My Muslim brother asked me the following questions to which I couldn't find an answer:1) He is a veterinarian and he wants to know what he should do when dogs are brought to him for treatment, because dogs are considered as ''Najas''? Is it Haram for him to treat dogs?2) Can he cut dogs' ears and tail and sterilize them? Your quick answer to these questions will be very much appreciated!

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The Prophet prohibited possessing a dog unless it is for the purpose of guarding or hunting. Abu Hurayrah narrated that the Prophet said: “Whoever keeps a dog, two Qiraat (a great portion) of the reward of his good deeds are deducted daily, unless the dog is used for guarding a farm or cattle, or for hunting.” [Muslim]

Therefore, possessing a dog only for entertainment or amusement is not permitted as it is being practiced by many people who spend a lot of money on them.

In spite of the above ruling, Islam always professes to be kind with all animals. Islam assures a good reward for being kind to an animal even if it is a dog. The Prophet said: “While a man was walking, he felt thirsty and went down a well and drank water from it. On coming out of it, he saw a dog panting and eating mud because of excessive thirst. The man said, 'This (dog) is suffering from the same problem as that of mine. So, he (went down the well), filled his shoe with water, caught hold of it with his teeth, and climbed up and watered the dog. Allah thanked him for his (good) deed and forgave him.’ The people asked, “O Allah's Apostle! Is there a reward for us in serving (the) animals?” He replied, “Yes, there is a reward for serving any living being.” [Al-Bukhari and Muslim]

It is also proved that the Prophet said: “A woman was punished and entered Hellfire because she kept a cat in captivity until it died; she neither fed it nor gave it water to drink; nor did she allow it to go out and eat from the vermin of the earth.” [Al-Bukhari and Muslim]

Therefore, you are permitted to treat dogs for the above Hadeeth and your act would be considered permissible. However, the person who possesses a dog without the above reasons mentioned in the Hadeeth is committing a sin, but you are not responsible for his deed.

Know that treating a vicious dog is not permitted, since the Prophet ordered to kill such a dog.

2. Cutting the ear or tail of a dog, or castrating it, is not permitted without any necessity since this act is a kind of changing Allah's Creation which is forbidden in the Sharee’ah. Allah Says (what means): {Whom Allah has cursed. For he had said, "I will surely take from among Your servants a specific portion. And I will mislead them, and I will arouse in them [sinful] desires, and I will command them so they will slit the ears of cattle, and I will command them so they will change the creation of Allah.”} [Quran 4:118-119]

Imams At-Tabari and As-Suyooti have reported in their Tafseer from many righteous predecessors that the prohibition of changing the Creation of Allah in the above verses means castrating the animals.

However, some Muslim scholars permitted such an act if there is any benefit for doing so, such as to diminish their sexual desire to protect them from fighting to control females.

Imam As-Suyooti narrated from Ibn Sireen that when he asked about castrating the animals, he replied, ‘if you let them without it they would eat each other’.

The same ruling is also narrated from Imam ‘Ataa’. Castrating the lawful animals is also permissible, if it was done to make their meat taste good.

On the other hand, if the cutting of animals' ears or tails or castrating them is to protect them from evil eye or to seek Satan’s or idols’ love; then it is forbidden.

Allah knows best.