Thank you Megan for the introduction and thank you guys, all for joining me this afternoon
just to talk a little bit about wildlife rehabilitation, which is one of my favorite topics. So I'm
gonna start the talk this afternoon, talking about just, like, an overview of wildlife
rehabilitation, some of the principles and goals underlying wildlife rehabilitation efforts
and then I'm gonna tell you a little bit about my research. Actually a good portion of my
research is based on rehabilitating animals, especially sea turtles, and so I'm gonna tell
you about that work. So some definitions for you: Rehabilitation means to restore to customary
activity through therapy and education and that usually includes treatment, which means
to give medical aid to. One of the main concepts of rehabilitation is that the focus is on
the individual animal or human rather than the population at large. There's a lot of
underlying ethics surrounding wildlife rehabilitation that I think are important to consider.
When we look at animals and animal welfare and animal treatment, animal medicine, a lotta
times it comes down to decisions that are made by the animal's owners and with our pets
we know who the owners are, farmers we know who the owners are but who owns wildlife?
So legally wildlife is owned by all of us. It's owned by the public trust and that's
in the United States so we all have a stake in animal welfare when it comes from wildlife
and I think most people would agree that we have a moral imperative to humanely care for
a wild animal in distress as their owners and especially when the distress is due to
human activities. So I'll just give you some examples. Of some horrible things that have
happened to the wildlife, this is a harbor seal who has outgrown his packing strap entanglement.
This is an oiled sea turtle.
This is from the Deep Water Horizon oil spill in the Gulf. Here is a Florida manatee who
succumbed to respiratory distress because of harmful algal blooms that are ultimately
due to human activities. This is a sea turtle in rehabilitation at the Houston Zoo who swallowed
some fishing hooks. Here's a California sea lion who some nasty person shot with a bow-and-arrow
probably because either for fun or because the animal was raiding his fishing lines or
nets. This is an American bald eagle that has lead toxicosis from scavenging on an animal
carcass that was killed with lead bullets and this is a patient that was at the International
Bird Rescue Center in California.
This pelican they think a fisherman probably – he was probably – again raiding the
line or the net and the fisherman got mad, caught up the bird and cut his pouch with
a knife, which is a horrible thing to do but actually this is a good story and this one,
too. These animals were rehabilitated and released so just some examples. So when we
talk about the principles of wildlife rehab, programs to rescue and rehabilitate sick animals
are founded upon two general principles: Altruistic assistance to the sick or injured and conservation
of wild populations and, in the process, we gain medical and scientific knowledge and
provide a valuable interface wild-animal welfare and the public. The ultimate goal of wildlife
rehabilitation is a successful transition and return of an individual animal back to
its natural habitat in a fit and healthy state to reproduce and perform all natural functions
and behaviors benefiting the environment and the species. So I think that's important to
remember that the outcome is release. Conservation: So the Second Principle of Wildlife Rehab
is Conservation, as I just mentioned. Conservation is a realistic motive for reintroduction programs
for threatened species so, yes, reintroduction programs for threatened species such as the
rhino.
For robust populations however conservation is not a defensible argument for rehabilitating
animals because reintroducing a few or even a few hundred of these animals will be of
little benefit to most stocks and even less benefit to the population as a whole. So when
we talk about rehab, a lot of people wanna focus on the good things but there are also
a lot of downsides to rehab that a lot of biologists will argue. First of all it's extremely
expensive. There are several recent studies indicating that rehabilitation of a single
animal can cost over $100,000.00, depending on the species and the duration of rehabilitation,
and this cost may be justified for endangered species who with populations that are imperiled,
however the cost is very difficult to justify for non-threatened animals. Also many biologists
would argue that rehab facilities divert money away from programs based on wild population
conservation and habitat protection.
Rehabilitation success rates vary by species but they tend to be quite low. For example
the sea-turtle rehabilitation success rate in Florida between 1986 and 2004 was 36.8
percent and when we look at – when we say success that means the animal was released.
In another study in California 14 percent of 35 rehabilitated dolphins over a 25-year
period were released so generally low success rates. There's few long-term, follow-up data
on rehabilitating animals. The data is logistically difficult to obtain and maintain. It's expensive
and it's difficult to track animals after you've released them. That's the bottom line.
