I gave spring vaccines yesterday, and my 6 year old TB got his tet combo. This morning, I placed his grain in the usual spot ground-level, and when his nose got about 6 inches from it, it was like he hit a wall. After a few seconds, he managed to lower his head enough to eat, but he seemed quite uncomfortable doing so. He pawed a few times, which is normal behavior for him if he's frustrated from not eating fast enough (e.g. I'm late with dinner). He's completely normal otherwise, if a little lethargic, so I was trying to figure out what was going on. And I wonder if he's just super sore from his tetanus vax that he got in the neck, and lowering it to eat hurts. He did have localized minor swelling at the injection site.
The most sore I've ever seen my horses get is not willing to bend under saddle. Am I correct in assuming this issue is just a sore neck?
My mare gets neck sore with ANY shots, so yeah, I can see this happening. My mare is also as you describe: slow moving, doesnt' have the range of motion she normally has, and sometimes, has seemed uncoordinated (like a drunk walking around). It wears off after a few days.
"If you think nobody cares about you, try missing a couple payments..."
For this reason I never vaccinate in the neck. An equine vet friend taught me how to give vacs safely, and all about alternate areas & the pros/cons of each. The best place is in the back of thigh muscle.
I wouldn't just go do it on a strange horse, however.
A video I made in 2009; back-of-thigh vaccinations on 3 different horses. Please forgive the rambling & stuttering: I can't do anything while talking; I certainly have trouble trying to talk and pay close attention to when I'm doing an activity that could instantly turn into a dangerous situation.
I agree this is probably normal, tetanus hurts (had one this fall and was sore for a week!) but watch the horse for fever and swelling in the neck wear the shots were given. If it does abscess you want to be on top of it ASAP.
Any shot can abscess though Banamine is most famous for it.
I wouldn't worry too much... just keep an eye out for any other signs of distress. You can give some bute for the next few days to try to make him more comfortable, if you want. Some light, gentle exercise would probably also help loosen those muscles up. Next time see if your vet can give the shot in a different location, as others have mentioned.
The last time I got a tetanus shot, I passed out on some concrete steps on my way out of the office and got a wheelchair ride back inside. It was great/mortifying seeing everyone's faces in the waiting room which I had just waltzed out of two minutes earlier.
"Winter's a good time to stay in and cuddle,
but put me in summer and I'll be a... happy snowman!!!"