She suffered a fractured skull and serious bruises to her entire body, including her face.
Shortly after the attack, local news photographer Karem Alzerii came to visit her in the hospital and take her picture.
Both of her eyes were swollen shut, but she forced one open so she could see the stranger trying to ask questions.
It's a tiny gesture, but it's made her a symbol of the violence tearing her country apart, and now the world is taking notice.
نجت الطفله بثينه بحفظ من الله عزوجل لتكون سبب من اسباب هلاك تحالف العدوان السعودي على اليمن باذن الله ..
Posted by Karem Alzerii on Friday, 1 September 2017
(The caption said: "The child survived with the blessings of God, to be a symbol of the loss of Saudi aggression against Yemen.")
Yemen lies at the end of the Arabian Peninsula, south of Saudi Arabia.
It's a relatively young country, having formed in 1990 when the north and south joined to form a single nation.
However, the two sides can't agree on how the country should be run, and this has resulted in violence between government and anti-government forces (also known as Houthi rebels), which has been pretty much continuous.
In 2014, Yemen descended into civil war, and rebels captured the capital.
The country's president, Ali Abdallah Saleh, fled to Saudi Arabia; meanwhile, the rebels established a new ruling group led by Mohammed Ali al-Houthi.
However, Saudi Arabia, together with major powers including the United Kingdom and the United States, have refused to recognise his authority.
In fact, the Saudi government has provided military support to Yemen officials.
Without an established government, the country has become a hotbed of recruitment for terrorist groups including al-Qaeda and Islamic State.
At the end of 2016, the BBC reported the British Red Cross said more than half the population don't have enough food, and about a quarter face starvation.
They estimate as many as 21 million people lack access to basic necessities.
(The caption said: "Thank you God, big interaction with a photo that I took of her yesterday on social networking sites. Each one comes down to a picture of him or his children.")
Conditions are so bad the World Health Organisation has recorded more than 600,000 cases of suspected cholera in the past four months.
Meanwhile, the death toll is continuing to rise.
A United Nations reported in January approximately 10,000 civilians had been killed and about 40,000 were injured due to air strikes and ongoing violence.
Buthaina doesn't yet know her family is dead.
She's now in the care of her aunt and uncle, who have kept a vigil by her bedside.
They told CNN she frequently draws pictures of her family, and often wakes up in the middle of the night screaming and crying.
Hundreds of people are now uploading photos of themselves mimicking her gesture, in a tremendous show of solidarity and support.
The image is going viral, along with the hashtag "#I_Speak_For_Buthaina".
