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The Pet Doctor, Your Pet Health Matters on PetLifeRadio.comBernadine D. Cruz, DVM, host of The Pet Doctor

Bernadine D. Cruz, DVM
Veterinary Media Consultant

Vaccines – What are They, How do They Work,
and Which Ones are Needed by Your Pet?”

Dr. Elizabeth Settles

Dr. Elizabeth Settles

Advances in the study of infectious diseases and immunology have radically changed vaccine protocols for pets. But what are vaccines? What are the up and downsides of exposing our pet’s immune systems to these agents of disease?

Which vaccines will provide optimal health for your pet will best be decided by your pet’s lifestyle, where it lives in the United States and by your veterinarian.

Questions or comments? Email Dr. Cruz at:


Dr. Bernadine Cruz: You’re listening to Pet Life Radio The Pet Doctor and I’m Dr. Bernadine Cruz. With the holidays you may think the best thing to do since you are listening to a pet doctor is to get somebody in the family a pet. Believe me this is a great idea but not now and you may find this person really doesn’t want a pet, it’s you who wants a pet. When you give a pet it’s always for life, their life. So if you want to have that Normal Rockwell moment under the Christmas tree when somebody opens up the package and sees that new little puppy or kitten better, idea than having a live one? Go ahead and wrap up a stuff pet then once all the craziness of the holidays have settled down then in a calm manner you can go out after doing your research as to what’s going to be the best pet for you and the family. Go out and really make it part of the family.

Talking about parts of the family that you already have, the dog or cat that needs its vaccines, we all need our vaccines even as people but what exactly are going to be the appropriate vaccines to give? What’s the new protocols that are out there? What is a vaccine and how does it really help? Are there any upsides, downsides to doing it?

Today we’re going to be talking to Dr. Elizabeth Settles. She works for Pfizer Animal Health. She has a degree in Veterinary Medicine but with special dual residency in cardiology and internal medicine. She is board certified in internal medicine. This is a woman who loves school because she also has a jurist doctorate, she is a lawyer and besides spending time in school she also has many hobbies such as scuba diving, hiking, cooking, traveling and playing with dogs and cats, her own.

Dr. Settles thank you so much for being with us. We’re going to take a short little break and we’ll be right back.


Dr. Bernadine Cruz: So vaccines, your veterinary says your dog and cat needs them but why exactly Dr. Settles? What is a vaccine?

Dr. Elizabeth Settles: Well, Dr. Cruz that’s an interesting question and it can be a very complicated answer but for the sake of time, what I think about a vaccine thing is really a way to modulate something that occurs naturally in the body. So what a vaccine does is take what is called a pathogen which is either a bacteria or a virus or even a parasite and makes it a weakened state or even a killed pathogen and puts it in the body in a small amount to get the body to provide itself its immunity. So if it was really challenged with a live deadly bug like that, that it could fight back, it can have antibodies produced that would kill those off.

Dr. Bernadine Cruz: So it’s safe. I know it’s a concern the people have and they go but why don’t you just give enough vaccine for this pet because you have this 5 lb Poodlelet or the 100 lb Great Dane and you give the same amount of vaccine, how can that be?

Dr. Elizabeth Settles: Well at this point in time, the research has assumed that we need to give the same amount and it looks like that really doesn’t—it’s something people look at as, “Oh is it wrong to do? Or right to do?” Because we get good immunity in both the big dog and little dog so the research really has been around what gives the best immunity and it’s not like there is a certain amount of immune system by the pound that we’ve ever seen in any research that’s been done. We don’t have any research evidence that there should be a different dose.

Dr. Bernadine Cruz: And we also know that puppies for instance and kittens will get a series of vaccines just like a human child and the rational for that—because isn’t there bitch the mother dog or queen the mother cat giving all the protection that this little puppy or kitten needs?

