Determining Age of Animals. Introduction The only accurate method of determining the age of an animal is to know its birth date. The only accurate method

Determining Age of AnimalsDetermining Age of Animals

IntroductionIntroduction

The only accurate method of determining the age The only accurate method of determining the age of an animal is to know its birth date.of an animal is to know its birth date.

In the absence of birth information, use other In the absence of birth information, use other criteria.criteria.

The examination of the animal’s teeth is the most The examination of the animal’s teeth is the most widely employed method to determine age.widely employed method to determine age.

Remember Mr. McMillan? What did he talk about?Remember Mr. McMillan? What did he talk about?


The eruption date is the time that a tooth The eruption date is the time that a tooth normally breaks the gum line.normally breaks the gum line.

It is more reliable than tooth wear for It is more reliable than tooth wear for determining age.determining age.


Tooth wear is subject to considerable Tooth wear is subject to considerable variation.variation.

Aging an animal using only this criterion is Aging an animal using only this criterion is often difficult.often difficult.

That is why many people say that this That is why many people say that this animal has the teeth of an animal that is ___ animal has the teeth of an animal that is ___ years old, rather than saying that the animal years old, rather than saying that the animal is ____ years old.is ____ years old.


Domestic animals develop two sets of teeth.Domestic animals develop two sets of teeth.– Deciduous teethDeciduous teeth– Permanent teethPermanent teeth


Deciduous teeth, also known as baby teeth, Deciduous teeth, also known as baby teeth, are typically smaller and whiter than are typically smaller and whiter than permanent teeth.permanent teeth.

Because young animals have much smaller Because young animals have much smaller jaws, there are always fewer deciduous jaws, there are always fewer deciduous teeth than there are permanent teeth.teeth than there are permanent teeth.


Age estimates of horses and ruminants are based Age estimates of horses and ruminants are based on the appearance of the lower incisors and on the appearance of the lower incisors and canine teeth.canine teeth.

While the eruption dates of cheek teeth (premolars While the eruption dates of cheek teeth (premolars and molars) are more accurate, they are seldom and molars) are more accurate, they are seldom used.used.

The upper permanent first premolars of horses are The upper permanent first premolars of horses are either absent or are small rudimentary teeth, either absent or are small rudimentary teeth, called wolf teeth, which erupt at 5 to 6 months of called wolf teeth, which erupt at 5 to 6 months of age.age.

Aging HorsesAging Horses

The incisor teeth of horses differ from those The incisor teeth of horses differ from those of other domestic animals since they of other domestic animals since they continually erupt (to a certain age) to continually erupt (to a certain age) to prevent a deficit in length.prevent a deficit in length.

Diagram of the horse head and teethDiagram of the horse head and teeth


The following presents important dates for The following presents important dates for aging horses. Keep in mind that these are aging horses. Keep in mind that these are average ages and that variations occur in average ages and that variations occur in many instances.many instances.– 1 week old1 week old

Deciduous central incisors eruptDeciduous central incisors erupt

– 1 month old1 month old Deciduous intermediate incisors eruptDeciduous intermediate incisors erupt

– 8 months old8 months old Deciduous corner incisors eruptDeciduous corner incisors erupt

Aging HorsesAging Horses 2 ½ years2 ½ years

– Permanent central incisors eruptPermanent central incisors erupt 3 ½ years3 ½ years

– Permanent intermediate incisors eruptPermanent intermediate incisors erupt 4 ½ years4 ½ years

– Permanent corner incisors eruptPermanent corner incisors erupt 4-5 years4-5 years

– Permanent canines erupt (males only)Permanent canines erupt (males only) 6 years6 years

– ““cup” gone from central incisorscup” gone from central incisors 7 years7 years

– ““cup” gone from intermediate incisorscup” gone from intermediate incisors 8 years8 years

– ““cup” gone from corner incisorscup” gone from corner incisors


Beyond eight years, age determination largely Beyond eight years, age determination largely becomes a matter of speculation.becomes a matter of speculation.

To determine the animal’s age, use several To determine the animal’s age, use several features, such as the shape of the occlusal features, such as the shape of the occlusal surface or the angle between the upper and lower surface or the angle between the upper and lower incisors.incisors.

The shapes of the occlusal surfaces begin oval, The shapes of the occlusal surfaces begin oval, then change to round, triangular, and biangular, as then change to round, triangular, and biangular, as the animal ages.the animal ages.

The angle between the upper and lower incisors The angle between the upper and lower incisors when viewed from the side becomes more acute when viewed from the side becomes more acute as the horse ages.as the horse ages.

