Horses

Question 1

What teeth in the horse are hypsodont, brachydont?

Answer 1

Hypsodont: incisors, premolars, molars
Brachydont: canines

Question 2

What is the dental formula of an adult horse?

Answer 2

2 (I 3/3 C 1/1 P3(4 - wolf tooth)/ 3 M 3/3) = 40 (42)

Question 3

What is the deciduous formula of a horse?

Answer 3

2 (i 3/3 c 0/0 p 3/3) = 24

Question 4

Describe why horses are obligate nasal breathers?

Answer 4

When the mouth is ‘resting’, the soft palate sits below the epiglottis, allowing only air to travel through the nose

Question 5

What are the extensive tonsils that are located in the pharynx and root of the tongue?

Answer 5

Diffuse follicular

Question 6

What % of the oesophagus is skeletal/ smooth muscle, also include if its caudal/ cranial.

Answer 6

Cranial 60-70% is skeletal

Question 7

What is the saccus caecus/

Answer 7

Enlarged fundus of the stomach

Question 8

What angle does the oesophagus enter the stomach enter, comment on the cardiac sphincter.

Answer 8

Abdominal oesophagus enters obliquely, the cardiac sphincter is well developed -> cannot vomit

Question 9

What approximate percentage of the horse stomach is covered by non-glandular mucosa? what does this mean for gastric ulcers?

Answer 9

~50%, gastric ulcers are commonly found here

Question 10

What is the border of the non-glandular and glandular mucosa in the stomach called?

Answer 10

Margo plicatus

Question 11

What organ is a major site for bacterial fermentation? where does it sit in the horses abdominal cavity?

Answer 11

Caecum, and fills much of the RHS

Question 12

Where can a horse be auscultated for sand colic?

Answer 12

Xiphisternum

Question 13

How many taeniae are located in the caecum

Answer 13

4, dividing into 4 rows of haustra (or sacculations)

Question 14

What structure separates the haustra?

Answer 14

Deep semilunar folds

Question 15

What structure does the dorsal and ventral band attach to?

Answer 15

Dorsal band: ileocaecal fold
Ventral band: caecocolic fold

Question 16

Describe how the ileocaecocolic junction is different in the horse.

Answer 16

The ileocaecal (ileum caecum) orifice and the caecocolic (caecum colon) orifice both open into the lesser curvature of the base of the caecum, meaning the ingesta must pass through the caecum as the ileum is not directly connected to the colon

Question 17

How large (approx.) is the ascending + descending part of the colon?

Answer 17

3-5m

Question 18

Which part of the colon is U-shaped and is double on itself in another U-shape?

Answer 18

ascending colon

Question 19

Name the seven parts of the ascending colon

Answer 19

Right ventral colon, sternal flexure, left ventral colon, pelvic flexure, left dorsal colon, diaphragmatic flexure, right dorsal colon

Question 20

What happens to the diameter in the transverse colon, following the ascending colon?

Answer 20

Decreases abruptly (to 7-10cm)

Question 21

What structure supports the descending colon?

Answer 21

Descending mesocolon

Question 22

Explain how the faecal balls are formed in the descending colon.

Answer 22

The deep sacculations in descending colon (caused by 2 wide and prominent taeniae) divide the contents into balls

Question 23

Name 3 structures or cells in the small intestine (and location if relevant) that contribute to secretions or health.

Answer 23

Brunner’s glands: secrete mucin (entire length of duodenum)
Crypts of lierberkuhn which contains paneth cells (to keep microbial population in check)