by Katharine Mertens, DVM
Of all the crazy things that happen in March—like my husband watching hours of televised collegiate basketball—none take the horseman’s cake so much as this: The grass at this time of year can hurt your horse!
“You’re kidding. Is that really true?” Carl asked me as I bent over the painful hoof of his horse, Duke.
“You bet, Carl. Today we’re not dealing with laminitis—this is just a hoof abscess. But laminitis season is here. I see you have a grazing muzzle handy. Will Duke wear it?”
“Cooperative” is not a word Duke chooses to live by, so I returned daily to help change the drawing poultice I used to treat Duke’s abscess. Carl did some research overnight. On the second day, he told me this:
“I was looking through the check book and just like you said—we paid you a bunch last year right about this time. I guess it was just a year ago that Duke had his laminitis problems. So how do you know it’s not laminitis that he has now? The grass is getting richer already. I can tell because the horses are eating less hay in their stalls overnight. “
“Yes, and it’s the overweight horses like Duke, here, that I’m already seeing with laminitis this year. But as for this being an abscess—for one thing, only one front foot is affected.”
Just as Carl had described for me over the phone, when he called me out because Duke “could hardly walk,” I had found Duke standing with his left front foot placed in front and a bit to the side of normal. He carried most of his weight on the right front.
“Generally speaking, laminitis will affect both front feet—possibly even all four feet—while an abscess is in just one foot at a time. That’s because the pasture laminitis is caused by the horse ingesting an overload of sugar, so it’s a systemic problem. But this abscess is just a local infection that comes from germs entering into a particular spot on one foot.”
“I see,” said Carl. “So Duke is just unlucky that he got this abscess. But the grazing muzzle? Come on. What are the chances of him having laminitis two years in a row?”
“Actually very high,” I emphasized. “Seriously, the grazing muzzle is important for him. Certain horses, like Duke, have the body type that indicates they are very susceptible to carbohydrate overload.” I raised my eyebrows at Carl as I poked my index finger into Duke’s side, searching for a rib.
“Aww, come now. You know Duke and I both like our food!” Carl chuckled.
“Hey—I’m only talking about your horse,” I chuckled back. “The fact that Duke had problems last year just proves that he’s vulnerable. Overweight horses like Duke are similar to a person with Type II diabetes. They are insulin resistant. Any amount of extra sugar in these guys and they’re likely to have problems. Specifically, they get laminitis!”
“How about if I just keep Duke in the arena during the day and turn him out at night? Skip the grazing muzzle?”
“You’ll still need the grazing muzzle. It’s true that sugar levels are likely to be lower at night, when the grass is using up all the sugar it got from the day’s sunshine. (Conversely, the sugar levels will be highest in mid-afternoon during a sunny day.) But ‘turned out at night’ still would mean several hours of unrestricted fresh grass access. He’d be much safer with the muzzle to slow down his intake.”
“Hmmm . . . and Mr. Uncooperative here might be safer with a muzzle during the day, in case he gets tangled up on something. Geez, doc—you better write an article about this so other people can keep their horses safe also.”
Now that idea, to me, made perfect sense! And please, call your vet if you have questions about how safe your horse will be on spring grass.
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Katharine Mertens, DVM is the owner of Mertens Mammals, LLC, a mobile, equine veterinary practice based in Boring. You can reach the practice at (503) 663-6400.