Dog in the flat

Hello,
I have a dog in the flat. Start having complains from the company, who owns the house. The company's solicitors send me a letter, which says: "The terms of lease do not allow dogs at the property".
Me and my husband are owners of flat for two years now, and bought a dog last Christmas. We haven't read  the lease terms before having puppy.
To loose a pet in own flat as he stays inside and we have two kids who loves him - it seems not good. But company asked to remove dog from the property in 14 days from today.
I dont know what to do... Can you suggest something?