Horse Side Vet Guide ®

Equine Health Resource

Lump, Bump, Growth inside Nostril

Code Yellow - Contact Your Vet at Your Convenience for an Appointment

Code Yellow - Contact Your Vet at Your Convenience for an Appointment

  • To ensure a correct diagnosis, have your vet examine the horse.

Soft smooth swellings found on the outside of the nostril are fairly common. This is the location for the so called False Nostril Cyst or “atheroma”, a benign growth filled with a cheesy thick fluid. As is true in any location though, a variety of other growths and swellings can occur here too, including tumors, abscesses, cysts, and granulomas – to name a few.


When assessing any swelling, carefully and gently feel its shape and consistency, and look for masses elsewhere. Take note of whether it seems painful to the touch, any break in the skin, and whether there is drainage. Consider how long it has been present and how quickly you think it has grown. Report this to your vet, or take a photo of it and share it with them.


Diagnosis of False Nostril Cyst is quite straightforward, based on the characteristics of the swelling and the location, and it is usually quite treatable. If the mass does not look like to them like a typical atheroma, your vet may choose instead to aspirate or biopsy it.

Author: Doug Thal DVM Dipl. ABVP


We're not around right now. But you can send us an email and we'll get back to you, asap.