When Penny has her dog inside the canoe, only 2/3*6 = <<2/3*6=4>>4 people could fit inside the canoe.
If every person in a trip where Penny had her dog inside the canoe weighed 140 pounds, the total weight of people inside the canoe was 140*4= <<140*4=560>>560 pounds.
The dog weighs 1/4*140 = <<140/4=35>>35 pounds
On the trip, the canoe was carrying 560+35 = <<560+35=595>>595 pounds
#### 595