Vaccinations – Who, What, When, Why and How?

January 15, 2014

Vaccinations are a controversial subject these days with both humans and animals. There are certainly many varying opinions as to whether or not to vaccinate and when it should be done. So, this week let’s talk about the Who, What, When, Why and How of it all. I’d like to break this all down so that our valued clients have a clear understanding of why vaccinations are necessary and sometimes not necessary. I would also like to talk about the immune system which works hand in hand with vaccinations as well as offer some relevant information about the origin of vaccinations in order to provide a bigger picture and hopefully a better grasp on the topic as a whole. I promise an interesting read!

Before we get this ball rolling, let me say this. Bringing your pets in for an annual exam is crucial to their health and well being. I cannot stress this point enough. Often the exam is MORE important than the actual vaccinations. With the annual exam, things can be caught early before they turn into serious and expensive problems. With your senior pets, exams should be done every six months. Just like people, good health becomes a bigger challenge with our pets as they age. Sticking with one veterinarian is also key. If you see the same vet year after year, that vet knows your pet and will quickly catch any major differences in body condition or lab work. Again, this is crucial in catching things early and fixing things before they grow into larger issues. Now, on to vaccinations.

I’ll start with this statement:  there is a tremendous amount of information and misinformation that is readily available to anyone who has access to the internet, much like our topic from last week – nutrition. So I think a good place to begin is with a basic understanding of the immune system, how it works and how it does what it does so amazingly well.

HOW

How does the immune system work? Suffice it to say that the immune system provides multiple layers of defense for an animal (and for people too) to resist infection. These layers interact with one another in a complex dance that keeps us alive and healthy in a microbial world. Some layers of defense are effective against many different types of invaders while others are very specific in their area of protection. Some act against bacteria, some against viruses, and some against parasitic, fungal, or protozoal invaders.

Think of the animal (or human) body as having layered defense mechanisms against microbial invaders. The big three, would be physical barriers such as skin, innate immunity such as inflammation and adaptive immunity such as antibody production. In general, think of the innate immunity as the rapid response that keeps things at bay until adaptive immunity can develop. Adaptive immunity not only recognizes foreign invaders, but also destroys them and retains memory of the encounter. If the animal encounters the organism again, the adaptive response is quicker and more effective. Adaptive immunity can work in two ways. One is the humoral immune response – think antibodies directed against invaders. The other is the cell mediated response – think invaders have gotten inside of cells and antibodies can’t get to them, so then specialized cells destroy these abnormal or infected cells. Make sense?

I think sometimes we lose touch with the fact we, in our modern society, think we are somehow above or distant from a microbial world. In reality, it’s quite the opposite. A healthy immune system constantly protects us and our pets from disease.  Here is a vivid example: the animal body (warm, moist and full of nutrients) is extremely attractive to microorganisms. The magnitude of this can be seen at the time of death, where, within hours, a body decomposes rapidly as bacteria invade its tissues because the immune system is no longer working. So these invaders are there, always lurking and waiting for the opportunity to wreak havoc.  Are all microbes a threat? No. The world is full of microbes (bacteria, viruses, fungi, protozoa, and worms). Enormous numbers of these colonize the skin and intestines, but don’t seek to invade and normally don’t cause disease.  These are called commensal organisms. Others, are more aggressive and do seek to invade and those are called pathogens. Influenza (the flu) is a pathogen as is canine distemper, HIV, Brucella abortus, rabies and a host of others.

Where did vaccines come from and when did it all start? In the late 1800’s Louis Pasteur (of pasteurization fame) discovered that by using an aged culture of the bacterium to be known as Pasteurella multocida, he could protect chickens against “fowl cholera”. He then worked on anthrax, and discovered growing the anthrax organism at high temperatures rendered it avirulent (it wouldn’t cause disease), but the avirulent organism was protective against the virulent organism when injected in sheep. Vaccination was born. These early scientists did not know why or how the immune system worked; it had been left to others to determine the molecular and cellular basis of antimicrobial immunity. Knowing this has enabled us to use immune mechanisms to develop resistance to infectious diseases, thus creating more vaccine possibilities. And that work is still being done today.  I think this is a good time to get into the who, when and what. 

