Crown vetch OK for most livestock, but can cause problems for horses

By CHRIS PENROSE
Contributing Writer

Crown vetch, a common perennial legume in the region, has been spreading over the years. It grows well in both low pH and low fertility soils and it is highly responsive to lime, phosphorus and potassium.

Related: Horse owners should watch for eastern tent caterpillars

It has a white and pink to purple bloom, can form a mat and is common on our roadsides.
It has been used for years for erosion control, a drought tolerant ornamental ground cover and as feed for livestock.

What I did not know is that it is toxic to horses, but not cows, goats or sheep.

Crown vetch contains nitroglycosides which is poisonous to horses and other non-ruminants.

Ruminants are not affected because they are able to convert the toxin in the rumen.

Symptoms

Signs of poisoning in horses include weight loss, depression, ataxia (lack of muscle coordination) and posterior paralysis and eventually death of the animal (source: A Guide to Plant Poisoning of Animals in North America, 2001).

The good news is some literature suggests horses do not care to graze it (but I would not take the chance, especially if the pastures are grazed close and they are hungry).

If you have horses, I suggest you try to get rid of the plant. It should be easy to kill. If you have small amounts, it can be manually removed or sprayed with a non-selective or broadleaf herbicide. For larger areas, fields can be reseeded or sprayed with a broadleaf herbicide.

If you have other fields that do not have crown vetch, consider moving the horses to those fields and let other ruminant livestock graze the fields with crown vetch.

For cattle, sheep and goats, it should not be a problem.

Treatment

According to Carey Williams, equine Extension specialist, Rutgers Cooperative Extension, if horses consume some crown vetch, feed alfalfa and prevent additional access to crown vetch

As this plant continues to spread, we need to be aware of this potential problem and be prepared to control the plant if needed.

(Chris Penrose is associate professor and Extension educator, Agriculture and Natural Resources, OSU Extension, in Morgan County.)