Some people argue that wildlife rehabilitation has no benefit to the population unless the
animal reaches sexual maturity and reproduces. Minimally the animal should have an annual
survival expectation equal to the age class of that population and anything less than
that is arguably a postponement of the animal's fate by the number of days that it was in
a rehabilitation facility. Another concept is that rehabilitated animals may be returned
back to health but it doesn't necessarily mean that they're releasable. The animal has
– in order to be released a wild animal has to be able to form all of its natural
functions, including movement, maintaining stable body weight by normal foraging behaviors,
have normal blood health, have no indication of infectious diseases and not be habituated
to or dependent upon humans for survival. So there's some pretty tall criteria and the
fact is that a lot of rehabilitated wildlife species end up as permanent captives. There's
also a risk of pathogen spread so when you bring an animal into captivity, there's a
risk to the humans who are interfacing with that animal, being exposed to zoonotic diseases,
and there's also a risk when you reintroduce that animal into their wild population that
they may have picked up some diseases during captivity that they would then take back to
their population so those are the downsides.
There are a couple other ethical dilemmas that underlie wildlife rehabilitation. There's
a lot of research that's been done on these concepts so the main question is that "Do
we invariably act in the best of the animal or are our best interests or our Number 1
focus is on, like, our altruism and that it makes us feel good to rehabilitate the animals?"
Also the question is "Is it humane to rehabilitate a non-releasable wild animal?" And also "How
can we ensure a released animal will survive in the wild or contribute to the population?"
Like I said you need long-term follow-up data that can be expensive to do and difficult
to maintain.
There's also a rehab bias and I just thought this is worth mentioning. We tend to focus
on species that we have a special affinity towards, there's this cute-and-cuddly bias.
We like adorable animals and who doesn't? There's also a flagship species bias where
we tend to gravitate towards charismatic megafauna and kind of ignore the less charismatic species
like snakes and things like that that people may not relate to as easily. So the truth
about wildlife is that humane, rapid euthanasia is often the best option for injured or sick
wildlife.
Euthanasia stems from the Greek word euthanatos, which means "good or easy death", and the
key to ensuring the welfare of individual wildlife casualties is a proven process of
triage that enables rapid euthanasia of animals that are considered unlikely to be released
back into the wild. Success in this sense may be judged in terms of preventing unnecessary
suffering whereby a high level of euthanasia could be considered successful. Once a decision
is made to bring the animal into rehabilitation, success is then defined as bringing an animal
back to health and releasing it into its natural environment and benefiting from this process,
in terms of public education and scientific knowledge. But, either way, the triage process
should be done quickly, animal-side and the decision should be made quickly if you are
going to euthanize. So again the key to successful rehab is a well-defined triage criteria, which
is supported by research, effective, appropriate intake criteria, which is often species-specific.
You need highly-trained personnel and lots of infrastructure including facilities, funds
and flexibility and usually a lot of those things.
So those are just some of the overall concepts about rehab and now I'm gonna talk about my
favorite part about rehab, which is access. So an important benefit of animals cared for
in rehabilitation is their role as sentinels of ecosystem health because rehabilitating
wild animals are so accessible, they can help contribute to the developing reservoir of
information on care and medicine that we can then apply to free-ranging wildlife needing
help. And this health knowledge is crucial for wildlife conservation and also veterinarians
gain skills and knowledge from rehabilitating animals that enable them to play a vital role
in conservation and also, in turn, to rehabilitate animals in the future better. So some of the
things that we learn from access to rehabilitating wild animals is information on physiology,
life history and nutrition, behavior, diseases, toxicology and medicine, including treatment
and diagnostics. Wildlife rehabilitation centers can be a valuable resource for the surveillance
and monitoring of pathogen activity and wildlife, which, in free-ranging animals can be cost-prohibitive
and logistically challenging. So although there are some inherent biases in this approach,
obviously, it can still provide valuable information to assist in management and conservation decision-making,
including approximations of disease prevalence in the general population, species variation
in disease susceptibility, clinical syndromes, standardization of diagnostic protocols, development
of medical approaches, therapeutics and outcomes associated with various pathogens. And we
can use this information to make these population-wide inferences that we can apply to general wildlife
populations and that we can also then, in turn, apply back to rehabilitating wildlife
to inform and improve future efforts. All right so that's just my introduction and now
I'm gonna tell you a little bit about my research. For the past seven years I've been working
on figuring out this disease that affects sea turtles, called fibropapillomatosis or
FP and since you live here in Florida you may be familiar with it. It's a debilitating,
infectious, neoplastic disease that affects all sea-turtle species but has reached epizootic
status in green turtles, meaning it's an epidemic in many green sea-turtle populations, across-the-world.
