APHIS Factsheet

Animal Care November 2012

Questions and Answers: 

Animal Care’s Use of 

Thermography

The Animal Care (AC) program, which is part of the U.S. 

Department of Agriculture’s (USDA) Animal and Plant 

Health Inspection Service (APHIS), enforces the Horse 

Protection Act (HPA). 

The HPA is a Federal law that prohibits horses 

subjected to a practice called soring from participating 

in shows, sales, exhibitions, or auctions. The HPA also 

prohibits drivers from transporting sored horses to or 

from any of these events. To enforce the law, USDA 

veterinary medical officers (VMOs) and designated 

qualified persons (DQPs) perform inspections at walking horse shows.

Q. What is soring?

A. Soring is a cruel and abusive practice some horse 

trainers and owners use to accentuate a horse’s gait or 

step. When walking, sored horses quickly lift their front 

legs to relieve the pain of stepping.

Horse trainers and owners who sore their horses have 

developed numerous methods to alter a horse’s gait. 

Some irritate or blister a horse’s forelegs through the 

application of chemicals, such as mustard oil. Under 

the HPA, the use of foreign substances is not allowed 

with the exception of petrolatum, mineral oil, glycerine, 

or mixtures exclusively thereof. Sored horses 

sometimes develop permanent scars in the pastern 

area due to the use of painful chemicals.

Some other trainers and owners sore their horses using 

inhumane hoof trimming, pressure-shoeing techniques, 

or by using mechanical devices, such as chains, pads, 

or shoes. Although such devices are allowed, using 

them in a manner that causes pain—such as by fitting 

a horse with shoes that are too heavy—is a violation of 

the law.

Q. Why would someone want to sore a horse to 

accentuate its gait?

A. At walking horse shows, owners enter horses into 

competitions, where winners are determined in part by 

the height and reach of their gait, known by some as 

“The Big Lick.” Walking horses are known for possessing a naturally high gait, but to succeed in competition 

their natural gait will often be exaggerated.

An exaggerated gait can be achieved with proper 

training and considerable time. However, some horse

exhibitors, owners, and trainers choose to use improper 

and inhumane training methods to shorten the time it 

takes to produce a winning gait.

Q. How is soring detected?

A. Soring is detected during inspections performed 

by VMOs and DQPs. USDA trains DQPs on the HPA 

regulations. DQPs, hired by the sponsors of walking 

horse shows, perform inspections at all affiliated walking 

horse shows, sales, and auctions. Designated industry groups, which sponsor shows but choose not to 

hire DQPs, have their horses inspected only by USDA. 

USDA performs inspections at less than 10 percent of 

walking horse shows.

During inspections, VMOs and DQPs evaluate a horse’s 

appearance and locomotion and physically examine 

the animal for any signs of pain, scars, blisters, or odors 

associated with soring practices. USDA also randomly 

swabs horse’s legs to test for foreign substances.

Over the years, the methods used to sore horses have 

become more sophisticated. This fact highlights the 

need for USDA to utilize modern technologies, such as 

chemical testing and thermography, and to inform DQPs 

and horse industry organizations about the availability 

of emerging technological resources to detect soring.

Q. What is thermography?

A. Thermography is a technology that measures the 

surface temperatures of an object. This technology has 

been incorporated into diagnostic equipment used by 

medical professionals, devices that enable firefighters to 

see through smoke, and some night-vision equipment. 

Thermographic images are taken with a thermal or 

infrared camera. Cooler areas appear blue and purple, 

while warmer areas appear yellow, orange, and red. 

Thermographic pictures of an animal can reveal areas 

that are excessively warm or cool—both indicating 

abnormalities and the need for closer evaluation. 

Q. What do areas of abnormal heat or coolness 

suggest?
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture

USDA is an equal opportunity provider and employer.

Mention of companies or commercial products does not imply 

recommendation or endorsement by USDA over others not 

mentioned. USDA neither guarantees nor warrants the standard 

of any product mentioned. Product names are mentioned solely to 

report factually on available data and to provide specific information.

A. Areas may appear excessively warm due to 

increased blood flow, irritation, or inflammation. Inflammation occurs when tissue is damaged or injured, 

causing the area to become warm (painful). Areas may 

appear excessively cool due to decreased blood flow 

or the application of cooling substances. Substances 

that cause a cooling effect are typically used to numb a 

horse so that it will not react with pain when touched by 

an inspector. 

Q. When did the AC program start using 

thermography?

A. USDA successfully integrated thermography into 

the AC program in 2008 without enforcement actions. 

Thermography continues to be part of the inspection 

protocol to screen for possible violations of the HPA.

Q. How is thermography used during 

inspections?

A. Thermography is an additional diagnostic tool that 

VMOs can use to obtain objective and scientific data to 

help identify sore horses. It provides additional 

consistency to the inspection process. VMOs are 

responsible for operating the thermal cameras and 

obtaining images of horse limbs and forelegs. VMOs 

review the thermographic images and may further 

evaluate the horse in the areas that appear excessively 

warm or cool. 

This image is of a horse in violation of the scar rule. 

The thermogram shows vertical “red streaks” that 

directly correspond to the inflamed and 

damaged skin.

Q. Has thermography replaced any of the other 

methods of inspection?

A. Thermography has not replaced any of the other 

methods of inspection. The technology is used as an 

additional diagnostic tool that can provide objective 

and scientific data during the inspection process. For 

example, if a thermographic image indicates an area of 

excessive heat, VMOs can further evaluate the area to 

determine if there is evidence of inflammation, a foreign 

substance, pressure shoeing, or other violations of the 

HPA. 

Q. How can I get more information on the HPA?

A. For more information on the HPA, visit APHIS’ Web 

site at www.aphis.usda.gov/animal_welfare.

Q. How can I get more information on 

thermography?

A. Many industry Web sites contain information about 

thermography, its uses, and the equipment associated 

with this technology. Among others, you may wish to 

visit Web sites such as www.meditherm.com or 

www.flir.com/US for more information about the technology. AC personnel currently use infrared thermal

cameras made by FLIR © Thermal Infrared Camera 

Systems, Inc.