Updated November 20th, 2020
- Last week I told you about the diseases of dogs and diseases of cats that we use vaccines to prevent.
- This week I’ll cover vaccine reactions, vaccinating safely and alternatives to vaccination like titre testing.
- In the third week I’ll tell you about the changes to vaccination schedules for your pet.
Are Vaccinations Dangerous?
We vets don’t want to talk about how safe our vaccinations are. It’s easier to sit in our ivory towers and take (what we think) is the moral high ground.
The stuff I’ve read about vaccinations makes me cross and sad. But I’ve also read some kernels of truth.
Vaccines aren’t perfect, and neither are vets. There are some concerns: here’s my attempt to separate truth from fiction. Everything I say is evidence-based and I encourage you to add your comments in the same way.
When you’re done, visit our related page on the Bravecto side effect controversy.
How dangerous are vaccines? Like any medical intervention, they have ways of causing harm as well as good. Here is what we know.
Vaccine-associated Sarcoma is a nasty tumour mostly observed in the USA in cats which appears at the site of vaccination.
The rabies and feline leukaemia virus FeLV) vaccines appear to be the most common culprits, although any adjuvanted vaccine may do this. The prevalence of sarcoma development after vaccination is approximately 1/10,000 but may be as high as 1/1,000 vaccines administered in certain cases.
Immune-mediated Haemolytic Anaemia occurs in dogs when the body’s immune system attacks its own red blood cells. Although it’s a rare disease (I’ve seen under 10), mortality rates are around 50%. There are probably many causes but a higher rate of this disease is observed in the months following vaccination. Read more about IMHA here.
Adverse Reactions can range from soreness or swelling at the injection site, fever, or even severe anaphylactic responses (like nut or bee venom allergies in people).
Birth Defects may occur if a vaccination is done during pregnancy.
Reversion to Virulence is when the ‘modified’ vaccine virus strain causes disease in its own right. Signs are often like the disease for which we are vaccinating. In the past this was a problem with Canine Infectious Hepatitis and Canine Distemper vaccines, but improved manufacturing techniques have solved this problem. It’s still possible that it may occur occasionally.
Vaccination Failure is rare but always possible. From development and testing, correct storage, choosing the right patient and correct use, making sure a vaccine will live up to its promises is our greatest concern. Next week I’ll discuss vaccine efficacy and making sure your pet’s vaccine stands the best chance of keeping them protected.
How Common Are Vaccine Reactions?
A 2003 study from the USA found that in the first three days after vaccination, a rate of one reaction per 261 occurred. The risk increased for young dogs, small dogs and those receiving multiple vaccines.
Most of these reactions were the minor type involving local pain or swelling. With the exception of the diseases mentioned above, other studies have not identified an increased risk of illness associated with vaccination.
Severe anaphylaxis is very rare. Rates are reported as around one per 15,000 doses in the USA and that’s probably not far off the truth. I have seen life threatening anaphylaxis once in my career, in the UK in 1999, and approximately ten times I have seen pets develop facial swelling after vaccination.
How Can We Make Vaccination Safer?
Give Less Vaccines.
Newer vaccines and more evidence allow us to give vaccines less often than before but still protect your pet to the same standard. Next week I’ll tell you how we use vaccines at Walkerville Vet and what the future may hold.
Did you know there are many more vaccines available that we don’t recommend? It’s up to vets to decide if a disease is rare enough or mild enough that it’s better not to give the vaccine. Examples at Walkerville Vet include Feline Leukaemia, Feline Chlamydia, Canine Coronavirus, Canine Leptospirosis and tetanus. We also don’t have Lyme Disease and Rabies to worry about in Australia.
Even with the vaccines we recommend, not all animals need them. For example, FIV vaccination is of no use to a cat that never meets other cats.
Use Safer Vaccines
Did you know there are two types of vaccine? Modified Live vaccines use actual viruses or bacteria created from the disease-causing agent. Sounds scary, but although the bugs look the same to the immune system, they have been modified until they don’t cause disease.
Adjuvanted vaccines use killed viral or bacterial particles. As these may not cause enough of a response on their own, the vaccine contains a chemical which helps stimulate the immune system.
Vaccines containing adjuvant are more likely to cause vaccine reactions. Therefore, whenever possible, we use Modified Live vaccines.
Live vaccines are just like what our immune system is doing every day when it meets random bugs, except this time we perform the introductions and be the matchmaker.
Use Vaccines Wisely
Here are our guidelines for using vaccines:
- Only vaccinate after a full physical exam
- Don’t vaccinate if pregnancy is possible.
- Don’t vaccinate when the patient is unwell or has a fever.
- Don’t use vaccines too soon after the previous dose.
- Don’t use vaccines with certain other medications.
- Always observe your pet for two hours after a vaccine
Use Titre Testing As An Alternative?
What if we just measure the antibodies to the viruses instead of vaccinating? Sounds sensible, doesn’t it?
Thanks to a client’s question I looked into it and have written a whole blog on the pros and cons of titre testing in cats and dogs.
Use Homeopathic Vaccines?
Here’s a quote from a vet selling homeopathic alternatives to vaccines:
We also offer the option to boost a pet’s immunity naturally with homeopathic nosodes rather than traditional vaccination. Nosodes cannot be guaranteed to be effective and will not result in a measurable titer.
Rely On Herd Immunity?
You don’t need 100% of the susceptible population to be properly vaccinated to stop a disease. This is the concept of ‘herd immunity’. The percentage of the population that is not vaccinated needs to be high enough for a disease to start to spread.
For cats, we will probably never reach herd immunity levels due to the number of unvaccinated stray cats. It’s more likely to occur in dogs but even now there are parts of Adelaide where we see annual parvovirus outbreaks.
Relying on herd immunity to keep your pets safe is like relying on other people for anything else important.
Not Vaccinate At All?
We believe we have a safe, modern product which saves lives and prevents suffering. Your opinion may not be the same, and if so, you may choose not to give vaccines to your pet.
If this is what you want, I have one very big thing to ask you. If you do this I guarantee you will still have my respect. Please, please, please keep getting your pet checked by a vet at least once a year.
You won’t realise how important those nagging little annual trips to the vet are unless you stop doing them. It’s fiendishly difficult to get people to bring their pets to the vet ‘just for a checkup’ but remember, animals can’t complain.
Pets that don’t make annual checkup visits often end up with severe illnesses by the time something is noticed at home. We pride ourselves on our abilities to sniff out disease. It’s what we do. Let us be the smoke detector, not the fire engine!
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!
Have something to add? Comments are welcome below and will appear within 24 hours.