This article is from the WSSF 2014 AFRMA Rat & Mouse Tales news-magazine.

By Carmen Jane Booth, D.V.M., Ph.D.

Marianne Graff (was Melody Gee last year), Facebook
QMyfancy white mouse’s eyeball is swollen—looks more pink than red (she has blood red eyes), and it looks like it’s going to explode (she was absolutely fine last night). There is no puss or any oozing, no crust—it’s her eyeball, not the eyelid, that is swollen. Could she have gone blind? She has been in great health until this incident. She is still alert, still eats, but at much less levels (she stays in her house most of the time), and doesn’t want to be handled. She doesn’t want to play much either—she would run on her wheel for hours, now she’ll just take a few spins on it. I have been washing her gently with spring water and soft towel. She does not seem distressed when I do this, otherwise she would cry in pain. I have no vets in the area that handle fancy white mice. She is about a year and a half old.

I was reading on several different sites where this seems to be common, but it doesn’t look like conjunctivitis or blepharitis.

I’m very concerned. I could use your help if possible, and I certainly don’t have $200 to take her to an unskilled vet. Most vets here don’t deal with exotic pets. I finally found one so I made an appointment. They said it sounds like an abscess. Her eyeball is big, almost coming out of her head but not as bad as last night.

Answer by Carmen Jane Booth, D.V.M., Ph.D.
AI would need a picture. If the eye is protruding from the orbit, then the most common cause is retrobulbar (behind the eye) abscess or tumor. Tooth root abscess of upper molars can cause this. Prognosis for abscess depends on extent of damage, response to antibiotics. Generally by the time you see this, the prognosis is poor. If the globe itself is the only thing enlarged, from glaucoma or intraocular tumor preventing normal fluid drainage, then treatment is to remove the eye. Antibiotics. Meds for pain. Both conditions are painful. Meloxicam can be used for pain. Careful exam and radiographs help determine the extent of involvement. Untreated, the eye will die and shrink down. If there is an abscess, without treatment, the mouse will die. Some may remove without radiographs. Antibiotics are mandatory. Need histopath to rule out tumor. Complications can include difficulty eating if the jaw joint is involved. You can feed Ensure (liquid diet). I had a rat with an Retrobulbar abscess, had the eye removed, and it did OK for a few months.

QUpdate: I got the appt with the vet last night, she said it looked more of a corneal abrasion, possible abscess . . . corneal abrasion because she found a scab on the outer most part of her ear, the same side of her swollen eye. After examination, she said it was a bit of excessive skin that is irritating her and keeps scratching same area on the ear, possibly causing the abrasion. She gave me tobramycin eye drops 3x/day, orbax suspension, 2 drops/12hrs for 14 days, and metacam oral suspension 5 drops orally 1x/day for pain. She also suggested that even if she did the surgery to remove this little skin growth on her ear, she may not survive anesthesia since they can’t intubate her, plus she is already 15 months old. She seemed pretty well versed on fancy white mice. She may not survive the surgery due to her age as well, since the breed is very delicate and small. She weighed her and said she had a very healthy weight, beautiful coat, and Athena was running all around the table, very alert and curious. Then she stopped to scratch her ear and the vet said it is definitely irritating her, but Athena seems to be careful enough to know not to scratch hard enough to cause a lot of bleeding to the ear. She was very playful last night after receiving the meds. She was running on her wheel and with those curious big ears came running over to the cage to be held and get her treat. I know her lifespan is not long, but I have to give every available but realistic chance I can. She is not in distress but if it worsens (the vet doesn’t think it will), I will put her down, which will break my heart completely. I will not put her thru surgery. I worked in a hospital for many years and I know what the odds are for her doing surgery, which are minimal at best. I’m home alone most of the time (my husband gets home late), so holding her while trying to take a photo, which I would rather you see it, rather than me describe it, it’s impossible. I have no idea how I’m going to get these drops in her later. The vet said her incisors are perfect in length, and said she is remarkably tame (once I held her to let her feel inside her mouth, the vet tech couldn’t get Athena to open her mouth). It’s just a sit and wait thing now. I would like to know what you think of this treatment and diagnosis. I want to keep her well and happy for as long as I can, she is such a sweetheart, she sits on my shoulder, combs my hair, gives me a manicure which is hysterical—heavens to Betsy if I should have a hangnail . . . no, no, no, that must go, and she quickly nibbles it off, always knowing how sharp her teeth are and never once bit me, she knows the right amount of pressure to apply without hurting me. Thank you so very much again, it is so very much appreciated, and I will always remain in gratitude to you and your excellent resources and advice.

