Determining Age of Animals

Introduction The 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?

Introduction The eruption date is the time that a tooth normally breaks the gum line. It is more reliable than tooth wear for determining age.

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.

Introduction Domestic animals develop two sets of teeth. Deciduous teeth Permanent teeth

Introduction Deciduous 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.

Introduction Age 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.

Aging Horses The 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.

Diagram of the horse head and teeth

Aging Horses The following presents important dates for aging horses. Keep in mind that these are average ages and that variations occur in many instances. 1 week old Deciduous central incisors erupt 1 month old Deciduous intermediate incisors erupt 8 months old Deciduous corner incisors erupt

Aging Horses 2 ½ years 3 ½ years 4 ½ years 4-5 years 6 years 7 years Permanent central incisors erupt 3 ½ years Permanent intermediate incisors erupt 4 ½ years Permanent corner incisors erupt 4-5 years Permanent canines erupt (males only) 6 years “cup” gone from central incisors 7 years “cup” gone from intermediate incisors 8 years “cup” gone from corner incisors

Aging Horses Beyond 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.

Teeth at age 3 ½ and age 20

Aging Cattle To determine age in cattle, the lower incisors must be examined because they do not have upper incisors. Several key dates aid in the estimation of an animal’s age.

Diagram of Cattle Teeth

Aging Cattle Less than – 1 year 1 ½ - 2 years 2 – 2 ½ years First permanent incisors erupt 2 – 2 ½ years Second permanent incisors erupt

Aging Cattle 3 years 3 ½ - 4 years 5 years Third permanent incisors erupt 3 ½ - 4 years Last permanent incisors erupt 5 years All permanent incisors show wear

Aging Sheep and Goats The 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.

Aging Sheep and Goats Less than 1 year 1 – 1 ½ years 1 ½ - 2 years First permanent incisors erupt 1 ½ - 2 years Second permanent incisors erupt

Sheep and Goat Teeth 2 ½ - 3 years 3 – 4 years Third permanent incisors erupt 3 – 4 years Last permanent incisors erupt

Aging Dogs and Cats The 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.

Canine Teeth

Aging Dogs Deciduous Teeth (Puppy Teeth) Permanent Teeth (Adult Teeth) Incisors: 3 – 4 weeks Canines: 3 weeks Premolars: 4 – 12 weeks Molars: None Permanent Teeth (Adult Teeth) Incisors: 3 – 5 months Canines: 4 – 6 months Premolars: 4 – 6 months Molars: 5 – 7 months

Aging Cats 2 – 4 weeks 3 – 4 weeks 4 – 6 weeks 8 weeks 3 ½ - 4 months Deciduous incisors coming in 3 – 4 weeks Deciduous canines coming in 4 – 6 weeks Deciduous premolars coming in on lower jaw 8 weeks All deciduous teeth are in 3 ½ - 4 months Permanent incisors coming in 4 – 5 months Permanent canines, premolars, and molars coming in 5 – 7 months All permanent teeth in

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?