Some friends of mine have just got a very cute little puppy and I was wanting to make him a little present for Christmas, I searched about online and came across something I knew would be perfect – this knitted dog ball: 
http://m.instructables.com/id/Knitted-dog-ball-that-helps-clean-their-teeth/?ALLSTEPS
The only problem was it was a knitting pattern rather than crochet, so to adapt this for crochet I just used dc stitch and did the following pattern, making two strips in three different colours (6 strips in total):

Crochet dog ball:

4mm hook

11ch 

Row 1: dc into 2nd ch from hook, dc rest of row 

Row 2-60: ch1 (doesn’t count as a stitch) dc along row  

Fasten off. 
Once the strips are made I followed the instructions to join and wrap the strips together to make the ball, I found it quite fiddly and it took me a few attempts to get it right, but when I did the following I managed to get it to work: 
1- Take a blue strip and sew the ends together to make a round, then take a red strip and pass it through the blue round and sew the ends to make another round. Now take the second blue strip and pass it through the red round and sew the ends together to make a final round.  

  
2- Lay the loops out flat as shown in picture below to make sure they are in the right places, a lot of the problems I encountered were because I didn’t have them like this. I put a stitch marker in one of the strips so not to get them mixed up.  

   

3- Take the second red strip and place it as shown in the photo below and sew the ends together. 

  

4- Put a little stuffing into the middle as it will make the next stage a little easier – although it is still quite fiddly! 

  

5- Take one of the yellow strips and weave it over the strip. Start by going under a blue, over the next blue and repeat going around the ball until you get back to the start and sew to join.

  

6- Take the second yellow strip and start going over the blue strip that you previously went under, then over the next and repeat around until you get back to the start and sew to join.  

  
7- Put more stuffing into the ball so it becomes fully ball shaped, now sew along the edges of the strips to seal them so the stuffing doesn’t come out.  

  
   
   

Despite the fiddly bit driving me a bit crackers it was worth it, and I know it’s recipient will have a lot of fun with it on Christmas Day! You could make these bigger too by increasing the number of rows, and by increasing the number of stitches on the starting chain to increase the thickness of the strips.