Page 72 - May 2018 Speedhorse

Dr. Kathleen Crandell, Equine Nutritionist of Kentucky Equine Research, says hair analysis can help determine what a horse may be lacking, can give an indication of metabolic, immunologic and dietary issues, and can clarify whether a horse has been exposed to plant toxins or drugs. She says results are best interpreted when considered together with the horse’s history, a physical exam and blood tests.
best interpreted when considered together with the horse’s history, a physical exam and blood tests,” Crandell explains.
“Where the hair analysis is helpful is inter- preting whether the horse has been exposed
to heavy metals, including toxic levels of selenium, detection of drug or medication use over several months, lipid intake and ingestion of plant toxins,” she says.
“As for using a hair analysis for determining the adequacy of the dietary intake of nutri- ents, this aspect is not as definitive as the drug detection. If a nutrient is grossly over-supple- mented, that will show up in a hair analysis, but when the levels being fed are slightly over or under the requirements, it is much more difficult to determine this from the results of
a hair analysis. Taking multiple samples for analysis over time can give a clearer picture of mineral intake than a single sample.”
Research on using hair analysis to deter- mine nutritional status has found that there
are several things that complicate the results. “There can possibly be differences in the results of the lab tests in horses of different breeds, age, sex and hair color, and even season of the year, in levels of certain elements in the hair,” Crandell says.
These factors have an influence on the levels found in hair, so you can’t just take one sample and expect the results to be completely accurate or to determine if a horse is deficient in a certain nutrient. “Further, it is amazing to see the amount of individual variation in mineral content of hair between one horse and the next
in published research studies, which makes a person wonder how someone could determine if a horse is deficient,” says Crandell.
“However, hair can be used to detect certain toxins. You can find the heavy metals, pesti- cides, certain drugs, etc., in hair. The advantage of using hair to detect the presence of drugs is that it gives you a long-term picture. Once the drug was present in the body and deposited in the hair, it stays there,” she explains. It takes a while for hair to grow and it shows you a history of ingestion of certain drugs, over time.
“For instance, if you gave a horse caffeine, it will show up in the hair roots if you’ve given it recently. It would be farther up the hair shaft if the caffeine was given several weeks or months ago. The best hair to use for analysis is mane hair because it continues to grow and is not shed seasonally,” says Crandell.
A hair sample can show environmental toxins the horse has eaten, such as plant toxins. Selenium levels can be very high in some plants that accumulate this mineral from the soil. “A hair analysis study that looked at selenium levels in horses found that there was a direct relation- ship with times when the horses were season- ally turned out on pastures with high levels of selenium. The cyclic changes in selenium intake showed up in the hair for up to three years. There are also some other studies that showed a definite correlation between intake and evidence of heavy metals, such as chromium, lead, mer- cury, aluminum, etc., in the hair,” she says.
Some horse owners think they can use hair analysis to tell them the nutrient status of a horse, but this becomes more complicated and inconsistent. “About 20 years ago the labs de- veloped a new way of performing hair mineral analysis, with Inductively Coupled Plasma Mass Spectrometry (ICP) and a similar method called Inductively Coupled Plasma Optical Emission Spectrometry. These techniques are much more reliable than the older methods. There is another new method called Particle Induced X-ray Emission (PIXE) which is easy, rapid and reliable. Some older studies with ambiguous results may be inconsistent because of the way the hair was analyzed,” she says.
Some new studies seem to show more direct relationships between mineral content of the hair and dietary intake. However, hair color can make a difference in the results. Samples of different-colored hair from the same horse give different results.
Gray hair also shows different results. “Gray horses’ hair shows higher levels of copper and zinc, and lower levels of calcium and selenium, for instance. In one study, there was no differ- ence found between the hair of bay and black horses, but grey was different. So, color affects the mineral content, as does the age of the horse,” she says.
“A 1990 study found different levels of many minerals in young horses compared to older horses. In horses between two and eight years old, the levels were different than in a group of horses that were nine years old and older. However, this study was done before the use of more reliable methods of analysis with ICP or PIXE, so that must be taken into consideration when interpreting the results. Another study done in 2015 looked at horses three years old and younger, comparing them with horses that were older than three years. This newer study didn’t see a difference in terms of age,” says Crandell. Perhaps the new technology in hair analysis was the reason for different results. Different labs may also use different techniques in hair analysis and may come up with different results.
“The 2015 study was interesting. It used horses of the same breed and color. Age was the only difference in the various horses. This study is one of the few that has shown there are some direct relationships with amounts of certain minerals the animal is ingesting and the amounts found in hair. The study found that the hair levels of calcium, cobalt, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, selenium, sulfur and heavy metals all reflected the dietary intake. This study also compared blood samples with mineral intake and found that blood was a poor indicator of mineral status and hair was more reliable,” she says.
“But as a rule, hair levels reflect excesses
of minerals better than a deficiency. If there
is a high level of a certain mineral in the hair, it might signify a problem with excess of that mineral in the body. But if a certain mineral
is low, or not in the hair at all, you don’t know whether there’s a true deficiency or if that mineral is just not being deposited in the hair. There may be another mineral interfering with deposition in the hair.” It’s a complicated pic- ture and not a simple way to look at nutrition.
“The presence of lead can interfere with iron deposition, for instance. You might look at a hair analysis and think the horse was short on iron, whereas the presence of lead kept the iron from being deposited in the hair. High cadmi- um level will interfere with copper. Interpret- ing results of a hair analysis can be tricky. Hair analysis may eventually be a way to look at general nutrition in a horse, but we’re not there yet. We still have much to learn, regarding how effective a tool it may be,” says Crandell.
“We can detect the presence of heavy metals, however, and that might help with di- agnosis if you suspected your horse had a toxic problem with one of those. Selenium toxicity can also be checked with a hair analysis.” In the future, we may be able to use hair samples to help with diagnostics in other problems as well. Research has shown that it may be possible to
70 SPEEDHORSE, May 2018
equine health