Wild chamomile in the pasture

My horses spend most of their time in a 3-4 acre space. It is surrounded by trees and brush. The open space has no/very little grass (which is a good thing for these horses). When we first moved in the whole area was overrun by what I am pretty sure is wild chamomile (not a plant person!). A few years later, it’s mostly gone, but in the early spring the horses can be seen out there “grazing” on the teeny tiny nubs of the chamomile, which they keep down in their area so it never has a chance to flower. I mostly appreciate that it still provides a shallow root system which keeps the mud and dust down.

But is wild chamomile in that sort of amount toxic? Google says both - toxic and can cause dermatitis and diarrhea, etc, and also can be a beneficial supplement. The horses seem fine, but we’ve had the occasional bout of itchy dry skin and low-grade fecal water events, and I am wondering if that could be why. Does anybody have actual pasture experience with it? I don’t know the species of chamomile but could try to find out.

https://www.aspca.org/pet-care/animal-poison-control/horse-plant-list

No species of chamomile turns up on the SPCA list. However there are some herb lookalikes and my first step would be to get a definitive ID from your local agriculture department. With herbs there are often plants that share features or folk names but are not even remotely related.

My understanding is that there are acutely toxic plants like yew that cause immediate death but also a lot of mildly toxic plants that cause liver damage over time in susceptible horses. Most horses won’t eat these but if you leave then in a degraded field with say only horse tails and buttercups they may very well start eating them.

Chamomile is on the list:

Toxic Principles: Volatile oil; bisabolol, chamazulene, anthemic acid, tannic acid
Clinical Signs: Contact dermatitis, vomiting, diarrhea, anorexia, allergic reactions. Long term use can lead to bleeding tendencies.

I don’t know that I would be terribly worried about it unless you have a lot of it or find that your horses seem drawn to it. There are lots of common “toxic” plants but most horses don’t eat them. (E.g. nightshade, buttercup, dock, fleabane…all probably can be found in my pasture and turnout areas).

Is it pineapple weed? It looks similar to chamomile and likes to pop up in disturbed soil areas. I don’t believe it’s toxic, but maybe eating too much could have some side effects?

Ah thank you I missed that. I would certainly not be encouraging my horses to eat this plant by leaving them in a pasture where its dominant. Horses can be ok on mildly toxic browsing until they aren’t. I’ve seen a couple of horses die from liver failure of unknown causes and its ugly and irreversible. In a couple of those cases I suspect things like clover mold and buttercup which are endemic here. Not my horses, but ones I knew and observed. I would not take chances at all. By putting them in this field you are guaranteeing they will nibble constantly.

Yes I thought the same thing. https://en.wikipedia.org/wiki/Matricaria_discoidea

It might be? I will do some more reading and try to find out. It definitely has white flowers (when it flowers, outside of the horse space) if that helps any of you who might know.

My vet is not very concerned but says she will do more research into it also. One of my horses gets yearly blood work (just done in mid January) and it was perfect, including liver values.

It’s a small enough space (it covers maybe 3/4 of an acre in the middle of the lot and is currently less than a quarter of an inch tall), I might look into eradicating the plant if there’s a reasonable way to do that.

What about sugar levels - even aside from any toxic risk, do you think it could cause issues for a sugar-sensitive horse?

You can get the plant tested for sugar levels same as hay or grass. I’d be more worried about toxicity.