Vaccines!

Dr. Michael Kent Speaks with Dr. Jane Sykes on Vaccines for our Small Companion Dogs and Cats.

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The Vetrospective Podcast Season 01 Episode 03 - Vaccines
Dr. Michael Kent with Dr. Jane Sykes
Dr. Sykes:
I think the future looks bright for vaccines as we have new vaccine
technology. And as bad as the pandemic was, one of the best things that
came out of it was just innovation in vaccine design.
Dr. Kent:
Welcome to today's segment of The Vetrospective. This is your host, Dr.
Michael Kent. I'm a professor at the UC Davis School of Veterinary Medicine,
where clinically I practice as a radiation oncologist. Vaccines. What comes to
your mind when you hear this word? The word vaccine comes from the Latin
root vacca, meaning cow. So how did this happen? The name of the cowpox
virus is Variola vaccinia, and back in 1796, a British physician, Edward
Jenner, used this in a sense to infect or immunize people with the cow
smallpox virus, which did not cause serious disease in people, but in turn
protected them from smallpox, which was a serious life-threatening disease at
the time.
Since then, multiple vaccines have been developed to prevent or even now
treat disease. Of course, most people are familiar with vaccines available for
humans, like measles, mumps, rubella, flu, and more recently, the COVID-19
vaccine. So what about vaccines for your dogs and cats? This is what we're
going to have a talk about today, a deep dive with Dr. Jane Sykes.
Dr. Sykes is a professor here at UC Davis, and she has a special interest in
small animal infectious diseases, particularly of dogs and cats and those
related to public health. She has published over 150 peer-reviewed scientific
publications and is the editor of several textbooks on canine and feline
infectious diseases. She founded the International Society for Companion
Animal Infectious Diseases and has held several leadership roles in the
American College of Veterinary Internal Medicine, including serving as
president and board chair. She has trained over 50 internal medicine
residents in her career and several clinical infectious disease fellows. She is
also director of our Center for Continuing Professional Education. She speaks
internationally on infectious diseases and also postgraduate veterinary
education. And then just as a fun side note, she is the person behind Ask a
Vet, the column she does for the Washington Post. So it's my pleasure to
have you here, Dr. Sykes. Thank you for taking the time to join me on the
Vetrospective.
Dr. Sykes:
Thanks for the opportunity to participate.
Dr. Kent:
It's great to have you. So I always ask this person, this person. I always ask
our guests this question because I find it really interesting. We always get
different answers. And why did you become a vet?
Dr. Sykes:
Yeah, I kind of have the classic story. I wanted to become a vet when I was
seven. So it's kind of as far back as I can remember. I actually remember
being in elementary school in the bathroom and telling somebody I wanted to
be a vet. And that was kind of the turning point. And I just loved animals. But
my dad was a doctor and my mother was a high school teacher. So I've been
fortunate enough to combine those aspects of my life to become a veterinary
educator.
Dr. Kent:
That's perfect. And what made you interested in infectious diseases in
particular? So, you know, that's a fairly specialized and important area, but a
specialized area in veterinary medicine.
Dr. Sykes:
Yeah, I was actually really became really fascinated in infectious diseases
during vet school. Especially, I really enjoyed microbiology and I had a great
microbiology teacher, professor, who encouraged me to pursue a PhD in
veterinary microbiology. And that kind of was the beginning of my infectious
disease career.
Dr. Kent:
That's very cool. So I think maybe starting with some of the basics makes
sense. So could you explain to me what a vaccine is and how they work?
Dr. Sykes:
Yeah. And so you've kind of introduced this with the story that you began
with, but a vaccine is a modified or a killed or a portion of a bug. And it's
usually a virus or bacteria, and it's given to stimulate an immune response
that's then going to protect you from natural infection.
Dr. Kent:
So your body remembers this. Not real infection, and then can protect you
later from exposure to it.
Dr. Sykes:
Yep, exactly.
Dr. Kent:
So what is the difference between, you mentioned killed and live, I know
there's modified live vaccines, and then even the new mRNA vaccines that
we've heard so much about over the last five years.
Dr. Sykes:
Yeah, so we have a lot more different types of vaccines now than there were
previously. One of the classic types of vaccines is a modified live vaccine. It's
usually a virus. It's sort of a weak virus or what we call an attenuated virus
and that replicates in the body. It doesn't make you feel really sick, but
stimulates an immune response. In contrast, a killed vaccine is a completely
inactivated bug that doesn't replicate. And so usually they have additional
components of those vaccines that help to boost that immune response. So
often contain things like adjuvants to help stimulate the immune response or
create that really strong immune response needed. You mentioned mRNA
vaccines. Yeah, so those are small pieces of nucleic acid, a little bit like DNA.
They're actually copied from a DNA template. from a bug. So, this is less
likely to actually cause all the same signs that an attenuated virus, an intact
virus, might cause. And there was a lot of innovation in these vaccines as a
result of the COVID pandemic. And now they're actually starting to appear on
the market for companion animals as well. And they're actually great vaccines
because they can be easily modified, such as when there are new strains of a
virus that starts circulating. It's much easier to scale up production of slightly
different mRNA vaccines that can stimulate an immune response.
