Would love some ideas/brainstorming about this somewhat weird set of events. I do have vets involved but hoping someone may have seen something similar and have some possibilities to explore.
Horse is 10 years old, had him for years, happy, healthy and barefoot. Has always had a very reasonable work load, light hacking, low level dressage consistently, small jumps a few times a month. 9 days ago had a great ride, nothing out of the ordinary, felt 100% and happy. Next day very quiet and sluggish coming out of turnout but seemed okay otherwise. Get on him and he is very slow, not wanting to go forward. Sound at walk, will only a trot a few steps with a lot of urging and seems touchy and sore up front. Maybe a touch more on right front but not significant. Get off, no heat, swelling, feet seem fine, nothing obvious. Put him on lunge line and does not want to go forward. Seems more off going left but only looked briefly because did not want to stress him. Cold hose and put to bed.
Next morning all 4 legs swollen and hot. Horse does not want to walk out of stall. Seems lethargic and unhappy. 2 grams of bute, cold hosing etc. do not help. Vet called. Does not feel any one leg is more sore than the others. Negative to hoof tests, normal digital pulses, no heat in hooves. Vet suspects anaplasmosis and starts him on doxy, also gives banamine. In 12 hours horse is significantly better, happy to walk out of stall, much less swelling and heat, perkier and happier. 2 days later banamine is stopped, horse continues to walk around happily and with energy. All swelling and heat in legs is gone. 4 days after starting doxy horse is put on lunge line to assess. Sound and happy at walk. Forward and happy to trot but funky up front. Worse to the right. Seems more like the right front but hard to saw for sure. Will seem okay, but is tripping, stumbling and will take a series of very off steps. Completely happy to go about like this, not at all resistant. Next day horse continues to seem fine unless asked to trot, no heat, swelling.....Still waiting for anaplasmosis PCR to come back so not sure 100% on the diagnosis, although something did seem to respond positively to the doxy.... CBC was normal except slightly elevated neutrophils.
That does sound like anaplasmosis, which generally responds better to oxytetracycline (IV) than to doxy. What was his fever like? If it was at or around 104, I'd be even more likely to suspect anaplasmosis.
FWIW, it took my horse a long time to feel 100% again after he had it last year. He also needed to be chiropractically adjusted because he was all out of wack following his illness. I suspect he fell while ill (they can become a bit ataxic).