Chinchilla Suddenly Attacks Its Cagemate

Why would a chinchilla suddenly attack its cagemate after three years together?

Once one chinchilla begins picking on the other, it is unlikely the pairing will ever be safe. Gina Cioli/Lumina Media

By Marty Hull


I have two chinchillas, ages 5 and 3. When I got the younger one, I introduced them slowly and they eventually became friends and shared a large cage for three years. All of a sudden, about three or four months ago, my older chinchilla started attacking the younger one, biting and pulling his fur out constantly to the point where I had to separate them. I tried for a week making loud noises to distract the older one, hoping he would stop, but he just kept on and on.

Why did he do this so suddenly? Is there any way of getting them back together? I can’t even let them out together to play because the older one chases and attacks the younger one constantly.


Possible chinchilla pairing options are two males, two females, or one male and one female. Some chinchilla pairings may last for the life of the chinchillas, but any chinchilla pairing may suddenly disintegrate due to attitude/hormonal changes in one or both of the pair, or due to external factors.

Male/Female Pairs

This is the most stable pairing, but hormonal changes in the female chinchilla can lead her to attack the male. She may bark and spray him with urine. Then she may chase him around the cage, biting out clumps of his fur. If the male chinchilla does not take the hint that she wishes to be left alone, the female may launch a full attack, which could severely injure or kill the male. This can happen even in pairs that have been together for many years. A female chinchilla that displays this behavior may not be receptive to accepting a male at that time or possibly in the future.

Warning: Once one chinchilla begins picking on the other, it is unlikely the pairing will ever be safe.

One approach is to separate the chinchillas for a cooling-off period and then try them together again. When re-pairing is attempted, the pair should be monitored constantly to be sure the aggression has passed. Carefully observe the chinchillas’ behavior. If one is excessively dominating, the more submissive chinchilla will be in a constant state of stress. This is not a healthy environment.

If the pair cannot be re-paired, a reasonable solution is to keep each in a separate cage, placing the cages next to each other with enough distance between cages so no toes get bitten off.

Male Pairings

From your question, it sounds like you have two male chinchillas. Pairing very young males can be successful, but issues of dominance usually develop and fighting is common as they mature and hormonal development progresses.

In a pairing of a mature male and a very young male, the younger chinchilla will be submissive. Issues of dominance do not arise. As the younger male matures, he may contest the older chinchilla for dominance. Again, fighting is usually the result.

If a female is anywhere in the vicinity of the male pair, the moment she comes into heat, the males will fight. Fighting can begin with chasing and fur-pulling. This can quickly escalate to biting and severe injury. If the chins are not separated immediately, one chinchilla may kill the other.

Chinchilla fights may result in death, because chinchillas have very long, sharp front teeth and powerful jaws. One quick bite may penetrate the skull, the spine or a lung. That can be fatal and can happen in less than a second.

Female Pairs

Female pairings are generally more successful than male pairings, but, like all pairings, the relationship may suddenly disintegrate. If this happens, separate the chinchillas.

If a male chinchilla is in the vicinity, the two females may compete for his attention and become aggressive toward each other. There may be hormonal shifts or one chinchilla may just prefer to live alone. If the pairing disintegrates, provide the chinchillas with separate cages.

Bottom Line

If a pair of chinchillas gets along, keep them together. If they have a significant disagreement, separate them immediately and then try to re-pair after a cooling-off period. Monitor the re-pairing very carefully and be ready to separate the chinchillas permanently.

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Chinchillas · Critters