3. What is bone spavin? Describe spavin lameness. 4. Give the causes and treatment of bog spavin. 5. Give the causes and treatment of capped hock. 6. Give the causes and treatment of curb. PART III.--THE TEETH CHAPTER XIX DETERMINING THE AGE OF ANIMALS [Illustration: FIG. 51.--Head of young horse with bone cut away, and showing position and size of teeth.] GENERAL DISCUSSION.--The teeth are the passive organs of digestion. They are hard organs, implanted in the superior and inferior jaws in the form of a long and narrow arch that is open posteriorly. The free portions of the teeth project into the mouth, and present sharp or roughened table surfaces for the crushing and tearing of food. In solipeds and ruminants the arch is interrupted on each side by the inter-dental space or bars (Fig. 51). The teeth that form the middle and anterior portion of the arch are termed incisors (Fig. 52). Posterior to the incisors are the canines or tusks, and forming the arms of the arch are the molar teeth. Animals have two sets of teeth, temporary and permanent. The following table gives the number of the different kinds of temporary and permanent teeth. Temporary Teeth Permanent Teeth Incisors Canines Molars Incisors Canines Molars Solipeds 12 12 12 4 24 Ox 8 12 8 0 24 Sheep 8 12 8 0 24 Hog 12 12 12 4 24 The tusks or canine teeth are not always present in the female. Ruminants do not have upper incisor teeth. The temporary teeth are erupted either before or within a few days to a few months after birth. The eruption of the permanent teeth and the replacement of the temporary teeth occur at different periods up to the age of four and one-half years (Fig. 53). It is well to keep the following table of dentition in mind when examining the mouths of animals for the purpose of determining their age.[1] Horses Cattle Hogs Teeth Temporary Permanent Temporary Permanent Temporary Permanent