Titre Testing For Dogs Explained
There is a lot of confusion out there about vaccinations, and here at Your Vet Online we get a lot of questions such as this one:
I have a 5 year old Groodle and am very worried about some of the stories I’ve heard about over vaccinating. I really don’t want to harm my dog, yet I don’t want to put him at risk either. I heard that there is a dog titre test and if it comes back as a negative titre test then you might still need to vaccinate. Is this true?
Dr Leigh answers:
This is a great question Jaenelle, I think it will be best to explain how vaccination works, then talk about dog titre tests. I will also shed some light on why over vaccination is impossible and vaccinosis is a made up term. Grab a cuppa and let’s get to it!
How Does Vaccination Work?
The aim of vaccination is to prevent infection against the disease that your pet is being vaccinated against.
How the Immune System Works
To understand how vaccines work you need to understand how the immune system works:
When the body is invaded by a germ (bacteria or virus) the immune system sounds the alarm.
- the body releases antibodies to fight the germ. This can take days.
- The antibodies work to attack, weaken, and destroy the germ.
- Once the body recovers, the immune system remembers the germ.
- If the germ invades again, the body can recognise it and quickly send out the right antibodies to fight the infection.
Once the body has fought a disease there is a certain amount of protection against against that disease. This is called immunity.
In many cases, immunity lasts a lifetime.
How Vaccines Work
The body can take a while to activate the immune system. Especially the first time it sees a germ. Vaccination speeds this process up in a safe and controlled manner.
Vaccines protect the body by inducing mechanisms (cells or molecules) that are capable of rapidly controlling replicating germs, or inactivating the germ’s toxic components.
Vaccines do this via producing antibodies (B lymphocytes) and T cells and some other mechanisms that get complicated (you can read more here).
The main benefit of vaccines is memory. They basically teach the immune system to remember the germs that they are protecting against, so if the body is exposed then it will be able to launch an effective immune attack.
The two components of the vaccine memory response are:
- humoral immunity – this involves producing proteins called antibodies
- cell mediated immunity – this involves special cells in the immune system (T cells etc, check out this paper for more in depth information) that recognise and attack invading germs.
What Type Of Vaccines Are There?
The viral particles or bacterial antigens in vaccines are either killed or weakened so they won’t make your pet sick.
Modified live vaccines contain live virus particles that have been altered so that they are in a non-disease causing state (attenuated). Although this type of vaccine is ‘alive’, it is incapable of producing disease. (e.g., modified-live canine distemper virus, intranasal and oral B. bronchiseptica).
Killed vaccines are made by taking real viruses or bacteria and killing them. There is a set number of viral/bacterial titer and this will never change i.e. no replication occurs. The immune response with a killed vaccine is less than with a modified live vaccine so adjuvants are added to amplify the immune response. These adjuvants can increase the risk of an allergic reaction to the vaccine.(e.g. leptospirosis, Borrelia burgdorferi [canine Lyme disease], canine influenza virus, and parenteral B. bronchiseptica vaccines).
Recombinant Vaccines contain part of a virus or bacteria that produce the best antibody response in the body. For example some bacteria or viruses contain certain antigens that cause a bigger immune response than the whole bacteria/virus. In the laboratory, scientists have found the genes that code for these antigens so they can make more of them. These are then put into liquid to be given to the animal. (eg., canine distemper virus (rCDV) vaccines).
Antibody Titre Testing In Dogs & Cats
As we have read above, there are two types of immune response:
- Humoral immunity
- Cell mediated immunity
Remember that humoral immunity is related to the development of antibodies.
When we discuss titre testing, we are talking about how many antibodies a body has developed against a specific disease.
It’s important to remember that we need to consider EACH disease separately as not all diseases and vaccinations work the same way.
For example antibodies against Feline Herpes Virus (FHV) or Feline Leukemia Virus (FeLV), don’t correlate well with protection against infection. It would therefore be unwise to use titre testing to measure immunity.
Cats with a high antibody titre against FHV may still be at risk and require vaccinating. Cats with a FeLV titre means they aren’t protected, but are infected.
Titre tests for Canine Parvovirus (CPV), Canine Distemper Virus (CDV) and Rabies do show excellent correlation with immunity.
How To Interpret Titre Tests
A frustrating part of titre testing is that sometimes a negative is not really a negative. Yep, you heard me! It can be hard to get your head around and it means you have to look at the WHOLE animal as an individual.
In an older dog that has been vaccinated in the past a positive titre test means your dog is adequately protected. A negative titre test doesn’t mean it is necessarily lacking protection, it may mean there are no circulating antibodies, BUT cell mediated immunity could be present.
We are unable to test for cell mediated immunity, so we need to look at the individual animal and work out the risks involved for this animal and the community it is living in.
- Are there puppies or aged dogs in the household?
- Do you visit the dog park, doggie daycare or boarding facilities?
- Do other dogs come onto your property ie. shearing dog teams, mustering teams?
- Is your dog immuno-compromised because of treatment for another disease i.e. cancer?
- Has your dog had a previous vaccine reaction?
- Has your dog suffered an auto-immune disease in the past?
Although we like to think a positive titre result indicates that we are protected, it is worthwhile knowing that the only true test of protective immunity is when we there is a challenge (exposure) to the germs that the vaccination is protecting against. If the animal remains healthy, then the vaccine is protective.
|A positive test result indicates the patient DOES have protective levels of antibody against the virus.
A negative test result indicates the patient does NOT have protective levels of circulating antibody. However,
a negative test result does not necessarily define if the animal is susceptible to infection.
A really good website that explains everything you need to know in detail is American Animal Hospital Association I have taken the following diagram from their website to share with you.
Over Vaccinating Or Vaccinosis – Is This A Thing?
Finally we will mention a common theme being presented by lay people with no scientific training – that you can over vaccinate or cause vaccinosis.
These are not real terms. It is a made up term that is used by those who practice homeopathy and other alternative or complementary medicine (CAM).
The use of the term vaccinosis is used to describe illness after receiving a vaccination. Doctors and Veterinarians refer to this as an adverse reaction.
IS VACCINATION SAFE FOR DOGS?
Vaccines are very, very safe. Many of the claims that you hear about are simply untrue and unable to be proven.
It is important to listen to your veterinarian regarding the risks of disease in your area, and what your dog, horse or cat may be susceptible to.
There is no point vaccinating against Rabies if you live in Australia or New Zealand. So while I advocate for vaccination, I advocate for sensible vaccination based on risk analysis.
Titre testing can be used, again, with risk analysis.
Decreasing your dog’s vaccination frequency needs to be based on evidence, good risk analysis and conversation with your vet. Don’t buy into the fear of over-vaccinating or vaccinosis.
Check out our articles on puppy vaccinations and whether you need to vaccinate yearly to learn more about how vaccinations.