Vaccination Titer Testing & the Immune System

By Dr Heather Matheson, DVM BSc
Balanced Paws Veterinary Care Ltd.
info@balancedpawsvet.com

The objective of any vaccination is to provide effective immunity by establishing adequate levels of an antibody. Antibodies are a primed population of cells (essentially memory cells) which can rapidly expand on renewed contact with antigen (virus) and so provide protection against infection.

Core or basic vaccines protect against severe life-threatening diseases that have a global distribution. Canine distemper virus, Canine parvovirus, adenovirus and Rabies are all considered core vaccines for our canine-companions. Core vaccinations for our feline-family include Feline Leukemia, Panleukopenia, Calicivirus and Rabies.

There are three basic types of vaccinations; Modified live vaccinations such as the Parvovirus vaccine. Killed vaccinations such as the Rabies vaccine. Antigenically similar vaccinations such as the Distemper vaccine.

Vaccination Titer Testing ArticleCanine Distemper Virus

The canine distemper virus is a highly contagious virus and has worldwide distribution. The fatality rate in non-vaccinated animals that contract the distemper virus is as high as 90%. The canine distemper virus is antigenically similar to the measles virus in humans. Essentially by vaccinating against measles we are creating antibodies and immune protection against the distemper virus.

Clinical signs of Distemper include: fever, runny eyes & nose, coughing, diarrhea, vomiting, weight loss, dehydration, skin rash, encephalitis, seizures, in-coordination, circling, blindness, vocalization and death.

Canine Parvovirus

The parvovirus vaccine is an example of a modified live vaccination. Although the vaccine contains live parvo virus, that virus has been altered and will not cause disease.

The canine parvovirus is highly contagious and has a worldwide distribution. Outbreaks of parvovirus are common even in highly vaccinated areas and pockets of disease crop up routinely. Although any dog may be affected, clinical disease is highest in dogs less than 1 year of age and our geriatric dogs.

The Parvovirus is stable for long periods in the environment and hence difficult to eradicate. Actively dividing cells are affected; these include the intestines, bone marrow & lymph tissue. The end result is intestinal crypt necrosis which results in severe diarrhea and eventual intestinal collapse. Decreased white blood cells and no intestinal lining allow the body absolutely no defense against invading bacteria.

Canine Adenovirus

Canine adenovirus is also known as infectious canine hepatitis. Adenovirus causes acute hepatic necrosis, liver cirrhosis, liver failure, anterior uveitis and glaucoma.

Rabies

Rabies is the only vaccine mandated by law and it is an example of a killed vaccine. Rabies should be given no earlier than 12 to 16 wks and often waiting until about 8 months is easier on the immune system.

Ideally the initial Rabies vaccine should be administered by itself at a later date than the original puppy or kitten series. The first Rabies vaccination is considered good for one year and subsequent vaccinations are then considered good for three years. However, recent studies do suggest that a single Rabies vaccination can elicit very long-standing protection.

Maternally acquired antibody

Maternally acquired antibodies are those memory cells passed onto a pup or kitten from Mom’s immune system and her previous vaccinations or exposure to disease. The great thing about maternal antibodies is that they provide the pup with protection prior to any vaccinations. However, maternal antibodies will also “cancel” out some of the pup’s ability to mount his own immune response to a vaccination.

A pup or kitten vaccinated at 6 weeks of age will have less than 50% response to the vaccine. At 9 weeks there will be about 75% response and at 12 weeks he will be 90% protected. This is why a series of monthly core vaccinations starting at 8 weeks is typically recommended.

Current Vaccine Recommendations

We recommend a puppy or kitten series starting at 8 weeks of age. We do try and split up the vaccinations as much as possible and follow up any vaccination with a homeopathic remedy which helps decrease any potential side effects to the vaccine. The initial complement of vaccines is very important in establishing a protective immunity and would be considered good for one year. At one year of age our preference is to check titers. This is a simple blood test that tells us how many antibodies or memory cells are present from the initial vaccination. If owners choose to vaccinate at one year of age instead of checking titers we would consider the vaccination to be protective for 3 years although a yearly examination is still recommended.

Unlike pharmaceuticals that are dose-dependent, vaccines are not based on volume per body mass (size), but rather a minimum immunizing dose.

