Fever of Unknow Origin?

[Critter]

Stressing about my old guy (19yo gelding). Rode him Sunday and he was super perky and fine…but suddenly refused his treats post ride. He will occasionally do this (ie, if you got ointment or something smelly on your hand and you offer a treat, he thinks you are trying to poison him). Ate dinner fine.

Next morning comes in, perky but won’t eat. Temp…103.7. Call vet, 2g bute…otherwise he’s looking pretty normal. No other symptoms. Temp comes down for the day. Temp spikes back up to almost 104 in the late afternoon…check in with vet, more bute. Temp doesn’t come down for 4 hours…yikes. He is blah, but otherwise no other symptoms.

Temp stays down next day (98 baseline)…then spikes to 102 early afternoon…bute, vet out to draw blood and run oxytet. Today, fever spikes are not as high, but still happening. Bute seems to be controlling them…he eats fine when the temp is down, but if it’s climbing won’t eat. Again, zero other symptoms.

Blood is showing only low platelets and low lymphocytes. Waiting for smear for anaplasmosis. Vet says blood suggests something viral.

No horses on or off property all winter, so no exposure to anything. My other mare (who is next to him all the time) is fine. Same feed/paddocks next to each other/etc.). Had all his spring vaccines a month ago. I hate not knowing a cause…and with him being older, he definitely had me worried the night the fever wasn’t dropping.

We are in a high tick area…and we have a lot of standing water right now (10 inches of rain last month!)…but it’s been cool still (NJ) so we’ve not had lots of bugs out. And he has zero other symptoms. Just can’t figure out how he would have gotten something viral?

[Roni4444]

I had a mystery fever which ended up being an abscessed tooth

[MorganMaresVT]

I would have also thought anaplasmosis. Seeing a fever 104+ is super scary. The one time I had a temp that high, it was anaplasmosis; mare responded almost immediately to two days of IV oxy. Temp came right down and appetite back. We kept her on a course of doxy and she recovered well.

Hope your horse turns around quickly!

[trubandloki]

Last time my horse dealt with a high fever the vets never figured out a reason, it was always just called a fever of unknown origin.

Jingles for your boy!

[S1969]

My vets treat for anaplasma even without confirmation as the test is often inaccurate at first. It’s been a while since any of mine have had it but without evidence of anything else they will administer IV oxytet (or did 10 years ago - I believe there may be other recommended antibiotic for tick borne disease now.)

[islgrl]

I would assume anaplasma…

[cayuse]

This was my first thought too. BTDT and have the big bills.
Jingles for your fella!

[Critter]

@Roni4444 and @cayuse how did you figure out it was the tooth? He’s eating fine when the fever is down and there is no odor in his mouth.

We have been treating as if it were anaplasmosis, since that’s the usual FUO cause here…but the vet said the bloodwork really didn’t suggest it.

He’s a little better since the oxytet…the fever spikes are not as high, but he’s still not his normal self and I’ve still had to do some bute each day. He was a bit off feed this morning…but was fine once the bute kicked in. I started him on some ulcer meds too…just because of the meds/stress.

[cayuse]

Well, we ruled out the tick born stuff then started thinking teeth as he is a mini and they don’t always have the best teeth in the world. IIRC mine did have a bit of odor but it was very, very faint with the first infection and we thought it might have been just packed feed in his teeth at first.

[Dressage8812]

I had the dentist out and he saw a tooth was bad and x rayed it. No obvious other signs. He ate his gay ok but less enthusiastic about his grain when the fever started. Bloodwork was all ok.

[Critter]

He’s been hanging in the 99.7 temp range (his normal is about 98)…so just low grade fever. Still a bit off feed and punky. This morning all 4 legs were stocked up. We are hesitant to do another dose of oxytet as when he got the one,he got super agitated right after…itchy and kicking out. Vet gave it very slow (he’s easy to dose)…but he does tend to be a bit drug sensitive. She agreed that he might have a much worse reaction with another dose…so we are just going with doxy. It just looks like an anaplasmosis, no matter what the blood is showing. Going to run a Lyme titer, but too early for that to be accurate, so will wait 2 weeks.

[S1969]

Definitely sounds like anaplasmosis now. As I said, my vets practically ignore the bloodwork, and I wouldn’t be surprised if they don’t always do it because it’s so inaccurate. And we’re in a very tick infested area.

Can they give Benadryl or anything?

[Critter]

Not sure about the benadryl…if we were at a vet clinic I would be okay with trying it, where they would have access to lots of options for treating and watching if he reacted worse. But we are 2 hrs drive from any of the large clinics. My farm vet is absolutely awesome and skilled with emergency situations…but single farm vet capability is still not the same as a full staffed clinic situation. Hopefully with adding in the doxy, we will see faster improvement.