Did you know the word "Cat" never appears in your Bible? However, the word "Dog" or "Dogs" appears 40 times in the AV1611 and one will notice that Dogs are often spoken of negatively in the Bible and in fact there is not one single verse in the Bible that speaks positively of Dogs.
Here is an inexhaustive list of verses about Dogs
1 Samuel 17:43
And the Philistine said unto David, Am I a dog, that thou comest to me with staves? And the Philistine cursed David by his gods.
In the above verse Goliath uses the word dog negatively.
Mephibosheth also speaks negatively about dogs
2 Samuel 9:8
And he bowed himself, and said, What is thy servant, that thou shouldest look upon such a dead dog as I am?
Old Testament Jewish doctrine also taught that a dog was an unclean animal
And whatsoever goeth upon his paws, among all manner of beasts that go on all four, those are unclean unto you: whoso toucheth their carcase shall be unclean until the even.
Hazael used dog negatively
2 Kings 8:13
And Hazael said, But what, is thy servant a dog, that he should do this great thing? And Elisha answered, The LORD hath shewed me that thou shalt be king over Syria.
Dogs are often a reference to wicked people and in this verse it is used to reference the men that crucified our Lord
For dogs have compassed me: the assembly of the wicked have inclosed me: they pierced my hands and my feet.
and also in verse 20
Deliver my soul from the sword; my darling from the power of the dog.
A fool is compared to a dog
As a dog returneth to his vomit, so a fool returneth to his folly.
The Bible also links greediness with dogs.
Yea, they are greedy dogs which can never have enough, and they are shepherds that cannot understand: they all look to their own way, every one for his gain, from his quarter.
And most of all our Lord Jesus Christ used dog negatively and used it as a reference to the wicked.
Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.
In Matthew 15 when a non-Jewish woman came to Jesus he referred to her as a dog (However, after seeing her great faith he then answered her request in v. 27-28.)
24 But he answered and said, I am not sent but unto the lost sheep of the house of Israel.
25 Then came she and worshipped him, saying, Lord, help me.
26 But he answered and said, It is not meet to take the children's bread, and to cast it to dogs.
Furthermore, Paul the Apostle used "Dogs" as a negative connotation as well.
Beware of dogs, beware of evil workers, beware of the concision.
Last but not least, in the book of revelation dogs are used as a connotation to mean the wicked in the list of those who are in hell.
For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie.