Our vet and our farm use a different protocol now.
all the vaccinations have been moved back on the foals - they get their first vaccine at no less then 4 months. Previously they were started at 3 months w/ Rabies (RV) at 4 months. The vaccine they get first is the EWT. Then 1 month later, if they are going to get it, they get a Flu/Rhino shot. Then, again, 1 month later (8 wks after 1st vaccine), they get the EWT. Then 1 month later, Flu/Rhino. After they are 6 months of age, they get an RV. But it isn't done at the same time as any other vaccination. Then they get the last dose of first one and then the other of the vaccines. All of the vets I have dealt with and/or spoken to have made recommendations not to give any vaccines w/i two weeks either way of weaning.
I don't know when they generally get the other vaccines they can get - such as PHF, Botulism, EPM, Strangles. I don't give those at all here. I no longer give West Nile either - but it was usually given as a separate vaccine by our vet at the same time as the EWT. I don't think I've ever given a 5 or more way vaccine to any of our ponies - just too much at one time...
The first 7 years I was here, while doing ride outs/volunteer work with our mobile horse vet - we saw a lot of reactions/sick horses to the 4, 5 & 6 way vaccines - both given by the vet and by the owner who may have purchased and given them themselves - but I can't say why that may have been the case and it may not have always been for the same reasons. Some had fevers and other reactions that were treated with fever reducing and anti-inflammatory. Some had abcesses were drained and then horses were put on antibiotics.
In 2011, I had the first ever reaction to an RV and it was pretty severe. The mare had a very swollen neck - had problems moving her head, eating/drinking and swallowing. We were just about to put her on IVs for fluid and nutrients, when she finally started eating/and drinking. I don't think she moved out of one spot for a full week - I carried her feed & water directly to her and cleaned up behind her - she'd already been separated from the group in the paddock she'd been in. The vet swore up and down it wasn't from the RV, since it was given more than 14 days before the reaction showed up - but it was on the same side/area that the RV had been given in... She had to have a 2nd round of antibiotics, too.
In Feb 2013, 60 days after getting an RV an 2 weeks after getting her WNEWT, Bit was off. She was started on antibiotics but her colt died in utero just 6 weeks before he was due she did pass him but was a VERY SICK pony for a while. It is not known if it was due to the vaccines, but I wonder... The body of the colt was necropsied and it wasn't Flu/Rhino related. He did have a full body coat and fully developed lungs/heart.
In October 2014 - 11 of the 15 ponies that received RVs had moderate to severe reactions. This was while we were doing our pack up and move, working full time. thankfully, we had friends and neighbors step in to help - those ponies were hot packed on their necks, chests and forelegs 2x daily along with all of them getting anti-inflammatory and antibiotics. The two that had trouble lifting there heads and moving - were separated (painfully) and handled the same way as the case in 2011...
In 2015, I "missed" most of our RVs on ponies, the youngsters only got 1 vaccine (EWT) and 1 booster, adults got only 1 EWT (instead of 2x year) and now in 2016, we've only given RV to babies (different company make) in the rump, and ponies younger than 15 yrs of age. Our current crop of 3 foals aren't old enough yet to have their EWT or RV.