Questions about glaucoma and molar issues in a 12 yo rabbit

[PamsWarren]

Hi all.

I have two questions - one about glaucoma and a semi-related question about teeth.

My 12yo rabbit, Fuzz (neutered male/angora mix), has been diagnosed with glaucoma. At one time, the pressure in his eye was about 45. We have been able to get it down to the mid 30's, but no further. He is currently on timolol eye drops, ketoralac eye drops and metacam. He also has a cataract on that eye and the eye appears to be completely non-functioning. I only have a very basic understanding of glaucoma; can someone help me understand how glaucoma meds work and why one glaucoma med may work better in controlling the pressure than another? I mean, it's not like we are dealing with bacteria where resistance is a factor, so how and why do the various glaucoma meds differ? I know there are options other than timolol; perhaps another may be a better choice. Something I'd like to discuss with my vet, but I would like to be better informed before I ask. Hope my question makes sense.

Fuzz also has molar issues. Up until January, he was having his molars done about every 4-6 weeks. Now the vet just files the sharp edges off of his molars approx every 4 weeks; the last molar grind was VERY hard on Fuzz so we are very hesitant to put him under again. Fuzz's appetite is mediocre, so I am supplementing his meals with syringe food (he readily eats about 120-150 cc of food per day and his weight is up to almost 2kg again, which is a good thing).

I've noticed that when I syringe feed him, he closes his bad eye. Syringe feeding also makes that eye tear, which makes me suspicious that there still may be a spur in there somewhere. I've had his teeth checked by two different rabbit savvy vets (no anesthetic), but they didn't find anything. I know that it's not the same as having an exam under anesthetic, but I like I said, I'm really am scared to put him under again. Could the pain from the glaucoma be causing the tearing? Why does he close his bad eye when he eats? BTW, the eye discharge is clear, although today it did appear a tiny bit milky. He had his duct flushed last week (it was patent). I have to follow up with the vet again this week, so I will keep an eye on the colour of the discharge and discuss with him.

Other than his mediocre appetite, he seems to be doing ok. Still hops around with ease, comes out of his room at night to visit with us and humps Muffy. Alot.

Would appreciate any thoughts on the eye or teeth.

With thanks.

Pam & Fuzz

 

[nicolevins]

Sorry i can't help, but i hope your bun gets better soon!

Im sure some one will be able to help you out (hopefully)

 

[tonyshuman]

I am not an expert on glaucoma or eye issues, but from what I've read, there are two main reasons that the intraocular pressure increases. 1) the cells that produce the aqueous humor (liquid between the lens and cornea) make too much 2) the methods for draining the aqueous humor do not work as well. In a normal eye, the input and outflow are equal, in a glaucomic eye, the input is greater than the outflow, whether that's because more is coming in, less is coming out, or a combination of the two.

Timolol works on cause 1 of glaucoma--it stops some of the cells that make aqueous humor from making quite so much.

Ketorolac and Metacam are both non-steroidal anti-inflammatory drugs, like ibuprofen. They decrease the pain and inflammation of his eyes.

There are medications that work on cause 2 of glaucoma--the drainage of aqueous humor, and ones that work on both causes. It's possible that in addition to reducing the production of aqueous humor, Fuzz also needs help draining the fluid from his eye. The vet should be familiar with the drugs that help with this, but they are also listed on the glaucoma wikipedia page.

I am a bit concerned that there may be a mechanical issue causing his glaucoma based on what you say about syringe feeding and that it's just one eye. The aqueous humor is at the outermost surface of the eye, between the lens and cornea. There is also vitreous humor, which is the liquid inside the eyeball itself. If there is pressure on the vitreous humor problems with blood flow around the eye, the pressure of the aqueous humor could also increase because the rest of the eye can push on the drainage canals to reduce drainage of the aqueous humor. Perhaps mechanical pressure on the vitreous humor or the blood vessels around the eye, due to changes in the shape of the eye socket, could cause this.

I wonder if there is a tooth root infection or overgrowth into the area normally occupied by the eye socket. The growth of tooth roots up into the eye socket area is pretty common and since he has tooth issues, ie they don't wear properly above the gumline (where you can see them), they may also be growing abnormally below the gumline. Infection/abscess of the tooth roots can also cause swelling that could put pressure on the vitreous humor as well.

I hope this helped, if not please let me know and I'll try to explain what I'm thinking better. Scientists are not used to talking to laypeople and the farther along in science, the fewer non-scientists we have to talk to, so I'm a bit out of practice.

http://en.wikipedia.org/wiki/Glaucoma

 

[tonyshuman]

I copied this from a Medirabbit page on eye issues that has pictures so gross I don't want to link to it.

Glaucoma:

Here the intraocular pressures were 45mmHg in each eye and the condition was glaucoma caused by the bu gene. Other possibilities might include retrobulbar abscessation, although this would be rare bilaterally, and venous congestion causing retrobulbar plexus engorgement, again a very rare condition. The bu gene is common in New Zealand White rabbits like this one, causing a dysplastic iridocorneal angle where drainage is very poor. A useful paper on the condition is Ueno and colleagues report on Histopathological changes in iridocorneal angle of inherited glaucoma in rabbits. Graefes Arch Clin Exp Ophthalmol. 1999;237:654-60

(c) 2005 Dr David L Williams

What they're saying is that in this rabbit, and in many New Zealand White rabbits, there is a genetic deformity of the structures that allow liquid to drain from the anterior chamber--the area between the cornea and the lens. The angle of this drainage area is small which impedes drainage.

