You may have gotten a bad or unsterile needle. I've had problems a couple times giving influenza shots where they actually absesed! Since we got most of our vaccines from Vet Supply, our vet said that the needle may not have been sterilized or the vaccines weren't kept cold enough. But this only happened on one horse one year and two horses another year.
I had the same problem only it was his back legs. Within two hours his back legs went from normal to the size of stove pipes! I hadn't made the link to vaccines as they had been administered the week before. Called the vet in a panic, described the symptons and she indicated that it was in fact a delayed reaction. Three days of bute, cold hosing several times a day and cold bandaging in between brought him back to normal no problems since. Very scary!
Ugh. Very scary. Glad to hear that everything turned out OK. A lot of vets I know are concerned about the number and frequency of vaccines we give our animals. One vet I work with feels that vaccines (and the enhanced immune response they cause) are the cause of many equine allergies and heaves in horses. It's a shame that it costs five times as much to pull a titer to see if your horse still has immunity than it costs to give them the vaccine. Many horses are getting vaccinated for diseases they have built up an immunity to. There are homeopathic remedies you can give your animals, when they get vaccinated, to help combat the negative effects of the vaccine. Nux vomica is commonly used for this but there are others as well.
I wrote an article on equine allergies last spring for TROT magazine. In my research the recommendations for vaccine reactions were:
1) split up the vaccinations up - so do one or two one day then wait and do others 2)check titers - ie antibodies in blood, to see if they are sufficiently high that the horse doesn't need to be vaccinated again (though this represents levels only at that moment in time and they could subsequently go down - there is also the cost associated, roughly $20-30 per antigen) 3)pre-treat the horse with antihistamine or steroids the day before, day of and day after.
I would consult with your vet Barbara and see what they recommend for spring inoculations. I'm sure each horse and case is a bit different.
Though I didn't include a section about vaccine reactions in the article in the end, if you want to check it out you can view it on my website at http://www.eqmassage.ca , just click on 'articles' and its the 3rd one down under the general health heading.