Cat Vaccines


Vaccination protocol update

Subscriber Question: Have been receiving info from different sources that the veterinarian schools are in the process of changing the protocol for vaccinating. All the information I've received states that vaccinations should be less frequent but they don't all give the same agenda. What is the proper protocol? I'm under the impression that adult dogs do not need yearly vaccinations and that rabies vaccines need be given only every three years. Also that in most cases Lepto and corona vaccines are not necessary. I must admit that I have not been giving either of these vaccines to my dogs for several years due to bad reactions in the past. Thank you, Jan

Answer: Jan- At the present time there is no universally accepted vaccination protocol for dogs or cats. Veterinarians are really divided over the best way to vaccinate. These are the main camps: 1) Vets who think that vaccinations should be given every year. Their logic: a) The labels say to do that and following label directions lessens liability. b) There isn't much published information in refereed (scientifically reviewed) journals that refutes the once yearly vaccination schedule. c) It is the way things have always been done and there is an obvious decrease in distemper, parvovirus, etc, so why stop something that is working? d) Bacterial vaccines (leptospirosis, Bordetellosis, possibly Lyme disease) are not noted for long term protection -- they may not even provide a year's protection -- so these vaccines may be necessary yearly or more often if they are necessary in a particular area. 2) Vets who think that vaccines should be extended to every three years. Their logic: a) It is obvious that some dogs react badly to vaccinations, either at the time they are given or several weeks later by experiencing immune mediated hemolytic anemia (IMHA). There is a documented rise in the cases of IMHA for the month following vaccination in dogs but it is a slight rise -- just barely enough to be statistically significant. Therefore, it seems important to give vaccinations only as often as is necessary. b) There isn't enough information to tell how long vaccines really last (see b above) BUT it seems pretty obvious they last longer than one year -- so every three years seems like a reasonable bet. It is likely the vaccines last that long just based on clinical experience alone and it cuts down some on the reactions to extend the interval to every three years. c) The veterinary schools and organizations have settled on every three years as a good compromise between what is known and not known, for the most part, so there is support for this approach in the literature, making it fairly safe from a liability standpoint. d) The duration of immunity provided by vaccinations probably varies from one vaccine to the next, depending on the strain of virus/bacteria used, the adjuvents used in the vaccine and the production methods -- therefore, until each vaccine is tested for duration of action, it will be hard to make blanket judgments about how long vaccine intervals should be. 3) Vets who think that it is OK to go to much longer vaccination intervals based on the available information which is primarily derived from unpublished studies that have been widely publicized at meetings and other information sources, but who believe strongly in the value of vaccination. Their logic: a) This information can be found despite its non-published status. The researchers are respectable within the profession. b) It is highly likely that parvovirus vaccine provides lifelong immunity and that distemper vaccine provides protection for more 5 to 7 years. It is reasonable to assume that other vaccinations for viral illnesses work as well. c) Vaccines can cause harm. Therefore, the individual risk to a particular illness AND of the vaccine should be compared for each individual patient and a vaccine schedule designed to fit the patient's needs. By doing this, the veterinarian is serving the best interest of the patient. With this in mind -- there will always be room for controversy about vaccine intervals if the logic of this argument is persuasive -- but it still could work out to be the best approach for most patients. d) Liability arguments don't seem to have much effect on this group of vets but that might change if pets are accorded a status somewhere between property and humans and things like "pain and suffering" are allowed in law suits concerning pets. Currently, this isn't the case in most states but is being considered in several localities. 