Q:"Not long ago you listed the tooth eruption times for ferrets.  Can you
repost it, but with more explaination of the teeth?...I think it would it
be useful in aging [kits] from pet stores...."
 
A: Useful is as useful does.
 
The majority of mammals have 4 basic types of teeth; Incisors, Canines,
Premolars and Molars.  Not all mammals; some, like dolphins or anteaters
have "molarform" teeth, but--as embryos--the basic four are there.  Many
mammals have lost some of the basic four, and in many cases, the basic
shape has been changed, so the tooth is hard to identify.  For example,
bovids (cattle, sheep, deer) look like they have 8 lower incisors, but
really they have 6; 2 canines only look like incisors.
 
Mammals also have two set of teeth; the baby teeth (deciduous) and the
permanent teeth.  In some mammals, the baby teeth are lost prior to birth,
and in others, teeth are completely resorbed without eruption, but most
have both sets.  There is an established sequence of tooth eruption and
loss for each species of animal.  For example, baby molars are not lost
until the permanent molars have erupted, and then they are replaced by
premolars.  Not all species grow or lose teeth in the same order or at the
same time, but within species it is quite consistent providing diet and
health remain constant.
 
While teeth are made of the same basic substance as bone, because of the
way the crystals are laid down and the lack of water, teeth are the hardest
substance in the body.  They are quite capable of crushing, cutting, and
fracturing bones; yet regardless of their hardness, they still continuously
wear down.  Unlike bones, teeth cannot repair themselves when broken.  A
broken tooth is permanently injured.  Because of chewing stress and wear,
the nerve and blood supply slowly withdraws from the root canal, and the
space is filled with dentine.  This gives the tooth a transparent look
because changes of how light passes through the enamel have taken place.
Small holes into the root canal are generally plugged with dentine within
a short period of time.
 
Incisors are the front teeth and are used for grooming, grasping, pulling
and holding.  Ferrets have 12; 6 on both the top and bottom (3 each side).
The third one on each side of the top is larger than the rest and a little
more pointed, the rest being chisel- or peg-like.  In ferrets, it is common
for the incisors to overlap, making the tooth row look uneven.  Maybe 1
ferret in 1000 has an extra incisor, almost always on top, in the middle.
This "supernumerary" tooth is almost always a baby tooth that is never lost
and there is no need to remove it.  The incisors are rarely broken or lost,
but such injury is unimportant to the health of the ferret, provide
infections do not occur.
 
Incisor eruption: Deciduous = 0(4)10 days; Permanent = 20(22)30 days.  The
first number is the earliest date erupted, the middle number is the average
or typical date, and the last number is the latest date.
 
Canines are the long fangs and are used for killing, protection, tearing
and ripping.  Ferrets have 4; 2 on top (1 each side) and 2 on bottom (1
each side).  The top canines are generally longer and slightly more curved.
In ferrets, the top canines are frequently injured, either by chipping the
tip, or a gum-line break.  While the ferret has a diminished ability to
protect itself from aggressive ferrets or larger predators, the loss of the
canine in pet ferrets is displeasing, but essentially unimportant.
 
Canine eruption: Deciduous = 20(20)30 days; Permanent = 45(50)55 days.
 
Premolars are the teeth between the canines and the permanent molars and
are used to cut, crush and tear.  Ferrets have 12, 6 each on the top and
bottom (3 on each side).  Although the name implies they look like molars,
that is not always true.  In ferret deciduous teeth, the front ones look
like little cones (if you can see them), and the back one is a cutting
tooth, called the sectorial or carnassial.  In the permanent dentition, the
front premolars are conical or triangular shaped.  The last premolar (PM4)
in the top jaw is the cutting tooth.  The loss of one of the conical or
triangular premolars is relatively unimportant, but the loss of the cutting
premolar is a serious problem because this tooth is used to cut food small
enough to swallow.
 
Premolar eruption: Deciduous: pm2 = 24(28)32 days, pm3 = 20(20)45 days,
pm4 = 20(20)50 days.  Permanent: PM2 = 55(60)65, Upper PM3 = 55(60)65 days,
Lower PM3 = 63(67)70, Upper PM4 = 55(60)65, Lower PM4 = 55(74)80.
 
Molars do not have a deciduous form; they are only found in the permanent
dentition and are generally used to crush food, although in the ferret they
are also used for cutting muscle and bone.  Molars don't have to look like
molars; in the ferret one is a cutting tooth.  Ferrets have 6 molars; 2 on
top (1 each side) and 4 on bottom (2 each side).  The top molar is a small,
oval shaped flat tooth.  The 1st molar on the bottom is a cutting
(carnassial) tooth.  The 2nd molar is a tiny roundish flat tooth.  The
loss of the tiny molars can impact somewhat on the chewing ability of the
ferret, but not much.  The loss of the cutting molar is a serious problem.
 
Molar eruption: Upper M1 = 48(53)55, Lower M1 = 48(50)53, Lower M2
70(74)80.
 
The typical eruption date (within parentheses) assumes the ferret is
healthy, well-fed and "average." The range of dates reflects individual
variation, nutritional status, and impact of disease and stress.  What this
means is, just because the lower M2 (2nd Molar) is erupting, it doesn't
mean the ferret is 74 days old.  It could be between 70 and 80 days old.
Most will be around 74 days old, but you cannot be sure if yours is one
of them, so use qualifier words like "about" or "approximately."
 
Bob C and 19 Mo' Tooth Terrorists
[Posted in FML issue 2651]