I have a required
<select name="service_id" class="Sitedropdown" style="width: 220px;"
ng-options="service.ServiceID as service.ServiceName for service in services"
<option value="">Select Service</option>
ng-show="myForm.service_id.$dirty && myForm.service_id.$invalid"
This means - if value is dirty (was changed) and is invalid. Remove first and you'll get what you want.