4) Vets who think that all vaccines are bad. I have to admit that I can't come up with any good logical reasons for vets to think this way, so it is hard for me to provide the logic that these vets use, unless it is simply that they have experienced some bad reactions and haven't been through a parvovirus, distemper, leptospirosis, etc. epidemic in their practice area. With all this in mind, this is what I do for my canine patients: I stick to a mostly every three year vaccination schedule for the rabies (after the initial one year vaccine) and DA2PP (distemper, parvovirus, adenovirus and parainfluenza) vaccine. I don't use coronavirus vaccine, leptospirosis (but I would as soon as I see enough cases to convince me it was a problem in my area), Lyme disease vaccine (probably would use this if I saw lots of cases but I'm not sure -- fortunately, I haven't had to make this decision) or giardia vaccine. I advise using Bordetella (kennel cough) vaccine on an "as needed basis", basically prior to boarding or for dogs that go to lots of shows or other events where there are other dogs. When a dog reacts badly to the DA2PP combination vaccine and they have had at least the puppy series and one booster, I just don't give it again. I figure the risk to that individual from the vaccine probably exceeds the risk of the diseases during their lifetime (at least where I practice). If there are reactions to the rabies vaccine we pre-treat with antihistamines or corticosteroids and just give the vaccine, because it is required by law and because the risk to the dog of not being vaccinated is high --- not only from rabies but from the public health laws if it bites someone and isn't properly vaccinated. In Virginia, fortunately, 3 year duration vaccines are accepted for rabies protection. As long as the vaccine is being boostered instead of being given for the first time, corticosteroids do not cause significant interference with the production of an immune response to the vaccine. You didn't really ask about cats, but this is how we handle cat vaccinations: We give the kitten series for RCP (rhinotracheitis ( or feline herpes) , calcivirus and panleukopenia (feline distemper)) and rabies at >12 weeks of age. We vaccinate for feline leukemia in kittens, unless the owner is certain that the kitten will be an indoor only cat and there is little chance for contact with other cats who might carry the disease. We don't use any other vaccines at the present time. We booster the vaccinations that seemed necessary at one year of age. At this point we go to an every three year schedule for RCP and rabies but we don't give feline leukemia vaccination to cats again. Our logic is that most studies show that cats have a strong natural resistance to feline leukemia after they are about 18 months old, so vaccination doesn't seem warranted given the risk of vaccine associated sarcoma (cancer) in cats and the low risk of acquiring the infection as an adult. This is probably the most controversial decision we make about vaccinations (stopping the FeLV vaccine). We use the every three year rabies vaccines but it is possible to make a very good case for using PureVax (tm, Merial) rabies vaccine, which is thought to be less likely to cause cancer at vaccine sites. PureVax has to be given yearly as it is only approved for one year use. One thing you have to remember about our vaccine protocol is that we developed it for our area. We live in a very rural community and we don't have dog parks or limited areas that lots of dogs play in --- we have mostly stay at home dogs who interact with a few dogs in their neighborhood. Our cat patients may also be less likely to interact with lots of other cats compared to suburban or urban cats, as well. So we made our vaccine protocol decisions with this situation in mind. Other vets have to make their decisions based on different circumstances that influence their decision making about the risks and benefits of specific vaccines in their practice area. I hope that this was helpful. Mike Richards, DVM 8/6/2003

