No, MeredithNa, it is always required to used the "a" in the Personal Direct Object. I know there are some countries where is commonly acceptable not to use it, but the Personal Direct Object needs the "a" and not using it is bad grammar.
There is the same discussion in a exercise in the English for Spanish speakers where some people say that it is correct and people say it is not. Grammar is fixed and it would be nice if we explain it like it is so the people of the course can learn it correctly. We have to try not to thing like we write or speak but like we should write or speak.
The verb "llamar" always requires the use of the personal "a" when using a direct object. If there is no direct object it is not used. And the exception to this rule is when the direct object is a reflexive pronoun (lo/la/los/las in this case because it is DO)
-I called // Llamé
-I called the police // Llamé a la policía
-I call the doctor // Llamo al doctor (or) Llamo a la doctora
-I will call them // Los llamaré
-I am calling him // Lo estoy llamando.
Not always for people, but generally yes. If you are talking about a general person, such as "the doctor" you wouldn't use "a".
For example. "voy a llamar a la doctora" means "I am going to call the doctor (that I always see and have a professional relationship with)"
If you say "voy a llamar la doctora" you mean "I'm going to ring the doctor (and I don't particularly care which one, just as long as they give me my drugs)".
Does that make sense?
It sounds a little weird without the "a". Even if you do not like the dog.
I would say that we use the "a" with specific animal or animals regardless if we like them or not. I mean, if you use the definite article you are talking about some particular animals and you are personifying them. ("a" is only used with people or personified objects) (you are personifying animals in this case, not in all cases you use definite article)
(Ellas) van a pesar al perro. = They will weigh the dog.
(Ellas) van a pesar a las vacas. = They will weigh the cows.
(Ellas) van a pesar a la foca. = They will weigh the seal.
(Ellas) van a pesar perros. = They will weigh dogs.
(Ellas) van a pesar vacas. = They will weigh cows.
(Ellas) van a pesar focas. = They will weigh seals.
PD.- If you are not talking about specific animals, you use the plural without the definite article.
Yes, of course, thank you! So it is not usual to say "...su proprio perro." or "...their own dog." Yet, I found a lot of sentences with " ...su perro" and "...sus perros" It is not like the animal is your own body part, as in "my head hurts" is "me duela la cabeza".
Just pets or animals that you are fond of. For example at the local zoo, there may be a lion who is named and well known and not actually a pet, but is thought of with affection. The personal "a" could apply to that one, but a stray dog whose name you don't know would not get the personal "a" even if he is actually someone's pet but you didn't know it. Wild animals without names do not get the personal "a", unless you just love them all and are characterizing them as if they were pets. Reminds me of shows in which they speak thoughts for the wild animals as if they were people.
Pff. If I'm being honest I don't know but I can tell you none of them sound natural to me. Both of them are understandable (with a little effort).
"Lo voy a seguir a usted" sounds a little bit redundant and pedantic (in my opinion) although it could be heard in normal speech. But "ellas lo van a pesar al perro" sounds awful. In this case using two direct objects ("lo" and "al perro") makes everything confusing.
"lo, la, le" are pronouns that are easy in the grammar theory but make everyone crazy in real speech, even we Spanish speakers have problems with them. I always use la and le in the wrong way.
Grammar tells us that "lo" and "la" is used to direct objects. Lo for masculine nouns and LA for femenine ones. "le" is used for all indirect objects.
You can used them dropping the respective object or just adding them keeping two direct objects or two indirect object (or both).
Despite this I would say that in most of the cases it sounds more natural dropping the object that simply adding. I don't really know why (we'll need a Spanish linguistic to answer this).
So, basically, if you drop the object instead of simply adding the pronoun it will sound better: "Lo voy a seguir" and "Ellas lo van a pesar".