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Jul
11

Dr. Dodds – titers

Please remember that the information I am posting comes directly from  Dr. Dodd’s seminar and handouts, I am not adding my own opinion to these posts. Please also know that this is not meant to replace your own Vet’s advice. Every dog is different and has different needs and different issues. I just want to provide you with this information so you are aware there are options out there and so that you can be informed. I wanted to mention something that was said at the  seminar - vaccinating a dog is the act of adminestering a vaccine but immunization occurs when the dog’s body produces antibodies.

The whole article  written by Dr. Dodd is on my site (copied onto my site with written permission) under my Natural Canine  link but here is a piece of it relating to titers.

 ”veterinary vaccinologists have recommended new protocols for dogs and cats. These include: 1) giving the puppy or kitten vaccine series followed by a booster at one year of age; 2) administering further boosters in a combination vaccine every three years or as split components alternating every other year until; 3) the pet reaches geriatric age, at which time booster vaccination is likely to be unnecessary and may be unadvisable for those with aging or immunologic disorders.  In the intervening years between booster vaccinations, and in the case of geriatric pets, circulating humoral immunity can be evaluated by measuring serum vaccine antibody titers as an indication of the presence of immune memory. Titers do not distinguish between immunity generated by vaccination and/or exposure to the disease, although the magnitude of immunity produced just by vaccination is usually lower.

Except where vaccination is required by law, all animals, but especially those dogs or close relatives that previously experienced an adverse reaction to vaccination can have serum antibody titers measured annually instead of revaccination. If adequate titers are found, the animal should not need revaccination until some future date.  Rechecking antibody titers can be performed annually, thereafter, or can be offered as an alternative to pet owners who prefer not to follow the conventional practice of annual boosters. Reliable serologic vaccine titering is available from several university and commercial laboratories and the cost is reasonable (Twark and Dodds, 2000; Lappin et al, 2002; Paul et al, 2003; Moore and Glickman, 2004).
Relatively little has been published about the duration of immunity following vaccination, although new data are beginning to appear for both dogs and cats.

Our recent study (Twark and Dodds, 2000), evaluated 1441 dogs for CPV antibody titer and 1379 dogs for CDV antibody titer. Of these, 95.1 % were judged to have adequate CPV titers, and nearly all (97.6 %) had adequate CDV titers. Vaccine histories were available for 444 dogs (CPV) and 433 dogs (CDV). Only 43 dogs had been vaccinated within the previous year, with the majority of dogs (268 or 60%) having received a booster vaccination 1-2 years beforehand. On the basis of our data, we concluded that annual revaccination is unnecessary. Similar findings and conclusions have been published recently for dogs in New Zealand (Kyle et al, 2002), and cats (Scott and Geissinger, 1999; Lappin et al, 2002).  Comprehensive studies of the duration of serologic response to five viral vaccine antigens in dogs and three viral vaccine antigens in cats were recently published  by researchers at Pfizer Animal Health ( Mouzin et al, 2004).

When an adequate immune memory has already been established, there is little reason to introduce unnecessary antigen, adjuvant, and preservatives by administering booster vaccines.  By titering annually, one can assess whether a given animal humoral immune response has fallen below levels of adequate immune memory. In that event, an appropriate vaccine booster can be administered.” …

NEW PRINCIPLES OF IMMUNOLOGY

“Dogs and cats immune systems mature fully at 6 months. If a modified live virus (MLV) vaccine is given after 6 months of age, it produces an immunity which is good for the life of the pet (i.e: canine distemper, parvo, feline distemper). If another MLV vaccine is given a year later, the antibodies from the first vaccine neutralize the antigens of the second vaccine and there is little or no effect. The titer is not “boosted” nor are more memory cells induced.”
Not only are annual boosters for parvo and distemper unnecessary, they subject the pet to potential risks of allergic reactions and immune-mediated hemolytic anemia. “There is no scientific documentation to back up label claims for annual administration of MLV vaccines.” Puppies receive antibodies through their mother’s milk. This natural protection can last 8-14 weeks. Puppies & kittens should NOT be vaccinated at LESS than 8 weeks. Maternal immunity will neutralize the vaccine and little protection (0-38%) will be produced. Vaccination at 6 weeks will, however, delay the timing of the first highly effective vaccine. Vaccinations given 2 weeks
apart suppress rather than stimulate the immune system. A series of vaccinations is given starting at 8 weeks and given 3-4 weeks apart up to 16 weeks of age. Another vaccination given sometime after 6 months of age (usually at 1 year 4 months) will provide lifetime immunity.”

