Page 810 - The Veterinary Care of the Horse

Buttercup poisoning is rarely seen, even when horses graze in pastures full of them. This is

because large amounts need to be ingested for them to have an effect and they are less
VetBooks.ir palatable than fresh grass. When signs do occur they include:
•
inflammation of the lips and mouth
• blisters

• increased salivation

• abdominal pain.

Death from buttercup poisoning may be preceded by convulsions, but this is very rare.

TREATMENT

Affected horses should be removed from the pasture. Treatment is symptomatic.

Clover (Trifolium spp.)

There are many types of clover found in the UK. These include red clover (T. pratense) and

white clover (T. repens). They may be introduced into pasture to enrich the grazing and to
increase the nitrogen content of the soil when ploughed in. Clovers contain a number of toxic

substances including:
• oestrogens

• cyanogenic glycosides

• nitrates

• goitrogens.

These can cause a number of problems in animals including reproductive problems, laminitis,
photosensitivity and blood coagulation disorders.

St. John’s wort (Hypericum perforatum)

St John’s wort is found in meadows, grassland and open woods. It is usually 30–80 cm (1 ft–

2 ft 6 in) high and has clusters of bright yellow flowers. All parts of the plant are poisonous
as they contain hypericine. It loses some of its toxicity when baled with hay but is still
dangerous.

CLINICAL SIGNS

• Photosensitization. Skin lesions develop when unpigmented skin is exposed to sunlight.