I am a Turk and no we don't call dogs Arab even they are dark in color, you heard it wrong.
i will edit to @amada's answer...
arap means those who are from arabic countries but it has a second meaning to us.. it it black or dark... so dogs included we can call anything arab. a book, a car, a horse etc... this part may be not good for arabs but does not include any hate.
besides its meaning, a hater person that sees dogs and arabs ( and probably all ppl besides himself) as low creatures, they may say that thing u described. it may have something to fo with islam but we cant say that everybody doing it.. actually i personally never heard or saw someone say that.. its a myth for me.
I agree with Airpole. Dogs are not called Arab. Sometimes Black dogs are. Sometimes Black horses too.
The Arab slave trade was the practice of slavery in the Arab world, mainly in Western Asia, North Africa, Southeast Africa, the Horn of Africa and certain parts of Europe (such as Iberia and Sicily) during the era of the Arab conquests. The trade was focused on the slave markets of the Middle East, North Africa and the Horn of Africa. Slaves were of varied race, ethnicity, and religion.
Because black slaves were associated with Arabs, Ottomans called them " Arab"
Thus, sometimes , black horses or dogs are called " Arab"
By using the word "arab" I do not think they insult any Muslims because they simply refer to the colour of the animal,(usually dark black), and not its religious orientation.
Now, if the Arabs are stupid enough to pass themselves for dogs, then they are entitled to be offended.
Besides, not all Arabs are Muslims.
yea we called them arab if their color black. but that not mean we think they are looks arap people. and yes moslty black dogs called as arab in Turkey... but we gived arab nickname to our friends if their skin black bc mostly turkish white.
lol ive never heard of this i live in turkey, they dont even name their dog arab