Pulse - October 2021 - 14

MEDICAL LEEWAY
MYVETZONE@GMAIL.COM
Why Do I Give Goats
Sheep Vaccines?
Christopher A. Lee, DVM, MPH, DACVPM
W
hy would I give goats sheep vaccines?
It seems counterintuitive, right? So,
we put horseshoes on horses, give cats
cat food, and inject goats with what? Another
species' vaccines? Are they getting shortchanged?
The short answer is no, and the longer
answer contains two reasons, one immunologic
and the other administrative.
When you become infected with a pathogen, like
rabies, a relationship between your body and the virus
has begun; and like all relationships, it is both deeply
personal and unique. Although rabies will kill you in the
same way it will kill me, a goat, or even a bat, how each
animal's immune system interacts with the virus is different.
This difference is witnessed not only from species
to species, but also from one individual animal to
another. In short, when an immune system generates an
antibody response, a series of antibodies will be made
against the virus and attach in dozens of unique locations.
Almost like a fingerprint, your DNA and resulting
white blood cells denote a specific set of attachment
sites (paratopes) that your body will create for a given
pathogen.
The rabies virus promiscuously interacts with different
individuals and species with similar, but unique,
results. Science named rabies after the goddess of rage,
Lyssa. If you court her, she will make you go mad and
destroy you, but you'll have the satisfaction that the relationship
will be uniquely shared between you.
Though individually vicious, this same virus kills
across species. Thus, an inactivated viral vaccine for
humans, dogs, cats, horses, cows, ferrets, sheep, and even
goats bears the same ingredient: a dead rabies virus. This
situation explains why the USDA labels some rabies
vaccines for multiple species. Since we know that each
species can interact differently with an antigen or pathogen,
the US government requires scientific proof that
the vaccine will work in each species for a specific duration
of time for a license to be granted.
Let's return to goats. Based on what we have covered,
a rabies vaccine labeled for sheep should work in
goats. But since we don't see goats on the label, could
this mean that vaccine studies on goats just haven't been
conducted and submitted to the USDA? Yep, you got it.
Goats aren't popular enough to warrant the cost. I
know, crazy. Who doesn't love goats? But let's look at the
study cost - 50 thousand dollars is a conservative estimate
to conduct a study that the USDA would require.
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OCTOBER 2021
PULSE
That's a significant cost to a biologics company, and it
doesn't cover the market research, marketing costs, label
changes, government fees, scientific project team, et
cetera. Not to mention the time required.
The Minor Use and Minor Species Animal Health Act
of 2004, or affectionately called MUMS, allows drugs in
minor species despite labeling for major animals. Major
species include horses, dogs, cats, cattle, pigs, turkeys,
and chickens. Excluding humans, we consider those
not defined as a major species as a minor species. For
example, fish, goats, honeybees, and sheep fall into this
category.
MUMS allows producers and veterinarians to utilize
drugs and biologics for other species without finding
themselves either without options or potential legal
trouble. This situation represents one example of " offlabel
use. " If a company wishes to design or label a drug
for a minor species specifically, they may do so, but there
is no requirement either way. For this reason, you will
see some drugs and biologics labeled for minor species
such as sheep and ferrets. Still, you will also find producers
and veterinarians routinely using non-labeled options
for minor species.
If someone asks you why you aren't using a goat vaccine
for your goat, you can simply respond, " The Minor
Species Act approves this use. " However, if you want to
get geeky, then you can start explaining the scientific
reasons why; to a degree, we are all just mammals and
thus respond in a very similar way to antigenic stimuli.
Alternatively, you can quote Shakespeare and remind
them that humans and many mammals are " hurt with
the same weapons, subject to the same diseases, healed by
the same means, warmed and cooled by the same winter
and summer. "
So, the Minor Species Act opens the opportunity to
provide prevention and treatment to species that otherwise
wouldn't have access to many therapies. This law allows
veterinarians and producers working with veterinarians to
safeguard their flocks and herds better. It provides a framework
for legal and medical approaches. However, it does
not remove the need for common sense, the need to continually
learn, or respect proper vaccine use. P
References, supplemental reading, and
podcasts available at www.MyVetZone.
com. To add in iTunes, search " vetzone "
on Spotify or iTunes.
http://www.MyVetZone.com http://www.MyVetZone.com
Pulse - October 2021

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