Spikes

Opal had been warned that werepanthers were different from werewolves. The rumor was that like their feline cousins, male werepanthers had penile spines (spikes) to keep the female from escaping during mating. And those spikes hurt like hell. But Markos was so handsome and sexy, Opal just had to have him. And when she looked in his pants, she didn't find any spikes, but what she did find impressed her.
However, once he was inside her, Opal found out the painful truth.