For those of you who don't know, in the Vietnamese zodiac, the fourth animal is the cat instead of the rabbit, which differs from the Chinese zodiac. However, the answer to why this is seems to be difficult to find. After searching online for a bit, I have found several "theories" but none of them seem convincing nor were they supported by any evidence:
1. Vietnamese "misheard" and confused 卯 mǎo (mão in Vietnamese) with 貓 māo (mèo in Vietnamese).
How is this even possible? Up until the late 1800's, Vietnamese, especially those who were in charge of such important things as the zodiac would have been fluent in classical Chinese and characters. Also the zodiac would've been introduced from China to Vietnam via written documents and not verbally. Lastly, the introduction of Chinese culture into Vietnam wasn't a one-time event. It was continuous for thousands of years. Had there been a mistake, someone would've noticed it soon.
2. The change from rabbit to cat was a recent event due to adoption of Quoc Ngu and lost of general knowledge of Chinese characters.
This is just as silly. This would've been a major change and it wouldn't have been adopted so quickly and universally in Vietnam without someone making a fuss. Also there would've been countless documents that needed to be changed and/or destroyed (and older documents to be faked) to support this change.
3. Vietnam didn't have rabbits when the Chinese zodiac was introduced.
Are you kidding!? First of all, what evidence is there to support there were no rabbits in Vietnam around 2000 years ago when the Chinese zodiac would've been first introduced? Also, the last time I checked there were no dragons in Vietnam too yet they seemed to have no trouble accepting it.
So what do you think, or more importantly, what do you know?