It's been reported in all oceans in many countries. It tends to mainly affect juvenile green turtles
after they migrate back to their coastal habitats so usually around four to seven years old.
It can affect any -- they can have tumors on any part of their body, including internal
organs and it can be fatal in some cases. There's a virus associated with these tumors
called Chelonid herpesvirus 5. It's the presumed etiologic agent of FP. Here's the virus right
here.
I say presumed because like many herpesviruses this virus is not able to be isolated in cell
culture, however the tumors have been proven to be transmissible via cell-free tumor extract,
meaning that a researcher cut off a tumor, ground it up, passed it through a virus-sized
filter, injected it into naïve turtles and they grew tumors. This virus is consistently
associated with FP tumors via multiple molecular techniques. The herpesviruses group into alpha,
beta and gamma herpesvirinae and this one is here. It groups with the alphaherpesviruses.
Phylogenetic studies show that the viruses coevolved with its sea-turtle hosts meaning
that the recent epizootic or epidemic is probably not related to the virus but probably something
related more to the host, which is the turtle, or its environment.
Other factors that have been associated with FP most significantly is the nearshore shallow-water
embayments so they tend to get tumors when they move from offshore to inshore. It's also
been associated with pollution, eutophication, harmful algal blooms and invasive forage species,
like macroaglae. It's been associated with warm-water temperatures, which is not that
surprising because a lot of herpesviruses are temperature-sensitive and also with host
immunosuppression. So the reason that I'm interested in FP is because when we talk about
emerging infectious diseases these days generally there's this, like, a triad that involves
the pathogen, the host and the environment so usually there's a bit of environmental
degradation or contamination or both. There's also host immunosuppression and then you have
a pathogen and when these three things meet, we see diseases that may not have been a problem
100 years ago.
Again you have environmental contamination or degradation, including exposure to this
type of environment. Then the host is immunosuppressed probably related to the environment so they
have decreased cell counts, decreased cell function and then they have an increased susceptibility
to pathogens that normally wouldn't affect them in that way and, in some cases, you get
neoplasia, which is cancer. So that's what we're seeing with this disease and you can
see that, again, it fits in really nicely with this paradigm so we have the host, which
is immunosuppressed probably due to a degraded environment and then we have a pathogen, which
historically didn't cause disease and now it does. In rehabilitating turtles FP is a
huge problem. It's infectious. It's horrific for an individual animal. It tends to necessitate
special husbandry conditions, including quarantine, like stringent quarantine.
The tumors can influence clinical progression, extend rehabilitation duration and complicate
prognoses and here are some examples. This turtle came in. I think she was hit by a boat.
This is at the Georgia Sea Turtle Center and she was in rehab for over a year and she was
doing fine, getting ready to be released. She was quite robust and then the staff noticed
a bulge in her plastron. They did an MRI and it turns out she had a huge internal tumor
and she was euthanized.
This is another turtle who came in with a boat-strike wound on the carapace and was
progressing quite nicely and then developed these tumors within the boat-strike lesion
and the turtle was euthanized. So I got interested in around 2010 during an externship. When
I was in vet school at the Georgia Sea Turtle Center I had some patients. Some of these
turtles I just showed you were some of my patients and I became really interested in
this disease and so I started out my journey of this research doing a retrospective case-series
analysis of all of the turtles that had or developed FP tumors at the Georgia Sea Turtle
Center since it opened. So that's over a five-year period and we looked at the occurrence, clinical
presentation and outcomes of disease. There were 25 turtles overall, which was – represented
12.6 percent of all the green turtle patients at the Georgia Sea Turtle Center, which is
not insignificant. In sea turtles we age them by looking at their size. Generally it's called
the straight carapace length so the bigger they are, the older they are and you can see
that it's pretty consistent that the juvenile turtles, these smaller animals are the ones
who are most affected by the disease.
