Mastitis

Part of Veterinary Medicine

Diagnosing and treating udder infection in dairy animals to preserve milk production and prevent systemic illness.

Why This Matters

Mastitis — infection of the mammary gland — is the most costly disease in dairy cattle worldwide and a significant problem in dairy goats and sheep. Beyond its economic impact, mastitis causes animal suffering, produces milk that is unsafe for consumption, and can progress rapidly to septicemia and death in acute cases. In a post-collapse dairy operation, losing a milk cow or doe to mastitis costs the community not just the animal’s production but a critical protein and fat source for the entire household.

Understanding mastitis means understanding that it is almost always preventable. The organisms that cause mastitis — primarily Staphylococcus aureus, Streptococcus agalactiae, coliform bacteria, and environmental Streptococcus — enter through the teat canal. Good milking hygiene, teat health, adequate nutrition, and stress reduction close that entry point. Prevention is not complicated, but it requires consistency.

When mastitis does occur, the difference between a recoverable case and permanent quarter loss (or animal death) is early detection and prompt treatment. Learning to detect mastitis early — before the animal is systemically ill — is the most valuable mastitis skill.

Classification by Severity

Mastitis presents across a spectrum from subclinical to peracute, and treatment decisions depend on the severity.

Subclinical mastitis: No visible signs in the animal. The milk appears normal. Detection requires either the California Mastitis Test (CMT) or observation of reduced production from a specific quarter. Subclinical mastitis may persist for months, causing chronic low-grade inflammation and gradual loss of productive tissue. It is the most common form and is often the source population from which clinical cases develop.

Clinical mastitis (mild to moderate): Abnormal milk (flakes, clots, watery appearance, or blood-tinged) is visible. The quarter may be slightly swollen or warm. The animal remains bright and eating.

Clinical mastitis (severe): Visibly abnormal milk. Quarter swollen, hard, and painful on palpation. The animal may be febrile, off-feed, and reluctant to be milked.

Peracute/toxic mastitis: Gangrenous mastitis (gram-negative coliform infections) can develop within hours. The quarter may be cold, purple-blue, and beginning to demarcate from living tissue. The animal is severely ill — high fever progressing to subnormal temperature, depression, not eating, not drinking, possible diarrhea. This is a life-threatening emergency requiring aggressive systemic support. The quarter itself is often lost even with full recovery of the animal.

Detection Methods

Fore-stripping: The first few streams of milk from each teat are directed onto a dark surface or strip cup before milking. Clots, flakes, or watery appearance are immediately visible against the dark background. This takes less than a minute and should be done at every milking — it is the most important mastitis detection practice.

California Mastitis Test (CMT): A field test using a simple paddle with four wells and a reagent (sodium lauryl sulfate). Mix equal parts milk and reagent — a gel-forming reaction indicates elevated somatic cell count, the cellular marker of inflammation. The CMT detects subclinical mastitis before visible milk changes appear. The reagent can be improvised from household detergent (1% sodium lauryl sulfate solution) for lower accuracy, or stockpiled before crisis.

Quarter palpation: After milking, palpate each quarter. A healthy mammary gland is soft and collapses with milking. Swelling, firmness, and heat indicate inflammation. Inspect the teats for chapping, cracks, or lesions — these are entry points for pathogens.

Production monitoring: A sudden drop in production from one quarter (or the whole udder) without dietary explanation is a mastitis flag. This requires knowing baseline production per animal and ideally per quarter.

Treatment Protocols

Mild to moderate clinical mastitis:

1. Milk the affected quarter(s) fully, completely, every 4–6 hours — more frequently than normal milking. Removing infected milk removes bacteria and inflammatory mediators.
2. Strip the quarter completely, then massage from the base of the gland upward toward the teat.
3. Apply warm (not hot) compresses to the affected quarter for 10–15 minutes, 3 times daily. Warmth improves blood flow and supports immune response.
4. Maintain hydration and nutrition — animals with mastitis often reduce water and feed intake.
5. If intramammary antibiotic tubes are available, infuse after thorough milking.

Severe clinical mastitis:

• All of the above plus systemic antibiotic treatment if available
• Anti-inflammatory treatment (aspirin in feed — 10–25 grams per 500 kg cattle twice daily — reduces fever and inflammation)
• Ensure adequate water intake; large animals with severe mastitis can become severely dehydrated

Peracute/gangrenous mastitis:

• Aggressive systemic fluid support (oral rehydration via stomach tube, or intravenous if possible)
• Systemic antibiotics for gram-negative organisms
• Anti-inflammatory drugs
• The gangrenous quarter will demarcate and eventually slough — do not attempt to milk it; it will rupture and drain naturally
• Focus is saving the animal’s life; the quarter is already lost

Herbal and traditional approaches (when pharmaceutical inputs unavailable):

• Fresh aloe vera gel massaged into the quarter — has documented anti-inflammatory properties
• Warm camphor oil massage — traditional in many cultures; warming effect and possible mild antimicrobial activity
• Repeated complete milking remains the most important non-pharmaceutical intervention — bacteria cannot multiply as rapidly when continually removed
• Cabbage leaf compresses applied to swollen quarters (traditional, some evidence for anti-inflammatory effect from raphanin compounds)

Dry Cow/Dry Doe Therapy

The transition from the end of one lactation to the beginning of the next (the dry period) is when major new infections are most often established. In conventional dairy practice, all quarters receive antibiotic infusion at dry-off to treat subclinical infection and prevent new infection establishment. In a resource-limited context:

• Prioritize dry cow treatment for animals with a history of clinical or subclinical mastitis in the preceding lactation
• Apply an internal teat sealant (bismuth subnitrate-based products) to block the teat canal during the dry period — this is available as a commercial product or can be improvised as a sterile bismuth paste
• Good udder hygiene at dry-off is important — clean teats before last milking of the lactation

Prevention

Milking hygiene protocol:

1. Wash and dry each teat individually before milking
2. Fore-strip before attaching
3. Milk in a consistent, calm manner — stress and interruptions cause incomplete milk-out which predisposes to infection
4. After milking, dip teats in a germicidal solution (dilute iodine 0.5%, or chlorhexidine 0.5%) — teat dipping prevents bacterial entry through the still-open teat canal
5. Ensure all milking equipment is clean and properly functioning

Nutritional support: Cows and does deficient in vitamin E, selenium, zinc, or copper have higher mastitis rates. Feed-quality analysis and targeted supplementation significantly reduce incidence.

Stocking density and hygiene: Overcrowded housing with wet, contaminated bedding dramatically increases mastitis rates. Clean, dry bedding, adequate space to lie down without contact with other animals, and good ventilation are protective.

Identify and cull chronic cases: Animals with chronic recurrent mastitis in specific quarters harbor reservoir infections that contaminate the milking environment for all other animals. Document quarter history and cull animals that fail to clear infection after appropriate treatment.