"My dog keeps getting sick."

Translation: 我的狗一直在生病。

[DING318658]

is the 在 scrictly necessary?

[KX3.]

Whether it is strictly necessary or not is a question of accuracy that I can't give a sure answer to, but it is necessary to sound smooth （顺） which is important when deciding whether or not to leave some characters, which are not always essential to the sentence 虚词, out or add others in.

It would sound at least a little unnatural to leave 在 out in this sentence. You can, perhaps, think of 生病 as a verb, not a noun, here.

[Gabrielle145359]

生 is a verb :-) 病 is the noun.

[tim981145]

So it's a Verb-Noun composition like 吃飯 and 爬山 and so on?

[Gabrielle145359]

Further research shows that both of those characters can be a verb or a noun in different situations, so perhaps it is not as clear cut as those other examples. However, I do still think that in this expression, 生 is the verb and 病 is the noun.

[JPSeaton]

Tell him I taught Chinese for 35 years and I would say you're right.

[Debonnaire]

IDK but I left it out too

[roman2095]

It is accepted without out it.

[tim981145]

Why is it not 我的狗一直生病了 ?

[StasioFigurka]

I wonder the same

[CharlesE780046]

Why is the Chinese not equivalent to: My dog is always sick or continuously sick. I would think that keeps getting sick implies multiple sicknesses and would therefore be 我的狗一直生病了。 to show the repeated change of state from healthy to sick.

[jim750574]

is it really necessary 的 ?

[EU1V14]

I think it is. You just omit it with close human relationships.