Bovine Mastitis

What is mastitis and why is it considered expensive for dairy farms?

Mastitis is one of the most common diseases on dairy farms; clinical mastitis can cost $444 per case due to treatment costs and lost milk.

What are the classic clinical severity scores for mastitis?

Severity score 1: only the quarter affected; score 2: entire udder inflamed; score 3: cow systemically ill.

What causes environmental mastitis and how is it usually contracted?

Environmental mastitis is caused by pathogens like E. coli and is typically contracted from bedding.

What are the common types of contagious mastitis pathogens?

Common contagious pathogens include Staphylococcus aureus and Mycoplasma spp.

What does an increased somatic cell count (SCC) indicate?

A high SCC indicates the presence of mastitis, with healthy cows having SCC of less than 100,000.

What is the California mastitis test (CMT) used for?

CMT is used cow-side to test for subclinical mastitis.

When is treatment necessary for mastitis with severity scores of 1 and 2?

Treatment is needed if there is a positive culture for gram-positive bacteria, otherwise no treatment is needed.

What should be done for severity score 3 mastitis regardless of culture results?

Systemic antimicrobials, fluids, electrolytes, and nutritional support should be provided.

Name one preventive method for mastitis management.

Proper milking routines that minimize cow-to-cow transmission.

What are the top three types of mastitis to remember for exams?

Contagious mastitis, Environmental mastitis, and Gangrenous mastitis.

What is the typical consequence of Staphylococcus aureus infection in the udder?

Causes chronic infections and can lead to abscesses.

How is gangrenous mastitis characterized?

It is characterized by an inflamed quarter that goes cold and purple, with signs of systemic endotoxemia.

What is the primary treatment for gangrenous mastitis?

Mastectomy to drain the quarter of the abscess.

What happens to bulk tank somatic cell count levels?

It is monitored by milk cooperatives to assess the health of the herd.

What common environmental mastitis pathogens are found in bedding?

Pathogens include E. coli, Klebsiella pneumoniae, and Enterobacter.

Clinical severity of mastitis?

Severity score 1,2,3. Remember quarter, udder, cow for severity

Severity score 1 - only the quarter is affected and inflamed, abnormal milk is present

Severity score 2 - entire udder demonstrates signs of inflammation. Hard, hot udder - swollen LNN, difficulty milking out

Severity score 3 - cow is systemically ill. Fever, off feed + recumbent in severe cases. High mortality w/o immediate Tx. Typically seen with coliforms due to associated endotoxemia.

Environmental pathogens?

1. Coliforms (E. coli, Klebsiella, Enterobacter, proteus, Serratia)

2. Streptococcus spp.

3. Coagulase negative Staphylococcus spp.

Usually contracted from bedding

Contagious pathogens?

Transmitted from cow to cow, typically in the milking parlor

1. Staphylococcus aureus

2. Streptococcus agalactiae (mostly eradicated)

3. Trueperella pyogenes

4. Mycoplasma spp. or M. bovis

Mastitis Dx?

1. Abnormal milk - serosanguinous, flaky, chunky or watery

2. Increased SCC

   • Somatic cells in milk are 75% WBC (Ne most common)/ 25% epithelial cells

   • Healthy cows have SCC <100,000

   • SCC becomes increased in mastitis

   • Tested with CMT cow side for SC cases

   • Measured in the milking parlor or from the bulk tank milk

3. Culture = gold standard, worth doing

Tx of mastitis?

Based on culture, G stain, and clinical severity score.

1. Severity score 1 and 2 score + no growth on culture:

   • No tx, immune system has already cleared the pathogen

   • Discard milk until it returns to normal

2. Severity score 1 and 2 + culture + for G- bact. or yeast:

   • No Tx, immune system will clear the pathogen

   • Discard milk until it returns to normal

3. Severity score 3 regardless of culture:

   • Systemic ABx

   • Fluids + electrolytes

   • Flunixin meglumine for antipyretic and endotoxic binding effect

   • Nutritional support

   • Milk out affected quarters as freq. as possible

Mastitis prevention?

