Twilight’s Syndrome, A Mysterious Toxin
by Suzanne Trayhan
In the last several years, we have seen a peculiar, unknown illness appear in rabbits, with several cases in New England. Within HRN, we have had about a dozen different rabbits come down with this ailment. We call it Twilight’s Syndrome, after the first rabbit in our care to go through this. He was a young mini-lop who was healthy. Symptoms came on suddenly, overnight, with the most obvious one being his nose down to the ground with the neck/back arched. Although some people will mistake this for head tilt, this is different. With head tilt the head is tilted to either the left or right, with one eye often straight up. In this case there is no tilt to either side, and the neck is not twisted. Rather the nose is straight to the ground, almost like they can’t lift it off the ground.
Twilight’s case was so unusual that we were referred to Angell Memorial Hospital in Boston where he saw specialist and a neurologist. The veterinarians had never seen anything like it. They performed tests, took bloodwork, x-rays, presented findings over lists searching for answers, all to no avail. Since then several other animal hospitals have also worked on patients without finding answers.
All but one of the rabbits recuperated, with recovery typically taking from 7-14 days. Once better, they appear completely healed, with no after effects of their illness. They often got worse the first one to three days, but after that showed steady improvement. Cases were reported in three different New England states and in different foster homes. Some of the homes had many rabbits, yet only one came down ill. Only once did we have multiple rabbits ill at the same time in a home. We have tried to find common elements, but at this point have been unable to determine anything.
With so much that we didn’t know, we had a necropsy (an autopsy performed on an animal) done on the rabbit we lost. The most important thing we learned was that there was a toxin involved. The unfortunate thing with toxins is that you can’t just run a blood test and find a toxin; rather each known toxin needs to be tested individually. Unless you can narrow down the scope to test, it usually isn’t done since there are hundreds of toxins to test for and it is rather costly to go through them all.
While we would love to figure out what the toxin is, it is still useful to know we are dealing with a toxin rather than some sort of bacterial infection or virus. It gives us some indication of how to treat it. In past cases we tried an antibiotic and Panacur® (prescription medication used to control and remove roundworms, hookworms, whipworms, and certain tapeworms), not knowing if they helped or not. It looks like they had no impact in recovery. Without isolating the toxin, the best course of treatment is likely fluids to help flush it out of the system, along with supportive care.
We have additional pictures and video that may help here: