Causes for elevated eosinophils

Question
QUESTION: Hi Dana,

are you familiar with what could cause elevated levels of eosinophils? I have 3 rabbits, 2 of them bonded. The bonded pair and the single live in two different rooms in the house. Just a few days ago I had a round of routine bloodwork done on all them. Their eosinophils are all elevated. Since they all seem otherwise healthy, and the elevation is found in all of them my vet ruled out the obvious culprits (infection, allergies, tested negative for parasite (i.e. feces, and none visible in blood)) She consulted with the lab and believes that the air quality in my apartment might be the culprit and recommended trying an air purifier. The last bloodwork was done 1.5 years ago, and all 3 rabbits came back with values around 80. The reference is up to 100. This time however my one single boy (age 5) and the girl out of my pair (age 2) came back at 270. The other boy from the pair (age 4) was only slightly elevated at 140. I do have rather annoying wall to wall carpet throughout my house which most certainly traps lots of dust etc. However I have lived here for the past 4 years. So at the time of the first test my boys had already lived in said place for 2.5 and 2 years with no obvious influence on the blood results. Also considering that boy No. 2 and my girl are living in the same room, I'd expect their values to be similar and not between my girl and my single boy who live in different rooms. The only other thing I could think of is, last year I found black mold growing on a window AC installed in my kitchen. Cleaned it the best I could with bleach (more like a 1st aid). Had a mold guy come in to test the air, who found some dead spores in the hallway air, but said it had no major impact on air quality. The bunnies' rooms are going off the hallway. Air circulation is generally poor in my apartment, i.e. the AC in the kitchen blew mostly air into the kitchen and the hallway but air didn't circulate well into the bunny rooms. So I am guessing whatever traces of mold there may have been never made it far. About 3 weeks ago, I boarded my guys for 3 days with a local rabbits rescue. They were setup in the basement. And as basements go there's always some mold no matter what you do. Any chance this short exposure could be the culprit? I am out of ideas. My vet says not to worry it's not a big deal, but I like to get to the bottom of things. After all there should be a reason their values are off the charts. Could stress play a role? I know it does with quite a few blood parameters.

Thanks for any insights you might have.

Astrid

ANSWER: Dear Astrid,

Well, this probably won't be news to you, but here's a nice overview of the various causes of elevated eosinophils:

http://hypereosinophilia.info/FAQs.htm#What%20causes%20an%20elevated%20eosinophi

Allergies can't really be ruled out unless every single allergen has been tested, and very specific antibody tests performed on the rabbits.  This would be logistically extremely difficult and cost prohibitive.  So the detective work you're doing is probably the right thing to do.

It seems really unlikely that they all have a cancer process going on.  And unless they are all related, it's seems even less likely that they have an idiopathic problem based in their genes.  So we're back at the most common culprits:  allergic or other immune reaction to a parasite, infective agent or allergen.  And from where I'm sitting, I unfortunately cannot even begin to guess at all the possibilities.  

I hope you are able to find the culprit.  Starting with getting rid of the mold and other household allergens is a good start.  Good luck!

Dana

---------- FOLLOW-UP ----------

QUESTION: Thanks Dana,

I figured it was worth a shot even though I am aware that the possibilities are endless. All my bunnies are unrelated, different breeds and totally different backgrounds - my first boy I got as a baby from a pet store (couldn't really adopt back back then), 2nd boy came into the shelter I volunteer at, dropped off by a smoking guy who didn't know what to do with that gift; and my little girl was picked up by animal control wandering the streets with a broken leg and wearing what seemed to be a professional splint! (makes you wander how she had ended up outside after somebody apparently had taken her to a vet).

All of them have been for regular exams twice a year, have regular fecal tests and have been rather healthy so far. So I agree it's unlikely that they all have cancer or share some sort of infection. I'll keep working on improving the air quality and hope for the best. This made me think that HRS should include the purchase of appliances in the maintenance cost of owning bunnies :) Just spent $700 on getting two high quality air purifiers for the two bunny rooms, not to mention two brandnew ACs for each room, and I might consider getting a steamcleaner to attack the trapped dust and allergens in the carpet. Oh the sacrifices we make. :)

Astrid

Answer
Dear Astrid,

Wow, what a devoted bunny mom!  You're the best.

On the plus side, whatever you invest in to improve the air quality of your home will be good for you, too.  I've known of people whose physicians said their lives were saved because a pet in the home started showing signs of illness that alerted the homeowner to a potential problem!  So thank your bunnies for being the "early warning system."

Hope all will be well soon.

Dana