It looks like dear Tracky has a thyroid tumor. 
I’ll be onto our vet first thing tomorrow and obviously want confirmation that’s what we are dealing with.
I researched these a bit many years ago when I went through it with Billy the pony. Some of you may remember Billy, who was rescued in a highly emaciated and neglected state. Poor little man had that many health issues, the least concerning of which was a huge thyroid tumor.
My understanding from going through it with Billy (if I remember correctly) is that they are not that uncommon in older horses and ponies and they are generally adenomas, which are benign. Even in Billy’s case where the tumor was quite large and unsightly, it was not impacting his ability to breathe or graze at all.
If that is what’s going on with Tracky (which I’m fairly certain it is), it will hopefully be very slow moving and will not impact his quality of life any time soon.
Dear Cooper the Arab has had several melonomas for the past few years. The percentage of grey horses with them is quite horrifying. I think it’s over 85%. 
With him I just continue to monitor them for any sudden changes. There is a nasty one under the base of his tail that can’t easily be removed, but I also want to talk to our vet about another potential option to help him now that it’s growing quite quickly.
Just like with us, cancer also invades our animal friends. 
I’ll let you know what I find out once he’s been vet checked.
