Dogs and cats are both popular pets in Bangalore. That said, the concept of having a pet is an emerging one, mostly popular with the upper middle class. There are plenty of stray animals (mostly friendly types) that roam the city streets and some Indians consider bringing animals into your home unhygenic, while others are afraid.
Bangalore isn't known for its sidewalks or walkways, however, there are several large parks, such as Cubbon Park, Lalbagh and Palace Grounds, which offer large outdoor spaces to walk your pet on a leash. Most street dogs are rather friendly so walking your pet shouldn't be an issue, though flees and ticks may become one if they become extra friendly.
Also, be sure to check if the apartment block you have chosen allows residents to keep pets or ensure that your real estate agent is aware that you have a pet while looking for a house, since some societies refuse pets on the premises.
Interestingly 'Bring Fido' ranks Bangalore as the #2 'Dog Friendly City in Asia' due to the presence of five pet-friendly hotels in Bangalore. Pet-friendly hotels/service apartments include Le Meridien Hotel and Chalet Tulips.