Horns and Antlers

Question 1

Purpose of horns and antlers

Answer 1

-great deterrents
-establish dominance
**not necessarily linked with longevity

Question 2

Horn growth

Answer 2

-grow gradually from birth
- single point, not branched but vary in shape and size
-present in both males and females (but may be smaller in females)

Question 3

What species have horns?

Answer 3

-Bovidae (ex. bison, buffalo, muskox, sheep/goat, gazelle, domestic cattle

Question 4

What are horns made of?

Answer 4

-made of bony core covered with a sheath of keratin

Question 5

Heat loss and horns

Answer 5

-horns provide a surface for losing heat in hot climates
-horns specialized for heat loss will have long bony core and thin keratin sheath
Ex. Longhorn cattle, kudu

Question 6

Horns in colder climates

Answer 6

-relatively short bony cores and a thick keratin sheath
Ex. pyrenees sheep, Dall’s sheep

Question 7

Growth rings in horns

Answer 7

-when stressed (calving, winters), the rate of horn growth is slower and horn is softer so wears faster
-However, number of rings is less than age because first calving and horn growth occurs after ~2 yrs

Question 8

Horn structure

Answer 8

-similar to hoof
-made of tubules and intertubular horn
-dermis base serves as periosteum and has dermal papillae that elongate and thicken the horn
-horn wall/sheath grows from epithelium that covers dermis between papillae (sheath actually modified cornified stratum of epithelium)

Question 9

Glossy sheen of horns

Answer 9

-soft outer layer (epiceras) gives glossy sheen

Question 10

Vascularization of horns

Answer 10

-horns are very vascular
-difficult to stop bleeding, need heat/cauterization

Question 11

Development of horns

Answer 11

-horns develop from germinal epithelium on top of bone
**it can be removed, damaged, or displaced

Question 12

Dehorning

Answer 12

-should be done early in life but if not, need nerve blocks

Question 13

Main nerve in cattle horn

Answer 13

-Cornual nerve (of zygomatico-temporal of maxillary nerve (V2)

Question 14

Other nerve blocks in cattle that may be needed if cornual nerve not sufficient

Answer 14

-Frontal nerve
-infratrochlear nerve
-ring block around horn base

Question 15

Nerve blocks in goats/sheep

Answer 15

-Cornual nerve of zygomatico-temporal nerve (V2)
-cornual branch of infratrochlear nerve (V1)

Question 16

Rhino “horns”

Answer 16

-made of compact hair/dermal papillae

Question 17

Giraffe horn

Answer 17

-not an extension of frontal bone
-develop from a separate cartilaginous bone
-horns present in both sexes
-have them since birth

Question 18

Pronghorns

Answer 18

-differ from both horns and antlers
-only present in American pronghorns- only member in Antilocapridae family
-made of bony core and keratinous sheath
-branched and shed annually (different than typical horns)

Question 19

Species that have Antlers and general information

Answer 19

-only present in males of Cervidae (and females of caribou/reindeer)
-no extension of frontal sinus
-vary in shape and size, with multiple points (branched)

Question 20

Antler growth

Answer 20

-grow and shed annually
-growing antler made of cartilage with velvet skin; dry antler made of solid bone
-whole weight achieved within a few weeks; one of the fastest growing mammal tissues (next to gravid uterus)

Question 21

Cervids and canine teeth

Answer 21

-sometimes have large canine teeth that have same purpose as antlers
-Muntjacs (barking deer) have both canines and antlers

Question 22

Velvet antlers

Answer 22

-in demand for traditional oriental medicine

Question 23

Where does antler come from?

Answer 23

-antler comes from antler pedical from frontal bone

Question 24

Antler shedding

Answer 24

-pedicle is chewed up by osteoclasts and antlers are cast
-Caribou: often times males don’t have antlers in winter when food is scares because they shed them after large increases in testosterone. Allows females to outcompete them

Question 25

Antlers and successive growth

Answer 25

-antlers get bigger in successive years for several years
-they will have a prime age though and eventually become weak/lose strength

Question 26

Caribou/reindeer

Answer 26

• basically the same species with small differences. Reindeer is domesticated, caribou is wild
• females have antlers through winter giving them advantage at feeding grounds over males

Question 27

Innervation of antlers

Answer 27

-infratrochlear nerve (of V1)
-Auriculopalpebral nerve (of VII)
-Zygomatico-temporal nerve (of V2)
-ring block around pedicle

**important for antler removal because of antler supplement market