Dr. Kent:
So they use the genetic code or a piece of the genetic code from the virus,
let's say, or I guess it could be bacteria as well, but I haven't heard of a
mRNA vaccine against a bacteria. And it takes that bit and replicates it in the
body. And is that how we get the immune response?
Dr. Sykes:
And it produces antibodies to what that codes for. And that can help to protect
you from natural infection.
Dr. Kent:
And I'm sorry, go ahead.
Dr. Sykes:
So I was also just kind of mention that there are other types of vaccines that
are even in more widespread use in companion animals. And so we have
these recombinant vaccines, for example, which are used for Lyme disease is
one example where we have just a little piece of protein from an organism
that stimulates this.
Dr. Kent:
So when you say recombinant, are you meaning that we're taking a coding
again and then somehow displaying that to the body? How would you explain
that?
Dr. Sykes:
Yeah, so again, these vaccines are actually produced by companies that
make vaccines using a bacteria such as E. coli, for example, where they
make large amounts of just a little bit of protein using that bacteria. And that's
the recombinant process that allows you to.
Dr. Kent:
So kind of how we make insulin a lot of ways now.
Dr. Sykes:
Yeah.
Dr. Kent:
Okay. So these are not necessarily new technologies, They're pretty proven
and the like. We're going to talk more about safety later because I think that's
a really important topic. But I kind of want to ask you first, what are the core
vaccines? What are the ones, you know, we hear about core vaccines these
days? What are the core vaccines for dogs and then for cats?
Dr. Sykes:
So vaccines for dogs and cats are broken down into these two categories,
core vaccines and non-core vaccines. The core vaccines are for every dog
and cat, right? They're important.
Dr. Kent:
The essentials.
Dr. Sykes:
The essentials, right? They're either bugs that cause really severe disease,
that can't easily be treated, for example, with antibiotics, or they're just really,
really common and then they're an important cause of what we call morbidity,
just kind of not feeling very good.
Dr. Kent:
Yeah.
Dr. Sykes:
And then we have the non-core vaccines, which are reserved for dogs and
cats that might be at greater risk for certain diseases, just as you might get
vaccines for yourself if you travel to certain countries.
Dr. Kent:
Okay. And so I know, like, for example, rabies is considered a core vaccine.
And while rabies is nearly always fatal, for people and for animals as well,
there's a real public health concern there also, right?
Dr. Sykes:
Yeah. So rabies is one really important reason for vaccinating dogs and cats
in the United States. In countries where dog vaccination for rabies is not
practiced, rabies is a really important public health problem as it results from
transmission from dogs. In the United States, rabies is mostly a problem in
wildlife like bats and raccoons and skunks and so it's important to vaccinate
dogs and cats so that they're not likely to be infected from those wildlife
species. And then, you know, when dogs and cats become infected, they can
spill over to humans.
Dr. Kent:
Usually a bite, right?
Dr. Sykes:
That's right.
Dr. Kent:
Yeah, and so actually the fact that they are vaccinated is what keeps these
spillover events from happening.
Dr. Sykes:
Yeah, there was actually a really amazing story about a softball tournament in
North Carolina where some kids found a kitten that was sick and they were all
playing with it at the softball tournament. There were people from multiple
states that came in and played with this kitten. And then over the next few
days, the kitten got sick and the mother of a kid took the kitten to a veterinary
clinic.
Dr. Kent:
Very responsible.
Dr. Sykes:
Yes, and the veterinarian actually euthanized this cat because it had bad
neurologic signs. And then the mother went back home to her house and she
started thinking about rabies. And she actually called the veterinarian and she
said, will you test that kitten for rabies? And her veterinarian hadn't thought
about rabies, but because she called the vet, the kitten was tested for rabies
and found to have it. And so as a result, hundreds of kids had to be treated
with post-exposure prophylaxis.
Dr. Kent:
Which is not pleasant.
Dr. Sykes:
Yeah.
Dr. Kent:
it's not pleasant. I know, you know, for humans, rabies vaccine isn't
considered a core vaccine. I mean, all of us who in the veterinary field are all
vaccinated for it, but the general population isn't. So it's a pretty scary disease
if a human is exposed.
Dr. Sykes:
Yeah, so you can see it still can be an important problem. It's another reason
why even indoor pets need to get vaccinated for rabies because bats can be
in houses. And so.
Dr. Kent:
And bats can carry it.
Dr. Sykes:
Bats can carry it.
Dr. Kent:
In fact, I've heard more of the main ways people now can get exposed is if
they're going to caves with bats and then they can actually inhale it from the
of the bat feces, right? So some of the other ones that we talk about also,
some of the other ones, let's say parvovirus for dogs, you know, why is that
something that we need to vaccinate for?
Dr. Sykes:
Yeah, so let's talk about dog-core vaccines.
Dr. Kent:
Yeah.
