Fox Kits!
Though most people call baby foxes "pups", the more accepted colloquial terms in the scientific community are "cubs" or "kits". However, there are generally no "official" correct terms for juvenile animals aside from, well, juvenile.
The female fox is called a "vixen", but we all knew that, right? A group of foxes is called a "skulk", thanks to their sneaky and skulking nature.
Familiar Life in Field and Forest. F. Schuyler Mathews, 1898.