Is requested repair necessary?

[Nyoka Fernandez]

Hi. I've had a tenant in a house for over a year. They renewed their lease just over a month ago and have now asked for me to install a gate/fence so that they can let their dog loose in the backyard. The quoted cost from the property manager (PM) is $488. They are proposing that I put the $250 pet fee to the cost of the gate. The tenant was ok without this fence for over a year. I proposed to the PM that I would install gate if tenant agreed to a $25 rent increase (even though they have been late with their rent 3 times over the past year). I don't think it's wise to forfeit the pet fee. Tenant does not agree to this as they are on fixed income, per the PM. PM says I'm at risk of loosing this tenant. Am I obliged to have gate installed? This tenant costed me over $1000 in repairs last year, including fixing blocked dryer line 3 times, blocked filters, among other repairs. I am weary of spending $500 now, only to have a mountain of other expenses as the year goes my. Any advice from the members on whether or not I should pay to install this fence is greatly appreciated!