17 – Horns and Antlers

Question 1

What are horns and antlers used for?

Answer 1

-great DETERRENTS
-establish DOMINANCE
-provide a surface for LOSING heat in hot climates
*biggest horns don’t always coincide with LONGEVITY

Question 2

Horns:

Answer 2

-grow gradually from birth
-male and females of Bovidae
>female may be smaller
-single point (not branched)
-vary in shape and size

Question 3

Bovidae:

Answer 3

-bison
-buffalo
-muskox
-sheep/goat
-gazelle
-domestic cattle

Question 4

What are horns made of?

Answer 4

-LONG BONY CORE covered with a THIN KERATIN sheath

Question 5

Horns of animals in colder climates:

Answer 5

-relatively SHORT bony core
-THICK keratin sheath
*minimize heat loss

Question 6

Growth rings of horns can be used for ageing:

Answer 6

-when STRESSED (winters, calving), rate of horn growth is slower
>horn is SOFTER so wears faster
*# of rings LESS than age
Ex. female cattle start calving at 2 years of age

Question 7

Horn structure:

Answer 7

-like a hoof
-made of tubules and intertubular HORN
-dermis at base
-horn wall (sheath)
-extremely vascular

Question 8

Dermis at base of horn:

Answer 8

-serves as periosteum
-has DERMAL PAPILLAE that elongate and thicken horn

Question 9

Softer outermost layer of horn:

Answer 9

-epiceras
-gives it a glossy sheen

Question 10

Horn wall (sheath):

Answer 10

-grows from EPITHELIUM that covers the dermis between papillae
-modified cornified stratum of epithelium

Question 11

Horn develops from:

Answer 11

-GERMINAL epithelium on top of BONE
>can be removed, damaged or DISPLACED

Question 12

Dehorning later in life:

Answer 12

-requires nerve blocks
*main nerve in CATTLE is CORNUAL nerve

Question 13

If cornual nerve block is insufficient in cattle, may need to block:

Answer 13

-FRONTAL
-infratrochlear nerves
-a RING block around the horn base

Question 14

What nerve block do you do for dehorning goat/sheep?

Answer 14

-cornual BRANCH of infratrochlear nerve

Question 15

Rhino ‘horns’:

Answer 15

-has a bone core, but the rest is COMPACT hair/dermal papillae

Question 16

Giraffe ‘horns’:

Answer 16

-NOT an extension of frontal bone
-develops from SEPARATE cartilaginous bone
-present in males and females
-have them since BIRTH

Question 17

Pronghorns:

Answer 17

-differ from both horns and antlers
-seen ONLY in (American) pronghorn (only member of Antilocapridae family)
-males and females

Question 18

Pronghorns are made of:

Answer 18

-bony core and keratinous sheath

Question 19

Unlike horns, pronghorns are:

Answer 19

-BRANCHED
-shed ANNUALLY
*get more branched through the year before falling off

Question 20

Antlers:

Answer 20

-grow and shed ANNUALLY
-only in MALES of Cervidae (except caribou/reindeer)
-no extension of frontal sinus
-vary in shape and sizes
-branched

Question 21

What is the growing antler made of?

Answer 21

-CARTILAGE with velvety skin

Question 22

What is a dry antler made of?

Answer 22

-solid bone

Question 23

What do some cervids have instead of antlers?

Answer 23

-large CANINE TEETH
>same purpose as antlers
Ex. Muntjacs (barking dear) have both canines and short antlers

Question 24

How long does it take for the whole antler to be grown?

Answer 24

-within a few WEEKS
-get bigger in successive years for several years
*one of the fastest growing tissues in mammals

Question 25

Which tissue may be faster growing than antlers?

Answer 25

-gravid UTERUS

Question 26

Velvet antlers:

Answer 26

-are in demand for traditional oriental medicine

Question 27

Antler pedical:

Answer 27

-base of antler
-stays even after antler falls off
*layer of antler stem cells

Question 28

What is the annual antler cycle for typical Cervidae?

Answer 28

-antlers are cast in April
-new ones grow and become hard antler in August
>testosterone levels have increased=fertile

Question 29

Caribou/reindeer:

Answer 29

-similar
-caribou: WILD
-reindeer: domesticated
*FEMALES have antlers

Question 30

Female caribou/reindeer antlers:

Answer 30

-keep them thru WINTER
>gives them advantage at feeding grounds

Question 31

What is the annual antler cycle for MALE caribou/reindeer?

Answer 31

-cast at end of November
-velvet in April
-hard antler in August/September
*conception

Question 32

What is the annual antler cycle for FEMALE caribou/reindeer?

Answer 32

-cast at calving (April)
-velvet right away
-hard antler in September

Question 33

What is the innervation of the antler?

Answer 33

-infratrochlearn nerve
-auriculopalpebral nerve
-zygomatico-temporal nerve
*ring block around the pedicle