Equus – August 2019

18 EQUUS 498 AUTUMN 2019

A:

Onions (Allium spp.) contain

N-propyl disulfide, a compound

that can cause severe anemia, weak-

ness and even death in animals. Cats

are very sensitive to poisoning from

onions, while horses and cattle are

much less so.

It all comes down to how much

of the wild onion is present in the

pasture and therefore how much the

horse has eaten. A mature horse would

likely have to eat several pounds of

onion daily for a few days before he

would develop anemia. It is hard to

imagine there is that much wild onion

in the pasture.

So, unless there is a massive amount

of wild onion in your pasture and very

little else to eat, there is minimal risk

to your horse and no need to remove the

onion. On the other hand, if your horse

shows signs of anemia such as pale

mucous membranes, weakness and

dark coffee-colored urine, remove him

from the pasture immediately and call

your veterinarian. In most cases a horse

will recover in seven to 10 days.

Anthony Knight, BVSc,

MS, DACVIM

Professor Emeritus

Colorado State University

Fort Collins, Colorado

THIS MONTH’S EXPERTS

An equine researcher with expertise

in laminitis, metabolic syndrome and

endocrinology, Nicholas Frank, DVM,

PhD, DACVIM, is associate dean for

academic affairs at Cummings School

of Veterinary Medicine at Tufts

University. He is an honorary professor

of the University of Nottingham in the

United Kingdom.

Brian Gilger DVM, MS, DACVO,

DABT is a native of Akron, Ohio.

After an internship and residency in

ophthalmology, he joined the Ohio State

University as an assistant professor

of ophthalmology in 1992. Three years

later, Gilger became associate professor

of ophthalmology at the North Carolina

State University College of Veterinary

Medicine and is now a professor of

ophthalmology there. Gilger is the editor

and author of three editions of the

textbook Equine Ophthalmology.

David Frisbie, DVM, PhD, Dipl.

ACVS, ACVS-MR is a professor of

equine surgery at Colorado State

University’s Equine Orthopaedic

Research Center, where he is the

director of research. He is also a

partner in Equine Sports Medicine,

LLC. Frisbie is a Diplomate of the

American College of Veterinary

Surgeons, a Founding Fellow in

Minimally Invasive Surgery (Large

Animal Orthopedics) and Diplomate

of the American College of Veterinary

Sports Medicine and Rehabilitation.

Born in Kenya, Anthony P. Knight,

BVSc, MS, DACVIM, received his

veterinary degree at the University of

Nairobi in 1968 and a Masters from

Colorado State University in 1971. After

40 years on the faculty in CSU’s College

of Veterinary Medicine & Biomedical

Sciences, he retired and moved to

Tucson, Arizona. He has published two

books on plant poisoning: A Guide to

Plant Poisoning of Animals in North

America and A Guide to Poisonous

House and Garden Plants.

Based in Big Lake, Minnesota, Tracy

Turner, DVM, DACVS, DACVSMR, owns

Turner Equine Sports Medicine and

Surgery, which specializes in sports

medicine, lameness and surgery. He

earned his veterinary degree from

Colorado State University and has

served on the faculty of the University

of Illinois, the University of Florida and

the University of Minnesota. Turner has

been a consultant to the Fédération

Equestriene Internationale and United

States Equestrian Federation.