Dr. Elizabeth Settles: There are a couple of issues there. One is that puppies and kittens get colostrums that first milk that has the antibodies from the queen, the cat mother or the bitch, the dog mother and in that particular situation they’re getting the antibodies and they are protected for a time. But it really depends on how much colostrums they get and what environment situation they’re in—if they’re in a warm house, they’re very protected, their immune system might develop more quickly than if they are out in the area where it’s cold and they’re just in a generally weakened state. Maybe they have parasite infection, maybe they’re not getting quite enough to eat.

So its based really on their own little immune system in the individual puppy or kitten and what happens with the maternal antibody—because it’s not always going to hang around in the body—in fact the longest it lasts most of the time is 16 weeks if they get a really good dose of it from the mother.

Dr. Bernadine Cruz: I think one of the things also very interesting too. I’ve seen for instance in Rottweiler dogs where Parvo vaccines or Parvo virus itself, people have heard a fair amount of it—I’m in the Southern California area and we’ve had some areas with recent outbreaks with Parvo vaccine which is an intestinal virus causes vomiting, diarrhea, bloody stool and for some pets it can be a fatal disease that even though you may have had a Rottweiler come in and you vaccinated it with the typical  vaccine schedule, sometimes it seems as though their own immune system just didn’t take so to speak.

Dr. Elizabeth Settles: Right also it’s also seen with Golden Retrievers. Sometimes they’re recommendations to revaccinate those pets six months of age because either their maternal antibody lasted a lot longer for some reason or their own immune system did not mature enough by the normal vaccine protocols we use up to 16 weeks.

Dr. Bernadine Cruz: Talking about vaccines and the immunity and how long it lasts, you know as child you and I were vaccinated for certain diseases and we’ve never had it bolstered and theoretically we’re still protected. Why is it that with our pets, we’re needing to revaccinate them?

Dr. Elizabeth Settles: There’s probably a couple of reasons. Some we just haven’t done testing out far enough to know. How long are they safe? How long are they protected? More research like that has been done in people but also if you think about the different kind of things that we get vaccinated for, for example influenza—so if you go get your flu vaccine, you’re getting that every year. So the flu, that particular virus is one that can mutate so there’s probably a couple of reasons. The vaccines don’t stay the same year after year after year as some of the different viruses mutate, the vaccines have to change a little too. So I think those couple of reasons and then it’s certainly possible that there are differences in immune responses between people and animals.

Dr. Bernadine Cruz: I know people are getting concerned at times with vaccines being given because they’ve heard that some vaccines can have downsides. Some vaccines have been known in rare cases to cause cancer and people just don’t want to take the chance and prefer for instance to have titers done. Take a blood sample and then see what is the strength of the—at least on the paper—the immune response. What’s your feelings about having titers and their relationship to the real world? What a pet is experiencing in his body with regard to immunity?

Dr. Elizabeth Settles: I certainly think vaccines are not something to be taken lightly. A vaccination is a medical procedure and there are certainly by the individual patients, certain risks and benefits. You have to look at things like what environment is the pet in, what’s the lifestyle of the pet when you’re making decisions about how to vaccinate. Your own veterinarian is probably the very best person to have that conversation with for your individual pet.

In general when you’re saying risks versus benefit, there is a lot of controversy about a particular type of cancer seen in cats. Some people believe that the research shows very strongly that there is a vaccine component to that. Other people believe any injection can cause that in a cat but I think in some respects the jury is still out on that.

In general if you are thinking about vaccine reactions those many times are pretty minimal. Those are local, so little bit of pain and swelling at the injection site or they can be just swelling of the face. Sometimes with cats, some vomiting and diarrhea, but you do occasionally see actual anaphylactic shock like people can get if they’re stung by a bee which can leave to death but that’s very uncommon. While there is a risk benefit analysis to be done, I think in most cases the idea of  being protected against a potentially deadly or very debilitating disease which is what we vaccinate against makes it many times much more pro taking the chance for maybe a vaccine reaction than against.