WHO, WHEN and WHAT

Ever wonder why we vaccinate at the age we do? Why 8 weeks of age? Why not 4 weeks of age? It’s called passive immunity. Newborn mammals are temporarily protected against infection by transfer of immunoglobulins derived from the mother. How that protection gets to the newborn depends on what kind of mammal you are. In humans and other primates, the placenta is hemochorial which allows certain maternal to transfer directly to the fetus. Dogs and cats have an endotheliochorial placenta, which basically means not a lot of passive transfer takes place in the uterus; 5 to 10% is transferred to the puppy or kitten. The rest is transferred in colostrum, the milk that is produced by the mother in the first couple of days of life. In horses, pigs, and ruminants, no transfer in the uterus takes place at all so colostrum is critical as their newborns are entirely dependent on antibodies transferred through milk. Maternal antibodies absorbed from a puppies intestine, reach maximal levels in serum by 12 to 24 hours after birth and have a half-life of about 9 days (kittens – about 10 days). On average, the level of maternal antibodies to distemper declines to insignificant levels by about 10 to 12 weeks, although this ranges from 6 to 16 weeks. Simply put, we don’t vaccinate puppies or kittens at 4 weeks of age, because passive antibody will block the vaccination. The vaccination will be not be effective. Several years ago, many people in an effort to “protect” their puppies were vaccinating against parvo virus at 4 weeks of age. Sadly, this resulted in no protection, a false sense of security and a waste of money. There is an exception to this rule which is the puppy or kitten that received no colostrum from the mother. These babies can and must be vaccinated “early”. For this colostrum deprived puppy or kitten, they can mount an immune response as young as 2 weeks of age.

The earliest age recommended to vaccinate a puppy or kitten with a reasonable expectation of success is at 8 weeks. Two additional vaccinations are recommended spaced about 4 weeks apart. Simply remembering 8, 12, and 16 weeks is the safest way to vaccinate a puppy or a kitten. This is because, some (and we cannot tell which ones), will be susceptible at 8 weeks of age, so they need to be vaccinated at that age. Some will still have maternal antibodies in sufficient numbers to block that vaccine so their first effective vaccination won’t be until the 12 week injection. All maternal antibodies will be gone by the time the 16 week injection is administered, with the 16 week injection acting to boost the amnestic (memory) response. A booster shot is then given at one year of age. Here are two charts for an easy and quick reference.

Core Vaccines for Dogs

##Dogs Distemper Adenoviru s 2 Parainfluenz a* Parvo Rabies
8 weeks xx xx xx xx  
12 weeks xx xx xx xx  
16 weeks xx xx xx xx xx
1 year xx xx xx xx xx

*Parainfluenza is not considered a core vaccine by many veterinary internal medicine specialists, however it’s inclusion in 4-way,   5-way and 7 way vaccine protocols is standard amongst vaccine pharmaceutical companies.

Core Vaccines for Cats

##Cats

FPV

Panleukopenia or feline parvo virus

FCV

Calici virus

FHV-1

Herpes Virus or

Rhinotracheitis

Chlamydia

*

FeLV**

Rabies

8

xx

xx

xx

xx

   

12

xx

xx

xx

xx

xx

 

16

xx

xx

xx

xx

xx

xx

1

xx

xx

xx

xx

xx***

xx

*Chlamydia, is often included by major vaccine manufacturers – in the “4 way vaccine” known as FVRCCP; it is felt by many to be a significant component of the feline upper respiratory disorders. It is not considered “core” by the American Association of Feline Practioneer’s Vaccine Advisory Panel. We include it in our core vaccination.

**Feline Leukemia Vaccination – as of 2013, the AAFP Advisory Panel has moved feline leukemia vaccination into the list of core vaccines. The reasoning – is that at 12 and 16 weeks of age, the ultimate type of home the kitten will be in is often unknown and the risk of Feline Leukemia is too great to overlook. At Washington Blvd Animal Hospital, a discussion of where the cat lives and with who, precedes a decision to vaccinate against FELV. If a decision is made to vaccinate against feline leukemia there must be a negative test for feline leukemia prior to vaccinating.

*** Feline Leukemia Core Vaccination at 1 year – at one year of age it is reasonable to know whether or not the cat is an outdoor cat, or an indoor cat. Or a mix of both. Outdoor cats, and indoor-outdoor cats, OR inside cats who have exposure to cats that are indoor-outdoor should be vaccinated against feline leukemia.

You will notice I didn’t fill out the chart for dogs and cats beyond the first year. In part, that is because I don’t think there should be a table of all possible vaccinations and when they should be administered. In addition, I believe the decision of how often to vaccinate, and against what, is a medical decision not just an automatic one. A discussion of your dog and cat’s vaccination needs should be part of every annual exam. For example, the dog that is frequently boarded and groomed at professional facilities and/or visits doggy day-care or dog parks certainly has different vaccine requirements than the 4 year old house dog that never leaves the house. In addition, while we now know that the core vaccinations have an effective “protective” life of 3 years or greater, many of the non-core vaccinations are only effective for six months (i.e. bordetella). 

