Dr. Jack Leonard, Director
Fox Run Equine Center
Lameness diagnosis has improved considerably over the
last several years. Many new technologies have been
adapted and improved to better facilitate equine lameness
diagnosis. These include radiology, magnetic resonance im
aging (MRI), computerized tomography (CT scan), nuclear
scintigraphy, and ultrasound.
As great as these new technologies are, we must remem
ber that they are only an aid to diagnosis. The mainstay of
good lameness diagnosis is still physical examination and
time tested techniques such as nerve blocks. However, as a
supplement to these things, technology can offer us a great
deal.
One technology that has distinguished itself as a highly
useful modality in equine lameness is Nuclear Scintigraphy.
Among laymen it is sometimes referred to as “bone scann
ing” since it is particularly useful in problems involving
bone. For this, it is by far the most sensitive imaging modal
ity available human or veterinary. However, it does much
more than that.
Scintigraphy involves giving the horse an intravenous in
jection of a radioactive isotope called Technetium 99 (Tc 99).
The Tc 99 then binds to the bone structure of the horse. The
horse is then placed in front of a gamma camera that is
linked to a computer. The computer then generates an
image based on the metabolic activity in the bone.
This is extremely reliable and useful information. We are
not just looking at a lesion on an X-ray and trying to deter
mine its significance. Now we have a true measure of activ-
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Lameness Diagnosis In Horses
06 Schering-Plough Animal Health Sales Corporation
ity in the bone that is not as much subject to interpretation
as other forms of imaging. One commonly overlooked but
important factor is that the negative results can be relied
upon as much as the positive results.
The scan itself consists of three phases. The first phase is
blood flow. It is done on a single area such as the front feet
in a laminitis case or the iliac arteries in an obscure rearlimb
lameness case or even blood flow through the heart or the
brain.
The second phase is called the pool phase, which allows
us to look at soft tissue structures such as muscles, tendons
and ligaments. Lastly is the bone phase. The gamma camera
allows us to evaluate every part of the horse’s body such as
the back and pelvis without the need for general anesthesia.
It is unaffected by medication and can be done on any size
horse.
Besides lameness diagnosis, scintigraphy, since it is so
sensitive, is being put to some new uses. These include diag
nosing sub-clinical problems such as in pre-purchase exami
nations, and staying ahead of potential problems by
allowing targeted preventive treatment such as in high per
formance athletes. These applications have proven ex
tremely useful.
Despite all of its advantages I believe scintigraphy is gen
erally under-utilized by practitioners and the public due to
lack of understanding or exposure to the technique. If a
lameness problem is difficult, obscure or longstanding with
out a definitive diagnosis, scintigraphy may be your very
best option.
Thomas M. Condrasky
Senior Territory Representative
Schering-Plough Animal Health Corporation
110 Wheatland Road
Lewisberry, PA 17339
Telephone: (717) 796-0417
Fax: (717) 796-0761
Voicemail: 1 (800) 962-1269
Mailbox; 8151