It’s not uncommon these days to walk into a veterinary clinic and find a group of practitioners gathered around a TV monitor. But don’t be misled–they’re not checking out a heated moment on the afternoon soaps. Instead, they’re most likely viewing the heat patterns of a horse’s infrared thermography exam, which can helpthem pinpoint problems and diagnose injuries.

Many veterinarians currently use this heat detection device for infrared imaging, which looks like a video camera. It’s used to scan the horse to determine variations in heat patterns on his body. The image it takes can be displayed on a monitor, like a TV screen, for analysis.

Thermography, called IRT for short, is especially useful in identifying fluctuations in blood flow, which can indicate problems in soft tissues. The blood flow can vary, depending on whether circulation is normal or affected by injury. IRT can be an early indicator of a problem because blood flow to an injured area may increase before clinical signs of pain and lameness become evident.

Tracy Turner DVM, of Anoka Equine, in Elk River, Minn., has been working with thermal imaging for a number of years at the University of Minnesota and in his private practice.

“Thermal imaging is detection of heat that an object emits. By measuring what the body emits, we can make a picture of the temperature of the body. What we’re looking for, in veterinary thermography, is differences. We can take that information and build conclusions,” he said.

The temperature of the horse’s skin primarily depends on local circulation, blood flow and metabolism of the cells. For the most part, the metabolism of the cells won’t be high enough to be a factor–unless there’s a cancer–so veterinarians see skin temperature reflecting the blood flow and circulation of underlying tissues.

Turner said there are five cardinal signs of inflammation: heat, redness, pain, swelling and loss of function.

“Going through the course of a lameness examination, the veterinarian looks at loss of function–that the horseman sees as a lameness problem,” said Turner. “Then I look for swelling, pain or heat when I palpate the area. Thermal imaging makes me, as a practitioner, 10 times more sensitive to finding the heat.”

Show Me The Heat (Or Cold)

Veterinarians use IRT to help them get a better look at the body’s reaction to a potential problem. But it’s not as simple as just looking for the hot spots and saying that’s where the problem lies.

“We’re dealing with a living, breathing object, and heat is produced for a lot of different reasons,” said Turner. “We have to understand what a normal thermal pattern is–where the normal hot spots are, where the circulation goes. Once we learn what normal is, everything else is abnormal.”

There are many reasons veterinarians might see an abnormality in a scan, such as the horse standing in a breeze. “Once we know the things that can cause an abnormal image, then everything else is pathology,” he said. “As we start to interpret it and look at the images, what we see are thermal patterns, and changes from normal patterns.”

IRT measures superficial temperature rather than how warm or cold the deeper tissues might be. Anything that might obstruct or insulate against heat radiation from the body–fat, long hair, a muddy coat–could interfere with a proper reading.

For instance, a Thoroughbred has finer and shorter hair than other breeds, which is less insulating. And if a horse is clipped there will be more heat that escapes and it will show warmer, with increased thermal emission. Some areas on the body with less hair, like around the eyes or tail, will show warmer than the rest of the body. Because you must know what’s normal before you can diagnose what’s abnormal, there’s a learning curve to thermography.

All patterns are based on normal physiology. For instance, after a veterinarian has examined many horses’ backs, he’ll find the warmest area is almost always down the midline. “When we start to see break-ups of these patterns, that’s a clue for us to look there more closely,” said Turner. “Sometimes hot spots are very important, but cold spots are just as important; a cold spot can be an area of swelling–where the circulation has decreased–and that area stays sore longer.

“We can do all sorts of things with IRT, and I find it invaluable in detecting back problems and upper limb problems,” said Turner. “These can be difficult to detect, otherwise. You can palpate the back, but you can’t use nerve blocks, so you just guess.

“Thermography can give us a look at the whole area,” he added. “We’ve done enough of this that we know a certain picture correlates with a certain problem. It can show us a sacroiliac [lower back] problem, or spots in the back where spinous processes are rubbing against one another.”

Turner also uses IRT to find joint problems. He said he finds thermography most useful for detecting something that’s causing a horse to be just slightly off. The horse isn’t lame, but the rider knows something’s wrong–and the veterinarian is scratching his head because he can’t see anything. There may be no overt signs, but IRT may identify something early on.