Dr. Sykes:
All vaccines for dogs are parvo, distemper, and adenovirus, which causes a
disease called infectious canine hepatitis, in addition to rabies. One of the
most common infectious diseases of that group is canine parvovirus infection,
which is a severe viral disease, most commonly affects puppies, but
sometimes we see it in young adult dogs that haven't been properly
vaccinated. And it causes really bad vomiting and diarrhea and dehydration
and bone marrow suppression and death if it's not treated.
Dr. Kent:
Aggressively. Yeah, I remember. during my internship, I was in inner city
Philadelphia and there were a lot of unvaccinated dogs coming in. And during
vet school, I had never seen distemper and I had never seen parvo, but in all
the unvaccinated dogs there, we regularly saw parvo and we regularly saw it
on a cat, had leukopenia, diseases I had never seen before and kind of was a
lesson to me on the importance of vaccination.
Dr. Sykes:
One of the really important things about parvo that makes it special and
makes it so successful as a cause of disease in dogs is because it can
survive in the environment for very long periods of time. It can survive more
than a year in the environment. So if a dog has diarrhea outside and that dog
has parvo, then the virus can persist there for a very long period of time. It's
one of the reasons why we say that dogs that are getting their puppy series of
vaccines should be kept relatively away from the outdoors, not just other
dogs, because they can become infected during that time that they're getting
their puppy series.
Dr. Kent:
Really important advice. So for the first three months or so, your dog is not
really protected, right?
Dr. Sykes:
That's right. And so these vaccines that we give to puppies and kittens,
they're called a series. They're not boosters. They're given multiple times over
a course of about 16 to 18 weeks, in order to wait for the time when puppies
and kittens lose the antibody that they get from their mothers.
Dr. Kent:
From the colostrum, right? Yes, when they're nursing.
Dr. Sykes:
Yeah, and so those antibodies actually stop vaccines from working properly.
And so we've got to wait for them to disappear, but we don't really know how
long an individual puppy or kitten is going to take to lose those maternal
antibodies.
Dr. Kent:
So it's important to get the whole series.
Dr. Sykes:
That's right. Yeah.
Dr. Kent:
And that's not considered a booster, like you're saying, but that's just the
initial vaccine.
Dr. Sykes:
That's right. So we give the series. And if the last vaccine in the series is
given before 16 to 18 weeks, then that puppy or kitten might not be protected
from that infection. And it's why we often give this additional vaccine at either
six months or a year for those animals that still had maternal antibody at 16
weeks.
Dr. Kent:
So that's the first booster in a sense is just it is really your insurance policy.
Dr. Sykes:
That's right, yeah.
Dr. Kent:
So what about cats? What are core vaccines for cats?
Dr. Sykes:
Yeah, so core vaccines for cats are feline herpes virus, feline calicivirus, and
panleukopenia, which you also mentioned, as well as rabies. And then for
cats that are a year or younger, core is also feline leukemia virus.
Dr. Kent:
Now, for feline leukemia virus, since that's a virus that's transmitted close
quarters or direct contact. Is that an essential vaccine for a cat who's indoor?
Dr. Sykes:
Yeah, so feline leukemia virus, as you said, it's actually shed in a cat's saliva
and so close contact among cats can transmit it. And actually bringing cats
indoors promotes transmission of that virus because cats are living closely
together. They're often sharing food and water dishes, for example. There's
mutual grooming that goes on, and all of those things can serve to transmit
the virus within indoor environments. And so for people who have a cat that's
not infected with feline leukemia virus, and then they might bring a new kitten
into their household, there's the potential for their existing...
Dr. Kent:
Existing cat to become infected from an introduced cat from the new kitten
they got, whether the shelter or breeder. You know, I know most cats are
tested for this, but the tests may not detect the infection at certain points,
right?
Dr. Sykes:
That's right. The tests have limitations. They can be negative if it's very early.
And then sometimes cats can go positive and negative and positive and
negative. And so you can miss a positive cat sometimes with those tests. So
they're not perfect. They're helpful. But it's good to have the insurance from a
vaccine because of that.
Dr. Kent:
So now some of the core, non-core vaccines we talked about or just briefly
mentioned. What about Lyme disease? Is that a vaccine that's considered
core or why not?
Dr. Sykes:
Yeah, so Lyme disease, just like people, dogs can get Lyme disease. It's not
a disease that we see in cats. So Lyme vaccines are just for dogs. It's a non-
core vaccine. It's used for dogs that are at risk. And that's because Lyme
disease has a very special geographic distribution in the United States, right?
It's most common in the Northeastern states and also in the upper Midwest.
And yes, we see some Lyme disease in Northern California here, but it tends
to be limited to just certain regions of Northern California. And it's nowhere
near as common as it is in those other parts of the country.
Dr. Kent:
Where the ticks carry the disease, right?
Dr. Sykes:
Exactly right.
Dr. Kent:
And now there's not a Lyme disease vaccine for humans at this point, is that
correct?
Dr. Sykes:
That's correct. The did used to be a Lyme vaccine for people called LYMErix .
And ultimately, because of controversies surrounding adverse effects of
vaccination, the LYMErix vaccine was withdrawn. But there is a new Lyme
vaccine that's currently going through clinical trials. It's looking really positive,
and it's a recombinant vaccine, like I mentioned, which is very similar to the
ones that are available for dogs.
