The 2026 Animal ForensiCon in Orlando, Florida

Dr. Rachel Sheffler shares information on the use of toxicology for the identification of substances that may be present in an animal victim of crime.

Dr. G:

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Alright, so excellent discussion

about toxicology, and here to

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let us know about it is Dr.

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Rachel Scheffler.

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Welcome to the junction.

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Dr. Rachel Sheffler:

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Hello.

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Thank you so much for having me.

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Dr. G:

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So can you start by letting our

audience know what's your background?

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Dr. Rachel Sheffler:

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Yes.

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And so I am a veterinarian.

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I did my, uh, veterinary education at

Michigan State, and then I stayed on for a

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formal residency in veterinary toxicology.

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Um, that's pretty unique.

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There are not a lot of residency

programs for veterinary toxicology.

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Um, and then I also did, at the same

time, a PhD in, uh, toxicology, and

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specifically having a focus on food

safety and ingredient toxicology.

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Um, so with that, I've had a

diverse background of experiences.

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Um, my primary interests are food

safety, agricultural terrorism, um, and

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ingredient toxicology, uh, as far as

what my graduate education is focused on.

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Dr. G:

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Awesome.

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So a lot of...

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I'm sure that you hear this a lot, too,

as a veterinarian, I get the people that

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say, you know, "Test it for poison."

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So what...

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why can we not do that?

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Dr. Rachel Sheffler:

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Right.

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And so that's an excellent question.

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So testing for poison,

there are so many poisons.

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There are more poisons than you or

I can even memorize, even in the

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most, uh, studious of people, and

we're always discovering new ones.

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Even some have been yet

to be characterized.

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You know, a, a very classic example is

we still don't know what the toxin is,

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uh, in lilies that causes the renal

failure in cats or, or the kidney damage.

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Um, and so with that, there's a large

diversity of chemical compounds.

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There are things that are

very, uh, soluble in fat.

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They like fats.

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There are things that, um,

readily move into water.

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There are things that

break down very quickly.

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There are things that stick around.

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Um, you know, one of the examples

that people are familiar with is

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PFAS or those fluorinated compounds.

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Uh, they don't degrade very easily.

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And so with that diversity, we have to,

uh, have multiple areas where we can have

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different extraction protocols to purify

those samples, um, as well as different

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technologies that we actually utilize.

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And so we have a specific instrument

called an ICP-MS that we use for metal

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and mineral analysis, whereas our

organics or, or like our carbon-based

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large molecule toxins or toxicants,

um, will be better suited for like gas

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chromatography or liquid chromatography.

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So with that, certain things play

really nicely on one instrument,

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other things don't, um, and need

to have a different technology.

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So there's not one size fits all for

toxicology testing or for that approach.

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Dr. G:

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So if, uh, an investigator or

veterinarian is sending you a sample,

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what kind of information should

they include to help narrow down

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what it is that you're looking for?

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Dr. Rachel Sheffler:

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Yes.

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And so that's, uh, a really good point,

and there are a lot of times where I

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get, "Found dead, test for poison."

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And that is- I use the analogy a

lot of the time, it's like throwing

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darts at a dartboard blindfolded.

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I'm hoping I hit a bullseye, but more

than likely, I'm probably throwing it way

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over onto the other corner of the room.

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I'm not very good at darts.

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But, um, as much historical information

as you can provide is really

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helpful to guide the toxicologist.

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Believe it or not, I spend quite a bit

of time trying to convince people that

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something is actually not a poisoning

based on, um, either the, the exam that

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was performed on the animal or the,

the necropsy or post-mortem findings.

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Um, so like a really good example

is there's a certain type of cancer,

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it's called a hemangiosarcoma.

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It affects the spleen.

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It can also affect the heart.

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It can spread to the lungs,

or what we call metastasis.

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And so with those animals, they

can have massive bleeding events,

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and that may put you down the path

of anticoagulant rodenticides.

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Bleeding and jumping straight to

anticoagulant rodenticides may not be

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the most appropriate test in that case.

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We may wanna characterize the cancer and,

and look for that cancer because it is far

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more common, um, as a cause, especially

in an older dog with a hemoabdomen.

