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Discussion on Crown Vetch, Coronilla varia L.
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Member:
1907
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Posted on Tuesday, May 30, 2006 - 12:12 pm:
Can anyone tell me please if you have information or experience with crown vetch being poisonous to horses. We are in the process to plant crown vetch on the steep sides of our pastures where there is no possibility to mow. Now I have heard about this plant being poisonous to horses. Any suggestions ???
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Member:
Hwood
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Posted on Tuesday, May 30, 2006 - 12:30 pm:
Hi, Alice,
I never had any trouble with purple vetch or crown vetch in my pastures in Vermont. I never heard that they were poisonous, but if you give your University Extension Service a call and ask them, I'm sure they can give you the information you need. Also, have you tried searching "CROWN VETCH" on google?
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Member:
Tpmiller
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Posted on Tuesday, May 30, 2006 - 12:32 pm:
Have had horses and mules on pastures infested with crown vetch for 11 years, none touch it. Cattle love it, good source of protein.
Crown vetch is a vine that spreads fairly rapidly once started and is difficult to eradicate. Here in PA planted on roadsides, in 20 years has spread 100's of yards into pastures. For that reason, I'd look for something else to put on the bank or be prepared to mow it down regularly as it spreads.
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Member:
Vickiann
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Posted on Tuesday, May 30, 2006 - 3:52 pm:
I've loaned my poisonous plant book for horse owners to a friend but I do recall "Vetch" being in there. Many horses will NOT eat certain poisonous plants but some will -- even seeking out strong tasting plants like lantana.
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Member:
Vickiann
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Posted on Tuesday, May 30, 2006 - 4:01 pm:
Wikipedia says some species of Vetch are suitable for ruminant animals (cattle, goats, sheep,etc.) but NOT for animals having a single stomach (horses); including humans, due to toxin.
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Member:
Leilani
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Posted on Tuesday, May 30, 2006 - 4:22 pm:
Crown Vetch, I believe, contains nitroglycosides which affects the nervous system in ruminants. Leilani
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Member:
Bodie
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Posted on Tuesday, May 30, 2006 - 10:51 pm:
Leilani,
Correct on the nitroglycosides, but it affects the nervous system of non-ruminants. Ruminants are able to convert and detoxify it, but simple-stomached species cannot.
Julie
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Member:
Leilani
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Posted on Wednesday, May 31, 2006 - 12:11 am:
Julie,
Mea culpa; forgot the 'non'. Leilani
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Moderator:
DrO
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Posted on Wednesday, May 31, 2006 - 7:04 am:
When you research Crown Vetch you get back recommendations for and against its use. Searching PubMed you don't find a case of poisoning. Considered its wide spread use (and the posts from above) it appears to be only of low toxicity but some references are adamant about it's toxicity. Oddly the actual cause of poisoning in horses seems confused as in this reference:
Crown Vetch
Coronilla varia - Fabaceae (Legume family)
Habitat
Crown vetch is frequently used as a DrOught-tolerant ornamental ground cover to help control erosion in the United States especially in the Midwest and Northeast.
Description
Crown vetch is a perennial herb with trailing or ascending, branching stems arising from a taproot. Leaves are alternate and pinnate with a terminal leaflet. The pealike flowers are produced from the leaf axils on a stalk 3 to 5 inches (7.5 to 12.5 cm) in length. Flower color varies from white to dark pink. Many brown, cylindrical seeds are produced in pods 1 to 2 inches (2.5 to 5 cm) in length.
Principal Toxin
Crown vetch contains nitroglycosides, the most toxic of which, coronarian is poisonous to horses and other nonruminants. Ruminants are not affected because they are able to convert the coronarian to 3-NPA that is readily detoxified in the rumen. Toxicity may be due to the development of methemoglobinemia and the inhibition of succinate dehyDrOgenase, an important enzyme necessary for energy metabolism. Crown vetch does not cause bloat in ruminants because it contains tannins that precipitate soluble proteins, which contribute to the rapid formation of a frothy foam in the rumen. Creeping indigo (Indigofera spicata), a legume introduced into southern Florida and Hawaii, also contains nitroglycosides that have caused poisoning in horses.
Clinical Signs
Nonruminants may show weight loss, poor growth rates, depression, ataxia, and posterior paralysis leading eventually to death of the animal.
Considering everything, I would not choose to use it in a pasture for horses.
DrO
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Member:
1907
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Posted on Wednesday, May 31, 2006 - 2:14 pm:
To all responded: Thank you so much for your input, it was very informative. I guess we will look for an alternative since the pasture is occupied by youngsters year round; just don't want to take the risk. Thank you all very much again.
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Member:
ceceb
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Posted on Wednesday, Aug 1, 2007 - 5:10 am:
Dr. O, My horse is in a pasture that is loaded with creeping indigo. I've fenced off the majority of the area infested and I'm trying to kill off the weed. There is still some patches so how much do they have to eat before it would make them sick. I'm using Roundup to kill it.
Thanks,Cece
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Moderator:
DrO
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Posted on Wednesday, Aug 1, 2007 - 6:45 am:
Hello Cecelia,
There have been no studies on how toxic this plant is so I would do everything practical to avoid contact and if removing all contact difficult be sure there is always a palatable alternative forage available.
DrO
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