Thanks for your enquiry.
The wording you have provided me with does mean that you are indeed entitled to keep a dog, PROVIDED he/she does not become a nuisance (whether that be by barking/messing in the communal areas).
If any neighbours were to complain about your dog, it would have to be investigated, and if there was evidence that he/she was a nuisance, they could serve Notice on you demanding that your dog be removed immediately. If you were to object, they would have to take you to Court!
So, provided you are 100% confident that he/she is not going to bark, you are perfectly fine to proceed with your purchase.
I hope this helps, and if so, please don't forget to rate my answer.
Thanks for your reply.
Even though you own a share in the Freehold, you are still under a duty to comply with the terms of the Lease, and hence why this covenant is important.
What is a nuisance comes down to the facts of each case, but it would be to the other residents to prove your dog was being a nuisance. If other people have pets, this certainly goes in your favour, and provided your dog was not barking continuously or for any length of time, a mere bark every now and then, would not constitute a nuisance. I don't therefore think you have much to worry about.