Vaccination protocols for dog boarding facilities

Question: having waded through a multitude of e papers, I am still at a loss at to vaccination protocol's when taking a dog into a boarding establishment. I operate a very strict policy on no vaccination no boarding. but........ rural vets tend to think people do not need holidays and therefore do not vaccinate dogs against bordotella as a matter of is the dilemma...... just exactly when can we accept dogs for boarding if we require them to have been vaccinated???????????? instantly?, after what period?, or yes you had shots last year and are not fully expired so that is fine???, also....our vet sanction's 9mths for bordetalla...what is the formal reconing, as every vet is different???????????? I would appreciate some continuity in the matter as I loose out on thousands every year because I am bemused!!!!!!!!!.. sorry ...I really need some clarification on this matter, as xmas is coming and I need to ensure all vaccinations are up to date and the information I give is correct..... I will appreciate your reply Dr. .Lovie

Answer: Dr. Lovie- There isn't a consensus of opinion among veterinarians about many of the details of vaccination because much of the information concerning the duration of immunity, effectiveness of vaccines and risk of exposure is either new enough to be unsubstantiated through additional studies or of questionable value beyond the region or scope of the original study. However, there are a few things that are reasonably certain that might benefit someone trying to make decisions about requiring vaccinations for kenneling. The vaccine information is partially obtained from the AVMA's Council on Biologic and Therapeutic Agents (AVMA Journal, Nov. 15, 2002) The first question that you have to think about is whether you are trying to protect yourself against lawsuits, customer dissatisfaction and other problems or whether you are trying to protect the pets being boarded against acquiring diseases at your facility. There is a big difference in these philosophies and thus a big difference in what you might require between them. The initial questions to think about are: What are the things that dogs and cats being kenneled most likely to be exposed to? How do you prevent exposure? If you can't prevent exposure will vaccination protect the pets? Dogs in kennels are most at risk from distemper, parvovirus, bordetellosis and parainfluenza. Rabies is unlikely but the disease is so devastating that all pets should be adequately vaccinated against it in the U.S -- but I don't know if that is the case in New Zealand. Distemper, parainfluenza and bordetella are potentially airborne pathogens. They are probably more commonly spread from dog to dog by allowing contact or by using cleaning rags that are not disinfected adequately between cages. This is a good reason to use paper towels and to throw them out after single use. Parainfluenza vaccination is considered to be of low effectiveness if given by injection and moderate effectiveness when given intranasally. Parainfluenza is usually a mild infection. Distemper vaccination after twelve weeks of age is very effective. Bordetella vaccination is moderately effective by intranasal route and less effective by injection. The duration of protection varies but is lost by 6 months in some dogs and lasts 9 months or more in others. Since this vaccine does not reliably last a year it makes more sense to vaccinate dogs approximately 2 weeks prior to boarding for maximum effectiveness and to repeat the vaccination at 6 month intervals in dogs who are frequently boarded or frequently exposed to other dogs, such as at shows or working events. Parvovirus is shed through the feces and is a durable virus. It is extremely difficult to prevent contamination of premises with high transient dog populations. You should probably assume that all dogs that come to the kennel will be exposed to this virus. Immunity can not be assumed during the puppy vaccination series until approximately 2 weeks after using a high titer vaccine at 12 weeks of age or a lower titer vaccine at 16 weeks of age PLUS a 5 day to 14 day period to allow the immune system to respond. Therefore, there is substantial risk of an infection occurring at your kennel if you board puppies less than 14 weeks of age, regardless of their vaccination status. Once a successful vaccine response occurs it becomes very unlikely that a puppy or dog will ever be ill with parvovirus since there is a strong natural immunity to clinical disease in dogs over 1.5 years of age and the duration of protection from the vaccine is probably > 5yrs. With these things in mind, I would not want to board puppies less than 14 weeks of age or who have not been vaccinated after twelve weeks of age and at least 2 weeks prior to boarding for distemper and parvovirus. If you have to board puppies keep them confined to a cage or run that you can effectively disinfect between boarders. I would consider vaccination against Bordetella optional, personally -- because it is going to be real pain if you insist that it be done correctly and because the efficacy of the vaccine is thought to be moderate. But if I was going to require it I would want dogs to have been vaccinated at least 2 weeks prior to arrival and no more than 6 months prior to boarding. This disease is usually mild but it is a pain for kennels in that it is upsetting to customers. Cats are most susceptible to exposure to herpes virus (rhinotracheitis), calicivirus and panleukopenia (pretty rare in the U.S. currently). Feline coronavirus exposure is possible. Feline immunodeficiency virus and feline leukemia virus exposure shouldn't occur unless you allow boarding cats to intermingle. This is also true for rabies but again risk of exposure to you, your staff and other pets to a disease with the public health risk associated with rabies justifies requiring vaccination in the U.S. (I have no idea what the situation is in New Zealand). Feline herpes virus and calicivirus have long been thought to be airborne pathogens but again are probably most likely to be spread by contact with objects that virus has contaminated. So again, using paper towels to clean cages and throwing them out between pets is often a very effective way to prevent transmission between cats in cages or confined spaces. Washing your hands between cage cleanings is also a good idea. Feline immunodeficiency virus is spread through bite wounds primarily. That shouldn't be happening unless you allow cats to intermingle. Feline leukemia virus requires direct contact and exchange of body fluid to be spread. Feline coronavirus causes mild diarrhea in most instances but when it mutates it causes FIP (a comparatively rare event). However, good sanitation is the only defense and should be practiced. Vaccination against FIP is of questionable value and should not be required by boarding facilities, in my opinion. Vaccination against panleukopenia (feline distemper) is very effective with the same guidelines as vaccination for dogs. It is less common than canine distemper in the U.S. and lot less common than canine parvovirus. Vaccination against feline herpes virus and calcivirus does not prevent infection but does lessen clinical signs significantly and could prevent major headaches for a kennel owner since these diseases are really irritating both to cats and cat owners. It wouldn't matter to me if cats were vaccinated against FIV or FeLV, unless I was going to allow them to have contact with one another. If this was the case I would consider requiring the FeLV vaccination and might consider FIV vaccination ( this is a brand new vaccine in the U.S. and so I am hesitant to endorse it before it has been used a while and any side effects have become apparent). On the differing recommendations among vets for bordetella (and probably the other viruses and bacteria) --- to some extent recommendations are based on who the vet believes. The vaccine manufacturers claim one year duration for many of the bordetella vaccines but other studies don't support this claim. So do you believe the vaccine label or the other studies? I tend to lean towards the results of studies not funded by the company but lots of people are comfortable believing label claims. I hope this helps some. Mike Richards, DVM 12/7/02

