The thickness of the wire is important - ideally you need a thick wire which will will not deform. Some wire fencing is made of very thin wire and when the horse kicks out the foot can go through and the horse's hoof gets trapped. The horse then struggles and cuts into the flesh down to the ligaments.
In such circumstances, if the horse is not rescued quickly then the horse does further damage to itself and eventually the wound can go gangrenous - which often means that the horse ultimately gets put down. If the horse is cut by fence wire then it need treatment as soon as possible - very often by anti biotics and Hibiscrub - infection is the enemy. Tendon damage can be disastrous.
Certainly rigging up an electric tape fence on the horse's side of the fence helps to deter the horse from going too close to the wire fence. But if the horse does get caught up in an electrified fence which does not cut out, then the horse is shocked by the pulses from the power unit.
The electric tape is itself razor sharp - run it through your own fingers and you will see for yourself. However a friend of mine uses only two lines of wide tape on the longer posts. It is important for the horse to know that the tape is electrified - then they will usually stear clear of it.
The problem is nearly always a fight over the fence between two horses. It can also be caused by a fight in a field between two horses when one decides to exit the paddock and in the process gets itself caught up whilst trying to jump out. Hormones are often involved.
A very sensitive time is when introducing a new horse to a paddock already occupied by a small herd. The introduction of a new horse could upset the heirachy already established. Ideally any horse should be carefully introduced over time to the existing herd and not just for reasons of infection.
Try not to mix mares with geldings, especially in the spring. Of course, stallions must always be kept separate.
The best fencing for horses is made up of wooden post and rail fencing backed up by a 3 foot deep natural hedge. Do you have hedges in your part of the world?
Some studs in the UK use a system of two parallel lines of wooden post and rail leaving a yard between each line of fencing. Lovely if it can be afforded.
Sheep graze down a pasture of the vegetation of weeds etc. They will eat what a horse won't. But in the process they cover the field with sheep dung. They also represent a different containment problem - especially in the lambing season. Even if sheep share the field you should still watch out for poisonous weeds - ie yew, deadly nightshade and ragwort - or whatever you have in your part of the world.
There is no gold plated answer to this fencing problem. It is a nightmare on a do it yourself livery yards where horses share large fields. Sooner or later there will be a fight and a horse can be maimed.
The carefully thought out segregation of grazing pasture is a mark of good management by the manager of the yard. Always ask about the policy operated. Sadly in modern times a farmer may know a lot about sheep and cattle but very little about modern horses.
The big risks to horses : ligament & tendon damage, fights, colic, laminitis, poison and a wide rage of infections are all to be found in the paddocks.
Judge where you leave your horse by how the farmer or barn owner manages his land over the 12 month cycle.
Be lucky and be cautious.