Plural de "Pet"

Normally you ask "what is your favorite pet?" (here a question about pets in general).

But sometimes, but not so often, "what are your favorite pets/animals?" Now to single out one or a couple of them, from a group - say, if are in a pet shop, veterinary hospital, zoo, etc. A place where you have many animals.
Or even in a general way, as the one above, but it´s used (with the plural form) once in a blue moon (or almost)!
So, if you use with the plural form you won´t be sued on it. But if you use the singular you will be with more company!

pet

1. (noun)
Plural form: pets

Examples:

Samantha has a lot of pets on her farm.
>> Samantha tem vários animais de estimação em sua fazenda.
_

English grammar rule: Adjectives and verbs do not take the plural ending. The verbs are conjugated.

2. (adjective)

A) One of her pet projects is the Veterinary Medicine.
>> Um de seus projetos prediletos é a Medicina Veterinária.

B) One of Samantha's pet peeves (AmE) / pet hates (BrE) is the animal neglect.
>> Uma das coisas que mais irrita Samantha é a crueldade com os animais.
>> O que deixa a Samantha zangada é a crueldade com os animais.
_

3. (verb)

A) The cats came to be petted.
>> Os gatos vieram para serem acariciados (=afagados).

B) I was cosseted and petted and never shouted at.
>> Eu fui (extremamente) mimado e favorecido (= tratado com favoritismo) e jamais levantei a voz.

REFERENCES:
(1) Pearson Education. Longman Dictionary. 2nd ed. 2009.
(2) Oxford Online Dictionaries.