Should Animals Be Buried When They Die?
Question

“Part of honoring the deceased is to bury him”– does the word deceased include even animals because I buried an animal of mine when I heard this Hadith?
Praise be to Allah.Is ‘Honouring the deceased means burying him’ a Hadith?
“Honouring the deceased means burying him” is not a Hadith; rather these are the words of one of the jurists. (See Mukhtasar Khalil by Al-Kharashi, 2/91) 
As-Sakhkhawi (may Allah have mercy on him) said in Al-Maqasid Al-Hasanah (p. 141): 
“I did not find the Hadith “Honouring the deceased means burying him ” in any report attributed to the Prophet (blessings and peace of Allah be upon him). Rather it was narrated by Ibn Abu Ad-Dunya in his Kitab Al-Mawt, via Ayyub As-Sakhtiyani. He said: ‘It was said that a sign of honouring the deceased on the part of his family is their hastening to bury him.’” 
But the meaning is correct and is in accordance with the Sunnah. 
Should animals be buried when they die?
We do not say concerning an animal, when it dies, that part of honouring it is burying it, as we say about human beings. But if burying an animal will ward off harm from the Muslims, then it is prescribed to do so, because burying it in that case comes under the heading of removing something harmful from the road used by the Muslims. 
If the Muslims will be harmed by an animal when it dies and bothered by its smell, then it is obligatory to bury it or take it far away from the highways and byways used by the people. Hence it is prescribed to bury it, in order to ward off harm from the Muslims, not just because it has died. 
Al-Bukhari (1492) and Muslim (363) narrated that Ibn `Abbas (may Allah be pleased with him) said: A sheep was given in charity to a freed slave woman of Maymunah, but it died. The Messenger of Allah (blessings and peace of Allah be upon him) passed by it and said: “Why don’t you take its hide and tan it, and make use of it?” They said: It is dead, O Messenger of Allah (i.e., it died of natural causes and was not slaughtered properly). He said: “It is only prohibited to eat it.” 
So he (blessings and peace of Allah be upon him) encouraged them to make use of its hide, and he did not tell them to bury it. 
The scholars of the Standing Committee were asked about vermin and animals and so on; should they be buried, or left unburied on the ground? 
They replied: 
“The matter is broad in scope, because there is no text in Shari`ah to indicate that it is prescribed to bury them or to forbid doing so. But it is preferable to bury them so that they will not harm or bother anyone.” (Fatawa Al-Lajnah Ad-Da’imah, 8/444-445) 
For more details, please refer to the following answers: 11437 , 14404 , 146155 , and 119652 . 
And Allah knows best.