NAVLE Reproductive

Feline Mastitis Study Guide

Mastitis is an inflammatory condition of one or more mammary glands, typically caused by bacterial infection.

Overview and Clinical Importance

Mastitis is an inflammatory condition of one or more mammary glands, typically caused by bacterial infection. While relatively uncommon in cats compared to dogs, mastitis represents a clinically significant condition that can rapidly progress to life-threatening sepsis or gangrenous tissue necrosis if not promptly diagnosed and treated. The condition occurs almost exclusively in lactating queens during the postpartum period, though it may also develop secondary to feline mammary fibroepithelial hyperplasia (FEH) or pseudopregnancy. Understanding the etiology, clinical presentation, and treatment options for feline mastitis is essential for NAVLE preparation and clinical practice.

Gland Location Blood Supply Lymphatic Drainage
T1 Cranial thoracic Internal thoracic a. Axillary LN (cranial only)
T2 Caudal thoracic Internal thoracic a. Axillary or Inguinal LN
A1 Cranial abdominal Cranial superficial epigastric a. Axillary or Inguinal LN
A2 Caudal abdominal/Inguinal Caudal superficial epigastric a. Inguinal LN (caudal only)

Feline Mammary Gland Anatomy

Cats normally have four pairs of mammary glands (8 total) arranged in two parallel chains along the ventral abdomen. The glands are designated based on anatomical location as T1 (cranial thoracic), T2 (caudal thoracic), A1 (cranial abdominal), and A2 (caudal abdominal/inguinal). Each nipple contains 5-7 lactiferous pores with 1-3 openings on the tip and the remainder on the sides.

Mammary Gland Nomenclature and Blood Supply

High-YieldThe caudal mammary glands (A1, A2) are most commonly affected by mastitis and are also the most common sites for mammary neoplasia. The intermediate glands (T2, A1) have dual lymphatic drainage to both axillary and inguinal lymph nodes, which has surgical implications for mastectomy planning.
Organism Characteristics Clinical Significance
Escherichia coli Gram-negative; facultative anaerobe; normal GI flora Endotoxin release can cause sepsis, SIRS, and multiorgan failure; common cause of gangrenous mastitis
Staphylococcus aureus Gram-positive; normal skin flora; most commonly isolated Beta-lactamase production common; can cause abscessation
Streptococcus spp. Gram-positive; environmental and skin flora Often causes acute mastitis; generally antibiotic-responsive

Etiology and Pathophysiology

Types of Mastitis

Septic Mastitis: Caused by bacterial infection of the mammary gland, typically through ascending infection via the teat canal during nursing. Bacteria may also enter through wounds, scratches from nursing kittens, or hematogenous spread from other infection sites (e.g., metritis).

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