我们现在知道为什么马会喷鼻——因为他们很高兴

snort:

v. 用鼻子哼（以表示不耐烦，轻蔑等）;  （马等）喷响鼻子;   （轻蔑、愤怒时）高声大笑;   汽锅)喷汽;  

n. 喷鼻息，鼻息声;   〈美俚〉一口酒; 

Snorts indicate positive emotions in horses

https://www.sciencedaily.com/releases/2018/07/180711141401.htm

We now know why horses snort – because they’re happy

https://www.newscientist.com/article/2174005-we-now-know-why-horses-snort-because-theyre-happy/

Mathilde Stomp, Maël Leroux, Marjorie Cellier, Séverine Henry, Alban Lemasson, Martine Hausberger. An unexpected acoustic indicator of positive emotions in horses. PLOS ONE, 2018; 13 (7): e0197898 DOI: 10.1371/journal.pone.0197898