Answer
Wa `alaykum as-Salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa
1- It should be known that it is not advisable for a Muslim to keep a dog except for reasonable reasons.
2- You are allowed, for a valid justification, to keep a dog for guarding, but you have to take every precaution not to have contact with its saliva.
Answering your question, Dr. Wael Shehab, PhD in Islamic Studies from Al-Azhar University and currently the Imam of the Downtown Toronto Masjid in Canada, states:
As you have said, a Muslim is not allowed to keep a dog except for an acceptable reason such as guarding.
You are allowed, for a valid justification, to keep a dog for guarding, but you have to take every precaution not to have contact with its saliva. You should also arrange for a separate living space for it.
Given the above, you may, in case of a real need, opt for a guard dog over personal protection dog in order to avoid direct contact with the dog.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.