A spike, which is functionally equivalent to a truncated spike, is also square in horizontal cross-section and similar in size, but has a prong penetrated, and the rail (or "board hold") head has two ears on either side (to help remove the spike), giving the impression of a dog's head.

dog spikes are railroad spikes

dog spikes are used to secure T-shaped railroad tracks to wooden pegs with an L-shaped head and square shank, with the lower side of the head angled to fit the top face of the track base. In order to meet the requirements of different piercing lengths, different piercing sizes are provided. The common track spikes are 5/8 "*6" and 9/16 "*5-1/2" for smaller track segments, which are usually fixed in 200-pound barrels or 50-pound barrels.

dog spikes https://www.hbrailwayfastening.com/Track-spike-Dog-spike.html