The phrasal verb attend to means 1) to work for or be a servant to, or 2) to apply one’s attention to. Tend to means 1) to have a tendency, 2) to work for or be a servant to, or 3), to apply one’s attention to. As you can see, attend to and tend to are synonymous in attend to‘s two meanings. Both verbs can be used intransitively—i.e., without the to—but often the to is necessary to avoid confusion with other senses of attend and tend.
Examples
For example, the writer wisely includes to in this sentence because attend alone could cause confusion:
Those that attend to the long-term energy needs of their companies will gain an edge over those that don’t. [Forbes]
When the to can be dropped without creating confusion, attend on its own carries the same meaning—for example:
Instead, time and again and in appalling weather, he went into no-man’s-land to search for and attend the wounded. [Telegraph]
With tend to, the to could more often be dropped without causing confusion. In fact, given the above-listed first definition of tend to, dropping the to is usually advisable for the second and third definitions. For example, these sentences do not need the to:
… Animal Control worked with the man to reduce the number to the legal limit of three, then left him to tend to his pets. [Chicago Tribune]
Her maternal urge to tend to her baby trumps the physical pain she has to endure … [Herald Sun]
In the end, it’s safe to use or drop the to according to what sounds best to you.
