42: Horses

Question 1

Determining the age of a horse by examining its incisor teeth is most accurate up to which of the following ages?

a] 6 years
b] 12 years
c] 18 years
d] 25 years
e] More than 25 years

Answer 1

a] 6 years

Recent studies have shown that aging a horse after all permanent teeth are present is highly inaccurate.

Question 2

What structure of the hoof is not desensitized by a palmar digital nerve block?

a] Wall
b] Dorsal part of the coronary band
c] Sole of hoof
d] Periople

Answer 2

b] Dorsal part of the coronary band

Question 3

What structures are most important in “fixing” the elbow joint as part of the stay apparatus in the horse?

a] Extensor carpi radialis, radial nerve
b] Biceps brachii, musculocutaneous nerve
c] Triceps, radial nerve
d] Teres minor, axillary nerve

Answer 3

c] Triceps, radial nerve

Question 4

Which of the following cranial nerves (CN) are involved in the menace response?

a] II and III
b] II and V
c] II and IV
d] II and VII

Answer 4

II and VII

The horse must see the hand (II) and blink his eyelids (VII). CN V is involved in sensation around the eye. CN III controls the pupil and some movements of the globe. CN IV rotates the globe inward and upward (dorsal oblique muscle).

Question 5

In the horse, sodium and water transport occurs primarily in which of the following?

a] Small intestine
b] Cecum
c] Transverse colon
d] Small colon

Answer 5

a] Small intestine

Sodium and water transport occurs primarily in the equine small intestine.

Question 6

The 4th tarsal in the ox differs from that of the horse in that it

a] contacts the lateral malleolus.
b] extends from the proximal intertarsal joint to the tarsometatarsal joint.
c] is fused to the central tarsal.
d] is split into two bones.

Answer 6

c] is fused to the central tarsal.

Question 7

The facial crest, infraorbital foramen, and medial canthus of the eye are used by equine surgeons as landmarks for a direct surgical approach to which of the following?

a] Frontal sinus
b] Ventral conchal sinus
c] Sphenopalatine sinus
d] Maxillary sinus
e] Middle conchal sinus

Answer 7

d] Maxillary sinus

The maxillary sinus can be accessed directly via trephination or a bone-flap technique using these landmarks. The rostral compartment of the maxillary sinus communicates with the ventral conchal sinus, and the caudal compartment of the maxillary sinus communicates with the frontal, sphenopalatine, and middle conchal sinuses. With extensive disease of the paranasal sinuses, other surgical approaches may be indicated.

Question 8

Which of the following statements is most correct concerning the equine larynx?

a] The muscle that controls abduction of the arytenoid cartilages, allowing for maximal airflow down to the lungs, is the cricoarytenoideus dorsalis.
b] The aryepiglottic folds connect the muscular process of the arytenoids to the ventral surface of the epiglottis.
c] Innervation to the adductor muscles of the arytenoid cartilages is by the recurrent laryngeal nerve.
d] The larynx is composed of three cartilages, including the epiglottis, arytenoids, and cricoid cartilage

Answer 8

a] The muscle that controls abduction of the arytenoid cartilages, allowing for maximal airflow down to the lungs, is the cricoarytenoideus dorsalis.

The opening of the larynx is controlled by cricoarytenoideus dorsalis and is innervated by the recurrent laryngeal nerve. The laryngeal cartilages consist of the epiglottis, thyroid cartilage, cricoid cartilage, and paired arytenoid cartilages. The aryepiglottic fold connects the corniculate processes of the arytenoids to the ventral surface of epiglottis.