In the study we also a modified tumor scoring system, based on tumor number, size, location
and severity so, like, how aggressive the tumors are and the tumor-scoring system ranges
from zero, which is unaffected, 1 mildly, 2 moderately and 3 severely affected . We
found that 48 percent of these turtles develop tumors over one week after entering rehab
and that ten of them did so during the warmer months so again there's a temperature component
to this, to the tumor outbreak and also probably – so they developed tumors after they entered
rehab so they were either infected when they entered rehab or they became infected in rehab
and what I think is most likely is that they were already infected and the stress of whatever
brought them into rehab and the stress of being in captivity led to them developing
tumors. FP tumors were most often first observed in the inguinal regions here so we can advise
rehabilitators to focus on these areas, looking for new lesions and we came up with this estimation
that overall about 10 percent of rehabilitating green turtles may develop FP within 90 to
120 days of rehab, which hadn't been described before. We found that ocular tumors, these
eye tumors, were observed in about two fifths of the tumor turtles and turtles with ocular
tumors were over 8 times less likely to survive rehab than tumor turtles without ocular tumors
so basically having tumors in your eyes is bad [laughs] and we also found that 10 out
of 25 of the turtles had these – only had these – plaques, these flat plaques, which
histologically and molecularly were consistent with FP but these turtles were significantly
more likely to survive rehab and over 50 percent of them had spontaneous tumor regression whereas
none of the other turtles that had the other types of tumors had spontaneous tumor regression.
So if you have flat, plaque-like tumors it's good. Laser surgery is the treatment of choice
for tumor removal and we found in this study that the number of surgeries is not significantly
related to case outcomes so a turtle could have up to 6 tumor-removal surgeries and it
wouldn't necessarily affect the outcome of the case.
So here's a good example. This turtle had severe FP. This is a patient at the Marathon
Sea Turtle Hospital. You can see she was blind. This is a pretty nasty case so here she is
having her tumor-removal surgery and then this is the same animal.
So just because they look horrible doesn't necessarily mean that they're gonna have a
bad outcome. I think that's important to note. However we also found in that study that 38.5
percent of turtles that had their tumors removed experienced tumor regrowth within 36 days.
So here's a turtle. These are the little FP lesions just developing in the inguinal regions.
This is the day that they were removed right after surgery and then 15 days later you can
see the tumors are back and they're even worse than before and this fits in with what we
know about herpes biology, right? So herpes is for life as we all know [laughs] and just
because you remove the tumors you're not removing the virus and so that's why it's so important
to bring the health of the turtle up as well as removing the tumors because the turtles,
their immune system has to be able to combat the virus as well.
Because of this study – this little study – we came up with a lot of recommendations
for rehabilitators, including – for green turtles – trying to release them within
90 days, if at all possible, to avoid tumor development in captivity because once they
develop tumors then you're in for the long haul. The animal has to be able to survive
in its current condition, like I told you guys before. But we also came up with the
recommendation that mild, stable, cutaneous FP that's not progressing and the animal's
otherwise healthy, eating on its own, healthy blood values, they can still be candidates
for release and this wasn't recommended before but because of what we know about herpesvirus
we know that they're not gonna get rid of that disease and the most important thing
is that the turtle overall is healthy so not – just because they have tumors doesn't
necessarily mean they can't be released. We recommend that they're released where they're
found to avoid introduction of a new disease into a naïve population, water temperature
over 18 degrees preferred and, if possible, it's important to track the patients just
like I told you before. We did this same thing for loggerhead sea turtles in the southeastern
United States. I looked at 3 rehab facilitates.
Just basically, briefly, we found that FP is not really a problem for loggerheads. They
do get tumors but they're typically incidental or mild. They are usually not that aggressive.
Interestingly they get these oral tumors that green turtles, in this area, don't really
get. They get a lot of ocular tumors but they're usually mild and exposure to green turtles
is a risk factor for loggerheads in captivity. So we recommend that green turtles are kept
quarantined away from all other species and then green turtles with FP are kept in an
even higher level of quarantine away from all other green turtles as well. However we
did find in this study that for individual loggerheads, FP can be a huge problem just
kind of like how diseases in people could be. So we had this one patient who had severe,
severe FP.
