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  Discussion on Hoary Alyssum
Author Message
Member:
Nadia

Posted on Saturday, Apr 15, 2006 - 10:31 pm:

Hi, Dr. O,
I was trying to find a post I sent last July about my horse, but I can't find it. He stocked up due to hoary alyssum being in the hay. The hay was removed from his stall and he has been fine, until a few days ago. I thought he was walking a little gingerly 2 nights ago when I brought him in. He seemed to have a head bob on every step. I felt his legs, tad warm, not swollen. Last night I noticed his back fetlocks were swollen. But I figured he may have been running around lot (really nice day - 80 in April in Wisconsin is not normal!). Today, I saw him just standing in the pasture - not moving or eating, resting a hind leg, just didn't seem right. All 4 fetlocks were swollen. I cold-hosed his legs at 3pm. When home to get wraps. When I got back to the barn, I went to the pasture to look at the hay, looking for the hoary alyssum. Can't believe I found some. Last year, it was very obvious in each flake, many white flowers. This time, I did not see any white flowers (maybe one). I looked in alot of the hay and I did find a few branches of it, I wasn't expecting it. I cold-hosed him again at 7 pm. I dried his legs off as best I could and wrapped them in standing wraps. I also gave him 1 gm of bute paste. (Vet said to do this last year).

There are many horses at this stable and it seems my horse is the only one who is sensitive to it. He does have some kind of spring allergies - he head-bobs and sneezes and his nose twitches alot. This only lasts about 3 weeks. I have given him Tri-hist in the past and it seems to help.

1. Is it be possible that smaller amounts of this weed could give more intense reactions now?
2. Could the tri-hist help with his reaction to this weed?

I won't have him turned out in that pasture until I am sure the hay is weed free, but this is like looking for a needle in a haystack. I was searching several flakes of the hay in the barn to make sure they were clean (they were, at least as far as I could see). Should I buy him hay cubes? How can I be sure that is ok? I know this is rare, but the vet said it is creeping down through hayfields from Minnesota.

Thanks for any advice.
Member:
Nadia

Posted on Monday, Apr 17, 2006 - 9:06 am:

I am hoping I can prevent him from eating anymore of this, but if this happens again, do I treat his swelling as stocking up or as possible laminitis? For stocking up, he needs to be walked/trotted to keep the fluid and joints moving; for laminitis, your article says that the horse should not do this as this may cause more damage to the bones in his feet.

Thank you.
Moderator:
DrO

Posted on Tuesday, Apr 18, 2006 - 7:52 am:

Hello Nadia,
1) Sensitization following exposure is not reported and the low rate of exposure you describe seems unlikely to cause symptoms.
2) Currently I don't think the cause of the symptoms is known. However Trihist, which is pyrilamine is not thought of as a very effective antihistimine in horses. I am uncertain if you are seeing a real effect or not.
3) If you have remarkable stocking up or signs of founder yes you should treat them. How will depend on the severity of symptoms and will require clinical judgement. All things being equal however the founder should be considered the more dangerous disease.
DrO
Member:
Nadia

Posted on Tuesday, Apr 18, 2006 - 6:42 pm:

On Sunday morning, he seemed to be out of pain (he wanted to get out of his stall and back to his herd). I unwrapped his legs and the front ones were just about normal (slight heat). The rear fetlocks are still swollen, but less so. I am keeping him in his paddock (checking his hay that he is getting-hay in barn appears to be different hay) until the pasture is no longer supplemented with hay (they have done this so the horses will be alternating between the hay and the new spring grass all day). I will slowly get him back on the grass when he is ready to be turned out again.

I added the Tri-Hist as I mentioned, but he doesn't want to eat it much (I assume it is bitter). I think he has eaten some as he wasn't headshaking and sneezing much yesterday. Do you have a better suggestion for an antihistimine?

Thank you.
Member:
Vickiann

Posted on Tuesday, Apr 18, 2006 - 9:22 pm:

As the alyssum is a toxin, it is unlikely an antihistimine would truly help your horse, in my humble and unqualified opinion.
Moderator:
DrO

Posted on Wednesday, Apr 19, 2006 - 8:09 am:

There are some toxins that might cause endogenous histimine release but I am uncertain that this might be one so don't know if any antihistimine is likely to be of benefit. Though we do not have a specific article on antihistimines we do discuss them in detail at, Equine Diseases » Respiratory System » Heaves & Chronic Obstructive Pulmonary Disease.
DrO
Member:
Nadia

Posted on Wednesday, Apr 19, 2006 - 8:16 am:

Just to clarify - the Tri-Hist is for his usual spring allergies. I was just asking if it would help his reaction to the hoary alyssum as a side benefit since he started those symptoms as well.

I'll check out the section on the respiratory system.

Thanks!
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