Outside Rabbits with Lumps?

[Bad Habit]

Situation
I have a 2ftx10ft(ish) grow out cage. It is outside.
In this cage, I had 10 rabbits. Three were New Zealand bucks that were about 10wks old. The other 7 were mixed bucks and does from a litter that was 8wks old.
Yesterday, when out feeding/cleaning/whatever, I noticed that the New Zealands all had large lumps on their ears.
Removed one for further investigation.
Lump was slightly warmer than the rest of the ear, but not HOT.
Colour was the same as the skin until I started messing with it.
After removing the hair from the lump, I did find some serum and blood oozing out, assumed due to trauma to the hair follicles(I'm mean, I just plucked the hair, it came out easily and did not seem to cause discomfort.)
Used a hastily sterilized knife to open the lump, it produced blood but no visible pus.
While palpating and attempting to express anything that could be in the wound, I found a large tear had formed at the bottom of the lump - unsure if this was the lump causing injury or not, but it looked to me like the lump itself was tearing away.
Culled and processed - everything looked normal inside. The lump, when cut open more fully, did not disclose any worms/bugs/pus anything like that I could find.
Rabbits were acting normal, bouncing around like idiots and eating/drinking/eliminating normally.
5 rabbits were lumpy, each one lump on an ear, of various sizes(smallest being pea sized, largest being grape sized).
The 5 rabbits were all butchered, all looked normal except for the one lump.
They were all male - the 3 NZ's had dropped their testicles already, or were starting to at least.
I did not think to take any photos of any of it, nor did I think to check to see the genders of the remaining rabbits(2 I know are female, the other 3 I am unsure).
None of my other outdoor rabbits have lumps - they all live inside the shed, whereas the grow out cage is outdoors.
Some of the rabbits did display scabs on their lumps or bleeding when the lump was manipulated.
There was no corrosponding spot on the inner ear.
They have not been tattooed.

Things that I have investigated and rejected as the possible causes(these were all suggested in other venues) :
Systemic Pasterella - there was only the one lump on each rabbit, and none expressed any sort of pus.
Myxo - Lumps come in the later stages of this, and there would have been some visible symptoms before hand.
Shope's Fibroma - Lumps were not in the correct location, and they did not display any other symptoms
Bot Flies - nothing inside the lumps and no breath holes
Flystrike - incorrect location, no maggots
Abscessed wound - no pus

When I checked this morning, the remaining 5 rabbits were lump-free. One may have had a small lump at evening feed, but it was dark and raining and I was checking them with a flashlight so impossible to be sure. I will check again and sex in the morning.

At this point, I am thinking that, despite not seeing pus, it may have been abscessed wounds or scar tissue, from the bucks fighting amongst themselves. I also suspect possible stings or bites of some sort(I have a healthy spider population out there). Anyone have any other suggestions?

 

[MaggieJ]

Nice to see you back, Bad Habit!

My first thought was spider bites--they can really swell up. Is the cage on the ground or elevated?

 

[Dood]

You do not specify where on the ear but I am assuming these lumps were in the flat upper cartilage part of the ear and not at the base near the skull.

With nothing in them it sounds like inflammation from trauma or a bug bite to me but you say one was the size of a grape :shock: a flattened grape I hope - meaning more like the circumference of a grape and not like a ball.

If it was more ball like then it might be a haematoma but I have no idea what could have caused it :shrug:

 

[Marinea]

I have a dog who loves to re-enact the movie "The Great Escape" on a regular basis. He probes our fencing and digs his way out. He has those types of bumps on his ears all the time. I vote injury, not illness.

 

[Bad Habit]

The cage is about 6" off the ground, under my cedars, but with a tarp roof to prevent the rain.
Sorry, yes, they were all on the upper half of the ear.
The inner ear was flat, with no swelling. The outer ear had the lump. So when I say pea or grape sized, I really mean 1/2 a pea, or 1/2 a grape.

I just mostly want to be sure it's nothing that the other rabbits are going to get. I have quite a number scheduled to leave in the next week or so, and I want to be sure that I'm not going to be inadvertently infecting other people's rabbits with something.

 

[Dood]

I have never heard of any contagion that would create the lumps you're describing so it believe it is something in the environment - bees and wasps get pretty dosey with cool weather, have you checked the cedars for nests?

 

[MamaSheepdog]

Hey Bad Habit!

:welcomewagon:

it might be a haematoma but I have no idea what could have caused it :shrug:

That was my thought as well. I would check everybunny for ear mites or other critters in the ears... maybe they are shaking their heads and bursting the vessels in the ears.

