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2 weeks ago my mare started coughing. I heard it when she was just standing still in the stall or when I'd get her respiratory rate up such as walking fast. No fever, no snot, no lethargy. I got some headwash from the vet. Seemed to help a little. Now she will only cough if you trot her, not just standing still. I haven't seen any snot other than yesterday when she had teeth done, she coughed up a bunch of clear snot out of one nostril. The dentist said sometimes sedation can loosen it up and make it come out. Already done the mustard, DeX, and ventipulmon. I was thinking it was viral but now I'm not sure. Vet appointment later this week. Theres been some improvement but its still definitely there.Thoughts?

Lots of black pepper on her feed. It's an expectorant and anti inflammatory. She'll love it.