1. Use proper milking routines that minimize spread of disease cow to cow

   • Pre and post dip cow with antimicrobial agent

   • Minimize cross contamination between cows by milkers

   • Properly clean and sanitize all parlor equipment post milking

2. Bedding management

   • Remove manure frequently

   • Add clean, dry bedding often

3. Supply fresh feed for cows after milking

   • Encourages cows to stand after milking

   • Allows external teat sphincter to close before lying down, thereby preventing new environmental infections

4. Vaccination can help for coliforms

5. Tx with intramammary ABx at dry off to help cure chronic infections

   • Add a teat sealant to protect udder from new infections during the dry period

Which organisms do not respond to Tx?

S. aureus and Mycoplasma spp. infected cows are culled to protect the rest of the heard

What are the parameters for accepting milk?

1. <750k SCC/ml

2. <10coliforms/ml

3. <100k bacteria/ml

Contagious mastitis CS?

1. Typically see new cases in first 60 days of milk

2. Often subclinical

3. Decreased milk production due to fibrosis and abscessation in the udder

Etiology of contagious mastitis?

1. S aureus

2. Mycoplasma

3. Strep agalactiae

4. Strep dysgalactiae

Contagious mastitis transmission?

Cow to cow via cross contact of infected udders. Milking equipment or workers hands

Contagious mastitis dx?

1. CMT

2. Milk culture or dx lab testing

3. Routine bulk tank sampling to identify new cases

4. String sampling of cows in the parlor to identify affected animals

Contagious mastitis Tx?

1. Ineffective due to inconsistent shedding and abscess formation (esp. Staph aureus)

2. Sanitation: proper milking procedures, workers wearing gloves, using 1 towel per cow to clean udders, proper cleaning of equipment

3. Segregate knows + cows and milk them last

4. Dry cow intramammary ABx are sometimes effective at curing chronic infections

5. Cull infected animals due to inability to Tx

Which pathogen causes deep abscesses in the udder?

Staph aureus, its a chronic infection that can rupture and shed in between period of normal milk

Environmental mastitis CS?

1. Acute or peracute for coliforms

2. Abnormal, serosanguinous, watery or chunky milk

3. Inflamed, hard, hot udder

4. G- infections more commonly cause systemic signs and endotoxemia

Environmental pathogens?

1. E coli

2. Klebsiella pneumoniae

3. Enterobacter aerogenes

4. Serratia spp.

5. Proteus spp.

6. Coagulase - staphylococci

7. Yeast or fungi

8. Prototheca

9. Trueperella pyogenes

10. Corynebacterium bovis

Environmental mastitis transmission?

1. Bedding (most common), water

2. Flies or other biting insects

3. Increases with poor teat end health

Environmental mastitis Dx?

Milk culture for clinical cases

Environmental mastitis Tx?

1. Most G- dont require Tx if infection is limited to the quarter; self cure

2. CNS species respond to intramammary ABx

3. Yeast often results from continued Tx with antimicrobials, will self cure with discontinuation and consistent milking out

4. Systemic illness needs injectable ABx (ceftiofur, and oxytetracycline) and supportive care; fluids, NSAIDs, nutritional support

5. Vaccination available for coliforms and Klebsiella

Where is prototheca seen?

In warmer climates with high humidity and standing water

Which mastitis has the highest mortality rate?

Coliform mastitis with clinical severity 3

Gangrenous mastitis CS?

1. Acute or peracute case with high mortality

2. Inflamed quarter that quickly progresses to cold, purple quarter

3. Sloughing of necrotic epidermis on udder

4. Systemic signs of endotoxemia

Gangrenous mastitis etiology?

Staph aureus is most common.

Cl. perfringens type A

Bacillus cereus rarely

Gangrenous mastitis transmission?

Contagious or environmental depending on eriology

Gangrenous mastitis Dx?

CS

Gangrenous mastitis Tx?

Mastectomy drains the quarter of the abscess. Most unrewarding, prognosis grave