Breathing problems in dwarf female.

Question
We have a 4 year old dwarf rabbit 'Benina'; 2.8 pounds, grey, spayed.  She is paired with a mini-rex male.  She has been having breathing problems for quite some time and it is getting worse.

Snuffles has been ruled out.

Our rabbit-savvy veterinarian took an X-ray and noticed that next to her heart there is a small lump - from listening to her heart beating he picked up that one of her heart valves isn't opening and closing properly.  As a result, her heart has elongated more into her lung cavity, thus producing more fluid build-up in her lungs.

We put her on Furosemide, 0.1 cc twice daily (solution is 25 mg/mL).  Her breathing was markedly better for a few months.  It began getting worse again, so the dose was increased to 0.15 cc twice daily.  Worked for a while, but now breathing is still laboured.  Further X-ray shows the heart 'bump' has grown in size.

Our vet then recommended we put her on Liquid Theophylline (a bronchodilator) 80 mg/15 mL solution, 1 mL given twice daily.  After three days of seeing a marked worsening of her condition, we put her back on Furosemide.


Is there anything else that could alleviate her condition at this point?  In your experience have you encountered something like this?  

[A few other things - We have 3 other rabbits - one in the same room as her, two others in a seperate room.  We use a HEPA filter for our furnace, she is not in a draft, her appetite is good (timothy hay and green vegetables) and her bowl of water is changed daily]

Her litter is recycled newspaper pellets.


Thank you for your time!  

Answer
Dear Renay,

This sounds as if your bunny might have a thymoma, a tumor of the thymus gland, which lies just cranial (towards the head) of the heart.  This is treatable, but you will need the help of both an experienced rabbit vet:

www.rabbit.org/vets

and a veterinary oncologist, for radiation treatments.  Please read these articles regarding this condition in bunnies:

http://www.rabbit.org/health/thymoma.html

http://www.rabbit.org/health/thymomastory.html

for more complete information.  I hope they will help you decide what to do.  But first, I'd find a vet who is very experienced with rabbits, and is aware of this problem and its treatment.

I hope this helps.

Dana