PureVax rabies vaccination

Question: Doctor,

Could you please clarify your statement: At the present time, we do not use the PureVax rabies vaccination. This vaccine does not contain adjuvents, the irritating substances that seem to be the cause of cancer at some vaccination sites in cats.

Do you mean you use the PureVax (single or combined?) because it does not contain adjuvants?

I live in France and I would like to know if you can recommend me a rabies vaccine that has no adjuvant for cats.

You also say: We follow the kitten vaccinations with booster vaccinations at one year of age. After that time, we vaccinate every three years. How can I convince my vet to follow this routine. I gave him a copy of what I found on the "1998 Report of the American Association of Feline Practitioners and the Academy of Feline Medicine Advisory Panel on Feline Vaccines" but he is still not convinced (partly because he doesn't read English very well I suppose). His main answer was that the labs have not proven the contrary and we should stick to a one-year booster because these medication have been formultated that way.

I'm wondering if you can help me, either by giving me access to other sources of information that can convince a vet (i.e. a professional vs. a lay person such as myself) and if you can recommend some brands rather than other, and MLV or killed virus vaccines, or recommend to me some. I want to vaccinate my cats against feline parvovirus and feline herpesvirus and feline calicivirus, and rabies. I don't want to give them a vaccine against FeLV because they are exclusively indoor cats. Due to the concern for sarcomas at the vaccination sites and with a personal opinion rather on the holistical side, I wish to vaccinate the least possible.

Thank you very much for your help. Lan

Answer: Lan-

We do not use the PureVax (tm) vaccine, which does not contain an adjuvent, because it is has two problems from our practice standpoint. The first is that it costs about 8 times as much as the other rabies vaccines and because it has to be given once a year. We are pretty sure that most of our clients will not support this option due to these problems, even with a slight decrease in the risk of vaccine sarcomas. We have offered to provide it to clients who have asked, though. This vaccine is made by Merial, which is a company that was founded by the veterinary divisions of Rhone-Merieux and Merck, so it should be available in Europe, although the name may be different.

I do not know how to convince your vet that the guidelines from the Association of Feline Practitioners are valid. This has been an ongoing battleground for American veterinarians, as well. Almost every month, in every journal that has letters to the editor, a veterinarian will write in on one side of this issue or the other. Many veterinarians feel that the present studies, which support longer vaccine intervals, are flawed because they involve a small number of dogs and cats and an even smaller number of "challenge" studies in which the patient is exposed to the virus after a certain number of years. The costs of challenge studies are high and it is not likely that there will be wide scale information from this type of study anytime soon. This issue has a huge economic impact in the veterinary profession and this is part of the issue, even though proponents on both sides deny that motivation in their decision making. Three years ago, vaccines represented almost 28% of our gross revenue (my practice's data). This has dropped to about 15% since we have gone to longer vaccine intervals, which seems like a big loss of income. In reality, we have not actually seen a drop in the gross income, or a significant drop or increase in net income, during this time. This is probably because people have a certain expectation for how much they are going to spend on their pets, so they are willing to do some other things, such as teeth cleaning or small tumor removal, that they might have put off if they were paying for the vaccinations. So our position is that the economics of practice won't be affected much by increasing the vaccine interval and the medical information available supports longer vaccine intervals. This is clearly not the most prevalent position among veterinarians. Some are afraid to give up the vaccine income and some are really not convinced that vaccines will last for three years, despite pretty good evidence that they do. We have been vaccinating cats on an every three year basis for four years now and so far, we do not see in increase in the diseases we vaccinate for.

The best discussions of this issue that I have found are on the Veterinary Information Network (, which is restricted to veterinarians. I know that there are veterinarians from all over the world who subscribe to this service. It is somewhat costly (about $450/yr) but well worth the price. I think your vet would enjoy it and also would be influenced by the opinions of some of the experts who provide their services on VIN, if you could talk him into joining. They do allow a one month free trial period, I think.

