"The dog is a pet."
Translation:Ο σκύλος είναι κατοικίδιο.
Two correct translations were given: the one above, and "Το σκυλί είναι ένα κατοικίδιο". So, the gender in one is neuter, and other is masculine, and the neuter one is not for "puppy". Two questions, then.
Is the neuter form used to indicate an animal that has been been to the vet for the operation?
And why is the indefinite article used in one sentence and not the other? (I would guess both are correct, but the article is optional?)
The genders of Greek words isn't based on the actual gender of the person or object. For example, the boy is το αγόρι neuter, but the chair is η καρέλα feminine.
Dog can be used as:
General: "το σκυλί the dog ιn general, boy or girl "I don't know which it is or it doesn't matter.. (no operation),
Male: but if you want to talk about a male dog you have "o σκύλος"
Female: or a female dog you have "η σκύλα".
It is written with double accent only if a completely unaccented word (e.g. a possessive) follows it.
το κατοικίδιο "the pet" but το κατοικίδιό μου "my pet".
Those possessives have no stress of their own, so they form a single (phonological) word with the word before them -- but the "word" κατοικίδιο μου would have the accent on the fourth syllable from the end, which is too far back. So the word takes another accent on the second syllable from the end (the final syllable of κατοικίδιο).