Andrea writes in concerning her 18-month-old male Netherland Dwarf rabbit that has suddenly become aggressive, especially when approached in his cage. Andrea has heard that neutering him might help this aggressive behavior and wants to know if, at 18 months of age, he might be too old for that procedure.
Netherland Dwarf rabbits are not, in general, an aggressive breed. The have been heavily bred over the years for their demure looks and small size and can make excellent companions. In fact, rabbits as a group can make excellent companions. They are very intelligent, inquisitive creatures that interact quite well with people. They can be house trained to use a litter box very easily, and I know of many families with rabbits in my care that allow them free roam of their house. This can work out just fine; however, I would caution you rabbit caretakers that these little guys are avid chewers and are not too discriminating on what they decide to chew. They can mutilate electrical cords, furniture, shoes, almost anything down at their level. This is a natural behavior necessary in keeping their front teeth, the incisors, filed down. Without this frequent chewing, their teeth will overgrow and cause severe health problems.
People are often surprised that rabbits can show aggression. They are often thought of as timid, passive little creatures, but as Andrea has noted, this is not always the case. Aggression in rabbits can occur for several reasons. In males, aggression is often seen when defending their territory as well as protecting breeding rights with females (does). In the case of Andrea's bunny, territoriality may be part of the problem. Since this behavior is more common in males, neutering is a likely solution.
Neutering a male rabbit, called castration, is a surgical procedure that is done by a veterinarian that is familiar with rabbits. This is an important point to understand. Rabbits are not dogs or cats and have different requirements for anesthesia than do other types of companions. When this surgery is performed, it is important to keep stress to a minimum in rabbits as it can be very detrimental to their bodies. This includes management of the pain associated with the surgery. As we've discussed in these pages before, pain management is important to all creatures undergoing surgery and rabbits can be especially sensitive.
When a male rabbit is neutered, the testosterone ("male hormone") level in his blood will drop. It stands to reason that any behaviors associated with testosterone will cease. This is an important point to understand. Not all behaviors considered inappropriate in male rabbits are testosterone related and thus are not likely to change with neutering. There are also cases in older male rabbits where certain behaviors such as urine marking (spraying), normally a testosterone related behavior, can become habit and even after neutering, the behavior may remain. To avoid this, neuter your male bunnies at a young age before objectionable male behaviors become habit.
Andrea also asked if 18 months is too old to neuter her rabbit. The answer here is clearly no. There is no age limit after which surgery cannot be performed on a healthy rabbit. The only drawback to having this procedure done later rather than sooner is the potential for certain behaviors to become habit as discussed above. I do feel in the case of Andrea's rabbit that neutering will be extremely helpful in curbing the aggressive behavior described in her letter.
Editorially speaking, I was quite happy to receive this letter from Andrea concerning her rabbit. I truly believe they make fabulous companions and with proper care, can live long interactive lives with their caretakers.
(Jeff Kahler is a veterinarian in Modesto, Calif. Questions can be submitted to Your Pet in care of LifeStyles, The Modesto Bee, P.O. Box 5256, Modesto, CA 95352.)