Question 9

Choose the MOST ACCURATE listing of accessory sex glands of stallion:

a] Ampullae, disseminate prostate, bulbourethral
b] Ampullae, bulbourethral, disseminate prostate, vesicular
c] Bulbourethral, bilobed prostate, vesicular, ampullae
d] Ampullae, bilobed prostate, vesicular

Answer 9

c] Bulbourethral, bilobed prostate, vesicular, ampullae

Question 10

Which of the following selections names the bones that are found distal to the knee joint in a horse?

a] Tibia, tarsal bones, metatarsal bones, phalanges, proximal and distal sesamoids
b] Femur, ilium, ischium, pubis
c] Scapula, humerus, radius, and ulna fused
d] Metacarpals, phalanges, proximal and distal sesamoids
e] Radius and ulna fused, carpal bones, metacarpals, phalanges, proximal and distal sesamoids

Answer 10

d] Metacarpals, phalanges, proximal and distal sesamoids

The knee is the common name for the carpal joint in the horse. Knee is not an appropriate term used to commonly name the stifle/femorotibial joint for a horse.

Question 11

The spinal white matter composed almost entirely of ascending nerve fibers is the

a] dorsal funiculus.
b] lateral funiculus.
c] ventral funiculus.
d] both lateral and ventral funiculi.

Answer 11

a] dorsal funiculus.

Question 12

Concerning retained deciduous teeth [in horses], which statement is least accurate?

a] Dental caps are deciduous teeth that remain attached to newly erupted teeth.
b] The 4th premolar is the most frequently involved deciduous tooth.
c] The upper incisors frequently become impacted as deciduous teeth.
d] The 4th premolar tooth is the last tooth to erupt, and its emergence may be compromised by adjacent teeth.
e] Wolf teeth usually cause no problems with respect to deciduous teeth.

Answer 12

c] The upper incisors frequently become impacted as deciduous teeth.

In rare instances, the incisors may be retained and become impacted.

Question 13

On rectal examination of a horse, you palpate a segment of distended bowel that is devoid of teniae. The segment of bowel you are palpating is most likely which of the following?

a] Small colon or small intestine
b] Pelvic flexure or small intestine
c] Pelvic flexure or right dorsal colon
d] Sternal flexure or small colon
e] Base of cecum or right dorsal colon

Answer 13

b] Pelvic flexure or small intestine

Only the pelvic flexure and small intestine are devoid of teniae.

Question 14

How many parts are there for the maxillary sinus in horses?

a] 3
b] 4
c] 1
d] 2

Answer 14

d] 2

The maxillary sinus in horses is divided by an oblique septum into a smaller cranial (cranial maxillary sinus) and a larger caudal (caudal maxillary sinus) compartment.

Question 15

What is the function of the reciprocal apparatus in horses?

a] Flex the hock when the stifle flexes
b] Extend the hock when the stifle flexes
c] Flex the hock then the stifle extends
d] Flex the fetlock when the hock extends

Answer 15

a] Flex the hock when the stifle flexes

Question 16

The horse uses which of the following for prehending grass or grain?

a] Upper lip
b] Lower incisors
c] Molars
d] Upper incisors

Answer 16

a] Upper lip

The equine upper lip is used for prehending food (gathering a food bolus of grass or grain).

Question 17

The horse uses which of the following for cropping grass from pasture or hay?

a] Upper lip
b] Lower incisors
c] Molars
d] Upper incisors

Answer 17

d] Upper incisors

Upper incisors are used for cropping grass from pasture or hay.

Question 18

Which nerves are embedded in the medial compartment of the guttural pouch in horses?

a] Cranial nerves VII, VIII, and X.
b] Cranial nerves IX, X, XI, and XII
c] Cranial nerves VI and X
d] None

Answer 18

b] Cranial nerves IX, X, XI, and XII

In the medial compartment of the guttural pouch, there are the cranial nerves IX, X, XI, and XII embedded together with the continuation of the sympathetic trunk beyond the cranial cervical ganglion and the internal carotid artery.

Question 19

Absorption of volatile fatty acids occurs primarily in which of the following [in a horse]?

a] Stomach
b] Small intestine
c] Cecum
d] Transverse colon

Answer 19

c] Cecum

Absorption of volatile fatty acids occurs primarily in the cecum and ventral colon.