The same thought process is true for cats, but with cats, we have the added dimensions of the stress of multiple cat households and lowering of immunity for that reason. Shelter cats, rescue cats, all change how we vaccinate.  The bottom line on vaccinations is that during the annual examination, the decision to vaccinate is brought up and discussed. In general with cats, this same every 3 years vaccination holds true, with the exception of the rabies shot, which is yearly.

WHY

Most of us see the requirement for a rabies vaccination, as a pain in the neck. It is seen as more of a government intrusion in our lives.  You might think “we have to pay for a license, we have to get this shot for our animals and we have never even seen a case of rabies”. Yet worldwide, rabies kills more than 50,000 people a year! Most of those cases are caused by being bitten by a rabid dog. The reservoirs for rabies in California are skunks and bats.  Rabid bats are also found every year in Los Angeles County believe it or not. According to the Veterinary Public Health and Rabies Control Program of the Los Angeles County Department of Public Health. Of note, LA County has reported record-setting numbers of rabid bats in the past few years. Usually between 8-12 are found per year, but 30-50 per year have been found in the last few years. These are not limited to mountainous regions. In fact, one was found in downtown Los Angeles not too long ago. You can find maps and more data on their website. Here is their rabid bat map for 2013: publichealth.lacounty.gov/vet/rabiesmap2013.htm  Overall, in North America, the top three mammals affected with rabies (other than the bat) are Raccoons, Skunks and foxes. Coyotes have been found with rabies as well (South Texas).

Vaccination and licensing programs are the key to keeping human rabies cases low in this country. Without a doubt, rabies vaccination programs save lives.

A special section of this blog should be devoted to the subject of feline injection site sarcomas. Vaccine associated sarcomas were first recognized as an issue in cats in the early 1990’s. Initial studies suggested a rate of 2 cases/10,000 and in one study that jumped up to 13-36 cases/10,000 (that’s a huge increase). Finally, current estimates based on very large studies suggest the risk of sarcoma development is actually low, well below 1 per 10,000. BUT, there is a risk. Some cats, who have been vaccinated against feline leukemia or against rabies, developed cancer. The risk is low, but we can lower it even further by vaccinating only those cats at risk. By using the appropriate type of vaccinations and by placing the vaccinations in a location that would allow better management of a cancer should it occur. The flip side of the coin should be examined as well. If you’re an outdoor cat, there is a greater risk of catching the feline leukemia virus and dying from it than there is developing an injection site sarcoma. Feline rabies cases are more common than canine rabies cases, so the need to vaccinate, the need to protect feline and human lives against rabies is real.  So yes, I still recommend vaccinating against feline leukemia for at risk cats. I still recommend vaccinating against rabies in cats as well. In some areas, you are not given the choice because the county requires it. In other areas, it becomes a choice of looking at who is at risk.

Which almost brings me full circle and I would ask your indulgence in a brief discussion of vaccinations in both humans and animals. I have been practicing veterinary medicine long enough (31 years) to have seen animals infected with disease that my younger associates rarely see.  Prior to my entrance into veterinary school in the early and mid 1970’s – I worked at this same hospital as a technician (remember the first blog). I dealt with cages of cats with severe upper respiratory disease that dwarf the upper respiratory diseases we see now.  In the early years of my practice career, cases of canine distemper were frequent. Puppies with severe distemper pneumonia would manage to survive only to die from the neurologic form of the same disease. I remember when “any sick cat” that showed up first had to have feline leukemia ruled out because it was so common. Parvo virus wiped out thousands and thousands of dogs when it first broke out in the late 1970s and early 1980s. It is now primarily a disease of unvaccinated puppies, but the virus is resistant, long lived and is spread by flies. This year I saw my first adult dogs with parvo virus in years. It is my sincere hope that this was just a blip on the radar, but let’s get something straight. Vaccines, in both humans and animals save lives. In veterinary medicine they have been blamed for immune mediated disease, hypothyroidism and other disorders. There is no evidence for this at this time in peer reviewed journals. When a vaccination has been linked to a problem, (as with the feline injection site sarcomas) it has been studied, published and answers and recommendations have come forth. In human medicine, vaccinations have been unfairly linked to epilepsy and to autism. It is natural to confuse subsequence with consequence. Many of the babies that were vaccinated against pertussis that developed seizures and severe neurologic disorders ultimately were found to have a genetic defect in the sodium transport system in their brains. Same goes for autism, there are no credible links of vaccinations causing autism. When we don’t vaccinate our dogs and cats, when we don’t vaccinate our children… we put the “herd” at risk. We risk being revisited by the diseases of my early veterinary career, and we risk being revisited by the diseases of my parents and grandparents generations. To quote another colleague of mine, Kathleen Barry M.D., “Vaccinations are the crowning achievement of the 20th century”. I simply could not agree more. Until next week……………… 

Dr. Voorheis

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