Aural Hematomas in Chimps
A hematoma is a localized accumulation of blood that is confined within an organ or tissue, sometimes referred to as a blood blister. The most common type of hematoma in animals affects the ears and is called an aural, or ear, hematoma.
How does it happen?
Aural hematomas occur when a blood vessel in the ear bursts and bleeds into the space between the ear cartilage and skin. This is uncommon in chimpanzees based on their ear anatomy, which is similar to ours, but can occur. They occur most commonly associated with trauma, such as a scratch or a bite from another chimp.
There is normally not a lot of space in this area of the ear so when it fills, it can be very tight and cause an uncomfortable amount of pressure. If due to trauma, there could be bacteria trapped inside and potentially lead to an abscess. As the body tries to fix itself, it sends a lot of its helper white blood cells and tries to remove the blood and repair the aural hematoma. This process can cause significant inflammation, which if you are a chimp and you feel something not right, you pick at, tear at it, and/or try to pull it off.
Rocko
That was the case for Rocko, a 32 year old male resident at Project Chimps.
Recently Rocko’s bachelor group was introduced to an all-female group. For most of these boys it was the first time being around a member of the opposite sex. Most of the group got along and found themselves fast friends. But with any new friendships, there are likely to be small arguments.
The caretakers observed that both Rocko’s ears had been bitten. This is a very common interaction with chimps as aides in establishing dominance and is not about inflicting damage. The ears healed really well and within a few short weeks, Rocko was strutting his stuff for the new girls like all the other boys.
However, a few months later a second injury happened, and it ruptured a blood vessel in Rocko’s left ear. Rocko now had an aural hematoma on the tip of his left ear.
Treating a hematoma
It bothered him immensely; he was more than eager to show us his ear and get help. With positive reinforcement training we were able to look at the ear repeatedly and monitor it for signs of inflammation, infection, and pain.
He was given medications to help initially, but it still continued to grow larger.
We spent three weeks training Rocko to present his ear and eventually to allow a light poke with a chop stick. He was happy to participate and made it clear when he was done by spitting in our face! Eventually we were ready to lance the ear using a scalpel blade and allow it to drain.
Rocko was pretty mad at us that afternoon and the rest of group told us of their disapproval for upsetting their friend. But the following morning the ear looked much better!
Within a week the entire group had forgiven us, including Rocko and Mama Bear of the group, Lindsey.
Today, there is still a slight swelling, but it is causing him no pain or discomfort. He will show it to anyone, anytime….just remember he expects his reward!
This is just one of many examples where mutual cooperation and dedication can provide the best care possible for chimpanzees in a fun and rewarding setting. While we hope no further injuries to his ear occur, we know that with time and training, any treatment is possible.
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