So sad to contemplate...

The actions that led to the Titanic's sinking claimed not only human lives but also those of innocent animals. A number of first and second class passengers had their dogs with them, and some were bringing livestock along, namely poultry.

One account I read stated that there were so many dogs aboard, a dog show was planned for April 15th.
("Story of the Titanic", with Dr. Eric Kentley as Consultant and Steve Noon as illustrator) There was also at least one cat.

"Very few of Titanic's animals survived the ship's sinking. Three of the dogs were taken aboard lifeboats by their owners. Margaret Hays' Pomeranian got away safely in Lifeboat 7 and lived until 1919, while Elizabeth Rothschild refused to board Lifeboat 6 unless her dog was allowed to come too. (Her husband was left on board and died.) Henry and Myra Harker brought their Pekingese aboard Lifeboat 3 but Helen Bishop had to abandon Frou-Frou in her cabin, much to their mutual distress. The dog made an unsuccessful bid to stop her by holding on to her dress with his teeth until the seam tore. Afterwards Bishop spoke of her sorrow: "The loss of my little dog hurt me very much. I will never forget how he dragged on my clothes. He so wanted to accompany me."

None of the other animals survived. At some point during the sinking someone decided to free the dogs from their kennels, leading to the surreal sight of a pack of excited dogs racing up and down the slanting deck as the ship went down. One female passenger is said to have refused to be parted from her dog and chose to stay aboard. Several days later, as the SS Bremen passed through an area still strewn with debris and bodies floating in the water, passengers saw the body of a woman tightly holding a large "shaggy dog" in her arms. Robert Daniel's bulldog Gamin de Pycombe was last seen in the water swimming for his life after the ship went down."

And let us not forget the rats! "Finally, like any other ship of the time, Titanic had a substantial population of rats. One was seen running across the Third Class Dining Room on the evening of the sinking, to the shock and amazement of the diners. Some of the women who saw it burst into tears, while men tried to capture the rat, but failed."

Quoted sections are from: http://en.wikipedia.org/wiki/Animals_aboard_the_RMS_Titanic