for the past 2 months I have been feeding my Mastiff with chicken and meat alone, is there any problem with this?

Yes, dogs need more than protein and fat unless you have been feeding complete and uncleaned then you may get away with it. You need to add some carbohydrates and trace elements, minerals & vitamins.

You also need a calcium source, unless your feeding whole chicken complete with bone, you also need some offal and a source of omega's such as salmon oil or oily fish.

i do feed whole chicken and also meat with bones, fish also.

Dogs need protein, minerals, vitamins, fats so you need to give bone or, if not, another source of calcium.

There is no proven need for carbohydrates in dogs and many people, like me, do not feed any except those found in fruit and vegetables.

I would strongly suggest you find a good book which lists the nutritional needs of dogs and the sources.

Yes as thome says only meat fish and bone is fine. It is one way of feeding raw that is perfectly acceptable and after research that was the method I choose for my three.
Others do include carbs but it is acse of doing your research and deciding which road you go down.
The important thing is to feed as wide variation as possible and as near whole as you can. ie whole rabbit is best, chunks is fine including fur and bones mince better than nothing
include liver kidney heart green tripe infact any kind of fish and meat you can get

Look up the dogs dinner by ann ridyard she also has awebsite if you cant find it pm me good information from  someone who has been raw feeding for a while
There are other sites  Ian billingshurst, Tom lonsdale one includes carbs one doesnt and Kathy shmultz (sp )

An odd name this one!  Kymythy Schultze - good book though

I like this book too by Tom Lonsdale

There's no reason not to just get started with raw but it's very important to do your research to make sure you are including everything, and the right balance of bones and offal to meat.

Thanks dab thats the one I got most of the letters but in the wrong order  doh !