18/04/2026
The Veterinary Medicines Directorate (VMD) has reaffirmed the safety of the Leptospirosis vaccinations.
Vaccines, like all medicines, are constantly monitored for issues and despite persistent internet rumours, both the L2 and L4 vaccines have consistently been shown to be unproblematic.
L2 has an adverse reaction rate (side effect) of 0.016%, or fewer than 2 per every 10,000 animals treated and L4 has an adverse reaction rate of 0.040%, or fewer than 4 per every 10,000 animals treated. Making the rate ‘rare’ on the official grading scale.
(This is what has led to the statements that L4 is ‘twice as dangerous’ as L2 and why it is always important to ask for the evidence behind proclamations like that!)
It is also important to realise that the vast majority of those side effects are mild and disappear quickly, like a lump in the skin where the injection was given or the pet being a little off for a day or so. These are simply signs that the immune system is reacting to the vaccine, which is exactly what we want it to do.
More serious illnesses after vaccinations can occur but they are extremely rare and even more rarely is the vaccine proven to be the cause.
Critics of the reporting system often say that adverse reactions are under reported, and this is true, but what is also true is that more serious illness is far more likely to be flagged than mild problems and that the monitoring system is set up to react to even very small changes in reporting patterns.
So we can be confident that if there were problems with the L4 vaccine, we would have known about it long before now, especially as it has been on the market for nearly a decade.
Leptospirosis is thankfully, not a common condition but it is regularly diagnosed by vets across the country. It is extremely serious, makes dogs very ill and requires prolonged, and costly, hospital stays to give them the best chance of survival.
There is absolutely no doubt that prevention is vastly preferable to cure.
Ad that prevention with vaccinations is safe and effective.
To learn more about this subject, check out;
https://www.facebook.com/share/183pDWpBiQ/?mibextid=wwXIfr (follow the references in this post)
https://free2read.dogstodaymagazine.co.uk/dogstoday_367 =7
https://www.gov.uk/government/news/vmd-reaffirms-safety-of-leptospira-vaccines-in-dogs
https://www.facebook.com/share/g/18GMFnsnGt/?mibextid=wwXIfr
