Carnivore Mammary Gland - Anatomy & Physiology

General Structure

Each mammary complex consists of 5-20 mammary units and their corresponding ducts. The ducts open separately on the tip of the teat. Shallow grooves indicate the border between complexes. An intermammary sulcus divides the right from the left row.

Species differences

Bitch

Usually has 10 mammary complexes. They are arranged in two bilaterally symmetrical rows and extend from the ventral thoracic to inguinal region. N.B. They are not always symmetrical and the number of complexes may vary between 8-12.

Cat

Usually has 8 mammary complexes. They are arranged in two bilaterally symmetrical rows and extend from the ventral thoracic to abdominal region.

Appearance

Juvenile or non-lactating carnivores have inconspicuous mammary complexes with short teats. During lactation, the mammary complexes increase in size and become hemi-spherical in shape. This does, however, vary among breeds and individuals.

Blood Supply

There is a blood supply from the mammary branches of the lateral thoracic artery.

Lymphatics

Lymph from the cranial thoracic mammary complex, drains into both the axillary and superficial cervical lymph node. Lymph from the cranial abdominal mammary complex, can either drain into the axillary or superficial inguinal lymph node and lymph from the caudal abdominal mammary complex may also drain into the medial iliac lymph nodes. There is interconnection between the left and right superficial inguinal lymph nodes.

Complications

Changes characteristic of the cycle of the bitch include, growth and proliferation of the mammary gland with each cycle even if the bitch does not conceive. Frequent proliferation and subsequent involution predisposes the bitch to mammary tumours.

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