He does not pray Fajr in the mosque because he is afraid of the stray dogs

Firstly: 

Praying in congregation in the mosque is obligatory for every adult male who
is able to hear the call to prayer, according to the correct scholarly
opinion, because Allah, may He be exalted, says (interpretation of the
meaning): “And establish prayer and give zakah and bow with those who bow
[in worship and obedience]” [al-Baqarah

2:43].
And there is other evidence which you may find in the answer to question no.
8918 

What is meant by hearing the call to prayer is hearing it at a normal volume
without any amplification when all other sounds are quiet and there is
nothing to prevent you from hearing it. It should be noted that the
mu’adhdhins at the time of the Prophet (blessings and peace of Allah be upon
him) used to give the call to prayer from a high place, such as the roof of
the mosque and the like, and the structure of the houses was such that the
sound could be heard and carried, which made it possible for the voice of
the mu’adhdhin to reach a considerable distance. 

Based on that, at a distance of ten minutes walking it is ordinarily
possible for the sound to reach you; in fact it could reach a distance
further than that. 

The Sunnah indicates that there is nothing wrong with praying in one’s house
and not going to pray in congregation in the mosque if there is an excuse
for doing so. It was narrated from Ibn ‘Abbaas (may Allah be pleased with
him) that the Prophet (blessings and peace of Allah be upon him) said:
“Whoever hears the call and does not come, his prayer is not valid, except
for those who have an excuse.” Narrated by Ibn Maajah (793); classed as
saheeh by al-Albaani in al-Irwa’, 2/337 

Based on that, if a person fears for his life or fears extensive harm, or
fears that he may be taken and put in prison wrongfully, this is regarded as
an excuse for his not praying in congregation, and for offering the prayer
in his house, so as to protect himself. 

Ibn Qudaamah (may Allah have mercy on him) said in al-Mughni (1/366):
The one who is afraid is excused for not offering prayers in congregation or
praying Jumu‘ah, because the Prophet (blessings and peace of Allah be upon
him) said: “A (valid) excuse is fear or sickness.” End quote. 

But if the place is safe and the dogs in the street only bark and do not
harm anyone, then in that case you must go to the mosque. 

If you can manage to get a car in which you can go to the mosque, that is
good and more appropriate. It was narrated that Ubayy ibn Ka‘b said: There
was a man, and I do not know of any man who lived further away from the
mosque than he did, but he never missed a prayer. It was said – or I said –
to him: Why don’t you buy a donkey that you can ride when it is dark or when
the sand is too hot? He said: I would not like my house to be next to the
mosque. I want my walking to the mosque and my returning when I come back to
my family, to be recorded for me. The Messenger of Allah (sa) said: “Allah
has gathered all that (reward) for you.” Narrated by Muslim (663) 

If you answer the call of the mu’adhdhin, even though you are far away and
you put up with the hardship of walking or come by car , that is good for
you and is preferable, and Allah will record your footsteps and efforts to
go to the mosque and return from it, if your intention is sincere. 

And Allah knows best.