and measured evidence gives a much better gauge of changes and getting in the habit of documenting for health records is a great idea.

In the case of a horse that is coming out of the winter thin, it is a good idea to have a veterinarian do some basic tests to determine if there might be any underlying medical or dental issues. Even if your horse is healthy, having a basic blood panel drawn is a great way to understand what your horse's ‘normal’ is. That way, if there are any issues in the future, you have something to compare them to. Dr Liburt suggested that in addition to working with your veterinarian, seek the advice of a trusted nutritionist to put together the best plan for your horse going forward. She stressed that quality forage is the first step to any feed program. Sometimes hay can get a bit scarce as spring approaches, but it is so important to make sure that your horses are getting what they need to maintain a healthy weight. If you are in an area where sourcing hay is difficult, there are other options such as soaked hay cubes or chopped hay that can supplement to get through the season. To add weight, the horse needs an increase in calories and Dr Liburt advised that adding fat is the best way to provide these calories. This can come in the form of a supplement or a feed that has a higher fat content.

For horses that have extra weight coming out of the winter, there are several things that can be implemented to help them. One of the important things that Dr. Liburt pointed out was that a horse's feed should never be cut drastically. She advised that even if a horse needs to lose weight, their requirements for vitamins, minerals and proteins stay the same. She recommends that a ration balancer be used to meet these needs. Similarly, when it comes to forage, hefty horses still need to have access to hay and should not go longer than four hours between meals. However, Dr. Liburt advises that the hay for horses that may need to reduce weight does not have to be of the highest quality, a good medium quality hay provides plenty of chew time without allowing them to overindulge. Using slow feeders, like bags or boxes, can really help slow down intake while keeping the horse busy. These horses are also great candidates for grazing muzzles once the grass does start to grow Just like their thinner counterparts, knowing a horse's health status can pinpoint issues like metabolic disorders that will need to be treated and closely monitored so they don't become a major issue with devastating results.

When it comes to gearing up for spring pasture turnout, Dr Liburt stresses that slow and gradual is key to getting horses used to pasture after having been on a dry lot or a winter field for the past several months. While not an option for everyone, she advised that rotational grazing is a great way to manage pastures. Similarly, monitoring when a horse is turned out during high growth periods can help manage sugar intake. Generally speaking, the grass has a lower sugar content in the morning, and it increases as the sun shines on it during the day With this in mind, she recommended allowing horses to graze in the morning and then adding a grazing muzzle or moving them to a dry lot with a hay source to avoid excess sugars that can exacerbate metabolic issues in the horse's system Strive to keep balance for your horse as they are acclimating to pastures in the spring

It is also important to think about your horse's increased activity in the spring and going into the summer. If your horse is going to be working a lot more, they may need to have their feed program adjusted to meet their needs. Dr Liburt recommended that any changes in feed should be done slowly and at minimum in a twoweek period to help avoid any upset in their digestive system. While we all like to see quick results, it is important that we are patient and allow changes in feeding programs to have time to work. It can take some time to see results and Dr Liburt shared that although you might see some positive changes around 30 days, it may take closer to 60 days to really notice your efforts in changing their program.

When it comes to nutrition, Dr Liburt encourages owners to get good sound advice for their animals from a qualified equine nutritionist and scholarly articles that are backed by scientific evidence. She mentioned that it is easy to get lost in misinformation on the internet and it can be detrimental to how we care for our horses. It is important that we seek out good sound advice from trusted professionals when it comes to our feeding programs both in the spring and all year long.

Lisa Kiley is a horse enthusiast and a proud member of the Cashman’s Horse Equipment Team in Delaware, OH. Cashman's Horse Equipment provides top quality products to the equine and agricultural community, with a commitment to sourcing environmentally conscious merchandise and items made in the U.S.A