Equus – August 2019

AUTUMN 2019 EqUUS 498 23

A new study from England offers yet

another challenge to the long-held belief

that corticosteroids increase a horse’s

risk of developing laminitis, a potentially

devastating inflammatory condition af-

fecting the hooves.

“The concern that corticosteroids

cause laminitis is based on a handful of

single case reports in the scientific liter-

ature in which animals that were treat-

ed with corticosteroids also developed

laminitis,” explains Nicola Menzies-Gow,

VetMB, PhD, of the Royal Veterinary

College (RVC) in Hertfordshire.

“[However,] there are also lots of stud-

ies in the scientific literature in which

horses were given high doses of cortico-

steroids over a prolonged period of time

and laminitis did not occur.”

To investigate whether a link

actually exists between these

powerful anti-inflammatory medica-

tions and the potentially devastating

hoof condition, Menzies-Gow and her

team embarked on an intensive review

of case histories of horses treated

at the RVC equine clinic and a nearby

private facility. For the first part of

the study, the researchers examined the

records of 205 horses who received

standard doses of corticosteroids as part

of their treatment at the clinic, along

with the records of 205 “control” horses

also treated at the clinic who did not

receive the medication. The researchers

documented the age, sex, breed and

medical history of each horse and noted

whether laminitis developed in the

14 days after treatment.

For the second portion of the

study, researchers collected similar

data on all horses treated with cortico-

steroids at the university clinic as well

as a private clinic between January

2015 and February 2017—a total of

1,565 horses.

The researchers found that in

the first part of the study, only four

horses developed laminitis—two from

the group receiving corticosteroids and

two from the group that did not. In the

second portion of the study, 10 horses

developed laminitis, for an overall prev-

alence of less than 1 percent. This inci-

dence, says Menzies-Gow, is no higher

than that of the general equine popula-

tion and “the risk is similar in this group

of animals, regardless of whether they

are treated with corticosteroids or not.”

However, the data revealed some

similarities among the horses who de-

veloped laminitis. The researchers noted

that some were obese or had previously

developed laminitis, for example, while

others had pituitary pars intermedia

dysfunction (PPID) or equine metabolic

syndrome (EMS). In addition, many who

developed laminitis were ponies.

“It is impossible to say whether the

steroids actually contributed to the lami-

nitis in this group,” says Menzies-Gow.

“It is just as likely that they got laminitis

because of their other risk factors and it

just happened to occur when they were

being treated with corticosteroids rather

than at another time.”

Despite these findings, Menzies-Gow

says that the specter of laminitis looms

large in treatment decisions: “Most vet-

erinarians will have had or know a col-

league that had a case where laminitis

developed when a horse was treated

with steroids. However, there is more

and more published evidence to show

that the risk of laminitis in an individual

animal is the same, regardless of ster-

oid treatment. [If steroids are] the most

appropriate therapy for a disease, they

should be used.”

As for owners, she continues, if

a horse is obese, has an endocrine

disease or other risk factors, “they

should worry all year-round rather than

just when the animal is being treated

with corticosteroids.”

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Reference: “Prevalence of and risk factors for acute laminitis in horses treated

with corticosteroids,” Veterinary Record, June 2019

STEROIDS AND LAMINITIS: A WEAK LINK?

CARE-protocol horses and
51 were control horses
who did not perform the ex-
ercises after colic surgery.
In addition to reviewing
each horse’s medical re-
cords, the researchers sent
owners or trainers a survey

asking about the horse’s

postoperative care and

progress. Questions

included how long the

horse was on stall rest after

colic surgery as well as

the number of days be–

tween surgery and initiation

of work under saddle, re-

sumption of full training

and return to competition.

Respondents were also

asked whether the horse’s

performance one year after

surgery had improved, was

similar to or had declined

compared to pre-surgery

performance.

The data showed that

the CARE horses returned

to work under saddle more

quickly---within an aver-

age of 60 days---compared to

control horses who returned