A Multitude Of Uses

Some of the uses for IRT include detecting hot feet, or locating an abscess or hot nail in the foot. In a laminitis case, for instance, you might expect a cold foot, depending on the stage.

William H. McCormick VMD, who practices at the Middleburg Equine Clinic, Middleburg, Va., also uses IRT as one of many tools.

“Thermal imagining can be very useful, but people often want to make a diagnosis just from this–and that’s a big jump,” he said. “The thermal image may be just an indirect indicator of a complex regional pain syndrome, so you then have to determine what’s causing it.”

To make a precise diagnosis of structural abnormality in the feet, for instance, IRT isn’t the best tool. What you see with thermography is just one sign, and you need to add it to other signs to discover a pattern that can lead to a diagnosis.

“A decrease in the circulation is often a more important guide than increased circulation,” he noted. “In horses, you can check balance on all four legs. They should be equally warm or cold. If one is different, there may be a problem–and it’s usually not the warm leg; it’s usually the cold one.”

If there’s more muscle tension in one area because of pain, the circulation is impaired–hence the cold spot.

On the other hand, a hot spot is also sends up a red flag. “By contrast, if you do a thermograph on the back part of the tendon [on both front legs, so you have the two to compare] and there’s a hot spot in the middle of one tendon, this can be a clue since the tendons should be the coldest part of the lower leg.”

The horse may not even feel pain yet in the tendon, but the change in thermal emission could be a danger sign that something has happened.

“If a horse is using one hind leg preferentially over the other, that horse will obviously be warmer on the side being used most,” he said. “You can pick that up quickly with a thermograph, even though you might not yet have any other signs. Pulled or strained muscles–if there’s sufficient damage–will also show up with thermal imaging, even without any structural damage that can be seen with ultrasound,” he added.

In a lameness exam where more than one leg is involved, IRT is often helpful in pinpointing the primary issue. “The lame leg is not necessarily the problem,” said McCormick. “It may be the result of another problem. Sometimes thermography can help you sort that out. If you want to get to the bottom of it, you need to check all the legs or affected sites.

“The important thing to understand about thermography is that you’re looking at how the body is responding to a stress–as opposed to radiology, which tells you about the structure, and not much more than that,” he added. “IRT will tell you how the body is responding metabolically in an area.

“By contrast, the nuclear [bone] scan will tell you how the deeper tissues are responding,” he said. “Thus the nuclear scan is often more valuable. The infrared is very easy to use, however, and at a moment’s notice. For a nuclear scan you must have the horse in the hospital for two or three days, read the image on a gamma camera, and it’s quite a production. The thermal imaging is much more instant and portable.”

Preventative Medicine

Today’s thermography equipment is fast, portable, and simple to use, so more and more veterinarians are using this tool in their daily routines.

William McCormick VMD, of Middleburg Equine Clinic in Middleburg, Va., said he regularly uses thermography for pre-purchase exams and in certain types of lameness exams. He also believes thermography is helpful for identifying suspensory or tendon damage.

“There are some circumstances where I really like to use the thermography, especially for purchase exams,” he said. “You’d be surprised at how many times the information can confirm your subtle feeling about something.

“You never want to use this technology by itself; you always want to add it to your other examinations,” he added. “When I first started using it, I was also doing acupuncture exams. I found that thermography and the acupuncture exam fit together quite well. I was getting more information from the acupuncture exam, but able to use the thermography to explain it to people.”

The thermography information provided on the TV monitor, which can be printed out for the client, involves the horse owner in the process as well. “You can write a few paragraphs or pages to go with the digital image, and clients love those multicolored images,” he said.

Preliminary experiments show that heat is created by injuries before they become injuries said Tracy Turner, DVM, of Anoka Equine, in Elk River, Minn.

“We spent two years at a local racetrack imaging the horses and predicting problems,” he said. “We found we were 95 percent right in picking up things before they were ever problems. We could see most things a little more than two weeks before they actually became a problem–so we could start making adjustments and head off an injury.”