Dr. Bernadine Cruz: I agree with you. Thankfully in my years of practice, I have seen very few animals have a severe reaction. I’ll usually tell a client, “Oh your pet might be a little bit under the weather. A little lethargic for the next 24 to 48 hours. There’s vomiting, diarrhea, hives, let me know about it.” And if a pet has ever had a history of vaccine reaction, it doesn’t mean that they can’t get their vaccines in the future. Many times what I’d do is go ahead and separate vaccines. Only give one at a time. Separate it by several weeks or often time give them a little short acting cortisone antihistamine prior to vaccinating them and it seems to help, just kind of ease that adverse side effect but still get all the positive benefits of getting the vaccine.

In the past few years there’s been some change in the philosophy regarding some core vaccines and the lifestyles you were mentioning a little bit about lifestyle. Would you mind touching on what are some of the core vaccines? For instance if you just have the little indoor poodlelet whose feet never went outside, does that pet still need to be vaccinated?

Dr. Elizabeth Settles: I believe they do. First of all, rabies vaccine has a very significant public health aspect to it and it’s also in almost every city required by law. I think rabies vaccine are kind of a no brainer on should we vaccinate for that? I do believe that you may never intend for your dog to go outside but maybe somebody brings another dog over or for whatever reason your dog does go outside. I do think that it is better to have them protected.

If you are looking at core vaccines, the rabies, and then distemper, adno virus which attacks the liver, parvo virus which is an intestinal disease and para influenza which can be a severe respiratory disease of dogs, are the ones that I think about as being the core vaccines and also being the American Animal Hospital Association has called as core vaccine set.

As far as cats go—and certainly there are a lot of cats that are indoor only but again they still may get out. They can be exposed to other cats and some of these things could be passed potentially through screens if you think about a cat having a lot of upper respiratory problems and is sneezing a lot and maybe they are fighting through a screen. So your cat can be exposed to that in some ways. Again rabies vaccine mostly for public health and those situations but also in many places rabies vaccines are required by law for cats. As far as the others go, many of them you think about the upper respiratory so the feline herpes, the feline calicivirus, and feline parvo virus which is similar to the canine parvo virus and Panleukopenia which is a problem very intense and particularly in shelter situations. So those are for me the feline core vaccines and also the ones recommended as core by the American Association of Feline Practitioners.

Dr. Bernadine Cruz: I totally agree with you. I have indoor kitties and every once in awhile when I’m home, I’ll let them get outside and just get a little exercise and much to my chagrin here is one of my own cats getting into a cat fight with a neighborhood kitty. So I know I need to get them vaccinated and all my clients would say, “Oh my cats are just indoor cats and they’ve never escaped.” Oh well yeah every once in awhile they do get out.

One of the things you touched and I think is very important is about owners trying to administer their own vaccines. There’s so many different internet companies where you can order almost any veterinary product. Your views on owners vaccinating their own pets?

Dr. Elizabeth Settles: As I said vaccination is a medical procedure and there are a number of different things that have to be taken into consideration. Really before a pet gets a vaccine, they need to have a physical exam performed by a veterinarian. If an animal has a high temperature, that’s not an animal that should be vaccinated. The vaccine might not work because of the high temperature, it might become inactivated in the body or it might even stress the animal further because you’re asking the immune system to respond to something while obviously if the temperature is elevated there’s some other problem already that the particular pet is fighting off.

Also it’s one of the situations where you really need somebody to look at the environment the pets are in again. The lifestyle and what’s the overall health of the pet and make a very informed decision because of their medical training a lot of it pet needs a vaccine and which ones that pet needs.

Another aspect that comes in besides the medical procedure part is, vaccines have to be handled in a certain way to maintain their viability so if the vaccine is shipped and it’s too hot or it’s shipped and freezes then that vaccine may not be active at all and you may not be protecting your pet at all.

