“Head-down syndrome” or “Twilight's syndrome"

Was it hepatic encephalothy ?



Suzanne Trayhan, with her permission

Twilight is a sweet young mini-lop who became seriously ill on Jan 20, 2010. His condition has been posted on many lists, and people are asking how he is doing would like more details on his story. To make it easier for people to follow, I will be placing all information on him here. I would also like to send a HUGE thank you to everyone who has shown interest in him and has offered tips/suggestions.

Basic information:

-      Born May 2009;

-      Came into HRN foster care July 2009;

-      Appeared to be completely healthy;

-      White mini-lop;

-      neutered Sep 8 2009;

-      Weighs 6 pounds / 2.7 kilos.

Here is some video of a healthy Twilight taken approximately 6 weeks before his illness.

Susanne Treyvan

Healthy Twilight 6 weeks before his illness.

Jan 20, 2010  First thing in the morning I went downstairs to feed the foster rabbits, and noticed that Twilight was having a problem lifting his head. The previous night he appeared healthy, with no obvious problems. I took him to the vet, who didn't know what was wrong with him. We started him on enrofloxacine (Baytril), fenbendazole (Panacur), puralube (sterile eye lubricant/tears) and meloxicam (Metacam). He is also receiving sub-q fluids and critical care. Here is some video of his condition.

Please note - he was only on the floor for filming to video. He has plenty of towels in his cage to make moving around easier.

Jan 21            He made it through the night, and appeared slightly worse. I took him into Angell Memorial Hospital in Boston where he could see specialists. He was observed by both Dr DeCubellis (exotics specialist) and Dr Farabaugh (neurologist). He had a fairly lengthy exam, along with radiographs (skull, neck, spine):



Latero-lateral and dorso-ventral X-rays obtained from Twilight do not show any abnormality in the neck region.

(click on the here to see captions of anatomy of the neck region in rabbits).

A complete blood test (CBC and blood chemistry profile) was also done. The results show elevated liver enzyme values and low phosphorus.

After getting a second opinion (2012), abnormalities were found in the blood panel taken on January 21. Glucose is very elevated, which may be the result of stress related to the travel and handling by different veterinarians. The liver values (AST, ALT and Alk Phos) are all elevated, which is indicative of liver failure. It is accompanied by low phosphorus, which may be the result of fulminant liver failure. This pathology may result in an accumulation of ammonia in the blood. Ammonia - a neurotoxin, will enter the brain via the circulation and cause neurologic symptoms.

Working hypothesis: Twilight suffered from hepatic encephalopathy.

(click on the image to get the full blood panel).

It is important to note that this is very localized to the back of the neck area. All of his legs are strong and seem to have full movement. The neck area was hypersensitive; sometimes it appeared to be twitching. There is no nystagmus. He has an excellent appetite but is having trouble positioning himself to eat. Initially they thought that he tore a ligament in the back of his neck, but later ruled that out. Also no signs of trauma. No swelling, redness, nothing. Radiographs and blood work came back normal. Many different ideas were bounced around, but the doctors were stumped.

Some random comments- this is NOT head tilt. It doesn't appear to be the parasite Encephalitozoon cuniculi, but no one feels it can be ruled out completely. No evidence of a spider bite. Many things people have suggested can easily be ruled out because he has good strength with his legs. There is no point of localization. He lives in a cage by himself; we don't believe he had access to any strange plants or poisonous objects. Food is fresh and had no signs of mold. He doesn't lean to either side, and has twisted his head to rest in both directions. Radiographs were taken at a couple of angles. A couple of people have suggested myastenia gravis – a neuromuscular disease characterized by muscle weakness, which isn't a first choice but hasn't been ruled out either. They ruled out an electrolyte imbalance.

Jan 22            In the morning he seemed a tiny bit worse. I gave him his critical care, which he rapidly eats, his fluids and meds. During the day he seemed stable. Late at night, it seems like he might be slightly improved. I spend a lot of time cradling him like a baby on his back.

Jan 23            Twilight has definitely improved. He can now lift his head up for short periods of time and is eating fairly well on his own. He can even go in and out of his litter box. Fingers crossed that he continues. Here is updated video. Yes, I woke him up, but needed to do fluids and meds on him.

We are discussing alternative care- acupuncture, chiropractic.

Jan 24           Twilight continues to get stronger. He is now keeping his head up for a fair amount of time. He is moving around his cage and eating well. He is more active and is looking for attention.

Jan 25          Twilight is getting stronger each day and is looking pretty good today. We still don't know what happened to him but are thrilled that he has improved so much. Here is more video of him.

Almost three years later, you would never know Twilight had been seriously ill. He is a happy, healthy, bratty bunny.

Since, more rabbits have suffered from “head-down syndrome”.

Another three rabbits were all from the Lemspter rescue (Oct 8 2011). I don't know if that means anything or if it is a coincidence but since this syndrome is so rare I think it is worth noting. The Lempster rescue is a large scale rescue of about 90 rabbits we pulled that were living in a shed in New Hampshire. These rabbits have been given fenbendazole (Panacur) and meloxicam (Metacam):

The three Lempster buns were:

·      Franklin who was a young male about 12 weeks old and came down with it the day after the rescue. Franklin was on antibiotics for a couple of days, but seemed to really show improvement once we started him on fenbendazole (Panacur). He recovered fairly quickly- within a week he was close to normal.

·      Midnight – the results of the blood tests (CBC and chemistry profile) show the same abnormalities as observed with Twilight: elevated values for liver enzymes and low phosphorus, which are related to fulminant liver failure.

·      Lewis is the third bun. The difference here is he was never in that shed. Rather he was from a litter born in our foster care from one of the pregnant Lempster buns we rescued. He came down with it just this past Sept 23 at about 10-11 months old. Lewis’ recovery was slightly slower, I would say 9-10 days.

A few more rabbits have been affected by this syndrome, and recovered, but there has been no follow-up.


Many thanks also to Bonnie Salt



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