There is no doubt that application of modern vaccine technology has permitted us to protect companion animals effectively against serious infectious diseases.

Some veterinarians have challenged the validity of using vaccine titer testing to assess the immunologic status of animals against the common, clinically important infectious diseases.

With all due respect, this represents a misunderstanding of what has been called the “fallacy of titer testing”, because research has shown that once an animal’s titer stabilizes it is likely to remain constant for many years. Properly immunized animals have sterilizing immunity that not only prevents clinical disease but also prevents infection, and only the presence of antibody can prevent infection. As stated by eminent expert Dr. Ronald Schultz in discussing the value of vaccine titer testing, these tests “show that an animal with a positive test has sterilizing immunity and should be protected from infection. If that animal were vaccinated it would not respond with a significant increase in antibody titer, but may develop a hypersensitivity to vaccine components (e.g. fetal bovine serum). Furthermore, the animal doesn’t need to be revaccinated and should not be revaccinated since the vaccine could cause an adverse reaction (hypersensitivity disorder). You should avoid vaccinating animals that are already protected. It is often said that the antibody level detected is “only a snapshot in time”. That’s simply not true; it is more a “motion picture that plays for years”. 

Furthermore, protection as indicated by a positive titer result is not likely to suddenly drop-off unless an animal develops a medical problem such as cancer or receives high or prolonged doses of immunosuppressive drugs. Viral vaccines prompt an immune response that lasts much longer than that elicited by classic antigen. Lack of distinction between the two kinds of responses may be why practitioners think titers can suddenly disappear. 

But, not all vaccines produce sterilizing immunity. Those that do include: distemper virus, adenovirus, and parvovirus in the dog, and panleukopenia virus in the cat. Examples of vaccines that produced non-sterile immunity would be leptospirosis, bordetella, rabies virus, herpesvirus and calicivirus — the latter two being upper respiratory viruses of cats. While non-sterile immunity may not protect the animal from infection, it should keep the infection from progressing to severe clinical disease. 

Therefore, interpreting titers correctly depends upon the disease in question. Some titers must reach a certain level to indicate immunity, but with other agents like those that produce sterile immunity, the presence of any measurable antibody shows protection. The positive titer test result is fairly straightforward, but a negative titer test result is more difficult to interpret, because a negative titer is not the same thing as a zero titer and it doesn’t necessarily mean that animal is unprotected. A negative result usually means the titer has failed to reach the threshold of providing sterile immunity. This is an important distinction, because for the clinically important distemper and parvovirus diseases of dogs, and panleukopenia of cats, a negative or zero antibody titer indicates that the animal is not protected against canine parvovirus and may not be protected against canine distemper virus or feline panleukopenia virus. 

Finally, what does more than a decade of experience with vaccine titer testing reveal ? Published studies in refereed journals show that 90-98% of dogs and cats that have been properly vaccinated develop good measurable antibody titers to the infectious agent measured. So, in contrast to the concerns of some practitioners, using vaccine titer testing as a means to assess vaccine-induced protection will likely result in the animal avoiding needless and unwise booster vaccinations. 

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Reasons for Vaccine Titer Testing: *

1. To determine that animal is protected (suggested by a positive test result).

2. To identify a susceptible animal (suggested by a negative test result).

3. To determine whether an individual animal has responded to a vaccine.

4. To determine whether an individual vaccine is effectively immunizing animals.

 

 * from: Schultz RD, Ford RB, Olsen J, Scott F. Titer testing and vaccination: a new look at traditional practices. Vet Med, 97: 1-13, 2002 (insert).