Currently, Turner is using thermography and other techniques for a wellness program for the athletic horse. There are wellness programs for the average horse–vaccination, deworming, nutritional programs–but this will go beyond that.

“Our athletes, when they’re getting into condition and being stressed, can be scanned on a regular basis,” he said. “Then we can hopefully pick up things before they become big problems. We can change the training a little and avoid a major injury. I’ve been in the horse business long enough that I feel comfortable with treating various injuries, but I’m tired of treating these–I want to prevent them. We can’t prevent them all, but we can put a big dent in them, so they’re not as big of a problem.”

Obtaining The Best Scan And Diagnostics

Infrared thermography is a valuable diagnostic tool in the hands of trained veterinary professionals who are skilled in the proper use of the technology. Unfortunately, due to the availability of the equipment, IRT has become a tool that some untrained individuals are using.

“Because of a lack of personal experience, an untrained person may not appreciate the value of the significant physiological information that can be obtained when the IRT exam is properly performed and the resulting images are skillfully interpreted,” said Donna L. Harper, DVM, of Roswell, N.M. “The physiological information obtained can greatly add to the accuracy of a diagnostic and/or prognostic process.”

Harper said the second problem that’s encountered by advocates of veterinary IRT is that almost anyone with the necessary financial resources can purchase an infrared camera. So there’s been a recent “mushrooming” problem of people with access to infrared cameras who are offering their services to perform veterinary IR scans or exams on animals without the proper knowledge or training to do so. This problem is becoming particularly prevalent within the horse industry.

“Generally, these ill-advised people are well-meaning in their desire to help the horse and its owner–as well as their own financial reward–but in fact they are doing just the opposite,” she noted. “By providing bogus diagnostic information that’s often wrong, inappropriate, or suspect at best, these illegitimate veterinary thermographers are creating bad press for those who provide a legitimate and reliable service that can be invaluable in resolving difficult cases.

“Perhaps even worse, such persons cause unknowledgeable veterinarians who might otherwise become interested in learning about IRT, to reject it as providing false and unreliable diagnostic information because it lacks proper regulatory control,” she added.

Just because someone can legally own an infrared camera, doesn’t mean that he or she can properly perform a veterinary infrared exam. Like many technologies, it takes education and experience to become proficient.

Harper cautioned that it might also be illegal for an unsupervised person to provide such a service or perform any type of interpretation of animal images obtained for veterinary medical purposes.

“In most, if not all 50 states, the interpretation of diagnostic information related to animals, including IR images, is defined by law as ‘the practice of veterinary medicine’ and as such, requires performance by a licensed, knowledgeable veterinarian,” she said. “If the individual owning the camera is not a veterinarian, then he or she will need referrals from participating veterinarians to stay within the law in most states.”

It’s difficult to police any large scale violation of the law, but efforts are under way to encourage horsemen to report violations to the appropriate state Veterinary Boards, which can help to see that appropriate diagnostic standards are upheld for the benefit of all parties.

Currently, infrared cameras and software are priced at $20,000 and up. Practically, not everyone can justify purchasing an IR camera, but it can be economical for one individual to purchase the equipment and take referral cases from other practitioners.

“Legitimate veterinary thermographers often have a capital investment of more than $30,000 in high-quality equipment,” said Harper. “Illegitimate thermographers providing cut rate exams hurt everyone’s chance of getting an exam done using high-quality equipment because the veterinarian, or other legitimate thermographer, has less volume to justify making the necessary investment in the higher quality equipment.”

Because of the interest that horse owners have shown in IRT, the American Board of Thermology–which is the only legitimate certifying body for veterinary medical thermographers–is in the process of developing uniform certification standards for veterinary thermographic technicians and veterinarians.

Harper is one of the four ABT certified veterinarians in the United States and Canada (there are also a few technicians). Veterinarians or other persons interested in learning to properly perform IRT exams on animals, or where appropriate, to interpret the images that result, can study veterinary IRT through training opportunities presented by qualified ABT members. Interested persons can also work toward eventual certification by the ABT if they wish to complete all of the requirements.