Is there an old way of pronouncing 牠?
I think it's an old pronunciation. I remembered this pronunciation appeared in a classic poem composed approximately in Tang dynasty.

珠泪纷纷湿绮罗，少年公子负恩多。当初姊妹分明道，莫把真心过于他。仔细思量着，淡薄只闻不好么？

The note says the correct pronunciation is &quot;tuo&quot;, which rhymes with &quot;罗&quot;,&quot;多&quot; and &quot;么&quot;. According to the poem's pattern,&quot;他&quot; should rhyme here.
In modern usage, I don't sound &quot;tuo&quot; in any case. &quot;ta&quot; is the only correct pronunciation. In order to rhyme, I'll read some characters with old pronunciations when reading classic poems.
Such a phenomenon is called &quot;古音异读&quot; (lit. special ancient pronunciation), however, while the languages is evolving as time flies, some special pronunciations have been ignored by the public, and thus get lost.
Some other examples for &quot;古音异读&quot;. The fomer pronunciation is &quot;modern pronunciation&quot;, and the latter is the &quot;special ancient pronunciation&quot;.

可汗 kě hàn vs kè hán
莫顿 mào dùn vs mò dú
斜 xié vs xiá
汤汤 tāngtāng vs shāngshāng
骑 qí vs jì

Sometimes I'm still confused when reading these characters. A typical one is &quot;骑&quot;, when I learned it in a famous verse &quot;一骑红尘妃子笑&quot;, I was taught the correct pronunciation was &quot;jì&quot; which means &quot;a rider on a horse&quot;; however, now in the dictionary, the pronunciation for this meaning is also qí.