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Many chinchillas have died in them
DO NOT USE!
None of the balls are big enough for an adult chinchilla and cause the animal to curve its back unnaturally while in it. This can cause back issues, especially for larger chinchillas. These issues often do not show up immediately, but rather take time to manifest.
Another problem is that these balls do not allow a chinchilla to move as they naturally would. Chinchillas do not run. They hop and jump; neither of which can be done in a ball. It is much safer and better for the chinchilla to allow it to run around in a chin proofed room for a short time than it is to put them in a ball. The room allows the chinchilla to run and jump as is natural for them without cramping them into a small, confined space.
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and is in need of immediate vet care.
Finally, and most importantly, these balls do not have adequate ventilation. When placed in these balls, chinchillas rapidly overheat and can die of heat stroke. Depending on the temperature of the room they are in and the activity level of the chinchilla, this can happen as quickly as just a few minutes. A good way of understanding what this is like for the chinchilla is to imagine being in a warm room, wearing a heavy fur coat, and participating in strenuous exercise.
Please, never place a chinchilla in an exercise ball!!!