She was really sick. This is from her intestinal tract. She was euthanized and – but she
– we actually learned a lot about this turtle and there – so far there have been three
studies and I'm involved in a fourth just on this one turtle alone so she provided us
with a lot of information even though she died. So ongoing research: What I'm doing
now to follow up with this is I'm doing it again. I'm doing a case series analysis but
on a much bigger scale and including all species, not just green sea turtles, involving the
Marathon Turtle Hospital, the Georgia Sea Turtle Center, the Whitney Lab, the Brevard
Zoo and the Clearwater Marine Aquarium, hopefully. And we think we'll have hundreds of cases
in this study so hopefully we'll get a lot more of this type of information that can
then be passed on to rehabilitators. And the questions that we're asking are "Does FP Tumor
Score accurately predict rehabilitation outcome? What percent of surgically-removed tumors
regrow? In what timeframe do the regrowths occur?" and "Is there a seasonality?", so
again looking at temperature. So changing gears I did a follow-up study of rehabilitating
green sea turtles using molecular biology to try to get a better idea of the herpesvirus
itself. For this study I developed validated and optimized PCR assay.
PCR stands for Polymerase Chain Reaction. It's just a way for us to detect and quantify
pathogen DNA. In this method we can provide absolute quantification of viral DNA. The
assay is extremely specific. It's very sensitive and it's repeatable and robust. And using
this assay I evaluated the relationship between Chelonid herpesvirus DNA loads and clinical
disease in rehabilitating turtles. So we looked at 351 samples taken from 67 turtles, 23 with
FP tumors and 44 without FP tumors.
We analyzed their blood, their plasma, cloacal and oral epithelial swabs, feces, urine and
skin biopsies and this is the data that we got, we found. So red is turtles with FP and
blue is turtles without FP and then these are the sample types where we got some results.
If the sample types aren't mentioned that's because none of them were positive. Interestingly
we found viral DNA in urine samples, which has never been described before. We found
viral DNA in blood, which has never been described before for this disease and cloacal swabs,
again, a novel finding. And we found that in a lot of skin biopsies so, which is something
that we had found with previous studies but it just supported the data. And you can see
that turtles with FP had a lot more samples that were positive but it was pretty interesting
that we had these asymptomatic animals that also had positive samples so basically telling
us we have asymptomatic infections in some green turtles. When we look at the level of
agreement between the different sample types taken from an individual turtle I thought
it was really interesting that there was 100-percent agreement between blood and urine taken from
the same turtle. We know that urine is a filtrate of the blood so this points to the potential
that urine is a method of transmission of this virus.
The fact that we found it in normal skin in this and another study of free-ranging turtles
points to normal skin being a potential route of transmission as well. And from non-tumored
animals as well as from tumored animals. I followed up this study by taking extensive
samples from 10 green sea turtles at necropsy, 5 of them had tumors. Five did not. We took
samples of all of their major organs, their neurological tissues, including optic nerves,
nerves innervating their front flippers and nerves innervating their hind flippers, skin,
tumors, blood and urine. These are some of the animals just to give you a picture and
this is a tumor that was on the kidney of one of the animals.
This is the tumor on cut surface. You could see the kidney was still trying to make urine
and we took samples of this fluid and did PCR on that as well for viral DNA. Interesting
results: We found again the urine samples were positive for viral DNA and then this
was really surprising or to me it was surprising that a lot of the kidney samples were positive
for viral DNA and also some of the nerve samples were positive for viral DNA, which has never
been described before. We know that alphaherpesviruses tend to go latent within nerve cells and so
this pointed to a potential site of latency, which has not been described for this virus.
So there's a lot of stuff that we don't know about this virus and I think by understanding
the basic biology of the virus then we can understand more about the disease process.
So this study gave me more questions than answers but basically made me wonder if the
kidneys are a site of persistent viral infection probably related to the presence of the viral
DNA in urine, pointing to a renal urinary route of viral excretion. Also the presence
of the viral DNA in nerves points to again potentially a site of latency of this virus,
which is typical of this type of virus. And the sites where we found virus-positive nerves
were nerve cells that innervated parts of the body that had tumors so we found an ocular
nerve, an optic nerve that was positive for the virus in a turtle that had a tumor in
that eye.