Question 20

Which of the following statements about the hoof is CORRECT?

a] Horn tubules are lined by endothelial cells.
b] The Stratum Lamellatum consists of Bone and Sensitive Laminae.
c] The Stratum Medium is produced by the Perioplic Epidermis.
d] The White Line is part of the Laminar Epidermis seen on the Sole.

Answer 20

d] The White Line is part of the Laminar Epidermis seen on the Sole.

Question 21

During a purchase examination, an oral examination is performed on a horse to determine its age. Which of the following is a horse’s age if the lower permanent incisors are all erupted and the cup is gone on the lower 1st and 2nd incisors?

a] 4 years
b] 5 years
c] 6 years
d] 7 years

Answer 21

d] 7 years

A horse can be aged by the condition of the lower incisors; it is therefore important to be able to age a horse by its teeth. A horse is 7 years old if the lower permanent incisors are all erupted and the cup is gone on the lower 1st and 2nd incisors.

Question 22

During natural breeding, the stallion ejaculates into which of the following?

a] The mare’s vestibule
b] The mare’s caudal vagina
c] The mare’s cranial vagina
d] The mare’s oviduct
e] The mare’s uterus

Answer 22

The mare’s uterus

“Belling” of the glans penis during ejaculation causes the jets of semen to directly enter the uterus

Question 23

When performing a palmar digital neurectomy in a horse, it should be remembered that the correct orientation of structures in the neurovascular bundle from dorsal to palmar is which of the following?

a] Vein, artery, nerve
b] Nerve, artery, vein
c] Artery, nerve, vein
d] Nerve, vein, artery
e] Vein, nerve, artery

Answer 23

a] Vein, artery, nerve

The acronym VAN can be used to remember this order.

Question 24

A 2-year-old quarter horse gelding has sustained a heel bulb laceration over the medial aspect of its left forefoot. Which of the following describes the synovial structures in this area that could be involved with this laceration?

a] Distal interphalangeal joint and navicular bursa
b] Distal interphalangeal joint
c] Navicular bursa
d] Metacarpophalangeal joint and distal interphalangeal joint
e] Metacarpophalangeal joint and navicular bursa

Answer 24

a] Distal interphalangeal joint and navicular bursa

These two structures must be assessed for their involvement with a laceration in this region. The metacarpophalangeal joint should be too far proximal to the laceration to be involved.

Question 25

In an equine patient, the presence of a menace deficit without blindness indicates disease is most likely localized to which of the following?

a] Cerebrum
b] Brainstem
c] Cerebellum
d] Spinal nerves

Answer 25

c] Cerebellum

A menace deficit without blindness indicates cerebellar damage, as do intention tremor and wide-based ataxia with dysmetria.

Question 26

Which of the following is the 1st permanent tooth to erupt in a horse?

a] Second premolar
b] Third premolar
c] Fourth premolar
d] First molar
e] Second molar

Answer 26

d] First molar

The permanent 1st molar erupts at 9 to 12 months of age.

Question 27

Concerning anatomic landmarks used during exploratory laparotomy in horses, which statement is least accurate?

a] The dorsal band of the cecum is continuous with the ileocecal fold, which can be used to locate the ileum.
b] The right ventral colon is connected to the cecum via the cecocolic fold.
c] The cecum and the right and left ventral colons have four bands (teniae).
d] The small colon has two bands (teniae).
e] The junction between the terminal duodenum and the proximal jejunum can be identified by palpation of the mesodiverticular band.

Answer 27

e] The junction between the terminal duodenum and the proximal jejunum can be identified by palpation of the mesodiverticular band.

The correct name for the structure is the duodenocolic ligament.

