Syracusan Cavalry, historical question

[Owain]

I have recently played a couple of games with a friend, Syracucans 280-211 BC versus Carthaginians 280-263 BC, myself as Syracuse. The games have been very interesting. I hadn't previously used the Syracuse army list but I wanted a challenge and I thought this would give me one. I thought I'd be massively outclassed in terms of cavalry. To my surprise, Syracuse is apparantly the best Greek army list for cavalry. I get a total of four heavy cavalry units, two at superior quality and two at average quality. By comparison, Carthage gets 6 units, all at superior quality, so they certainly have the edge, but with my generally superior heavy infantry I think the balance is more in my favour. I checked the other Greek army lists and at the same army sizes you would only get one or two cavalry units. Even some of the Macedonian style army lists for the same period, such as the Pyrhic army, just get 3 units.

Now this got me thinking about the historical justification for so much cavalry in the Syracusan army. I remember the importance of cavalry in defeating the Athenian expedition Syracuse, but other than that I don't know of any justification for such a good amount of cavalry. Any ideas on the historicity of this and sources?