Dr. Bernadine Cruz: Dr. Settles this has been some interesting information. Hopefully people are realizing that taking your pet into the veterinarian for their twice yearly wellness exam is so much more than just getting vaccinated. There’s a reason why that pet is going in the wellness aspect, determining the lifestyle of your pet and what vaccine are necessary because it is a medical procedure. A medical procedure that will sometimes have adverse side effects but thankfully those instances are very, very rare.

You’re listening to the Pet Doctor on Pet Life Radio. We’ll be right back after these few words.


Dr. Bernadine Cruz: Dr. Settles you’ve been talking about various vaccines that are out there. You’ve mentioned rabies. Now I heard something recently that rabies has been eradicated in the United States. Am I missing something, I thought it was still out there?

Dr. Elizabeth Settles: It’s interesting what happened with that, the Center for Disease Control in Atlanta reported that dog rabies have been eradicated. What they meant by that is that the rabies disease is caused by a type of virus called the [indiscernible] virus and there are different variants of that virus that are out there. There’s a dog, one in a cat and there’s a bat one and there’s various live wildlife ones. Just because the dog variant has been eradicated, that doesn’t mean a dog can’t get cat rabies or bat rabies or some type of wild life rabies. The terminology of the variant term something like dog or cat rabies is the original host but unfortunately those viruses can be passed back and forth between any mammals. So between people and other pets and wildlife.

One of the more alarming things is that there has been an increase in the United States for bat rabies and there have been some humans infected with that and there are some concerns that the current rabies vaccine we have—because there are some of course for people—veterinarians and animal handlers vaccinated with those because of their increased risk for exposure—but even for the pet vaccine if that bat rabies may not be covered by those vaccines and it may be something if it’s really emerging that we’re going to have to address.

Dr. Bernadine Cruz: I live in Southern California and there last year two stories I remember very vividly where number one a child was with a parent in a shoe store and was just looking at boxes of shoes, playing with it and all of sudden let out a scream and you see this little bat fluttering away while it turned out that bat was rabid and the child had exposure.

Another instance where a child found this little bat fluttering around on the ground and took it to school for show and tell. It also had rabies. So it really high lights that people need to be very careful around wild life. If you see an animal behaving atypically, a bat is not going to be down on the ground, some place where you can approach it. There could be a problem I think that’s one of the reasons why I think cats right now are in such high risk because number of one many of the states and city laws do not require that cats be vaccinated for rabies for licensing purposes. But those are the kitties that would be out there saying, “Hey look at that, kind of looks like a bird, let’s go chase it” and had it’s exposure that way. So the bottom line is keep vaccinating your animals.

Are there other diseases that have that zoonotic disease that can go between people and animals that vaccines that help to keep certain diseases under control?

Dr. Elizabeth Settles: One in particular that there has been a resurgence of over the past 10 years is leptospirosis. There’s been a couple of outbreak in the last 10 years. Actually in people in triathalon, one was in British Columbia area. People exposed in water that were in the swimming part of the triathalon and then there is also one outbreak in Illinois a few years ago, in one of those situations. So we are seeing leptospirosis in people in individual outbreaks and there are more reports in dogs. Part of that is people have backed off years ago from vaccinating from leptospirosis because we weren’t seeing much of it and that particular old vaccine, those were very reactive and you had a lot more reaction like the facial swelling and those sort of reactions. They were undesirable and people thought well maybe we’ve gotten rid of lepto and we don’t have to worry about it. Actually what we found in the last 10 years is maybe that’s not so good that now we have a very susceptible population in many areas where they haven’t been vaccinated.

Another factor is as we keep building and pushing out into the wild areas around cities, kind of the urbanization of many areas that have been traditionally all the raccoons and possums live, those types of animals carry leptospirosis. Raccoons in particular, they carry and always wash their food and they’re very cute when their washing their food in your fountain out in your backyard but they also are carrying leptospirosis and exposing you and your family and your pets.

