Just received the following reply from Subaru of America customer service:
Thank you for contacting Subaru of America, Inc. We appreciate you taking time out of your day to contact us.
When you lock your Subaru with the keyless entry system, the alarm system defaults to active. However the alarm is only triggered if a door, hood or tailgate are opened, or if there is a very strong impact on a window. Dogs in the vehicle, even if they are moving around a bit, would not normally be enough to trigger the alarm. There is a way to temporarily deactivate the alarm and put the vehicle in "valet" mode where the keyless entry locks the door, but the alarm will not sound. You can find out more about how to select the valet mode/alarm deactivation by referring to page 2-26 in your owner's manual. Basically, you sit in the driver seat, shut all doors, turn the ignition switch to on, hold down the rear (unlock) side of the driver's power door locking switch , open the drivers door within the following one second and wait an additional 10 seconds before releasing the switch. You will then see ALOF for "alarm off" appear in the combination meter display. The same procedure is used to reactivate the alarm system and it displays ALON when it is reactivated.
So there you have it! Thanks again to those who responded.