Now there is an option to send  sms to the client when they have a specific state.
The vet/nurse can also be informed by sms through the same stage.

Frontpage - Records - Cases - Stages

Choose the tab Casestages and click on the stage you want to attach the notification on.

Go to the field Client SMS notification and/or Vet SMS notification, remove the "-" and press tabulator to get the list of notification.

Choose the notification you want to attach to the stage and press Save.

When using a stage that has a sms notification, it will show with a little phone icon.