The reference that sparked most of this controversy can be found at the PubMed web site by searching on the author's name - Scott FW

Hope this helps.

Mike Richards, DVM 2/19/2001

Annual Rabies vaccinations for older cat

Question: Do you think a 15-year-old cat with CRF and hyper-T should continue to receive an annual rabies vaccine? I am concerned with compromising her immune system in any way. Is the Merial Purevax adjuvant-free rabies vaccine any less invasive? Anne

Answer: Anne-

There are two ways of looking at the rabies vaccination question. The first is the medical point of view. Do I think that giving the rabies vaccine is necessary on a yearly basis in order to prevent a cat from getting rabies? The answer to that question is no. I think that the rabies vaccinations provide a much longer duration of immunity than one year. This is probably just as true for PureVax (tm) as for other vaccinations but it hasn't been proven yet, as far as I know. If it were just a matter of medical reasoning, I doubt that I would vaccinate housecats nearly as often for rabies as we do now. However, the problem is that there is another way to look at rabies vaccination. It is a legal requirement to have cats vaccinated yearly in some states, so in these states there isn't a lot of choice if you wish to remain a law-abiding citizen. If your state allows three year vaccination but you decide to use PureVax because of the decreased likelihood that it will cause vaccine reactions, especially vaccine associated sarcomas (cancer), then you still legally have to give it every year, because that particular vaccine is only approved for one year use. There is a chance that situation will change soon but there is no way to be sure of that at this time. It is unlikely that PureVax would have a major effect on the immune system or cause problems in conjunction with hyperthyroidism or renal failure, so it wouldn't worry me too much to vaccinate, if it was necessary. PureVax is less likely to cause local vaccine reactions and is probably less likely to cause vaccine associated cancers and being a killed vaccine it may cause less immune system response but I am not actually certain of that. It is probably not a highly significant difference. The biggest problem with not vaccinating is that it causes complications when a pet bites someone and its rabies vaccinations are not up to date. This can trigger quarantines and in some cases even death of a pet for examination of its brain, so in this case the legal question trumps the medical one and I do think it is best to follow the rules, which means vaccinating once a year. Mike Richards, DVM 1/8/2001

Vaccines for FIP and Ringworm

Question: As a purebred cat breeder I am continuously trying to stay informed and up-to-date regarding current vaccines that may help my animals live a more healthy and comfortable life. We always vaccinate our kittens with a 4 way vaccine at 8, 10 and 12 weeks of age. We have recently started vaccinating them for FeLuk, although to some controversy, as well.

My question is: Are the new vaccines for FIP and Ringworm effective and safe enough to add to our regimen or should I wait for awhile until all the "kinks" get worked out. I have heard that both these new vaccines are in the 40 to 60% effective range, which could lead to false security on the part of myself as well as my kitten owners.

Thank you for your help. Sphynxlover

Answer: Sphynxlover-

Both the FIP and the ringworm vaccination remain pretty controversial, among veterinarians, at the present time.

The ringworm vaccine (Microsporum canis vaccine) doesn't produce sufficient immunity to make it worthwhile. It may help with suppressing symptoms in a patient that has ringworm but it doesn't produce enough immunity to allow the patient to kill the fungus, so the symptoms usually return. Since an infected cat can spread the fungus to other cats, and to humans, masking the symptoms doesn't strike me as a good idea. So we don't use this vaccine at all in our practice. I don't think that is a particularly controversial stance. I think the great majority of vets don't use this vaccine.

FIP vaccine is also controversial. We don't use it, at all, either. But there are a lot of vets who do use this vaccine. We don't use the vaccine because it doesn't seem to be effective enough to warrant taking any risk with it and because there is a small chance that it could make some cats more likely to develop FIP (this is the reason for controversy over this vaccine).

At the present time it appears that most cases of FIP occur due to mutation of "normal" coronaviruses, which are a common infectious agent. Cats that are infected with intestinal coronaviruses are thus susceptible to FIP, even if they are vaccinated against it, since the vaccine doesn't interfere with virus already present. About 80% of cats in catteries have intestinal coronavirus infection. Coronavirus titers are run by most commercial labs, so it is possible to tell if your cats have been exposed to the virus but it probably isn't worth doing.

There is ongoing research into new ways to vaccinate for FIP, so this situation may change.