Dr. Kent:
Now, I know I haven't practiced general practice or been on the East Coast in
a long time, but I know when I was, again, in my internship, we used to talk
about how the Lyme vaccine at the time might actually cause worse disease
in animals. So is this still the same vaccine that it was 25 years ago?
Dr. Sykes:
I mean, yes, the vaccine's very similar, but I think that there really wasn't very
good evidence to support that concern. And what's really neat about the Lyme
vaccine is that it actually works in the tick rather than in a dog. So you
vaccinate your dog, it develops antibodies to the Lyme organism, Borrelia
burgdorferi. And then when the tick bites your dog, it ingests those antibodies
and the antibodies work in the tick. and not in the dog.
Dr. Kent:
So it bites the next dog and they can’t infect it.
Dr. Sykes:
And then the organism is not transmitted. So it's actually a really cool vaccine
because it's working in the tick.
Dr. Kent:
It works in a different way. So you're almost vaccinating against the tick. So
what about rattlesnake vaccine? I know that's been controversial too at
points.
Dr. Sykes:
Yeah. So there is a conditionally licensed rattlesnake vaccine. This vaccine
has been a little bit controversial and the studies that have looked at it have
shown, in some case maybe that it is beneficial and other studies not, but the
studies haven't been very large studies. So I don't think we have great studies
out there to be able to make a conclusion.
Dr. Kent:
Yeah, that's right. And you know, rattlesnakes are around us here in Northern
California, but they are not really that widely spread throughout the US. So it'd
be a regional vaccine regardless.
Dr. Sykes:
Definitely like a non-core vaccine. There's also been some concerns about
allergic, bad allergic reactions to that vaccine. It's especially been seen in
animals that got the vaccine and then got bitten by a rattlesnake.
Dr. Kent:
And now I was going to ask you about Bordetella, which is something for
dogs that is often required by kennels if you're going to board the dog. So
what's the effectiveness of that vaccine and should it be given to dogs who
aren't going to necessarily be boarding?
Dr. Sykes:
So Bordetella is again a non-core vaccine. It's really reserved for dogs that
are likely to be exposed to pathogens that cause canine infectious respiratory
disease.
Dr. Kent:
What we call kennel cough.
Dr. Sykes:
Yeah. So it's, definitely dogs that are going into doggy daycare environments
or be you boarded. Dogs that contact other dogs, like in dog parks, potentially
could get infected. But most of these respiratory diseases are going to be
best transmitted in indoor type environments where dogs are congregated.
Dr. Kent:
Yeah. Is Bordetella the only agent that causes Kennel cough.
Dr. Sykes:
No, there's actually at least 17 different bugs that could cause.
Dr. Kent:
So it's not necessarily going to be fully protective either, but it's the portion we
can vaccinate for, right? For, yeah. Not the number four, but what we can
vaccinate for.
Dr. Sykes:
Yeah, there's lots of different viruses and bacteria that can cause that
disease.
Dr. Kent:
And I know I'm making this a laundry list, but I'm I think it's pretty interesting to
go through these, so I hope you don't mind. What about canine influenza?
Dr. Sykes:
Yeah, so canine influenza, there's two different types of canine influenza that
we have vaccines for. One is the H3N8 type, and one is the H3N2 type.
Dr. Kent:
So those are just designations for the type of influenza or flu. Just naming
them, right?
Dr. Sykes:
Yeah, just like we've been talking about H5N1 viruses circulating. We don't
have an H5N1 vaccine, but these vaccines for influenza are subtype specific.
So they are only going to protect against that subtype, which is why we've
had these two different vaccines for dogs. The H3N8 virus, though, which
emerged in the early 2000s and actually jumped from horses to dogs, was
mostly a problem in shelters. And now it's believed that that's extinct in the
United States. So we really probably don't need vaccines for H3N8 anymore.
But the H3N2 virus keeps getting brought back into the United States from
dogs in Asia, especially Korea and China. And we keep getting
reintroductions of that virus, which then causes outbreaks. again, oftentimes
in shelters, but sometimes it can spread to the community.
Dr. Kent:
So is that, that's why it's not a core vaccine, because it's not a pandemic or
epidemic in a sense, it's just sporadic infections in the US. Is it serious
enough that you should consider getting your dog vaccinated if you're, let's
say, in an area with, you know, a lot of dogs? et cetera.
Dr. Sykes:
I mean, I think if your dog mingles with a lot of other dogs, again, indoor
environments is going to be the most common way, then there's a reason to
vaccinate. So usually dogs that are getting Bordetella should also get H3N2.
Dr. Kent:
There's also some non-core vaccines for cats. And we actually are having Dr.
Terza Brostoff on to talk about FIP and we'll be talking about FIP vaccines on
a different episode, but maybe you could run through some of the non-core
vaccine for cats and how effective they are and which cats might be best,
vaccinated with them.
