To find this information, I recommend checking the following sources:
* Massachusetts Department of Agricultural Resources: They likely have statistics on livestock populations, including horses.
* Massachusetts Farm Bureau Federation: This organization may have information on the number of farms and livestock in the state.
* Local agricultural organizations: You can contact agricultural organizations in specific counties or regions of Massachusetts for more localized data.
Remember that the number of horses can fluctuate over time, so it's essential to find the most up-to-date information.