Florida is not exactly known for doing things that make sense. 
Re: the South Florida debate
If it’s any consolation, the Tampa area feels like South Florida temperature wise. Which means the actual South must feel like hell.
It can, but in my experience, anything over 95º is just Fucking Hot™ and another couple degrees here and there don’t make fuck-all bit of difference. Once you get past the Fucking Hot threshold, it’s all the same.
And it ain’t really the heat that gets to me… it’s the stupidity. 
Well, that’s not limited to the South.
Yes it is. It definitely feels like bone . Also, the “bite area” is very smooth to the touch almost like it was worn down. I accidentally broke a piece off and it kind of splintered like bone also. Thanks for the help
Okay, maybe my thought process was just “hmm… what do they have in Florida”, but could it be a manitee tooth? I agree with the others that said it looks like a mammoth or elephant tooth but is wayyy to small. Manitees have the same kind of teeth as elephants where as the molars wear down new ones come in from the back. I can’t find a good picture on the internet, but I wouldn’t be suprised if they look a lot like what your dog found.
Even if you’re not in a part of Florida that currently has manitees, it seems they’re fairly common fossils all over the state.
ETA: Oh, I missed that Colibri already discussed that possibility.
Similarly, down near -20 is the Fucking Cold™ threshold, and going down any further than that doesn’t make any real difference. The only other thing that matters is the wind speed.
Just to pile on the Florida hijack, I lived in the Tampa area for over 40 years. Second the Fucking Hot™ sentiment. With temperatures consistently above 95°F and humidity above 90%, the “Heat Index” (or “Feels Like” temperature) was well over 110°F (frequently over 120°) all day, all night, all year. 3 am in February could still be over 95°, and I have a low tolerance for the heat. Ten years ago I finally came to my senses and got me and my wife to Colorado, away from the “Humbug” (Humidity + Bugs) of Florida.
Manatee teeth: http://www.valleyanatomical.com/catalog/popup_image.php?pID=349&osCsid=8muskliiajetgqj84hgqa4q274
I’m back to horse, I think: http://pmimages.worthpoint.com/thumbnails2/1/1206/04/1_069e09afc28ad43851d7b418f3ced4cc.jpg
The object is not a tooth, of any kind, period. Neither of your links resemble the object except in a very vague way. Horse teeth show no more than three or four “columns” along each side. The object has six columns on one side, and seven on the other; it looks like it is made up of three rows of parallel columns. The cusps of the horse tooth are curved and folded, like this;the upper surface of the object is made up of the ends of about 18 or 19 nearly circular, hollow units, completely different from horse (or manatee) teeth. The shape of the object lengthwise is much longer than a horse tooth.
Trust me, it’s not a tooth.
Organ pipe mud dauber nest cells, fossilized and replaced with chert.
More likely, some variant on a tube worm colony. You get the bone like density and structure for free with tube worm shells.