"My heart is going to explode," the 39-year-old reality star wrote alongside a pic of Sailor snuggling up to Kash. Zolciak and Kroy Biermann's son also received a bike and got to smash a piñata on his big day!
In April, Kash was seriously injured after getting bitten by a dog and had to undergo surgery. Luckily, all went well, with Zolciak frequently updating fans on her son's progress and treatment following the traumatic incident.
On Tuesday, Zolciak also posted a sweet birthday message for her 5-year-old on Instagram and even surprised him at school during lunch.
"Car ride to school😍 Happy 5th Birthday to my sweet @kashbiermann no words to describe how much joy, happiness and excitement 😉 you have brought to our family," she wrote. "We love you so very much❤️ (a lot for me to handle 1st day of kindergarten yesterday & today his birthday) 😭 my animal loving, heart of gold, smart, sweet little angel I'm forever grateful you chose me to be your mommy!! You are in for an INCREDIBLE day and some BIG surprises!! ❤️🎁🎊🎉🎈🎊🎈."
"Is it OK to drink wine at 7am?!!" Zolciak wrote on Instagram on Monday. "I'm such a mess over my 'kashew' starting kindergarten tomorrow.. I couldn't snuggle him hard enough tonight (Kroy is sad too) you know he is when he says it's OK for them to sleep in our bed."