There are journal references which advocate vaccination for FIP in cattery situations, with the current vaccine. So there are definitely veterinarians, including some specialists, who do advocate vaccination. The situation is a little confusing and your vet may feel differently than I do about this particular vaccine.

Mike Richards, DVM 1/28/2000

Vaccination risk - killed vaccine vs modified live - Bengal Cats

Q: Hi Dr. Mike! I have a 13 week old SBT Bengal kitten. The breeder who I purchased him from insisted that he be vaccinated with a killed virus vaccine (Felovak?) only. When I mentioned this to my vet, she strongly disagreed with the breeders advice. My veterinarian said that a killed vaccine does not provide adequate protection against diseases. She suggested using a modified live vaccine instead. I have contacted other Bengal breeders on this matter and they all agree that a killed vaccine is the safest route to go with these cats. My question is, does the killed vaccine offer protection against disease and if one type of vaccine was used can you safely switch to the other type for future shots? Also, have you had to deal with the Bengal vaccine controversy in your practice? I just adore my kitten and I want to do what is best and safest for him. Any information you can give me regarding this matter would be greatly appreciated! Thank you so much for your time. Sincerely, Barb T.

P.S. He will be an in-door only cat and I will be getting another kitten in about a month who will also be kept in the house and not allowed outside.

A: Barb- The question of how to vaccinate occurs in all cat and dog breed discussions, not just in Bengals. Vaccination was considered to be a very safe alternative to risking contact with the diseases themselves for a long time. Initially in the use of vaccines this was very true. The risk of feline distemper (panleukopenia), feline leukemia, etc. was fairly high in cat populations and the style of care (more outside cats vs. more inside cats) was conducive to disease spread.

The first veterinarians to have access to vaccines felt that the benefits FAR outweighed any risks. They were probably right. Gradually as the dependence on vaccination increased veterinarians developed the mindset of ignoring the risks all together and promoting vaccine administration as nearly completely safe. It was hard to ignore the occasional anaphylactic shock reaction but otherwise vaccine risk was pretty much ignored.

As vaccinations began to be used pretty much indiscriminately, problems surfaced. Modified live vaccines occasionally caused disease. It was noted that there were sometimes delayed reactions to vaccination and certain conditions, such as hypertrophic osteodystrophy began to be seen as an occasional side effect of vaccine administration. The ideal solution to these problems appeared to be the use of killed vaccines. A dead virus could cause no harm, right?

The difficulty with this approach is the the body pretty much ignores dead viruses, too. So special compounds, known as adjuvents, have to added to killed vaccines. These adjuvents are designed to irritate the immune system and cause a reaction in which antibodies are formed. I believed, as did many veterinarians, that good killed vaccines would be much safer. Unfortunately, this has not been true as time went on. At present, there is evidence of a link between the use of killed vaccines and fibrosarcoma (a form of cancer) in cats. Since killed vaccines do not produce as strong an immune response in most instances, even with adjuvents, they have to be boostered more frequently and there is an increased chance of reaction to them due to this. Fibrosarcoma is a serious risk and it has caused many veterinarians, including me, to rethink the value of killed vaccines.

There is another class of vaccines coming into the market now. These are the recombinant gene technology vaccines. It is possible to change benign viruses so that they produce elements of the disease viruses the body can recognize and react to. This gives the best of both worlds -- a real virus is used so that it replicates and stimulates the immune system. The virus is known to be harmless but it produces proteins that the body remembers and allows it to identify disease causing viruses by. When the disease causing virus is encountered later, the body is ready to defend itself against it. Right now, the Meriel vaccine Recombitek for canine distemper is the only vaccine on the market made with this process that I am aware of but soon there will be others. Will these finally be the virtually safe vaccines we are looking for? Time will tell, but they look good.

In the present circumstances the best thing to do is to assess the risk of disease for an individual cat against the risk of vaccination and to make decisions based on that. I consider killed vaccines to be significant enough risk that I will not use them currently, except for rabies vaccine which only comes in the killed virus forms. I recognize the risks associated with modified live vaccines but do not believe that there is evidence to support the long term immune system problems touted as the major risk by some people. Even so, I think that vaccines should be used cautiously and with a lot of thought about what the real risks are to a particular cat.

Mike Richards, DVM

Do I Really Need to Vaccinate My Pet

The short answer is YES - for many vaccinations and MAYBE NOT for others.

For more details, keep on reading!

