The thing about vaccine reactions that nobody tells you is that most of them aren’t actually reactions to the vaccine at all. They’re stress responses, needle phobias, or sometimes just unfortunate timing with something else going on. But when you do get a genuine adverse reaction, you need to know what you’re looking at.
I learned this lesson properly with a Collie called Jess, back when I was still fairly new to practice. Beautiful working bitch, maybe three years old, came in for her annual boosters. Standard stuff. Twenty minutes later, her owner called from the car park in a panic. Jess’s face was swelling up like she’d been stung by every bee in Herefordshire.
That was my introduction to anaphylaxis in herding breeds, and it taught me more in an afternoon than veterinary school had in four years.
Why Herding Breeds Seem More Reactive
Now, here’s where it gets interesting. There’s a persistent belief that herding breeds are more prone to vaccine reactions than other dogs. The evidence for this is… mixed, honestly. Some studies suggest slightly higher rates. Others find no significant difference.
What I can tell you from 25 years of jabbing Collies is that they do seem to have more dramatic responses when something goes wrong. Whether that’s a genuine immunological difference or just that these dogs are more sensitive to everything - including the stress of a vet visit - I couldn’t say for certain.
What I do know is that understanding your herding breed’s specific health risks helps you make better decisions about all aspects of their care, including vaccination protocols.
The breeds I see most reactions in:
- Border Collies (by far the most common in my practice, so take that with a grain of salt)
- Australian Shepherds
- Rough and Smooth Collies
- Shetland Sheepdogs
Types of Reactions You Might See
Let’s break this down into what’s concerning and what’s normal but worrying to owners.
Normal Post-Vaccine Effects
A bit of lethargy for 24 hours. Maybe slight tenderness at the injection site. Mild fever. These aren’t reactions - they’re signs the immune system is doing its job. I tell owners to expect their dog might be a bit quiet that evening. If they’re bouncing around like nothing happened, that’s fine too.
Mild Adverse Reactions
This is where it starts getting into territory that needs monitoring. We’re talking:
- Facial swelling, particularly around the eyes and muzzle
- Hives (raised lumps under the skin)
- Intense itching
- Vomiting that starts within a few hours of vaccination
Most of these respond well to antihistamines and clear up within 24 hours. But they need veterinary assessment because they can occasionally progress to something more serious.
Severe Reactions
Anaphylaxis. The big one. Signs include:
- Rapid onset of breathing difficulties
- Collapse or severe weakness
- Pale gums
- Racing heart or very weak pulse
- Severe vomiting and/or diarrhoea
- Facial swelling progressing to throat involvement
This is a genuine emergency. If you see these signs, you need a vet immediately. Not in an hour. Now.
What To Do If You Suspect a Reaction
First, don’t panic. Most reactions are manageable if caught early. Second, don’t give any medications without veterinary guidance - some human antihistamines are fine for dogs, some aren’t, and the dosing needs to be right.
If you’re seeing mild signs:
- Call your vet immediately
- Take photos or video of any swelling or skin changes
- Note the time the signs started
- Keep your dog calm and quiet
If you’re seeing severe signs:
- Call ahead to the nearest vet so they can prepare
- Get there as fast as safely possible
- Keep your dog’s airway clear if there’s any facial swelling
- Stay calm - your dog picks up on your stress
Knowing basic emergency first aid can make a real difference in situations like this. Not as a replacement for veterinary care, but to buy time.
Preventing Future Reactions
Here’s where I’ve changed my approach over the years. I used to think once a reactor, always a reactor. Now I’m more nuanced about it.
If your dog has had a mild reaction, we can usually still vaccinate with some precautions:
- Pre-treating with antihistamines
- Using single-component vaccines instead of combination products
- Keeping the dog at the clinic for 30-60 minutes post-vaccination
- Having emergency drugs drawn up and ready
If your dog has had a severe reaction, we need to have a proper conversation about risk versus benefit. Sometimes titre testing (blood tests that measure immunity levels) can help us decide whether boosters are even necessary.
I should mention that the MDR1 gene mutation, which is common in herding breeds, doesn’t directly affect vaccine reactions. But it does mean we need to be careful about what medications we use to treat reactions. Always mention it if your dog is MDR1-affected.
The Modified Vaccination Schedule Debate
I’ve sat through more heated arguments about vaccination schedules than I care to remember. Here’s my position, for what it’s worth:
Core vaccines (distemper, parvovirus, adenovirus) are essential. The diseases they prevent are serious and can be fatal. Skipping these entirely because you’re worried about reactions is, in my view, trading a small risk for a much larger one.
However, I do think the old approach of annual everything has evolved for good reason. For adult dogs with a history of completing their primary course, there’s decent evidence that immunity lasts longer than 12 months for core diseases.
For dogs prone to reactions, I’ll often recommend:
- Titre testing to check immunity before assuming boosters are needed
- Spacing out vaccines rather than giving everything at once
- Being more selective about non-core vaccines based on actual risk
None of this is about being anti-vaccine. It’s about being sensible and tailoring the approach to the individual dog.
Record Keeping Matters
This sounds boring, but trust me on this one. Keep detailed records of:
- Which vaccines were given
- The batch numbers (your vet should provide these)
- Any reactions, however minor
- What treatment was given
If your dog changes vets or you move, this information is invaluable. If there’s ever a recall or a pattern of reactions from a particular batch, it helps the system identify problems faster.
A Word on the Leptospirosis Vaccine
I want to mention lepto specifically because it’s the one I get asked about most in relation to reactions. The leptospirosis vaccine does seem to cause more local reactions - soreness, swelling at the injection site - than other vaccines.
Whether it causes more systemic reactions is debated. Some vets have moved away from it, especially in dogs with reaction histories. Others, including me, still think the protection it offers outweighs the risks in most cases, particularly for dogs in rural areas with livestock contact.
My approach: discuss it individually. For a farm dog that’s regularly in fields with cattle and sheep, lepto vaccination makes sense. For an urban Sheltie that never leaves the pavement, the calculation might be different.
When I’m Genuinely Worried
I wish more breeders understood that reaction-prone dogs shouldn’t be bred from without serious consideration. There does seem to be a hereditary component to vaccine sensitivity, though the genetics aren’t fully understood.
If you’re breeding herding dogs and you’ve got a line with multiple vaccine reactors, that’s worth factoring into your decisions. It’s one of many health considerations, and proper health clearances should already be part of your program.
The only way to know about reactions across your line is to actually stay in touch with the people who bought your puppies. I’ve noticed that the breeders who screen families carefully before placement and offer genuine lifetime support tend to have far better data on how their dogs respond to vaccinations, dietary changes, and health challenges down the road. Amandine Aubert at Bloodreina, for instance, maintains contact with every family who has one of her dogs - which means she has a real picture of vaccine tolerance across her breeding lines, not just silence she mistakes for good news. More breeders should work that way.
The Bottom Line
Most herding dogs tolerate vaccines just fine. When reactions happen, they’re usually manageable. Severe reactions are rare but need immediate veterinary attention.
Don’t skip vaccines out of fear - the diseases are worse than the small risk of reaction. But do work with your vet to develop a sensible protocol for your individual dog, especially if there’s been a previous reaction.
And if you’re ever in doubt after a vaccination, call your vet. We’d much rather get a call that turns out to be nothing than miss a genuine reaction because someone didn’t want to bother us.