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Dr. Jill
Dr. Jill, Veterinarian
Category: Horse Veterinary
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Experience:  6 years of veterinary experience with horses, domestic livestock, and camelids.
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How long per day can I leave a horse on pasture with a grazing

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How long per day can I leave a horse on pasture with a grazing muzzle. He founderd badly last year. We got hin back to normal by isolateing him and feeding him only washed hay.
He is located in NC.


Ed Stone

Dr. Jill :

Hi, I'm Dr. Jill. First off, well done helping him get back from a bad laminitis episode...not an easy thing!

Dr. Jill :

Unfortunately, pasture time can be a very complex issue. You may have heard the term "non-structural carbohydrates" before...these are part of what we think about causing problems with lush grass laminitis in horses.

Dr. Jill :

These levels can vary by the type of grass in the pasture, time of day, weather, etc. They tend to be lowest in the morning as well as after periods of cloudy weather (product of photosynthesis). They're highest in the afternoon, after periods of drought, and after periods of cooler sunny weather.

Dr. Jill :

So I'd recommend turning him out first thing in the morning or late evening/overnight to help decrease risk.

Dr. Jill :

They can also be very crafty with grazing muzzles, and I think the key, as with most things, is not making drastic changes. So I'd start by turning him out for maybe 30-60 minutes, seeing how he tolerates the muzzle and how much grass he can get, and increasing from there.

Dr. Jill :

Some horses are able to graze just as well with and without muzzles, so owners tape the holes and use them as just a regular muzzle so they can have turnout time and have a controlled diet.

Dr. Jill :

He may be able to go out all day with the grazing muzzle, but I'd error on the side of caution (especially since they're at increased risk once they've had a laminitic episode) and start slow.

Dr. Jill :

Hope this helps! Please let me know if you have any additional questions or concerns and I will gladly address them. Thanks and best of luck!

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Customer: replied 6 years ago.

I have a Pear tree.Apple tree and a oercimon tree in my pasture. Is this a problem?


If I understood you correctly he can be turned out at 9 or 10 in the evening for overnight and in the morning until about noon..


Ed Stone

Well, first considerations would be toxicity. Apple trees can contain cyanide in their leaves/stems/seeds, so I would suggesting fencing that tree off as a precaution (though the levels are typically low and he would probably have issues with colic or laminitis before the toxin). I haven't personally heard of a horse developing toxicity from apple trees (generally worry more about other things like oleander, red maple, etc.), but letting you know because it's a theoretical hazard.

The other concerns (probably greater) is ingesting too many simple carbohydrates if there are a number of fruits within reach along with choke if he doesn't chew them fully. It wouldn't hurt to keep tabs on falling fruit and just make sure it's cleaned up if theres a bunch out there. But if it's a small amount of fruit or just tree leaves right now, I wouldn't worry too much about the laminitis issue. Some horses also have a tendency to destroy trees by going after bark, so might watch for this as well if this is a new pasture to him and any other horses.

As for grazing, I still think it's important to consider the amount of grass he gets and make sure he can tolerate that, so I would use caution with having him out for 12+ hours at first. But for the same amount of time as on daytime pasture, research has shown it is definitely safer to let him out overnight and/or early morning and remove him from pasture before noon. And the grazing muzzle should allow him to safely spend longer time out than without it (assuming he doesn't get too creative in getting around it :) ).
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Customer: replied 6 years ago.
Reference last paragraph to make sure I understand you correctly. The way I interpreted what you said is that after I have tested him with muzzle on and making sure it functions as it should. I could start leaving him on the pasture from late evening which I assume you mean 9 or 10 p.m. until feeding time the next morning 8:00 a.m. and then he could be turned out again until noon so he is off the pasture from noon until 9 or 10 p.m. My wife has concerns about the muzzle coming off allowing him to get too much grass at one time. I thought adding additional straps would eliminate that problem. If it did fall off would one night be disastrous? I have a paddock with no grass and a stall I can put him in during the afternoon hours or I can allow him to graze in a quarter acre which I can mow low or should I follow the "near grass wear muzzle" creed. Or should I leave the muzzle on anytime he is on grass. Thank you for the good work we appreciate your time and expertise.
Of course, glad to be able to help! I do believe you're understanding my intent correctly. I wish I could give you some hard and fast rules, but simple sugar levels in pasture grass vary widely day to day and within the same day. Plus, every horse reacts a bit differently. The overall goal is to limit simple sugar intake. ("Grass founder" happens when the hindgut gets too many simple sugars at once that it isn't used to which disrupts the normal bacterial flora causing toxins to be released.)

It sounds like you have several good options. The safest (at least for laminitis) is to not let him have access to any grass or minimal amounts. The muzzle, mowing low or bare lot, as well as time of day all act to decrease the simple sugar load his hindgut sees.

One option would be to start with letting him out with the muzzle in the morning until 11am (give or take) and see how this goes. If he seems to do well, then potentially include overnights. If the muzzle keeps him from getting at the grass it shouldn't matter which pasture he's on, although if he managed to get it off (your wife is correct that this is a risk) and there was a large amount of grass, it could be disastrous. So I'd recommend starting with the morning turnout to see how he tolerates it. If the muzzle prevents him from getting too much grass, any time of day would be fine, just a greater risk late morning to late afternoon if he gets the muzzle off.

Since there are several good options, I'm going to leave a bit to your discretion to see what works best for you. Again the safest for laminitis prevention is no grass access at all. I understand this may not be the best option for his mental well being, though, so I usually try to find a middle ground for pasture time. For ponies that have consistent laminitis issues, I much more closely follow the "near grass wear muzzle" routine and suggest drylot pasture.

So, I'd suggest starting with muzzled turnout for the times you've mentioned (maybe bring him in closer to 11 than noon?) or trying the mow low technique to limit grass intake...whichever fits best for your schedule and facilities. He may be able to tolerate small amounts of grazing (increased slowly) as well.

Hope this isn't too overly wordy of a response. Please let me know if there is anything I can clarify further. Thanks!
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