Is it haram to keep pets in your house? I know that if you have a dog in your house then the angels may not enter you house but what about other pets such as cats?
Pets are allowed in your home. You can have any animal as your pet, but you need to keep an eye on them too, to take their care and to keep others in care from them.
Dogs aren't allowed, not because they're dogs. But as you have mentioned that Angels won't enter your house. Basically you're taking the most literal meaning or the understanding to this fact.
Guests are taken as the blessings. And Angels bring blessings alongwith them. A dog at home, would sometimes try to bark at them, here in Pakistan dogs are more often to bite the guests too, I remember my neightbours dog bit his cousin (female) who never came back to visit his home again.
Thus, that is why dogs were never allowed, since they're not very welcoming. However, if you can tame them. Then you can keep them in your home, without any issue.
As MAKZ has already provided an example, and I think no one would be able to give an example then his. Hazrat Abu Hurraira(R.A), was given this title because he had a cat as a pet.
Thus, it won't be haram to have pets. It is just their effects on other people. Since the pet you're having won't harm you. But it might not be as much friendly to other, and Islam forces us to take a good care of our neighbours and our friends and family. That's why we must keep those animals as our pets that might not be that much dangerous to our fellows.
A Muslim is allowed to have pets on the basis that the animal isn't oppressed.
There's a hadith attributed to Rasolullaah saying =
دَخَلَتِ امْرَأَةٌ النَّارَ فِي هِرَّةٍ رَبَطَتْهَا، فَلَمْ تُطْعِمْهَا، وَلَمْ تَدَعْهَا تَأْكُلُ مِنْ خِشَاشِ الأَرْضِ
"A woman entered the Fire because of a cat which she had tied, neither giving it food nor setting it free to eat from the vermin of the earth. " [al-Bukhar, Muslim]
So, the woman didn't give the cat its rights, thus, she was punished for it.
As for dogs, I want to mention something first. Dogs are NOT unclean or najis. This needs to be made clear. People say dogs are impure animals without any Islamic proof.
Now, they're forbidden in the house not because of Angels not entering. This was only for Rasolullaah since the angels of revelation didn't come while 'Aisha had her puppy.
If someone claims any angel won't enter, we should ask what about the angel of death? What about the angels writing our deeds? Will we never die or never have our deeds written?
Therefore, angels not entering our home was restricted to the Prophet only, no one else.
However, dogs are forbidden because of another hadith attributed to Rasolullaah, he said =
مَنِ اقْتَنَى كَلْبًا لَيْسَ بِكَلْبِ مَاشِيَةٍ أَوْ ضَارِيَةٍ، نَقَصَ كُلَّ يَوْمٍ مِنْ عَمَلِهِ قِيرَاطَانِ
"Whoever keeps a dog, which is neither a watch dog nor a hunting dog, will get a daily deduction of two Qirat from his good deeds."
As you can read, dogs are forbidden because two qirat of our good deeds will be taken away. Allaah tells us in the Quran not to destroy our deeds.
But, the Prophet made two exceptions to have dogs = watch dog or hunting dog.
If dogs were impure, or najis, the exceptions wouldn't matter.
As for pets in general, there's no prohibition as long as you don't oppress the animals.