The Vaccines


In all states, rabies vaccinations are required by law. The first rabies vaccination is good for one year. In many states subsequent vaccinations are good for three years. In other states, they are only valid for one year by law. Please check with your vet to determine the legal requirements in your state. Vaccinating your pet for rabies may literally save its life for two reasons. Rabies is a threat in many areas and it is a horrible disease. In addition, an unvaccinated pet who bites a human being, even by accident, is subject to long quarantine periods or even death for the purpose of testing for rabies infection. Don't risk your pet's life. Get its rabies vaccination.

There are a number of vaccinations available for cats. The need for them depends on the risk of exposure for your cat. An indoor cat, kept alone or with only one other cat, is pretty unlikely to be exposed to diseases which require contact with other cats. An outdoor cat who roams the yard freely is probably interacting with other cats whether you see them or not. This cat needs to be protected against more diseases, since the risk is much higher. (Distemper

Panleukopenia (Distemper):

Panleukopenia is the cat disease most often referred to as "distemper" in this species. It is a deadly disease. Fortunately, it is not a very common disease as vaccination against it appears to be very successful. Kittens require a series of vaccinations every 3 to 4 weeks from the time vaccinations start until they are approximately 16 weeks old. Since this virus does not always require direct contact for transmission, it is generally included in the series of recommended vaccinations for all cats. Rhinotracheitis:

Rhinotracheitis is caused by a herpes virus. It causes respiratory disease in its acute phase. Chronically, it can be the cause of persistent eye irritation and corneal disease (cloudiness or blood vessel infiltration in the clear part of the eye). Due to the potentially chronic nature of this disease it is also usually recommended for most cats. It appears that the protection against this disease from vaccination is of relatively short duration and yearly boosters seem to be a necessity.


This virus also causes respiratory disease in its acute phase. It also can become chronic. Affected cats may have persistent gum disease or chronically recurring upper respiratory disease. This virus is also recommended for most cats. Feline leukemia:

Feline leukemia virus (FeLV) requires direct contact with an infected cat in order to spread. For this reason, it may not be necessary for cats confined to the home. Some veterinarians feel that the risk of a cat getting loose from the house justifies using this vaccine, anyway. We think this might be true if vaccines were risk free. We don't think they are, though. This vaccine should be administered to cats who live full-time or part-time outdoors. We recommend that cats who live indoors exclusively not be vaccinated. Feline Infectious Peritonitis:

We think that there are very few instances in which the use of this vaccine is warranted. If you have a large number of cats, it might be worthwhile. Otherwise, skip it. There is a great deal of question about how well this vaccine works. Chlamydiosis:

This is a bacterial respiratory disease of cats. It is generally believed that vaccine combination injections which include this bacterin are the most likely to cause reactions. Still, there are times when this disease is so prevalent in a group of cats or in a neighborhood that its use is warranted. Discuss this one with your vet.

Some veterinarians recommend the use of "nosodes" instead of vaccinations. I have seen no scientifically valid evidence at all that nosodes effectively protect against disease.

It is likely that as time goes on we will discover that some of the vaccinations we use last much longer than a year. There is already evidence to support this conclusion. This does not appear to be true of all vaccines. The current vaccine combinations will probably continue to be the most economically viable way to ensure that pets get the vaccinations they need for the near future but this is an area of veterinary medicine in which traditional recommendations are being challenged and changes may be coming.

Even if revaccination intervals do become longer, please continue to have your pet examined at least yearly by your vet. There are a number of problems for which early detection can be very beneficial for your pet!

Mike Richards, DVM

Vaccination at home

Q: I have 12 cats, all rescues, which live indoors but play in the back yard. They cannot get out of the yard--I've rigged bird netting above the 6-foot privacy fence--but stray cats have been getting in! So, I need to keep them vaccinated. It's just a bit expensive to get vaccinations for 12 cats at the vet's office. I love my vet and trust him, but I just can't afford to keep up with the vaccines. I have been considering vaccinating them at home, but in my research I found out about the sarcoma problem, which concerns me greatly. When I asked my vet, he said "it never occurs with intramuscular vaccinations, just those under the skin". Is this your experience? And if so, is it safe for me to give my cats intramuscular vaccines, even when a vaccine is typically given under the skin? (I'm hiring a vet-tech to help me the first time.) I will not attempt to give rabies (I don't think I can, legally, anyway). Also, what is safer--killed or modified live? Is it safer to give Fe-leuk separately from the others or together? Is one company better than another? I have Foster-Davis and Omaha catalogues. I'd appreciate any advice you can give. Thanks! B.

