Equus – August 2019

24 EqUUS 498 AUTUMN 2019

DON’T TOUCH:

Wild parsnip,

a member of

the carrot family,

is an invasive

weed found

throughout

the United

States. Horses

may develop

photosensitive

skin reactions

after coming in

contact with

the plant’s sap.

to work in 90 days. In ad-

dition, the CARE horses

returned to full training in

75 days, while the control

horses resumed full train-

ing in 120 days. Finally,

nine of the 11 owners of

CARE horses reported that

their horses’ performance

improved after surgery;

by comparison only

four of 51 owners of the

control horses reported

an improvement in per-

formance post-surgery.

These results suggest

that a CARE-type protocol

may be benefi cial not only

after surgery but during

any recovery that requires

long periods of rest.

“Stall rest for horses

is likely similar to bed

rest for people,” Holcombe

says. “Exercise and move-

ment is key to health. The

CARE program described

and tested in this study

used easily performed ex-

ercises to strengthen the

core and back of the horse.

Horses requiring box stall

rest for musculoskeletal

injuries could perform this

program daily to maintain

or enhance core and back

strength and fl exibility.”

Researchers in Utah

have discovered that

wild parsnip---an invasive

weed found throughout

the United States---can

cause phototoxic reactions

in horses even if they

don’t eat it.

Many photosensitive

skin reactions occur after

a horse ingests a plant that

contains photodynamic

compounds. When ultra–

violet rays from sunlight

pass through the horse’s

pink skin, they interact

with the compounds in

the skin and blood, result-

ing in painful burns with

extensive blistering.

However, Utah State

University and U.S.

WILD PARSNIP: ANOTHER WEED TO WORRY ABOUT

Department of Agriculture

researchers recently deter-

mined that horses and goats

may develop photosensitive

skin reactions after simply

coming in contact with the

sap of wild parsnips.

A member of the car-

rot family, wild parsnip

(Pastinaca sativa) can grow

up to four feet tall, and looks

and smells similar to the cul-

tivated root vegetable found

in grocery stores. The sap of

wild parsnip contains furano-

coumarins, chemicals known

to cause intense localized

skin reactions in people who

come in contact with them on

sunny days. Affected areas of

skin can remain sensitive to

sunlight for up to two years

after initial contact.

The researchers re-

port that only one of

four goats that ingested

wild parsnip developed

skin irritation, but when

a horse and the goats

came in contact with the

plant, they developed

severe photodermatitis.

The researchers deter-

mined that exposure

to sap on the surface

of the wild parsnip’s

leaves was the cause

of the reactions.

Reference: “Wild

parsnip (Pastinaca

sativa)-induced photo-

sensitization,” Toxicon,

September 2019

Reference: “The effect of

core abdominal muscle

rehabilitation exercises

on return to training and

performance in horses after

colic surgery,” Journal of

Equine Veterinary Science,

April 2019

LESLIE J. MEHRHOFF, UNIVERSITY OF CONNECTICUT