There was one neighbour's feral cat in particular which just hated all other cats for some reason, and would fight viciously with every one in sight as soon as she was let out. Unfortunately, one of our cats seems to enjoy the adrenaline rush of facing an opponent. So it was not a good combination to have these two cats outside near each other.
It also didn't help that one of our cats liked to taunt other cats by parading herself as fight bait outside our back door. The opposing rival cat would see her and be lured across the back fence and attack, and then we would have to run out and break up the resulting fight before it escalated.
The options we had for protecting both cats were as follows:
1) Keep one or both cats inside.
- Both cats would go mad, and complain all day about not being allowed out.
- Somebody is going to slip up eventually and a cat is going to run out.
- No point living in a house with a yard because you have pets, if they can't even use the yard.
2) Cat proof the fences.
- Very difficult to achieve, as cats are master escape artists.
- May look unsightly, don't want your property looking like a prison yard.
3) Council involvement.
- Difficult to bait the offending neighbour cat
- Great way to make a mortal enemy in your neighbours
- Only works if your neighbour is a tenant
- Another fine way to make a mortal enemy in your neighbours
- Cats quickly get used to stuff like water spray, essential oils, spices, Vaseline and just ignore it. Possibly see more success with pine cones or sticky strips, but didn't have any.
- Cats can jump over or dodge stuff easily.
I initially thought about stapling chicken wire over the tops of the fences at a 90 degree angle onto metal brackets. But we have trees in the yard, and this would be very difficult to install onto crappy leaning wood. And anything sharp protruding from the fence catches wind and looks really terrible. It's also a pain to take down or repair if you need to.
So then I tried slathering the fence tops with Vick's VapoRub and Vaseline, creating a sticky coating for applying pepper and cinnamon powder. Cat got used to it all in a few days and ignored everything. I'm not sure how well essential oils (Lavender) did, but it probably didn't do a whole lot.
The solution was to cap the tops of our fences with 50mm diameter PVC pipe. Just cut a 30-35mm wide slit in the pipe length-ways so you have a long C, and slot the pipe over the fence tops. Now the cats can no longer grip the wooden fence tops with their claws to pull their body weight up and over into our backyard. If they do manage to jump in by climbing an overhanging tree, the cat risks being trapped in the yard, and is too scared to return. This will also prevent your cats from leaving your yard to seek out a fight or moving car.
We also installed security cameras to record any yard activity to make sure there weren't secret spy cats sneaking in at night. I recommend buying the cheap Wyze ones you get from Amazon USA (if you don't live in the US), as they work decently for monitoring pet activity.
Are PVC pipe capped fences 100% cat proof? Well, we have seen one or two cats leap over the fence without thinking, only to get cornered in the yard and get stared at by strange humans. This spooks them enough that we haven't seen the same cat twice after some intense up close staring, you don't even seem to have to spray them with water or anything. I think this method destroys their confidence by forcing them to use their fearful imagination to predict what you might do if you actually catch them next time. The fence capping also cuts off many possible escape routes. No more cat attacks so far since the PVC pipe caps went on, so that's good enough for me.