Bob C: Q&A: Capt. Hook and the Case of the Ferret Penis Bones
 
Q: (A ditzy blonde sent this question to me with an ominous threat if I
didn't address it fully, I would get into trouble): "No way, Bob!  Can
this actually happen?  Peeing out the penis bone and all?  Do you think
this is a urban myth?"
 
>"You know, we actually had someone call our clinic saying they founnd
>what looked like a bone in their ferret's litter box after he used it,
>and his peepee area looked swollenand indeed, his little penis bone
>had somehow broken and the broken part came out in the litterbox!"
 
A: Why do I think someone will be out to break my bacula after this post?
 
Most male mammals have penis bones of some type, as a lot of female
mammals have clitoral bones.  They are missing in the large ungulates,
because, frankly, where the hell would you put it?  These animals have
large penises because they are large and can't easily close the gap.
Imagine a bull or a horse walking around with a three-foot penis
bone...it would be too big to put inside the body, that's for sure.
It would have to be left outside the body, taking its chances as the
animal wanders through the shrubbery.  I bet they wouldn't walk through
many cactus patches.  Could you imagine an elephant with a five-foot
penis bone?  I bet THAT would be on some internet website!
 
Penis bones are common in mammals, including whales, seals, walrus,
carnivores, most primates (including chimps), insectivores, rodents, and
bats.  Besides ungulates, you don't see them in the primitive mammals,
including the monotremes (platypus etcegg laying) and the marsupials
(opossum etcpouched).  There are two bones that are thought to support
the pouch in marsupials.  Embryological theory suggests these two bones
fused to form the penis bone in placental mammals, such as the ferret.
Indeed, in canines, the penis bone looks as if two long and flat pieces
of bone were glued down their length to form a v-shaped trough.  The
common ancestor of all placental mammals had a penis bone and if you
can't find one in a male placental mammal, it is because it was lost
during the course of evolution.  This is why they are not found in large
ungulates.  You could define natural selection with the image of a large
bull elk in a dead run while fleeing a cougar, but slowed down by a
non-retractable 3-foot bony penis flapping about with each bound.  That
elk is gonna die.
 
The penis bone (os penis, baculum) in ferrets is about 2 inches long
and looks like a short crochet needle, except the hook part has a small
flared (or wing-like) tip.  That is the end that is embedded in the head
of the penis and is why when the ferret's penis is extended, it looks
like a small fleshy hook.  The opposite end is slightly broad and
flattened and is connected to a thick elastic ligament that attaches it
to the base of the pelvis.  The retracted penis is not actually brought
into the abdominal cavity; it is layered between the outer abdominal wall
and the inner layer of the skin, and dense connective tissue holds it
tight to the skin layer, preventing the ferret from poking itself in the
belly.  The penis bone also has a groove on the top surface that extends
from the tip to about 2/3rds of the way to the base.  This groove holds
the urethra, and is coincidentally called the "urethral groove."
Realizing the urethra is part of the mammalian spermatozoa delivery
system, protecting its ability to conduct fluids to a location of choice
would be a good thing, which *IS* the paramount function of the penis
bone.  For those of you into biological oddities, the average penis
length of a 150-ton, 100-foot whale is about 6 feet; a 500-lb, 6-foot
gorilla is about 3 inches; a 200-lb, 6-foot human is about 5 inches; but
a 4-lb, 2-foot hob is about 2 inches.  Makes you think of short, small
guys a bit differently, hummm?
 
The penis bone is embedded within the tissue of the penis, so if you can
see it, you either have x-ray vision or there is something drastically
wrong with the ferret.  Seeing a penis bone in a living ferret is in the
very least a life-threatening situation, not to mention extremely
painful.  It is the equivalent of seeing your femur pushed through your
thigh, except in this case, its a bone pushed through a PENIS!  That is
a "drop-everything-and-dash-off-to-the-vet" situation!  Every time that
poor guy has to pee it will burn like a hot pepper enema, and the urine
leaking onto the tissues can and will cause significant damage or cell
death.  Bone and penile tissue is extremely vascular, so blood loss could
be significant.  The urethra could be plugged with blood, bone fragments,
or even swollen shut by tissue damage, which could cause significant
kidney damage if the blockage is not resolved immediately.  An injured
penis is a top-ten reason to pay for a vet clinic emergency call.
 
There is considerable difference in the morphology (size and shape) of
the penis bone depending on if the ferret was whole, late neutered, or
early neutered.  The penis bone continues to thicken as the ferret ages,
especially down at the base.  The relative size of the ferret's penis
bone is actually a good indicator of age; HOWEVER, for aging purposes,
you can only compare whole males to whole males, late neuters to late
neuters, and early neuters to early neuters.  The reason is because
castration DRASTICALLY reduces the size of the penis bone, even leaving
it malformed and diminutive.  I am currently collating data on this
phenomenon, so I can't be quoted as saying this is a fact, but it APPEARS
there is a strong correlation between early neutering, adrenal disease,
and urethral blockages.  At this time, I CAN say the risk of urethral
blockages during adrenal disease is significantly greater in ferrets that
were early neutered.
 
The bone material that makes up the penis bone is very dense, relatively
thick, and hard.  Because bone is continuously deposited on the outside
surface, the penis bone gets harder and stronger with age.  This makes
the bone very hard to break.  I have only seen a few broken penis bones
in wild polecats, BFFs, and weasels, and maybe a half-dozen in pets
(total population of more than 500 animals).  The broken penis bones I
saw in pet ferrets all belonged to early neutered animals.  I've seen a
couple of pathological penis bones that belonged to ferrets with severe
adrenal or kidney disease, where the degree of osteoporosis was clearly
abnormal, but these are very rare.  The penis bone in ferrets HAS to be
rugged, strong, and resistant to fracture because of their protracted and
vigorous sexual activities.  A protesting female can not only ruin a
hob's day, but the rest of his reproductive life, so those little bones
are designed to withstand the type of stress produced by a jill dragging
a hob around by his, um, bacula.  My research (which is still ongoing so
liable to change) suggests ferrets (weasels and polecats actually) have
one of the lowest penis bone fracture rates in the Carnivora.  Coyotes,
fox, raccoon, and bears have higher fracture rates than ferrets, even
those early neutered ferrets with relatively tiny, slender penis bones.
 
The most common problem I've seen with penis bones in ferrets is due
to urethral blockages.  My current opinion is that the reduction in size
and girth of the penis bone due to early neuteringand especially the
morphology of the urethral grooveis directly responsible for the
increased risk of urethral blockages during adrenal disease.  I am
currently looking at a population of about 500 male ferrets, BFFs,
polecats, and New Zealand feral ferrets, so I can't say for sure until I
am done with the analysis.  Nonetheless, at this moment the statistics
are overwhelming.  The only other common problem is fractures of some
type, but these are actually quite rare.  The two most common reasons I
have found for penis bone fractures in pet ferrets are 1) hooking the
penis on the cage or other object, and 2) a female ferret not wanting a
hob at that moment in time.  I've seen a few unhealed penis bone
fractures in ferrets that suffered extensive trauma resulting in death.
 
end part 1
[Posted in FML issue 5125]