Dr. Bernadine Cruz: What would be the signs that somebody would see with their pet with leptospirosis and besides vaccinating how can they protect themselves?

Dr. Elizabeth Settles: Leptospirosis is a disease that can present a number of different ways. There’s actually over 200 different [indiscernible] variants of leptospirosis out there but only a few we know cause disease in pets. In those situations usually its kidney or liver disease and those can present with a pet that has vomiting and diarrhea. They can present with all of sudden a great increase in thirst and urinating even in the house besides having to go out many times. If they have a form that causes severe liver problems, they can actually get jaundice. Their skin can turn yellow, their eyes can turn yellow and it can be fatal if it’s not treated.

Dr. Bernadine Cruz: And when you see a sign like that, vomiting and diarrhea, you think maybe the pet just got into the leftovers from the holiday meal and that’s what’s causing it where in reality it maybe from the walk that you took with the pet in the wooded areas and got exposure that way. 

You had also mentioned some of the other types of adverse reactions that animals can get with vaccines, the anaphylactic reactions, just of the hives. Can you also touch a little bit more on the cancer causing aspects of vaccines? How much do people really need to be worried about vaccines causing cancer?

Dr. Elizabeth Settles: I personally feel like there’s a lot of answers that we still need to find. One of the things we do know is that the biggest concern is fibrosarcomas in cats and these are tumors that occur anywhere on the cat but usually we see it in between the shoulder blades when we’re thinking they might be associated with the vaccine or an injection because that’s an area where we have commonly over the years given an injection. In fact only one in 10,000 cats will have a fibrosarcoma occur and if the concern is injections in general then—an antibiotic injection or anything—potentially could cause there are some of the research that suggests that.

One of the things that happened a number of years ago and people may have noticed when they go to their veterinarian to have their pet vaccinated that we actually spread the vaccines out. We used to give them in one place between the shoulder blades but now we have certain—when we give them the rabies and the kitty distemper and the feline leukemia the cats can get that.

Dr. Bernadine Cruz: I agree with you. Before it was just so easy to just grab a bit of fur between the shoulder blades, pop the vaccines in there, they’re on their way and life was good. Now I know my practice and other practitioners that I’ve spoken to, that the vaccines are spread in various legs and with the leukemia vaccine by some convention at this point in time, given in the left rear leg.

It sounds terrible sometimes for people to think about this but the fibrosarcoma was such a nasty locally re-invasive type of tumor, once you remove it, it seemed like sometimes even before we remove the sutures from the surgery, the cancer was back. We just kept getting more and more invasive so now finding that the vaccine was given low in the left rear leg. If perchance a cat were to develop a cancer because of this, that leg can be amputated. Yes it was terrible you had a three-legged kitty but you had an alive three-legged kitty.

If somebody is concerned about what vaccines to give to their pet what would be your recommendations?

Dr. Elizabeth Settles: We talked about the core vaccines and I think that’s where you start and all pets really should get those. And then from there it becomes a discussion about what’s occurring in your area. There are certain areas that are seeing a lot more leptospirosis than they had in the past and there are certain areas where things like lyme disease are an issue. That’s the kind of information that your veterinarian has and you can sit down and discuss what are the risks for my particular pet to be exposed because of the area I’m living in.

Dr. Bernadine Cruz: So when in doubt ask your veterinarian. You and your veterinarian as a team can best serve the health issues for your pet, keeping your pet healthy. Keeping it active, keeping it a great member of the family.

We’ve been talking today with Dr. Elizabeth Settles. She is with Pfizer Animal Health. We’ve been talking about vaccines, what they are, how they’re helpful and that yes your pet should be vaccinated. When in doubt what to give, ask your veterinarian. Why is it important? Because it’s your pet. Health matters.

Thank you for listening to Pet Life Radio. I’m Dr. Bernadine Cruz and this is the Pet Doctor.


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