This should answer some questions
QUESTIONS AND ANSWERS
1. Q: DO TENNIS BALLS CONTAIN HARMFUL CHEMICALS?
A: According to Wilson Sporting Goods and Penn Racquet Sports Company, their tennis balls are made of rubber and latex, and the felt covering the ball consists of wool and nylon. The dyes used to color the felt are non-toxic. I currently do not have information from other manufacturers, so I cannot say anything about the safety of their balls. If you come across such information, please let me know. Latex is probably the most harmful of these materials, since some dogs could be allergic to it. Latex is generally used in rubber gloves, for example, and some humans are allergic to it too.
2. Q: DO TENNIS BALLS NEED TO BE WASHED BEFORE GIVING THEM TO A DOG?
A: This probably does not make a big difference, since the balls will get dirty when rolling on floor and ground. If you are worried about chemicals, use non-toxic tennis balls and see question 1. For information about washing tennis balls, see question 3.
3. Q: HOW DO I WASH THE TENNIS BALLS?
A: Rinsing the tennis balls occasionally with water is a good idea. You can also use dish washing detergent to wash the ball. Remember to rinse well, though. Tennis balls can even be washed in a washing machine! Here's a quote from Keith Yockey, who competes in flyball with his BC: "I do wash my balls in the washing machine, and the spin dry cycle is plenty good. After all, a slobbery covered ball dries as quick as a spin dried one, and I have had no problems in this area." So, looks like a dryer cycle is not required.
4. Q: WHAT IF MY DOG EATS A TENNIS BALL?
A: Be careful with what your dog eats, since dogs eat anything! Dogs can eat all kinds of things, such as socks and shoes. In the worst case these could block your dog's digestion and require surgery! If your dog is big enough to chew the ball into pieces, your dog may well eat some of the pieces. Also, if your dog is large, he may try to swallow the ball whole, which could choke your dog.
I have been trying to figure out a rule of thumb of the dangers of a tennis balls for a dog, and this is the best I have come up with so far: If your dog is capable of opening the mouth wide enough to be able to chew a tennis ball with molars, then there may be a risk of your dog chewing the tennis ball apart and eating the pieces or even trying to swallow the ball whole. If your dog is not able to chew the ball with molars, then a tennis ball should be quite safe, since your dog can only wear the ball out by pulling the felt off the ball.
If your dog chokes on something that is in the back of the mouth, you can try to pull the object out the mouth and possibly use a tool such as a spoon. Be careful that the dog does not bite you at this point, since he may panic. If your dog chokes on something in the throat, you can use Heimlich's (A special squeeze around the dog to pop the object out) or for a smaller dog to lift the dog by rear legs and swing the dog with head down. However, I'm not a specialist in this area; if you have a dog you should read books and FAQs about animal first aid. So, observe your dog first to see what happens to a tennis ball before you leave your dog alone with a tennis ball. In general, do not let your dog eat anything that could block your dog's digestion or choke him!
5. Q: DOES CHEWING ON TENNIS BALLS WEAR TEETH?
A: Reportedly the tennis balls may wear down teeth, and washing the balls would solve the problem.
I had hard time believing this theory at first based on my experience as a tennis player. Most of my experience with tennis balls comes from when I was playing lots of tennis and stringing tennis racquets. When playing tennis on a hard court, the felt on tennis balls tends to wear out after couple hours of playing. The hair on the balls comes so much shorter that you can actually notice a difference in the ball diameter when comparing to new balls. Also, during the play typically at least three balls are used, and they all wear down. This makes me think that tennis balls are not very abrasive.
Also, the strings on a tennis racquet tend to wear down after about 10-100 hours of play depending on the players skills and spin used on the ball. Racquet strings mainly wear down because of the friction between crossing strings when they move relative to each other. I have not noticed really any wear on the strings from the balls, except when playing on red clay, which leads me to think of the following theory:
When playing tennis on a red clay, sand gets deposited in the felt of the ball. The sand deposited in the felt acts as abrasive powder, and wears down the racquet strings. In the same way, if tennis balls are used outdoors for dogs, sand will get deposited in the felt of the tennis ball. The sand can then act as abrasive powder if the dog chews on the ball, which could wear down the teeth. For example, Flyball is mainly played outdoors, and Cris Waller, who has experience in Flyball dogs, responded that many Flyball dogs he has seen have worn teeth where the tennis ball is held.
So according to this suggested theory, it is not the tennis ball that is abrasive, it is the sand deposited in the felt. If so, it means that washing the tennis balls on regular basis is very important. Please see question 3 for information about washing tennis balls. If anybody has further information on this subject, please let me know.
6. Q: WHAT MAKES SOME TENNIS BALLS BETTER THAN OTHERS?
A: There are differences among various tennis balls. Be careful that you give your dog only good quality tennis balls! Basically there are two things that define how good a tennis ball is from a dog's point of view. These requirements are not necessarily the same as the requirements from a tennis player's point of view. Firstly, the felt has to be attached to the ball so that a dog cannot pull it off and eat it. This problem occurs a lot in cheaper tennis balls. Secondly, the ball has to be made of thick rubber, so a dog cannot chew it apart that easily. According to my personal studies, Wilson Championship and Advantage tennisballs, and Penn's Championship and SpinTrak tennis balls have a good quality felt attached to them which does not peel off easily, and the balls are made of thicker rubber than most other balls making them more durable. Probably the most durable tennis balls available are Wilson Advantage tennis balls, which are non-pressurized training balls. These balls have a lot thicker rubber layer than regular tennis balls. However, these balls are also a bit more expensive than regular tennis balls.