Re: Treatment by Carmen Jane Booth, D.V.M., Ph.D.
AThe front of the eye is dry (looks ulcerated) because it is likely protruding. Scab on the ear is most likely mites. Excessive skin??? I need pictures. As for anesthesia, we never intubate mice. At 15 months she is still young enough to withstand anesthesia. Besides, you can do a quick procedure with isoflurane on a cotton ball in a 20 cc syringe case to knock the mouse out. You can use injectable lidocaine or benzocane topically or inject where you want to cut to numb the ear, clip what ever needs to be clipped, then apply pressure or topical hemostatic agents (styptic powder) if there is nothing to suture, and wake the mouse up. The mouse’s nails can be trimmed as well. It is not the incisors that cause retrobulbar abscesses but molar tooth problems. You can use a cat ear cone on an otoscope and look in the mouth. If I can get pictures, I can give you more information.

Update from Marianne Graff
The protrusion has seemed to go down a wee bit, but it’s still visible that it is still not normal. She is eating, playing, alert, and can’t wait to come out of her cage. She doesn’t have cagemates. Athena has no open sores, has a beautiful shiny coat, but has this scab on her right ear which she scratches and scratches and may have injured her eye in scratching so much. Since giving her the pain meds, her appetite is normal again. I think if she had mites, it would ravish her whole body, not just the ear perhaps? I don’t think I explained it right when I said excessive skin. The vet said it was a small lump which is irritating her, and it may grow to which it may block her ear entirely, causing her to lose some of her hearing in that ear. She chomps away on the seeds I feed her, in no distress at all, so wouldn’t that cause pain to chew if it was a molar? She chews on her wood toys, carries them around, knocks them up against the cage to get my attention and that means she either wants to come out or she wants a cheerio cereal which she loves.

Update 4 days later: The protrusion/bulging has gone down considerably, you don’t notice it unless you are looking for it. However, it’s still lighter in color than the other eye. I wanted to test her to see if she is losing her sight, and she reacted appropriately when I placed my finger from behind her back towards her, to pull away, as she did with her normal eye. I touch her eye, she shows no distress. My husband looked under a higher magnifying glass at the eye, and he said he clearly saw a line or scratch right across the cornea of the eye. The scab in her ear is gone. I’m still keeping a watchful eye on her. She eats very well, drinks well, hasn’t lost weight, and is active. I think that because she scratched that ear so much (sometimes she gets small patches of itchy skin and she’ll scratch, but never to open bleeding wounds like my males had, so they occur at anytime, then go away as quickly as they came. I absolutely agree with you, that had it been a lump there causing her to itch, general anesthesia wouldn’t be used (I used to run an anesthesia dept), a local would have been given and the lump removed without incident. I am so appreciative of your help and advice, as always you have been there for me always, no matter what. One question, will this abrasion heal or will she lose her eyesight? The eye still has fluid in it, and she still gets the antibiotics orally and the drops. I’m moving in a few weeks, so should I ask the vet to give me another round of all 3 meds just in case? I would hate to see her go through this again or have it relapse because the course of treatment is for only 2 weeks.

Since I’m moving, I was thinking of getting a younger doe to keep her company. Where I live now, I’m not allowed to have pets so keeping Athena hidden was hard enough, but where I’m going they allow pets. Since she is about 15 months old, do you see that as a problem? My males did NOT get along, and had to be kept in separate cages. Athena is very patient, has NEVER bitten me, no matter what, she is very calm, very tame. Thank you again.

Answer by Karen Robbins
AGlad to hear Athena’s eye is doing better. In regards to getting friends for Athena, it’s hard to say if she would accept them since she has been alone for so long. If you do decide to get new mice, get 2–3 so if she doesn’t like them, they can be their own group. Also, if you only got one, if they were to get along, you wouldn’t be left with a single lonely mouse again when the existing mouse dies. Yes, it is normal for males to not get along so keeping them in separate cages is a must.

Re: Protruding eye by Carmen Jane Booth, D.V.M., Ph.D.
AWhen the globe of the eye is enlarged that is usually due to an increase in ocular fluid, the term is called buphthalmia. Other synonyms for this include congenital or acquired glaucoma, and hydrophthalmia or tumor.

When the globe of the eye is protruding from the eye socket, that is called exophthalmos or ocular proptosis. The etiology is trauma, or swelling of the tissues behind the eye. In rodents I have seen this from retrobulbar (behind the eye) abscesses, or tumors. The gland behind the eye is the Harderian gland which is actually larger than the eye. Common causes included upper molar tooth root, upper abscesses, or food penetrating the upper jaw leading to an abscess. Uncommon causes of retrobulbar abscess include Harderian gland abscess. As rodents age, Harderian gland adenomas are common in some mouse strains. Reports in rats are limited and Harderian gland adenoma or adenocarcinoma are uncommon. In my years with pet rats and working with rodents, the majority of causes of ocular proptosis are retrubular abscesses from foreign material (food) and tooth issues. Very uncommonly the cause is from a tumor. If treated with antibiotics, some abscesses resolve where there is no long term damage. Unfortunately, if the pressure behind the eye persists, the eye will die despite treatment. Sometimes, the eye has to be removed to clean out the abscess. In one pet rat, the abscess damaged the facial nerve and the rat had to live on a liquid diet and have its teeth trimmed for the rest of her life (8 months).

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