That's just to show that it's not just tooth issues, but also genetic things that can cause problems with drainage.

My vet has this poster in her office and it's really helpful to understand how tooth issues can affect other facial structures:

 

[PamsWarren]

Thanks, Tonyshuman. Yes, I, too, feel there is more going on here than just glaucoma. Unfortunately, given Fuzz's age, I feel that time is of the essence and that our options are somewhat limited. Your point about infection/abscess of the tooth root is a very good one. Initially, Fuzz was also on Baytril (20mg/kg 2x per day) and at one time, the pressure in his eye was back down below 20. After the month long course of baytril, the vet took Fuzz off of the oral meds and the ketorolac (he was still getting timolol and metacam) and the pressure went back up to 40. We added the baytril and ketorolac back and the pressure went down to the mid-thirties.

We just finished another course of baytril a day or so ago. Now that we are done with the baytril, I think I should take Fuzz back in the next week to have the pressure and eye checked again. It would not surprise me if Fuzz needed to be on antibiotics, timolol (or some type of glaucoma med), ketorolac and Metacam for the rest of his life. And that would be ok (the vet has already prescribed Metacam and timolol or some glaucoma med for the rest of Fuzz's life); Fuzz doesn't mind his meds at all, so stress is not an issue. I would also like to ask the vet about adding a med that would help with the drainage of the aqueous humor.

I should also add that Fuzz is the bun in my avatar photo. He has one of the flatest faces I've ever seen on a bun. He had molar issues when I first adopted him at age 3 and now again much later in life. Would not surprise me if his teeth were involved.

 

[tonyshuman]

OIC, yes he does have a flat, nethie/lop-style face. You might want to ask about doing an injectible penicillin G procaine/benzathine combo to combat what may be a tooth root abscess. This method is a bit more aggressive at treating abscesses than oral Baytril, although the fact that the Baytril seemed to decrease the eye pressure is a good sign that the drug may have been helping.

http://www-unix.oit.umass.edu/~jwmoore/bicillin/bicillin.htm

 

[PamsWarren]

Vet originally suggested bicillin injections, but another vet that I had taken Fuzz to previously (who suggested that I get the second opinion) had already started the baytril. Honestly, I've tried to give Fuzz bicillin injections several years ago. It was one of the hardest things I've ever tried to do. He is one VERY tough skinned rabbit. I will discuss with the vet again, though. I want to do what is best for Fuzz, but not cause unnecessary stress for either of us. ullhair:

I have been finding Fuzz's food choices very strange. Of his "regular" bunny food, he will eat alfalfa hay (including the stalky stick like pieces), hay cubes, bunny cookies (although the last batch I baked for him don't seem to excite him much), broccoli, carrots, dill, kale and some pellets. He'll also occasionally nibble at other greens and some grass hay, but not much. It's his choice of hard crunchy foods that I find so strange. :?

 

[ra7751]

The only reason the Baytril had any effect is that it might be affecting some of the "tag along" bacteria. It won't work on those for long and it won't treat an anaerobic abscess which is most likely what is causing all these issues. We use a 21g Butterfly on nearly all injections except very young neonates. The Pen should be buffered which will lessen the chances of necrosis at the injection site, will lessen the burn caused by the Pen and will allow the very thick Pen to be shot thru a smaller needle. A possible alternative, taking into account his age, is Chloramphenicol but that drug can be difficult to find and the humans coming into contact with this drug have to take special precautions.

Randy

 

[PamsWarren]

I wondered if Chloramphenicol might be an option.I have no trouble getting this drug here; in fact, the vet prescribed a course of Chloramphenicol for Fuzz's URI symptoms a year or so ago and Moccasin rabbit (RIP) was also on this drug within the last year. It really helped Fuzz andhe did well on the drug.

Thanks for the info. I'll speak to my vet.

 

[tonyshuman]

It's a pretty strong antibiotic and as long as you're comfortable handling it (it can cause side effects in humans that are pretty nasty) it would be a good choice, I think.

 

[PamsWarren]

Just wanted to post a brief update on Fuzz's condition...

Fuzz has been on chloremphenicol for just over a week now. For the first 4 or 5 days after starting the drug, his appetite was very poor (which I did not expect, since Fuzz has taken this drug before without apparent loss of appetite), but he is now doing so much better. The milky white discharge from his eye has stopped, his eye is tearing less, he's much brighter and more active and his appetite has returned pretty much to normal. He's now eating his normal bunny diet of pellets, some hay and veggies (more of a variety than just kale and dill). It's hard to know if he's actually eating as much as he would normally eat (Fuzz has always been one to just pick and graze at his food), but atleast he is eating a normal mix of foods again. I bought a food scale so that I can weigh him regularly. Just have to figure out how I can get him to sit on the scale long enough to get an accurate weight (it's a digital scale with a flat top). onder:

Anyway, just wanted to thank everyone who offered advice. Without your advice, I probably would have never pushed for antibiotics (the vet wasn't too optimistic that they would help), but I'm really glad that I did.

 

[tonyshuman]

That is so good to hear! I put my bunnies in a big mixing bowl on top of the scale to keep them mostly still. If the scale has a Tare function you can automatically subtract the weight of the bowl.