Marshall has some serious issues with the lawn mower. I wish I could get in his little mind to understand what he thinks it is. I haven't mowed much this year so haven't had a strong chance to get Marshall desensitized, but as a young pup, he could have cared less. So something in his perception changed some where along the way.
The only solution I have found to excessive barking and trying to attack the mower is to put him on a leash and let him walk beside me. It is interesting that he walks calmly at my side back and forth while I mow. But if I have to stop for some reason, when I restart the mower he starts barking and getting all crazy. As soon as I tell him heel and start forward he stops.
Is it the restraint or does he have some other perspective? It is a herding thing? that by walking behind it he feels like he is controlling its direction? I don't have an answer but it is an interesting study in behavior.