We found brachial plexus nerves that were positive for the virus in turtles that had
tumors in those flippers and so it supports that idea. So when we put all this information
together we can kind of get a sense of this Chelonid herpesvirus infection cycle whereby
the virus – this is our little virus – enters the skin, enters the host. We're not sure
of all the transmission routes at this point. The virus undergoes primary replication and
then disseminates throughout the body via blood and/or nerves probably to the kidneys
and potentially other sites of persistent secondary infection. The virus probably establishes
latency maybe in nerves, maybe in other things.
The virus is then shed. We know the virus is shed through the skin and through tumors
and maybe through the urine as well. And then to follow up on this research now I'm doing
a study with the University of Florida and the Brevard Zoo where we're looking at abnormal
kidney samples from green sea turtles so you can see this top turtle, this is a normal
kidney sample here and then this is in situ or in the turtle. And then this is an abnormal
kidney we have generalized severe fibrosis tract through medullary regions and this lesion
is extremely common in green – in juvenile green – turtles in Florida to the point
where it has been called normal because it's so common and we're wondering if maybe it's
due to herpesvirus infection. And so for this study what we're doing is again molecular
biology paired with histology to see if maybe this – these types of lesions – test positive
for the Chelonid herpesvirus and maybe that's why we're seeing those lesions even though
these turtles don't have tumors. And throughout this research we've found a lot of subclinical
disease carriers so you guys may not realize it but subclinical disease carriers are really
important within the epidemiology of a disease. So the fact that we have animals that are
infected but asymptomatic points to an environmental and/or host factor that plays a role in tumor
development, like I've said before. It also suggests that this virus is endemic in some
populations. These animals serve as a reservoir so you can see in this diagram these are the
subclinical infected animals.
They serve as a reservoir that can lead to infections in susceptible animals just as
clinical animals can serve as a source of infection and so they can be a source of viral
dissemination within a population and this, actually, probably explains why there was
one study where they looked at the exposure – viral exposure – of this virus in green
turtles in Florida and found really high percentages of exposed turtles in populations that had
zero tumor prevalence. So how did they become infected if none of the turtles have tumors?
So this is a likely explanation for that. To follow up on that study right now I'm doing
a study on loggerhead and green sea turtles in North Carolina. Historically FP has not
been a problem for sea turtles in North Carolina, however it's becoming more and more prevalent,
either because the water is getting warmer or the sea turtles are transmitting it northward
or both.
We're not sure but we're just doing a survey of free-ranging turtles, working with NOAA
to get samples from them and also rehabilitating turtles at the Karen Beasley Rehab Facility
to see if we can identify the prevalence of this virus in asymptomatic turtles or subclinical
turtles. I'm doing another study – so in all these pictures you may have realized or
you may have noticed that the tumors can take lots of different types of appearances. They
can be these flat plaques. They can be sessile and smooth. They can papillomatous.
This is the most common presentation in Florida or they can be polypoid and smooth like grapes
and, in another study, they noticed that there are four different variants of this virus
in Florida. There's A – where's B – B, C and D. These have only been reported in
loggerheads and A, B, and C have been reported in greens and so it got me to wondering are
these viral variants related to tumor morphology so is the – does the – variant identity
predict what the tumor looks like and therefore its virulence within the host? So we're doing
a study now with the Marathon Sea Turtle Hospital where we're looking at using molecular biology
to look at virus variant identity in loggerheads and greens, again, and statistically evaluating
those relationships between morphology or tumor morphology, species and variant and
looking at both free-ranging and rehabilitating turtles and comparing the results. So just
to summarize, overall, I think I tried to make it clear that wildlife rehabilitation
has both benefits and drawbacks. It can have conservation benefits in cases of threatened
or endangered populations but the most important concept to me is that access to wildlife provides
an excellent avenue for disease research and education. And I just wanna thank all of my
collaborators.
I work with a lot of people, certainly could not have done any of this stuff alone, including
the rehab facilities and University of Georgia and Harbor Branch and I'll take any questions
and also this is my email address if you have other questions or wanna email me, have ideas
you wanna share, please feel free. So thank you very much.
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