EMS and swollen thyroid.


Well-Known Member
13 November 2006
Has anyone got any experience of an enlarged thyroid in a horse? Especially along with EMS.

A bit of background: I have had my Connemara 4 years, she had an episode of laminitis shortly after I bought her and she has never had it since as I manage her weight and diet carefully.

She put some weight on over this last winter as I was out of action and she was on full livery and not ridden for 4 months. I recovered and brought her gradually back into work and on a controlled diet. The weight was coming off nicely as she got fitter then, around April, it stopped coming off and even seemed to start increasing and I noticed a swelling on her neck which I suspected was her thyroid.

The vet took bloods which came back positive for EMS. Pony is being kept in, on Metformin and on soaked hay (6.5kg per day) to get her weight down which is happening slowly. She doesn’t have a crest, her fat is over her ribs, behind her shoulder and over the tail head. She is totally sound and perky and being ridden every day. Her thyroid is still enlarged and it is this that is worrying me. The research I have done doesn’t tell me anything except that thyroid problems are rare in horses.

The vet did mention that when she visits again after the course of Metformin has finished to assess the pony’s progress she will measure the thyroid swelling again and we might try levothyroxine.

Any insight or experiences please as I am worrying so much about this pony. She’s my poppet ☹️