Thanks to Zenoss Community member Michael Hoffman for his new Veritas Netbackup ZenPack.  This ZenPack monitors Veritas Netbackup Client Image Sizes.  Zenoss goes to the device and attempt to execute the netbackup client image list command provided by the Veritas Netbackup Client.  This will then pull the Size and Files fields for a given Netbackup Profile.  By default the Size of the backup image is charted and can be used to alert on failures.  There is extensive documentation available on the ZenPack page.

Thanks Michael!