The current Catechism of the Catholic Church is one of Pope John Paul II major endeavor, some consider it his greatest work. It was completed in 1997. The information within is* both *timeless and current. By current I mean there are issues within that did ot exhist at the time of Christ such as IVF etc.
In regards to the section on animals, it falls under the Seventh Commandment,* Thou Shall not Steal. * The placement of animal rights in this section is significant. Please note that it does not fall under the Fifth Commandment,
Thou Shall not kill The fifth commandment also covers issues of wrath.
Also note that most Vatican documents are originally in the Language of the Church, Latin. It is then translated into other vernacular languges. This translation if not an easy task, especially for English, because English is not a Romance language. (a language with mostly Latin Roots). When one translates, one must take into account vocabulary, grammar and syntax. It seems that you are not sure of the meaning of the word"needless"
So let us look at the Latin text:
2418 Humanae dignitati est contrarium animalibus inutiliter dolores inferre et eorum dilapidare vitas. Indignum pariter est pro illis pecuniae expendere summas quae potius hominum miserias deberent sublevare. Animalia amare licet; affectio solis personis debita ad ea averti non deberet.
In the original Latin the word* inutiliter *is used. If we look at the meaning of the word in a Latin dictionary, we find:
inutilis, inutilis, inutile ADJ [XXXBX]
useless, unprofitable, inexpedient, disadvantageous; harmful, helpless;
So while needless is used in the English translation, the meaning of needless is closer to the above.
The word
need in latin is:
necessitas, necessitatis N F 3 1 F [XXXAO]
need/necessity; inevitability; difficult straits; poverty; obligation; bond;
Note that this term does not appear in the original Latin.
Hope that helps.