There was a FML question as well as several e-mails on if teeth really were a good indication of age. Answer? Sometimes; depends on the technique. The first technnique is to estimate age using tooth eruption sequences. There are two periods of time when the detention is fairly accurate at predicting age: 1) during the eruption of the deciduous (baby) teeth, and 2) during the eruption of the permanent teeth. The eruption times are fairly consistent, for example, the eruption of the permanent upper canines (fangs) at about 8 weeks. However, it is important to realize that all values can be off by as much as a week or more. But of all the techniques, it is the most reliable and accurate, but is limited to the first few months of the ferret' life. Another technique is to estimate age using tooth wear as a criterion. The idea is the average tooth wear is fairly consistent over time and space. (Right, and I'm a hunk...) This technique does not result in knowing the age of the ferret; only that one ferret is older than the other because its teeth are more worn. A slightly modified version of the technique takes into account the number of missing teeth. Generally (and I mean *very* generally) the sequence of tooth loss is a) incisors b) premolars c) molars d) canines. While this method cannot take into account genetic differences between animals, individual diet, malnutritional changes in the dentine, etc., it is quite effective at guessing which animals within a limited population are older than the others. Because most ferrets in the USA eat a dry pelleted chow, the wear rates can be fairly constant accross the board (on the *average*, mind you. Still lots of room for error) and the method can be and is used by lots of people, including in my experience, vets. With practice, the careful observer may be able to guess an age within a year. but there is no scientific way that age can be prove. It is an estimate only. But it is quite prone to error, only shows one ferret is older than another, and requires lots of experience to recognize the differences in wear. A third method is to use the transparency of the canines as a guide. This is based on the idea that as teeth get older, the root canals fill with dentine, which changes the light absorbancy characteristics of the tooth, making them appear transluscent, and canines are long and thin enough for these changes to show. Since the root canals fill-in from the crown of the tooth towards the root, the relative amount of transluscence can be used to estimate age. This technique suffers from all the problems of the 2nd method (wear) plus one more problem. The deposition of cement and dentine in the root is highly influenced by load bearing (the amount of work the teeth do). Like poeple, ferrets can be highly individualistic in terms of chewing, so this technique is subject to great gobs of error. The least accurate of the three. A fourth technique is the patterning method. Knowing the only technique that gives a real age is tooth eruption, and after that, all you know is one ferret has more wear or tooth changes than another, this technique compares the general state of the teeth to other physical changes in the ferret's body to arrive at an estimation of age. The method is quite subject to individual error; still, the experienced observer can generally estimate a ferret's age to within a year or two, using some combination of all three techniques (and body condition, alertness, etc). Other techniques that can be done to estimate age from teeth, but they are destructive to the tooth, or require the tooth to be placed in scanning electron microscopes, or even radioactive chambers. Hard to do when the ferret is alive, unless you don't mind pulling a tooth. (I do). With dead animals, lab techniques can give good ages for the first three or four years, then the error rate increases to a year or more. Like with humans, it is easy to say "this ferret is *at least* X-years-old" but very hard to say "this ferret *is* X-years-old." (A cool trick is to know the average age at death is between 7-10 years old. When you come across a middle-aged ferret, inspect it carefully, then say "This ferret is between 4- and 7-years-old, plus or minus 3 or 4 years." The statement covers almost every ferret over a year old. You are rarely wrong, and those times you get a really old ferret, just comment how *young* it looks--a certain reflection of owner care--and they won't care if you are wrong.) Thats the tooth, 'n I'm sticking by it. You can crown me if you like; even snap at me (I'll re-fang from nasty replies), but that's the tooth of it (or at least a quick re-dentition). If you have an apatite for more, ask and we can chew the subject privately. I won't bite your head off; I'd rather cement our relationship than to damage it at the root. In either case, my cap is off to anyone enameled enough with the subject to learn more. BTW, BIll, you'll never get a copy of the tape. Elizabeth hopes to date during her immediate lifetime. (Ba ha ha ha!) Besides, she wants to run in the Nationals (he he he). Bob and the 14 Masticating Monsters. [Moderator's note: FERRET BITE ALERT!!! We have to test Bob for rabies before it's too late! Now let's see, how do we test... hmmm... Bobbit, one O? (Of course if we had the tape we may be able to figure out what *really* happened without resorting to testing....) BIG] [Posted in FML issue 1615]