I am under the impression that fibrosarcomas are just as likely following intramuscular injection and that they are often more difficult to deal with if they occur following an IM injection, because they tend to be less noticable until they get very large. I can not remember the author of the study on this but I am sure there is supportive data for this conclusion. In addition, the risk of an anaphylactic reaction to the vaccine is much higher since the risk of inadvertently getting the adjuvent into the circulatory system is much higher, according to Dr. Greene at the University of Georgia.

There may be some benefit in giving the rabies vaccination and the feline leukemia vaccination at different times, although there is little evidence to support doing this or to show that it is a problem to give them at the same time. Do not give them in close proximity, though, since increasing the amount of adjuvent at one site does seem like it may be a problem. These vaccines are only available in killed forms. There may be some benefit to using one of the feline leukemia vaccines that does not contain an adjuvent, since adjuvents have been identified as the most likely cause of fibrosarcoma.

I think it is better to use modified live virus vaccinations for the feline rhinotracheitis, calicivirus, panleukopenia combination vaccinations. You may even want to consider using the intranasal vaccine from Heska if you are especially worried about fibrosarcoma -- although the MLV vaccines do not contain adjuvents and are less likely to be the cause of fibrosarcoma than other vaccines. I have no idea of the availability of specific vaccines through catalogs, so it may not be possible to get the intranasal product in that manner.

A: My biggest fear when people elect not to have their veterinarians vaccinate their pets is that they will skip the physical exams, as well. Since a good yearly physical exam is the best way to find and treat problems early, I see this as a severe disadvantage of home vaccination. There are many more problems other than the ones that can be prevented by vaccination alone.

Vaccinating on an extremity may be best with the adjuvenated products because the limb may be amputated if fibrosarcoma occurs, giving the best shot at a wide surgical margin. This seems like one of those recommendations not actually practical in "real life" but it is worth considering, I guess.

Hope that helps.

Mike Richards, DVM

Feline leukemia vaccine

Q: I have a question....I have two cats aged 6 and 12.....yesterday they were due for their feline leukemia vaccinations. Their doctor informed me that they didn't need this vaccination since they are indoor cats and are not exposed to outdoor cats. The doctor said there have been findings in the last couple years that certain tumors have been linked to feline leuk and rabies vaccinations. What is your opinion on this? Because of the doctors persuasion, I opted not to vaccinate them for feline leukemia, but now I have nagging doubts. In fact, I called the vet back today and scheduled an appt. for Friday to get them vaccinated afterall. What do you think?? ]

P.S.: in case you need to know this, I also have two dogs which go outside, three parrots and four parakeets. Thank you very much. I think this is a great service you provide!

A: I agree with your vet. I think that we need to move away from thinking all cats should be vaccinated for everything whether their risk of exposure is low or not. There are problems with vaccine reactions in cats leading to fibrosarcoma. This risk is about 1 in 10,000 but it is a severe problem. It would be hard to tell you the exact risk of feline leukemia in an indoor cat but I think it is less than the risk of the vaccination, personally.

It is important to be sure your cats stay indoors if you choose not to vaccinate, since they will be more susceptible to feline leukemia if they are exposed to it later.

It is a tough decision to make in some ways. I can understand your confusion and the difficulty in making a choice. In either case, the risk of having made a mistake is very small (1 in 10,000 is pretty good odds that things will be OK) so do what makes you feel most comfortable. I am comfortable with the decision not to vaccinate in this situation.

Mike Richards, DVM

Late Giving Shots

Q: Because of this & that - I'm almost a year late in getting my cat shots, he's a pain to take anywhere. My sister wants me to take another cat but I'm not sure. Can my cat give the other cat a disease ? He's an indoor cat and never comes in contact with other animals. Would you put my mind at ease?

A: The vaccinations last longer than a year in many cats and yours is not likely to have been exposed to disease, anyway. I don't think you have much to worry about there. It doesn't sound much like your cat would like to have another cat around but you might try having a friend bring their cat over to see how yours reacts. If he is interested then it might work out. If he runs and hides or seems aggressive then it probably isn't a very good idea to get another cat.

Mike Richards, DVM

Last edited 04/26/04


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...