Dr. Sykes:
So first of all, I'll talk about FeLV and FeLV for cats older than a year of age is
a non-core vaccine. The thing about FeLV is when cats get older, when they
get to adult age, their own immune system protects them well from that viral
infection. So it's mostly going to be cats that are really at risk of exposure to
the virus, especially cats that go outdoors and could encounter other cats that
might be shedding at FeLV, because that FeLV can be transmitted through
biting as well. So non-core for cats older than a year of age, but because we
really often don't know what people are going to do with kittens, it's core for
cats under a year of age.
Dr. Kent:
Yeah, and then let's just jump to FIV.
Dr. Sykes:
Yeah, so there is no vaccine available for FIV anymore in this country?
Dr. Kent:
Just like the HIV there isn’t.
Dr. Sykes:
Yeah, and there used to be one here, actually, it was discontinued about
seven or eight years ago now. And one of the problems with that vaccine, in
addition to it not working very well for all strains of FIV, It also interfered with
diagnostic testing for infection. And we still have some cats that were
vaccinated seven years ago that have antibodies from vaccination that test
positive for the disease and we still are struggling with that even now. So
there's no FIV vaccination in the US. There is in other countries like Australia.
Dr. Kent:
Yeah, And are there other vaccines I'm missing for cats? I think there's like for
There are a few others, maybe you could touch on those.
Dr. Sykes:
Yeah, so we also have a Bordetella vaccine for cats. And we also have a
chlamydia vaccine for cats. And chlamydia causes conjunctivitis, runny eyes,
and sometimes sneezing in cats. It's a respiratory pathogen. And those
Bordetella and chlamydia vaccines, mostly probably in young cats and
catteries, so typically reserved for those cats. And then we've had a
somewhat controversial FIP vaccine, which I think you're probably going to
talk about with Dr. Brostoff.
Dr. Kent:
Yes.
Dr. Sykes:
Our current FIP vaccines are not very effective.
Dr. Kent:
Not effective. Problematic, yeah.
Dr. Sykes:
One of the other vaccines that's really important and that has recently had a
change in recommendations is the lepto vaccine for dogs.
Dr. Kent:
Actually, I meant to ask you about that because that's something that I know
changed over the years.
Dr. Sykes:
Yeah.
Dr. Kent:
And so lepto or leptospirosis, that's a bacteria that can cause kidney
infections, right?
Dr. Sykes:
That's right. It's A bacterial infection. It's transmitted in urine and often wildlife
or domestic animal reservoir hosts like cattle and sheep and horses can shed
this virus, this bacteria ,in their urine. And then that can contaminate water
sources and dogs can get infected through exposure to those water sources
or through eating rodents. And actually rodents are the most important
reservoir hosts for lepto, like, there's a one in three chance that a brown rat
that you see is shedding lepto. Yeah, really common.
Dr. Kent:
Which is also a public health concern, right? I mean, because people are
susceptible to this bacteria also.
Dr. Sykes:
People can get lepto and it's become a big issue in big cities where there's
been rodent overpopulations recently.
Dr. Kent:
Because most of the time viruses don't jump between species easily, but
bacteria is bacteria and infects everyone. So like rabies is kind of the
exception, right? Where rabies infects all mammals and it's one virus. But
leptospirosis really affects any mammal.
Dr. Sykes:
Any mammal, even people. And actually any mammal can just look perfectly
healthy and be shedding lepto in its urine, including people.
Dr. Kent:
And sometimes you're clinical for it and sometimes you're not. Let's say you
are infected and you're susceptible to this infection. What's the consequence
of it being affected?
Dr. Sykes:
Yeah, so when it causes disease, like you mentioned, it causes severe kidney
disease and also liver problems, but any organ in the body can be affected. It
can cause lung problems, gastrointestinal problems, even involve the brain.
So it's a multi-systemic disease. it can be fatal if not treated aggressively.
Dr. Kent:
So now there's different forms of leptospirosis or serovars, I think they're
called, right? So how good is the vaccine at protecting dogs, cats from... from
this disease.
Dr. Sykes:
So these different serovars all have different outer coatings and the vaccines
only protect against the seravar that they contain. So our lepto vaccines for
dogs have four different serovars in them. So to protect against at least those
four different seravars.
Dr. Kent:
And are those the most common serovars out in the environment?
Dr. Sykes:
We actually don't know, but we do know that the vaccines stop dogs from
getting disease because dogs that are vaccinated for lepto don't get sick. And
so we've actually been studying a really interesting outbreak of lepto in
Southern California that involved over 200 dogs in the West Los Angeles
area. And so people got to know about this outbreak, which was connected to
a couple of doggy daycares in the area. And they were actually going to their
vets and saying that they'd heard about this outbreak and they wanted their
dogs to be vaccinated for Lepto. But because Lepto wasn't a core vaccine
and the practitioners in that region were not vaccinating for Lepto, they didn't
even have the vaccines in stock.
Dr. Kent
Wow.
Dr. Sykes:
And so they started vaccinating because of owner demand, because they
learned about this outbreak and were worried about their pets. And now Lepto
is recommended as a core vaccine. So since that outbreak occurred, the
recommendations have changed from non-core to core. So every dog, every
year, lepto.
Dr. Kent:
And how effective is it? Like you said, it will stop disease.