Teeth at age 3 ½ and age 20Teeth at age 3 ½ and age 20

Aging CattleAging Cattle

To determine age in cattle, the lower To determine age in cattle, the lower incisors must be examined because they do incisors must be examined because they do not have upper incisors.not have upper incisors.

Several key dates aid in the estimation of an Several key dates aid in the estimation of an animal’s age.animal’s age.

Diagram of Cattle TeethDiagram of Cattle Teeth


Less than – 1 yearLess than – 1 year

1 ½ - 2 years1 ½ - 2 years– First permanent incisors eruptFirst permanent incisors erupt

2 – 2 ½ years2 – 2 ½ years– Second permanent incisors eruptSecond permanent incisors erupt


3 years3 years– Third permanent incisors eruptThird permanent incisors erupt

3 ½ - 4 years3 ½ - 4 years– Last permanent incisors eruptLast permanent incisors erupt

5 years5 years– All permanent incisors show wearAll permanent incisors show wear

Aging Sheep and GoatsAging Sheep and Goats

The lower incisors are also used in age The lower incisors are also used in age estimations of sheep and goats.estimations of sheep and goats.

Because they develop teeth at about the Because they develop teeth at about the same age, sheep and goats have similar same age, sheep and goats have similar eruption dates.eruption dates.

Aging Sheep and GoatsAging Sheep and Goats

Less than 1 yearLess than 1 year

1 – 1 ½ years1 – 1 ½ years– First permanent incisors eruptFirst permanent incisors erupt

1 ½ - 2 years1 ½ - 2 years– Second permanent incisors eruptSecond permanent incisors erupt

Sheep and Goat TeethSheep and Goat Teeth

2 ½ - 3 years2 ½ - 3 years– Third permanent incisors eruptThird permanent incisors erupt

3 – 4 years3 – 4 years– Last permanent incisors eruptLast permanent incisors erupt

Aging Dogs and CatsAging Dogs and Cats

The permanent teeth of dogs and cats have The permanent teeth of dogs and cats have all erupted by the time the animal is all erupted by the time the animal is approximately six months of age.approximately six months of age.

While the wear of teeth is somewhat While the wear of teeth is somewhat accurate in large breeds of dogs, it is often accurate in large breeds of dogs, it is often misleading, and in smaller dog breeds and misleading, and in smaller dog breeds and cats, it is seldom used.cats, it is seldom used.

The best way to determine a dog’s or cat’s The best way to determine a dog’s or cat’s age is to know its birth date.age is to know its birth date.

Canine TeethCanine Teeth

Aging DogsAging Dogs

Deciduous Teeth (Puppy Teeth)Deciduous Teeth (Puppy Teeth)– Incisors: 3 – 4 weeks Incisors: 3 – 4 weeks – Canines: 3 weeksCanines: 3 weeks– Premolars: 4 – 12 weeks Premolars: 4 – 12 weeks – Molars: NoneMolars: None

Permanent Teeth (Adult Teeth)Permanent Teeth (Adult Teeth)– Incisors: 3 – 5 monthsIncisors: 3 – 5 months– Canines: 4 – 6 monthsCanines: 4 – 6 months– Premolars: 4 – 6 monthsPremolars: 4 – 6 months– Molars: 5 – 7 monthsMolars: 5 – 7 months

Aging CatsAging Cats 2 – 4 weeks2 – 4 weeks

– Deciduous incisors coming inDeciduous incisors coming in 3 – 4 weeks3 – 4 weeks

– Deciduous canines coming inDeciduous canines coming in 4 – 6 weeks4 – 6 weeks

– Deciduous premolars coming in on lower jawDeciduous premolars coming in on lower jaw 8 weeks8 weeks

– All deciduous teeth are inAll deciduous teeth are in 3 ½ - 4 months3 ½ - 4 months

– Permanent incisors coming inPermanent incisors coming in 4 – 5 months4 – 5 months

– Permanent canines, premolars, and molars coming inPermanent canines, premolars, and molars coming in 5 – 7 months5 – 7 months

– All permanent teeth inAll permanent teeth in

ReviewReview

What is the difference between deciduous What is the difference between deciduous and permanent teeth?and permanent teeth?

Why is tooth wear not a reliable factor when Why is tooth wear not a reliable factor when trying to determine age?trying to determine age?

What is the only accurate way to determine What is the only accurate way to determine the age of an animal?the age of an animal?

Documents

Determining Age of Animals. Introduction The only accurate method of determining the age of an animal is to know its birth date. The only accurate method