 

[Bad Habit]

Have checked the ears, nothing in them. No fleas or anything either. I treat regularly with DE to prevent fleas, and also dust the pans to try and prevent flies. I'll have to look into haematoma, because I'm not entirely sure about what it is and what causes it. I suppose, if it can be caused by shaking heads, then it is possible that the flies are causing them to shake their heads?

No wasp/bees nests, I'd have had that dealt with. However I do have an apple tree and the windfall apples don't always end up in my yard to be cleaned up - often the squirrels take them, or they land on the shed roof or on the neighbour's land behind the shed/cedars and I cannot go on their property to clean it up. The building has a new superintendent and he FREAKED on me because I went on their property to access the shed roof to repair a minor leak. The way things are set up, I can access the shed roof with only a step stool from their property, but need a 8ft ladder to access it from mine. The windfall apples, and those partially eaten by squirrels, do tend to attract a fair number of wasps.

Wasps would make more sense than bees, as there has not been any stingers left in any of them.

I do intend to inform purchasers about the issue. I'd rather lose a few sales than end up spreading some disease. I would just prefer to have a "this is what I think it is" type rhetoric to give them, rather than "well, some had lumps, others did not, but everyone acted normal and I dunno what it was."

 

[MamaSheepdog]

I'll have to look into haematoma, because I'm not entirely sure about what it is and what causes it.

It's basically a big "blood blister". It is often seen in dogs, more rarely in cats (less ear to flop around), and they usually get it because of some persistent irritation of the ears, although cats sometimes get them from fighting.

The inner ear was flat, with no swelling.

I have always seen swelling on both aspects of the ear... imagine that the ear is two pieces sewn together, and then is filled with stuffing of some sort. It bulges out both sides...but maybe rabbit ears are different somehow? :? The placement of the cartilage, perhaps?

I suppose, if it can be caused by shaking heads, then it is possible that the flies are causing them to shake their heads?

I suppose so, especially if the flies keep landing on them or biting them.

I would just prefer to have a "this is what I think it is" type rhetoric to give them, rather than "well, some had lumps, others did not, but everyone acted normal and I dunno what it was."

It doesn't sound like disease to me. If they were pus filled I would be worried, but blood? No. It has to be some type of traumatic injury or venom that is causing it.

 

[Bad Habit]

Yeah, I was confused as to the lumps only being present on one side. I would have thought it would have been like a pea inserted into the ear, being round all the way through.

I really wish I'd thought to get photos of it, but I was concerned with getting it investigated and then processing them as quickly as possible, in case they were in any pain(it only seemed to bother them when I mucked about with it, though). If any more pop up, I'll take photos for sure, but I'm hoping that they won't, mainly because I was planning on growing the rest out for prime pelts to make my momma mittens for Christmas.

 

[MamaSheepdog]

I just remembered you mentioned the fur falling out... that makes me think it is some type of venom. When animals have abscesses, the heat generated by the infection causes the hair to fall out, and I bet a really irritated bug bite would cause the same type of reaction.

Any chance that you could get some mosquito netting or something to make a tent around the cages? Or barring that, make some wasp traps. I used to use Gatorade bottles with a few wasp sized holes drilled near the top, and baited the bottles with Gatorade, soda, or even meat. They crawl in and then can't find their way out again.

 

[Bad Habit]

Eh, we're supposed to get a frost and much cooler temperatures in the next week or so. Hopefully after that it won't be much of a problem.

Why would they irritate the rabbits in the pen outside the shed, but not irritate those in the shed? The shed door is wide open, and the window is only covered with chicken wire, so won't keep out bugs. <br /><br /> -- Sun Sep 14, 2014 7:50 am -- <br /><br /> May have figured it out. I'm not exactly sure what it was, but I got bit by some nasty bug when I was cutting down my dahlias yesterday, and now have a big lump where it bit me. I think it was a carpenter ant, but I'm not sure if it's the right time of year for that.

 

[michaels4gardens]

The only time I found mysterious lumps on rabbit ears, I found a wasp nest nestled in a upper corner of the rabbit enclosure roof, -so -when they were hoping up on the upper level shelf or running around playing , one or two of the wasps would dive down and sting them, -- I only found the nest when I was moving all the rabbits out of the cage, because one stung me while reaching a rabbit that was up on the shelf, -- I had to put my head and shoulder inside to be able to see the hidden wasp nest.