Dr. Sykes:
Yeah, and like I said, like we have not seen lepto, basically not diagnosed
lepto in dogs that have been fully vaccinated for lepto. All the dogs that we
diagnose here at UC Davis have not received lepto vaccines.
Dr. Kent:
You brought up another point, which I'm just going to shift our conversation a
little bit. You said every dog lepto vaccine every year. So now the question of
how often do we vaccinate? Should all these vaccines be given yearly? How
do you determine how often a booster is needed? You know, because there's
concerns about over vaccinating or vaccinating too often.
Dr. Sykes:
Yes. So this is a really good question. And for these bacterial vaccines, the
ones that are, that use killed vaccines or recombinant vaccines, where you.
Dr. Kent:
So Bordetella is bacterial or viral.
Dr. Sykes:
So Bordetella is a bacterial.
Dr. Kent:
Bacterial. So that's a yearly one.
Dr. Sykes:
Yes, although it's also a respiratory vaccine, and so the respiratory pathogens
usually need yearly vaccination.
Dr. Kent:
And then lepto is a killed bacterial, so we need that yearly.
Dr. Sykes:
Yes.
Dr. Kent:
And what else?
Dr. Sykes:
So Lyme would be another example that's a recombinant or killed vaccine
that has to be given yearly as well.
Dr. Kent:
Okay.
Dr. Sykes:
But now we have a core vaccine that's an annual vaccine, whereas in the
past, our modified live viral vaccines, our distempo Pavo vaccines, herpes,
calici and cats, we were giving every three years.
Dr. Kent:
Yeah, and even rabies is every three years. After the first booster. Yeah.
Dr. Sykes:
So that's a major shift, right? Because for dogs that were just getting core
vaccines in the past, they were coming in every three years for vaccination.
But now because lepto is core, all of those dogs are coming in yearly to get
the lepto vaccine.
Dr. Kent:
That's a big shift. That's a big shift. And so do we still need to do every three
years, let's say for the parvo and distemper and parainfluenza, those cores,
does the protection only last three years?
Dr. Sykes:
Yeah, so for parvo and distemper and adenovirus, the three organisms that
are core in dog vaccines, really those vaccines are going to probably provide
lifelong vaccination once the puppy series has been completed, so long as
you got that last vaccine at the right time, probably it's going to be lifelong
immunity. The recommendation still is every three years, the vaccines are
really safe and unlikely to cause side effects. So it's felt that three years is
appropriate at this time. But I think in this era of vaccine hesitancy, we are
starting to think about some of those vaccines like parvo and panleukopenia
and whether those ones which have really strong long duration of immunity,
do they really need to be given every three years? Still the recommendations
from AAHA and WSAVA is that they'd be given every three years.
Dr. Kent:
And those are some of the main veterinary groups that look at this. Yeah. So
is there other ways that you can tell if you're still protected? You can run
some blood tests for that.
Dr. Sykes:
Yeah, so there are tests that are available to look for antibodies, but if you
don't have antibodies, it doesn't mean that you're not protected. And so I think
also these vaccines have become so safe in recent years with improvements
in vaccine technology that there's such a low risk of having any sort of side
effects from them ,that it's better to vaccinate.
Dr. Kent:
So now I really wanted, I want to take this conversation in two directions
based on what you said. Now I can't decide which to do first, so I'll let you
choose. I want to talk about vaccine hesitancy, but I also want to talk about
the safety of vaccines. So maybe let's talk about safety of vaccines first. I'm
going to take that from you, sorry. And then we'll talk about vaccine hesitancy,
because that's something that's come up more and more. So what are the
risks of an allergic reaction to a vaccine?
Dr. Sykes:
Yeah, the risk of any sort of allergic reaction is extremely low, like less than
0.5%. Maybe even less than 0.1% for some vaccines. But the risk is not even.
Like there are some animals that are more likely to have reactions than
others. And remember that a vaccine is designed to produce an immune
response.
Dr. Kent:
Yes.
Dr. Sykes:
It's designed to cause inflammation. And so it's normal to have a little bit of a
fever, you know, and pain at an injection site, just like we all do when we get
vaccinated. A vaccine is supposed to produce an immune response. So we've
kind of got this balance between wanting to create inflammation and immunity
and wanting to minimize the side effects of those. Most reactions in dogs and
cats are going to be soreness at the vaccination site or sometimes just a little
nodule, local reaction, bump, at the vaccination site. Really rare are these sort
of anaphylactic type reactions that people worry about where animals can get,
you know, swollen faces or they can collapse and need emergency treatment.
Dr. Kent:
And that was more common. decades ago, right? With some of the
formulation of the vaccine. So that's, do you think some of that's holdover
from old knowledge?
Dr. Sykes:
Yeah, I mean, we still, we still see them. I still talk to practitioners on a regular
basis who have seen allergic anaphylactic type reactions. So they're not, you
know, completely gone, but they're certainly less frequent now than they were
decades ago.
Dr. Kent:
And they're treatable, right?
Dr. Sykes:
Yeah.
Dr. Kent:
So What about autoimmune disease? Because I've heard people talking
about that too. the concern that over vaccinating or repeated boosters can
cause autoimmune disease in dogs.