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So clinical context is key.

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The more information you can give

your toxicologist, the better that

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we can help you, um, for those cases.

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So, um, physical exam findings, necropsy

reports, historical information,

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all of that can be really important.

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Dr. G:

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Yeah, I can definitely relate.

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I had a cat that was brought to me

for potential antifreeze poisoning,

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and then during the necropsy, the

cat actually was a blocked cat,

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and it's similar clinical signs.

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Dr. Rachel Sheffler:

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Right.

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Dr. G:

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But immediately the, the owners have

this propensity of just jumping into the

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neighbor poisoned my, my animal, right?

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Dr. Rachel Sheffler:

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Yes, and that is so common.

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Um, again, , it's a lot of times, you

know, "My neighbor poisoned my dog.

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It's the pet food company that, you

know, put poison in my dog's food."

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Um, so there are- A lot of cases, you

know, where we take those types of

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consultations and we have to be delicate

in the way that we work through them

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'cause those cases certainly do occur.

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I don't wanna dismiss someone's concerns.

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Mm-hmm.

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But if there's more information that

we need to be seeking or additional

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context, that can be ex- extremely

important, and those, those conversations,

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uh, can be delicate to, to manage.

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Dr. G:

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Mm-hmm.

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And I suppose also in trying to figure

out what compound it was, not every organ

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or tissue or sample fits all, right?

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Like there's- Mm-hmm ... a difference on

what you can get from one versus another.

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Dr. Rachel Sheffler:

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Yes, absolutely.

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And, and time is kind of

the forgotten variable here.

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And so if...

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And the animal is having clinical signs,

um, you know, it comes in with a seizure.

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Um, blood can be really helpful in

those animals because we can correlate,

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uh, drug concentrations to what is an

established or toxic dose, um, because

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particularly for pharmaceuticals when

they're going through safety testing,

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a lot of those, uh, studies or what we

call pharmacokinetics or toxicokinetics

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studies, um, have published literature

that I can reference back to.

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Whereas, you know, something like a

liver, it can be much more difficult

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for me to extrapolate what is a toxic

dose versus what is, you know, just

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an accidental incidental exposure,

um, that might not mean intoxication.

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And to your point, uh, as far as tissues

being not one size fits all, again,

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getting back to this idea of chemical

behavior, some things really like fat.

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They stick around in fat

for a very long time.

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You know, THC from marijuana is

an example, or, uh, some of these

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persistent organic pollutants like,

uh, PCBs or polychlorinated biphenyls

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that are environmental contaminants.

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They accumulate in fat versus

things that are very water

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soluble or are eliminated quickly.

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Um, those wouldn't be found

in that specific tissue.

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And so it can be very tricky.

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A lot of times I need much more

context to be able to tell you what

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sample is best for a specific case.

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Dr. G:

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So in preparation, if a veterinarian is

going to be looking at a case, doing a

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necropsy or even if it's a live patient,

prior to obtaining the samples, where can

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they find this information as far as what

they should collect, and more importantly

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too, how they should collect it?

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Dr. Rachel Sheffler:

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Yes, absolutely.

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And so not every veterinary school, um,

has specific training in toxicology.

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As far as specific toxicology sample

handling or, uh, you know, the

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advanced diagnostics of toxicology.

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We get basic training, you know,

what are the common intoxications

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we have to know for our board exam.

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Um, but beyond that, not every

veterinary school has a veterinary

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toxicologist nor a toxicology laboratory.

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So, um, one of the things that can

be really helpful is calling your

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friendly neighborhood toxicologist.

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I love getting on the phone with

veterinarians to talk about their cases.

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I am so willing to help you.

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Um, so it's never, it's never a

harm to pick up the phone and call

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your diagnostic laboratory and see

if there's either a pathologist,

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a toxicologic pathologist, or a

toxicologist who's available to help you.

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Dr. G:

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Excellent.

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Well, thank you so much

for this information.

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I think it is extremely useful and

helpful, and congratulations on your

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recent graduation with your PhD.

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Dr. Rachel Sheffler:

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Thank you.

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Thank you.

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It was so nice to, to meet you

and to be here at this conference.