Duration of Immunity

Duration of immunity is the length of time an animal is protected from a disease. Dr Ron Schultz & Dr Jean Dodds are heading an independent study on duration of immunity for the rabies vaccine. (See rabieschallengefund.org)

Adverse Vaccine Reactions

Immediate hypersensitivity or anaphylactic reactions are those that occur soon after the vaccination is given, typically within 20 minutes. This type of reaction is life threatening and must be treated immediately.

Acute vaccine reactions are those reactions occurring within 24-48 hours after the vaccination. An acute reaction may cause the following: fever, stiffness, sore joints, vomiting, abdominal tenderness and increased susceptibility to infection.

Delayed vaccine reactions are those reactions occurring 10-45 days after the vaccination. Delayed reactions are caused by immune complex formation. A delayed vaccine reaction may manifest as collapse with autoagglutination of red blood cells & jaundice (also known as immune mediated hemolytic anemia), pinpoint hemorrhages or bruises, elevated liver enzymes or worsening of pre-existing conditions.

Immune complex formation

Vaccinations are extremely important for establishing baseline immunity to diseases. However if that baseline immunity has already been established and there is a full compliment of antibodies present in the body the result of revaccination would not be a further increase in antibody titer, but possibly a hypersensitivity disorder. Vaccination of pet & research dogs with polyvalent vaccines (vaccines containing more than one virus) containing rabies vaccine or rabies vaccine alone was shown to induce production of antithyroglobulin autoantibodies, important implications for the subsequent development of hypothyroidism. (Scott-Moncrieff et al, 2002)

What is this elusive thing we call a titer?

A titer is a measurement of antibody (memory cell) to a specific virus (or antigen). Titers are measured on the liquid portion of the blood and are measured on a dilution. A 1:10 titer means the blood has been diluted 10 times & antibodies are present. A measurement of 1:50 means the blood has been diluted 50 times and antibodies are still present. Any measurable antibody indicates protection in vaccinated dogs older than 16 weeks of age. Remember antibodies are memory cells designed to jump start the immune system hence we don’t need a lot of them we just need one.

Immune memory vs. Disease

Titers do not distinguish between immunity generated by vaccination and immunity generated by exposure to the disease.
Typically vaccination will elicit titers no higher than a 1:200 dilution. If no previous vaccination has been given a positive titer of 1:200 would indicate previous exposure to the disease. Active disease will elicit titers up to 1:1800 dilution.

Negative Titer & Genetically susceptible breeds

A negative antibody (titer) test suggests the need to vaccinate or revaccinate as no baseline immunity has been established. Genetically susceptible breeds are those that are considered to have a poor immune system & a genetic predisposition for certain immune related diseases. Occasionally animals will fail to establish any baseline immunity no matter how many times they are revaccinated. The titer test is always negative. These animals are called “Non-responders”. If a “non-responder” comes in contact with one of the pathogenic viruses such as canine distemper virus the animal will likely succumb to the virus.

Reasons to Titer Test

There are many reasons to titer test rather than revaccinate. Animals are all individuals and, as such, their immune system is individual. How can we possibly know the individual response to a vaccination? The answer is we can’t, not without testing. We may be able to venture an educated guess and play the odds but we truly do not know without a titer test. Titer testing at least gives us a clue towards the animals established immunity and whether revaccination would be beneficial or detrimental.

Here are just a few obvious reasons to titer test prior to vaccination:

Modified live virus vaccination may cause disease in these situations and killed products may not be effective or may aggravate underlying disease.

Think Outside the Box

Vaccinations are important, they are the reason we are virtually free of horrible diseases such as Rabies, Canine Distemper. However, when an adequate immune memory has already been established, there is little reason to introduce unnecessary antigen, adjuvant, and preservatives by giving booster vaccinations.

Vaccination Programs

Vaccination programs should be tailored to the specific needs of each animal. Establishing that baseline immunity is relatively standardized, however, once immunity has been established the decision to revaccinate should be individual and based on antibody levels (titer testing).

Although advice may come from many places the burden falls on the shoulders of the dog or kitty’s human to ensure that age, health, environment and lifestyle are all taken into account when designing an appropriate vaccination program.

 

For an integrated veterinary assessment call
Balanced Paws Veterinary Care at (250) 871-4355
or email info@balancedpawsvet.com.

We are located at 2785C Mansfield Drive in Courtenay (across from the Air Park).

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