Dr. Sykes:
Yeah, there's actually been quite a lot of studies looking at this and no link
between vaccination and autoimmune disease. We have not found a
connection, proven connection, between vaccines in dogs and cats and
autoimmune disease. However, for dogs and cats that have been diagnosed
with autoimmune disease, which is more common in dogs and in cats, so cats
rarely get autoimmune diseases. I say cats don't like to self-destruct, worse
dogs self-destruct a lot more often. So for those dogs that have, you know,
had autoimmune hemolytic anemia or autoimmune joint disease, If those
animals have been controlled with the drug therapy that they're in remission
and their signs are being controlled, I think it is possible for a vaccine to then
sort of disrupt that balance and they can.
Dr. Kent:
Re-stimulate the immune system, which may include stimulating the immune
system against your own body.
Dr. Sykes:
Yeah
Dr. Kent:
So that's something that you would talk to your vet about, the benefits and
risks and maybe consider holding off on the vaccines where possible. So for
cats though, there is a real risk. We see injection site sarcomas, being an
oncologist, I still see those, though much less frequently than we used to. So
the risk is very low. I've seen numbers saying anywhere 1 in 10,000, 1 in
50,000. No one really knows how commonly they occur, but they do. Even
with the new reformulated vaccines, We still see them on occasion. So how
do you balance the risk for infectious disease versus that's a true potential
side effect of a vaccine?
Dr. Sykes:
Yeah, you know, I think that the risk of injection site sarcomas is really a lot
lower than it used to be.
Dr. Kent:
I agree with that, but it's still there, but it's lower.
Dr. Sykes:
I don't know. I think that, yes, it's a risk, although extremely low. And I think
that these infectious diseases like panleukopenia are really severe. Feline
leukemia is a horrible disease. We see it all the time.
Dr. Kent:
I mean, both of those could be fatal. And panleuk is almost always fatal,
right?
Dr. Sykes:
Yep. And calici and herpes are a really big problem in the cat population.
They cause bad respiratory diseases. So I think the risks of injection site
sarcomas are outweighed by the severity and frequency of these infectious
diseases.
Dr. Kent:
So now I'm, this may be a little bit of a loaded question. I'm not trying to bait
you or maybe I am, but what about the risk of autism in pets after
vaccination? I've heard this is a concern that's been raised.
Dr. Sykes:
Yeah. So can I actually just back up a little bit on the injection sites?
Dr. Kent:
Oh yeah, please, And then you can answer that question.
Dr. Sykes:
So one other thing that I have to say about injection sarcomas is that owner
awareness of this issue is very important.
Dr. Kent:
Yeah.
Dr. Sykes:
And so the reason for that is that then owners can be monitoring injection
sites, not just vaccines, but other injections for any little lump that appears at
the site and early diagnosis of injection is going to lead to much better
outcomes than if they're left.
Dr. Kent:
Definitely, important. So if you see a persistent lump at the site of an injection,
you need to go in and have it checked is what we tell people. And we want to
make sure because it could be a fairly small surgery if you catch it very early
as opposed to needing surgery, radiation, and chemotherapy if it goes later
and we may not be able to control it. So definitely thank you for bringing that
up.
So what about the autism question?
Dr. Sykes:
Autism, and I wasn't trying to skip that one.
Dr. Kent:
Maybe you should.
Dr. Sykes:
But yes, I mean, there has actually been some studies that suggest that some
people might believe that vaccines in pets can cause autism, but dogs and
cats don't get autism. So there's been no connection between vaccination and
actually any sort of cognitive problem in dogs or cats. One of the problems
with vaccination is because pets are vaccinated quite frequently, like every
year, and especially in young dogs where they're getting vaccinated.
Dr. Kent:
Multiple vaccines, yeah.
Dr. Sykes:
It's difficult to separate vaccination from disease that might just be occurring
anyway, right? So your pet could get a vaccine because it's being vaccinated
every single year. And then a few months later, it could develop diabetes or
some other condition. And you might be tempted to say that the vaccine
caused that when it just was just a coincidence. So it's sometimes difficult to
disconnect the vaccination for a problem that occurs after vaccination. And
yes, there's been concerns about autism and diabetes and other things, but
there's absolutely no proven link to any of those problems.
Dr. Kent:
So I wanted to just quickly ask also is, should a pet get multiple vaccines at
the same visit or does that make them less safe or is there more risk with
that?
Dr. Sykes:
Yeah, and actually it's very common for vets in practice to try to spread out
vaccine components to try to reduce the risk of having a reaction. So spread it
out in time, in other words, rather than on a pet's body.
Dr. Kent:
Yes.
Dr. Sykes:
But really we recommend that now with the vaccines are so much safer than
they used to be, it's better to use the opportunity to vaccinate your pet and
give multiple vaccines at the same time. Using combination vaccines is
recommended, just like they are used in human medicine. The problem with
spacing them out is if you give vaccines too close together, the immune
response to one vaccine can interfere with the immune response to the next
vaccine. So when vaccines are spaced out, like for example, I'll give one
vaccine this week and another vaccine next week, then you might not get an
immune response to the second vaccine.
