Mastitis

• Cause: usually ascending bacterial (Staphyloccus aureus, Escherichia coli, etc) infection through nipple during nursing (may be hematogenous or lymphogenous) - predisposed or exacerbated by trauma, unsanitary conditions. 
• Signs: one or more mammary glands that are hot, eliciting signs of pain at touch or when trying to nurse, with purulent or blood-tinged mammary secretions; pyrexia, anorexia; kittens may be unable to feed - restless, cry, appear bloated or fail to thrive. At early stages of infection, it may be subclinical with only galactostasis of affected glands. 
• Diagnosis: clinical signs; milk cytology showing degenerate neutrophils and bacteria; complete blood count may reveal neutrophilic leukocytosis with left shift. 
• Treatment: systemic antibiotics, application of cold compresses to affected mammary glands; may need to wean kittens or feed artificially until infection controlled. 
• Prognosis: good with prompt treatment.

• Lactating queen. 
• Hot, mammary glands painful to touch. 
• Purulent mammary secretions. 
• Kittens unable to feed - restless, crying and may appear bloated

• Escherichia coli Escherichia coli, Staphylococcus spp Staphylococcus spp , Streptococcus spp Streptococcus spp  most common.

General 

• Queen and kittens under unsanitary conditions in nursing box. 
• Ascending bacterial infection predisposed by: 
  • Constant nursing in queens with large litters.  
  • Secondary galactostasis in queens nursing small litters.

• Ascending bacterial infection through nipple during nursing.
• May be hematogenous or lymphogenous spread, eg metritis Acute metritis.

• Young restless, not feeding, crying.
• Swollen mammary glands.
• Pyrexia Pyrexia: overview.

• Nursing female.

• Hot mammary glands painful to touch.
• Purulent mammary secretions.
• Kittens unable to feed - restless, cry, appear bloated.
• Pyrexia.
• Anorexia.

Hematology

• Neutrophilic leukocytosis with left shift. 
• Early/severe cases may show neutropenia with degenerative left shift. 
• Toxic neutrophils may also be seenHematology: neutrophil Hematology: complete blood count (CBC).

Bacteriology

• Milk sample - culture and sensitivity Bacteriology.
• Escherichia coli, Staphylococcus spp or Streptococcus spp most commonly present.

Cytopathology

• Examination of milk sample shows neutrophils (with intracellular bacteria)/red blood cells.

Definitive diagnostic features

• History and clinical signs.
• Bacteriological culture and sensitivity results.

• Excessive milk production and lack of feeding leading to milk pooling in mammary glands (galactostasis). 
• Mammary neoplasia Mammary gland: neoplasia.
• Mammary hyperplasia Mammary hyperplasia.

• Start antibiotic therapy Therapeutics: antimicrobial drug with drugs considered safe for queen and kittens; eg broad spectrum beta-lactam antibiotics, eg amoxicillin Amoxicillin/clavulanic acid Clavulanate or cephalexin Cefalexin.  
• Modify antibiotic therapy based on culture results and evaluation of milk pH. 
• Remove kittens until therapy instigated. 
• Suppress lactation by administration of cabergoline Cabergoline. 
• Wean, feed artificially Milk replacers - this is controversial, some authors recommend nursing to empty gland. 
• Most milk secretions from mastitis are alkaline, which favor the distribution of weakly acidic drugs such as ampicillin Ampicillin or cephalosporins. 
• Distribution of weakly alkaline drugs such as trimethoprim sulfa  Trimethoprim, erythromycin Erythromycin may be compromised if the pH is > 7.4

• Remove kittens - may need to wean/feed artificially until infection controlled. 
• Suppress lactation by administration of cabergoline. 
• Appropriate antibiotic therapy ideally according to milk culture and sensitivity results. 
• Cold and hot packing of affected glands. 
• Surgical drainage Drain: surgical wounds or mastectomy Mastectomy of abscesses/debridement of gangrenous areas as necessary. 
• Antiseptic infusions into gangrenous or abscessed glands.

• Septicemic animals require IV fluids, antibiotics.
• Kittens weaned need good husbandry techniques.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Wilson C R (2013) Feline gangrenous mastitis. Can Vet J 54 (3), 292-294 PubMed. 
• Dernell W B, Kreeger J (1992) Peracute necrotizing mastitis as a cause of fatal septicemia and endotoxemia in a dog. Canine Pract 17 (6), 25-29 VetMedResource.