Iris and the frisbee

This is the kind of frisbee I've used for three dogs now.  They're a little pricey, especially since I have to order them on the Internet and pay shipping; but it's the only kind I can throw.  I got my first one for Mandy, who never showed much interest in chasing after an inanimate object; when Sadie came along, though, she found her true calling the day I dug out the old superdisc.  

Notice the long leash; I couldn't turn Sadie loose for most of her life with me, not until the last few months.  She would run away, paying no heed to my calling.  I always figured she'd end up getting killed on the highway during one of her escapes; I never imagined her dying from a pork bone.   
And now Iris chases the frisbee with as much passion as did Sadie.  I'm pretty sure she never had any experience with one, though, before she came here.  She was familiar with squeaky toys, and knew how to bite repeatedly in different spots until she found the squeak.  She had obviously chased balls before, and even knew what the word "ball" meant.  

But here's what Iris has done with the frisbee.  Those are toothmarks, and there are even some actual holes where she's pierced through the soft plastic with her teeth.  Although she brings it back to me after she's caught it, she feels she has to kill it before I take it.  When I first got her, I tried giving her a regular cheap, hard frisbee, figuring she couldn't bite holes through it.  
She broke it into jagged pieces, and I threw it away before she could hurt herself swallowing bits of it.  
I've been working with her and the Superdisc, and she is getting much better.  Hopefully this chewed-up one will be sufficient until I get her past the "wanting-to-kill-the-frisbee" stage.  
In the last month or so, Iris has even started jumping high, trying to retrieve the thing in the air.  She's getting pretty fancy!