2 IntroductionThe only accurate method of determining the age of an animal is to know its birth date.In the absence of birth information, use other criteria.The examination of the animal’s teeth is the most widely employed method to determine age.Remember Mr. McMillan? What did he talk about?
3 IntroductionThe eruption date is the time that a tooth normally breaks the gum line.It is more reliable than tooth wear for determining age.
4 Introduction Tooth wear is subject to considerable variation. Aging an animal using only this criterion is often difficult.That is why many people say that this animal has the teeth of an animal that is ___ years old, rather than saying that the animal is ____ years old.
5 Introduction Domestic animals develop two sets of teeth. Deciduous teethPermanent teeth
6 IntroductionDeciduous teeth, also known as baby teeth, are typically smaller and whiter than permanent teeth.Because young animals have much smaller jaws, there are always fewer deciduous teeth than there are permanent teeth.
7 IntroductionAge estimates of horses and ruminants are based on the appearance of the lower incisors and canine teeth.While the eruption dates of cheek teeth (premolars and molars) are more accurate, they are seldom used.The upper permanent first premolars of horses are either absent or are small rudimentary teeth, called wolf teeth, which erupt at 5 to 6 months of age.
8 Aging HorsesThe incisor teeth of horses differ from those of other domestic animals since they continually erupt (to a certain age) to prevent a deficit in length.
10 Aging HorsesThe following presents important dates for aging horses. Keep in mind that these are average ages and that variations occur in many instances.1 week oldDeciduous central incisors erupt1 month oldDeciduous intermediate incisors erupt8 months oldDeciduous corner incisors erupt
11 Aging Horses 2 ½ years 3 ½ years 4 ½ years 4-5 years 6 years 7 years Permanent central incisors erupt3 ½ yearsPermanent intermediate incisors erupt4 ½ yearsPermanent corner incisors erupt4-5 yearsPermanent canines erupt (males only)6 years“cup” gone from central incisors7 years“cup” gone from intermediate incisors8 years“cup” gone from corner incisors
12 Aging HorsesBeyond eight years, age determination largely becomes a matter of speculation.To determine the animal’s age, use several features, such as the shape of the occlusal surface or the angle between the upper and lower incisors.The shapes of the occlusal surfaces begin oval, then change to round, triangular, and biangular, as the animal ages.The angle between the upper and lower incisors when viewed from the side becomes more acute as the horse ages.
16 Aging Cattle Less than – 1 year 1 ½ - 2 years 2 – 2 ½ years First permanent incisors erupt2 – 2 ½ yearsSecond permanent incisors erupt
17 Aging Cattle 3 years 3 ½ - 4 years 5 years Third permanent incisors erupt3 ½ - 4 yearsLast permanent incisors erupt5 yearsAll permanent incisors show wear
18 Aging Sheep and GoatsThe lower incisors are also used in age estimations of sheep and goats.Because they develop teeth at about the same age, sheep and goats have similar eruption dates.
19 Aging Sheep and Goats Less than 1 year 1 – 1 ½ years 1 ½ - 2 years First permanent incisors erupt1 ½ - 2 yearsSecond permanent incisors erupt
20 Sheep and Goat Teeth 2 ½ - 3 years 3 – 4 years Third permanent incisors erupt3 – 4 yearsLast permanent incisors erupt
21 Aging Dogs and CatsThe permanent teeth of dogs and cats have all erupted by the time the animal is approximately six months of age.While the wear of teeth is somewhat accurate in large breeds of dogs, it is often misleading, and in smaller dog breeds and cats, it is seldom used.The best way to determine a dog’s or cat’s age is to know its birth date.
24 Aging Cats 2 – 4 weeks 3 – 4 weeks 4 – 6 weeks 8 weeks 3 ½ - 4 months Deciduous incisors coming in3 – 4 weeksDeciduous canines coming in4 – 6 weeksDeciduous premolars coming in on lower jaw8 weeksAll deciduous teeth are in3 ½ - 4 monthsPermanent incisors coming in4 – 5 monthsPermanent canines, premolars, and molars coming in5 – 7 monthsAll permanent teeth in
25 Review What is the difference between deciduous and permanent teeth? Why is tooth wear not a reliable factor when trying to determine age?What is the only accurate way to determine the age of an animal?