The mammary gland of the cow takes on added significance due to the importance of milk as a human food source.

General Structure

Mammary gland comprises four mammary complexes, which are separate units, consolidated in a single mass - the udder.
- Udder hangs from the caudal abdomen and pelvis.
  - Quarters: all four parts of the bovine udder, each associated with one teat. All four quarters are completely separated from each other.

Accessory teats, sometimes associated with functional glandular tissue common.
- Undesirable, may complicate milking if fused or too close to principle teats.

Appearance

Schematic Diagram of the Blood Supply to the Bovine Udder - Copyright Prof. Pat McCarthy

Main artery to the udder is a direct continuation of the external pudendal artery.
- Enters the base of the udder on its dorsocaudal aspect after passing through the inguinal canal.
- Forms a sigmoid flexure before dividing into a cranial and caudal mammary artery.
  - Sigmoid flexure permits the artery to stretch when the udder is full of milk, thus heavier than usual.
- Mammary arteries anastamose with the superficial caudal epigastric artery, which is connected to the cranial epigastric artery.

Due to the requirement for extensive blood supply during lactation, there is a small contribution from the internal pudendal artery.

Drainage from the udder is through
- External pudendal vein
  - Drains through the inguinal canal
  - Sigmoid flexure to allow stretching when the udder fills.
- Superficial cranial epigastric veins.

Superficial cranial and caudal epigastric veins anastamose to form the abdominal 'milk vein':
- Large, tortuous on ventral abdomen.
- Incompetent valves allow blood to flow in either direction. This is important for maintaining drainage of the extensive amount of blood present. For example, if the cow were to lay down, the thin walled veins on that side would be easily occluded.
- passes through the abdominal wall caudal to the costal arch to join the internal thoracic vein, known as the 'milk well'.

Furstenburg's venous ring: the venous circle at the junction of the teat and gland sinuses.