Question 28

A common intramuscular injection site used in horses is the right and left gluteal muscle groups. This site can be located by using which of the following sets of landmarks to appropriately triangulate the correct location for administering the injection?

a] Distal to the ischiatic tuberosity, caudal to the femur, proximal to the stifle
b] Lateral to the lumbar spine, caudal to the last rib, cranial and medial to the iliac crest
c] Distal and cranial to the greater trochanter of the femur, cranial to the femur, proximal to the stifle
d] Ventral to the ligamentum nuchae, cranial to the spine of the scapula, dorsal to the esophageal groove
e] Caudal and medial to the tuber coxae, cranial to the ischiatic tuberosity, proximal/medial to the greater trochanter of the femur

Answer 28

e] Caudal and medial to the tuber coxae, cranial to the ischiatic tuberosity, proximal/medial to the greater trochanter of the femur

a] would get you to the semitendinosus and semimembranosus; b], to the lumbar epaxial muscles; c], to the quadriceps; and d], to the cow and horse lateral neck.

Question 29

The equine stomach represents approximately which of the following percentages of the total size of the digestive tract?

a] 2%
b] 4%
c] 6%
d] 8%

Answer 29

d] 8%

The equine stomach holds about 8 L and makes up about 8% of the total size of the digestive tract.

Question 30

What is the function of the check ligament in horses?

a] It connects the common digital extensor muscle and the interosseous muscle to give support for the fetlock joint.
b] It connects the superficial digital flexor and the splint bones for the stabilization of the carpal joint.
c] It connects the deep digital flexor tendon and the cannon bone for the passive stabilization of the legs.
d] It totally controls the stay apparatus in the limb of the horse.

Answer 30

c] It connects the deep digital flexor tendon and the cannon bone for the passive stabilization of the legs.

Question 31

Where is most of the cerebrospinal fluid (CSF) produced in horses?

a] Ventricular choroid plexuses of the two lateral ventricles
b] Ependymal lining of the ventricles
c] Meningeal blood vessels
d] Third and fourth ventricles
e] Mesencephalic aqueduct

Answer 31

a] Ventricular choroid plexuses of the two lateral ventricles

Most CSF (70%) originates in the ventricular choroid plexuses of the lateral ventricles.

Question 32

From which primary nerve does the medial palmar nerve branch in the forelimb of the horse arise?

a] Ulnar
b] Musculocutaneous
c] Saphenous
d] Median
e] Metacarpal

Answer 32

d] Median

Question 33

Active transport of glucose and amino acids and absorption of B vitamins occur primarily in which of the following [in a horse]?

a] Stomach
b] Small intestine
c] Cecum
d] Transverse colon

Answer 33

b] Small intestine

Proteins are broken down in the small intestine by nonspecific oligopeptidases. Individual amino acids and dipeptides are absorbed

Question 34

In horses, which nerve block is used to paralyze the orbicularis muscle of the eyelids?

a] Auriculopalpebral
b] Frontal
c] Zygomatic
d] Infratrochlear
e] Lacrimal

Answer 34

a] Auriculopalpebral

The auriculopalpebral branch of the facial nerve supplies motor innervation to the orbicularis oculi. The other nerves are sensory.

Question 35

Which of the following represents the average daily saliva production by a horse?

a] 1 to 2 L per 100 kg body weight
b] 3 to 4 L per 100 kg body weight
c] 5 to 6 L per 100 kg body weight
d] 8 to 10 L per 100 kg body weight

Answer 35

5 to 6 L per 100 kg body weight

Saliva production in the horse is approximately 5 to 6 L/100 kg body weight per 24 h period.

Question 36

In horses, the flehmen response introduces nonvolatile material into which of the following?

a] Vomeronasal organ
b] Organum vasculosum
c] Guttural pouch
d] Circle of Willis
e] Ventromedial hypothalamus

Answer 36

a] Vomeronasal organ

Experiments on goats have proved that urine moves into vomeronasal organ during flehmen response.

Question 37

What is the function of the check ligament in horses?

a] It connects the common digital extensor muscle and the interosseous muscle to give support for the fetlock joint.
b] It connects the superficial digital flexor and the splint bones for the stabilization of the carpal joint.
c] It connects the deep digital flexor tendon and the cannon bone for the passive stabilization of the legs.
d] It acts to check the length of the forward stride during galloping.

Answer 37

c] It connects the deep digital flexor tendon and the cannon bone for the passive stabilization of the legs.