Mammary Glands

Question 1

describe the anatomy of mammary glands in the dog (2)

Answer 1

1. two rows from thorax to inguinal region with generally 5 glands per row
2. cranial and caudal thoracic, cranial and caudal abdominal, one pair of inguinal glands
3. secretory tissues drain to gland sinus, which drians to teat sinus, which drains to teat canal and out through teat orifice

Question 2

describe the anatomy of the mammary glands of the cow (4)

Answer 2

1. each mammary gland formed by multiple lobules, which are formed by a collection of alveoli
2. milk is secreted by alveoli and carried via alveolar ducts to the lactiferous ducts that carry milk to collecting ducts
3. a dozen collecting ducts drain milk to the gland cistern/gland sinus
4. from there, milk goes into the teat cistern and papillary canal before exiting via a teat orifice (1 per quarter)

Question 3

describe the anatomy of the mammary glands of the horse (5)

Answer 3

1. divided into left and right mammae by the longitudinal intermammary groove
2. glandular portion organized into cranial and caudal lobes with secretory cells organized as alveoli that open into dicts (alveoli + duct = lobule), surrounded by myoepithelial cells
3. lactiferous ducts converge into a milk cistern, one per lobe (2 in each half)
4. cistern has a glandular portion and a teat/papillary portion that drains into an orifice via the papillary duct (2 per half)
5. 2 orifices per lobe

Question 4

describe the suspensory apparatus of the udder

Answer 4

the lateral suspensory ligament arises from the lateral border of the inguinal ring and symphyseal tendon and splits into outer (medial femoral fascia) and inner (mammary fascia) sheathes

the medial suspensory ligament arises from the tunica flavia and borders the linea alba and the symphyseal tendon, thicker than its lateral counterpart

both ligaments become smaller as the travel distally on the quarters;

symphyseal tendon is a key party of the apparatus! supports and attaches the caudal portion of the udder to the pelvic floor, midline lamina attaches here

see Cjaza’s picture for struture of this

Question 5

describe the blood supply of the canine mammary glands (3)

Answer 5

1. cranial superficial epigastric arteries; continuations of interal thoracic arteries
2. caudal superficial epigastric arteries; branch from external pudendal arteries
3. external pudendal arteries

Question 6

describe the blood supply to the horse udder (2)

Answer 6

1. main blood supply is via the external pudendal artery, which branches into cranial and caudal mammary arteries
2. venous plexus present at base of each mamma that drains to external pudendal veins (caudally) or to the superficial epigastric vein then to the superficial vein of thoracic wall caudally, or to the obturator caudally or to branches of the internal pudendal caudally

Question 7

describe the blood supply of the cow udder, describe cow milk vein

Answer 7

1. external pudendal arteries (branch to form cranial and caudal mammary arteries) and ventral labial artery (branch from perineal artery)
2. venous drainage, 3 pathways:
   2a. milk vein: superficial epigastric vein (cranial and caudal mammary veins cranially connect to)
   2b. external pudendal vein (cranial and caudal mammary veins drain to at their junction)
   2c. ventral labial vein (cranial and caudal mammary veins drain caudally to)

milk vein: fusion of cranial and caudal superficial epigastric veins with internal thoracic vein in PREGNANT AND LACTATING COWS

Question 8

describe the lymphatic drainage of the canine mammary glands

Answer 8

1. thoracic and cranial abdominal glands drain to axillary lymph nodes
2. caudal abdominal and inguinal glands drain to superficial inguinal lymph nodes

Question 9

describe the lymphatic drainage of cow and horse udder (2)

Answer 9

superficial inguinal (mammary) lymph node: primary lymphatic drainage, easoly accessible

subiliac node: drains cranial portion of udder

Question 10

describe innervation of the canine mammary glands (6)

Answer 10

1. lateral branches of the 4th, 5th, and 6th thoracic spinal nerves
2. branches of genitofemoral nerves to inguinal and caudal abdominal glands

then the ventral branches of the first 3 lumbar spinal nerves
3. caudal hypogastric
4. caudal iliohypogastric
5. ilioinguinal nerves

and
6. some sympathetic fibers also innervate the dog’s mammary glands

Question 11

describe innervation of horse udder (3)

Answer 11

1. main innervation via genitofemoral nerve through the inguinal canal
2. also supplied by nerves of the flank (likely iliohypogastric and ilioinguinal)
3. also supplied by a branch of the pudendal nerve

Question 12

identify the nerves that would be needed to fully anesthetize the udder of the cow (4)

Answer 12

1. skin and teats of front quarters innervated by iliohypogastric, ilioinguinal, and the cranial branch of the genitofemoral nerve
2. skin and teats of hind quarters innervated by caudal branch of genitofemoral nerve and mammary branch of pudendal nerve
3. body of udder innervated by cranial and caudal branches of genitofemoral nerve

Question 13

compare the papillary ducts/teat sinuses of dog, cow, horse

Answer 13

cow: 1 teat canal, 1 orifice
horse: 2 teat canals, 2 orifices
dog: 8-16 canals that drain into a single teat with multiple openings/orifices