Dr. Kent:
Because your body's already busy in a sense, fighting off this non-existent
infection from the first vaccine.
Dr. Sykes:
Exactly.
Dr. Kent:
So I saw this, I tried to do a little research before talking with you, so I don't
sound entirely stupid, but I saw this 2023 study that was published in the
journal Vaccine that says about 45% of dog owners now think vaccines are
unsafe. 20% think they're not effective and 30% don't think they're necessary,
which I was kind of shocked when I read this. And I'm sure you've heard this,
but what are your thoughts? What do you think is behind this? Why have we
lost confidence in a large portion of the pet owning population?
Dr. Sykes:
Yeah, so I think first of all, just got to be a little bit careful with some of the
studies. They have different populations that are being surveyed and so there
may be some biases and, response biases in that are choosing to do the
survey because I am concerned about vaccination. Therefore, it's not
representative of everybody.
Dr. Kent:
Of all of America.
Dr. Sykes:
Yeah, that's right. And we also know from other studies that people really,
they have a lot of confidence in veterinarians' advice. And when veterinarians
make recommendations surrounding vaccination, you know, people do tend
to believe them and they're, They are very, veterinarians can be very helpful
in choosing vaccine protocols. So I think that's the caution. But yes, there has
been concern about vaccine hesitancy, especially along with the vaccine
hesitancy for human vaccination and some evidence of spillover into pet
owners.
Dr. Kent:
Into veterinary medicine, it is happening as well. And What's the danger to our
pets for that, to our dogs, to cats? is this a real problem? I know we hear
about, measles outbreaks in humans now. And does this bode poorly for us in
the veterinary world?
Dr. Sykes:
Yeah, I mean, it's not good. And I think that, I think first of all, rabies is a
public health issue. makes vaccination of pets essential. And of course, it's
required by law. And for cats in many states, it's required by law as well. So
we have the legal need for vaccination. And many people don't know that
rabies vaccines are required by law for cats in many states.
Dr. Kent:
Yeah, and actually the penalty for not vaccinated, depending on your
particular county, if your dog or cat bites someone and they're not vaccinated,
it could be quite severe, can either lead to long quarantines or even in
euthanasia, forced euthanasia. So that's obviously very important from public
health perspective as well.
Dr. Sykes:
And then for the organisms like parvo that don't cause human disease, I
actually know people who had vaccine hesitancy and didn't vaccinate their
puppies for parvo and their dogs got parvo and died. So.
Dr. Kent:
Gosh, that's terrible.
Dr. Sykes:
You know, it's a bad disease and it's really common.
Dr. Kent:
Well, and it's expensive. Like even if you have pet insurance, it can be
thousands, many, thousands to get a dog through parvo. And not easy. So I
don't want to end on kind of a sour note, but if you could make a vaccine
today for an infectious disease that we don't currently have, an effective
vaccine, what disease would it be for? And why?
Dr. Sykes:
Yeah, so for cats, I would say FIP. Gosh, yes. You know, even though we
have antivirals now that are very effective, vaccines that work for FIP are
really needed.
Dr. Kent:
And our team is working on one, and we'll be talking more about that with Dr.
Brostoff.
Dr. Sykes:
Awesome. And then for dogs, a couple of organisms. One's Ehrlichia canis,
which is a tick transmutative bug that is actually one of the most common
infectious diseases of dogs worldwide next to parvo. And, a challenging
organism to develop vaccines for, but that would definitely be something that,
for dogs can be very hard to treat in some cases. I would say also globally,
leishmania, which is a protozoal disease, that's also a public health problem.
And then for fungal diseases, the one that I study, which is Valley Fever.
There's vaccines in development right now for that, which would be the first
fungal disease vaccine ever available.
Dr. Kent:
Yeah, I hadn't heard of that. That's pretty cool. So what is the future of
vaccines? What do you... see where we're headed? What do you think our
future holds for us?
Dr. Sykes:
Yeah, you know, I think we'll see, we'll continue to see better and safer
vaccines and new vaccines for like some of those organisms I was talking
about. I think the future looks, looks bright for vaccines as we have new
vaccine technology. And as bad as the pandemic was, one of the best things
that came out of it was just innovation in vaccine design. So I'm hopeful that
we'll also have lepto vaccines that protect against all strains.
Dr. Kent:
All serovars, all strains, yes.
Dr. Sykes:
I think that will happen too. So we've got lots of optimism.
Dr. Kent:
I like that. Being an oncologist, I like to say that I'm an optimist by nature. And
so Dr. Sykes, thank you for taking the time out to speak with me and for our
listeners. From the Vetrospective, it's an honor having you on.
Dr. Sykes:
Thanks for the opportunity to talk to you about vaccines.
Dr. Kent:
The Vetrospective, as with life, takes a village. I want to thank those who
suggested I start this project and everyone who has encouraged and
supported me along the way. Particularly, I want to thank our producer and
director, Danae Blythe-Unti, Nancy Bei, who is our program coordinator, our
sound mixer, Andy Cowitt, and theme music was composed and produced by
Tim Gahagan. Thank you all, and we'll see you next time.