Medicina pediátrica en pequeños animales

PrESEnTATIon BroChurE

Bovine mastitisMaria E. Prado

ESSENTIAL G IDES ON CATTLE FARMING

Mastitis  is  the  inflammation of the mammary gland and udder 

tissue, and represents a major endemic disease of dairy cattle. 

Sometimes permanent damage to the udder occurs. Severe acute 

cases can be fatal and lactations may be compromised despite of 

the apparent recovery of the mammary tissues. This condition is a 

very complex disease affected by several factors and it is usually 

presented subclinically  in herds. Moreover, mastitis  treatment 

and control supposes large costs and losses to the industry. In 

accordance with  the current  situation,  an updated  review has 

been carried out using graphic resources such as photos, tables, 

flowcharts, etc. The author, a specialist in this field, has developed 

an accurate handbook analyzing the most highlighted features of 

this condition and pointing out the main control measures to prevent 

it as maximum as possible.

Bovine mastitis

Author: Maria E. Prado.

FormAt: 17 x 11 cm.

Number oF pAges: 70.

biNdiNg: Paperback, wire-o.retAiL priCe

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Bovine  mastitis

Presentation of the book

Mastitis is the inflammation of the mammary gland and udder tissue, and represents a major endemic disease of dairy cattle. It occurs as an immune response to bacterial invasion of the teat canal by variety of bacterial sources present on the farm or as a con-sequence of chemical, mechanical, or thermal injury to the cow’s udder.

There is sometimes permanent damage to the udder. Severe acute cases can be fatal and lactations may be compromised despite of the apparent recovery of the mammary tissues. This condition is a very complex disease affected by several factors and it is usually presented subclinically in herds.

Mastitis treatment and control supposes large costs to the industry and there are lots of losses due to this illness (reduction in yields, milk thrown away, extra labour, veterinary care and medicines, reduced longevity).

In accordance with the current situation, an updated review has been carried out using graphic resources such as photos, tables, flowcharts, etc. The author, a specialist in this field, has developed an accurate handbook analyzing the most highlighted features of this condition and pointing out the main control measures to prevent it as maximum as possible. An interesting chapter referred to case investigation has been included to illustrate this topic in a more practical way.

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Bovine  mastitis

The author 

Maria E. PradoMV, PhD, DACVIM.

Dr. Maria E. Prado obtained her veterinary medicine degree (MV) from the University of Zulia in Maracaibo, Venezuela in 1987. Following two years of bovine private prac-tice, she came to the United States to further her education. She completed a one year internship in Food Animal Medicine and Surgery and Equine Theriogenology at Okla-homa State University (1993-1994) followed by a residency in Food Animal Medicine and Surgery (1995-1998) and board certification in the American College of Veterinary Inter-nal Medicine (2000). Dr. Prado performed graduate studies in Veterinary Pathobiology and obtained a PhD at Oklahoma State University in 2003 and a postdoc in Molecular Virology. Since 2005, she has been employed by the University of Tennessee where she conducts research in the areas of bovine mastitis and respiratory disease as well as teaching.

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Table of contents

1. the bovine mammary gland

macroscopic anatomy

microscopic anatomy

physiology of the lactationmammary gland growth (mammogenesis)

milk production and lactation

milk ejection reflex

defense mechanismsphysical barriers

Cellular defenses

Noncellular defenses

2. epidemiology

prevalence and incidence

distribution and frequency of isolation of pathogens from clinical mastitis

source and transmission of infection

risk factors

3. pathogenesis

infectious aetiology

4. Clinical presentation

5. diagnosis

subclinical mastitissCC

Clinical mastitisphysical exam

milk culture and sensitivity

6. treatment

7. Control and prevention

8. Case investigation

herd goals

mastitis problem investigation

9. references

Bovine mastitisThe bovine mammary gland1

4

» The bovine udder consists of four separate glands or “quarters” and each drains into a teat.

» A medial suspensory ligament separates the udder into two halves and provides its major support.

» Fibers from lateral ligaments extend from the medial ligament to each side of the gland providing support via a “sling” of connective tissue.

» Blood, nerves and lymph vessels supply the mammary glands from the abdomi-nal cavity through inguinal canals.

» The fore teats are morphologically longer but the rear quarters have larger ca-pacity (ratio 40:60) and tend to have one or more supernumerary teats (~ 40 %).

Macroscopic anatomy

THE BOVINE MAMMARY GLAND

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Figure 1. Anatomical attachments of the bovine udder.

Pelvis Pelvis

Connective tissue (attaches udder to the abdominal wall)

Lateral suspensory ligament Median suspensory ligament (separates left from right quarters)

Left Front

Right

Rear

Teat Skin

Fine connective membranes (separate front and rear quarters)

Bovine mastitisThe bovine mammary gland1

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Milk ejection reflex

» Mechanical stimulation of receptors in the teat skin, either by suckling or manipulation of the gland, triggers an impulse that travels to the posterior hypothalamus which acts on the posterior pituitary to release oxytocin.

» Milk letdown occurs about 1 minute from first stimulus. Peak oxytocin levels occur within 2 minutes and return to basal levels by 10 minutes.

» Oxytocin binds receptors on the myoepithelial cells stimulating their contraction and increasing alveolar intraluminal pressure with subsequent expulsion of milk.

THE BOVINE MAMMARY GLAND

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Figure 6. Milk ejection reflex (milk let-down).

Lobe

Posterior lobeAnterior lobe

Oxytocin

Hypothalamus

PituitaryMammary quarter

Milk

Alveoli

Milk

Duct

Oxytocin

BrainHeart

Udder

Suckling

Contraction of myoepithelial cells

Milking machine sound or touch of gland by milker

Epidemiology2

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Bovine mastitis

Source and transmission of infection The infected cow is the source of infection for contagious path-ogens. Transmission usually oc-curs during milking by exposing the healthy gland to contami-nated milking equipment, tow-els and/or milker’s hands.

Environmental pathogens are ubiquitous to the cow’s environ-ment and infections may develop anytime as the mammary gland is continuously being challenged.

Figure 11. Transmission of mastitis in dairy cows. Adapted from Dr. Jerry Roberson.

Healthy cow Cow with mastitis

�Manure � Contaminated bedding � Soil �Water HandsTowels

Contaminated equipmentEnvironment

Between milkings During milking

EPIDEMIOLOGY

23Figure 12. (a) Milk residue in milking liner is a good source for transmission of contagious mastitis pathogens from cow to cow; (b) unsanitary bovine udder and improper placement of teat cups (hanging low); (c) worker spraying udder with water (this practice favours the development of environmental mastitis); (d) milker’s hands and towels are good sources of conta-gious mastitis pathogens. Courtesy of Dr. Jerry Roberson.

a

c

b

d

Diagnosis5

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Bovine mastitis

Table 6. Current methods for detecting subclinical mastitis in the lab, on-farm and/or on-line (where available).

Somatic cells (SC) Changes in milk composition

Method Flow cytometer (FC)* Portable counters California mastitis test (CMT) Electrical conductivity Sensors

What it does Quantify SC concentration Relative estimate of SC concentration

Determines increases in conductivity of milk samples caused by alteration of ionic concentration (sodium, potassium, calcium, magnesium and chloride)

Monitor milk components (i.e. fat, protein, lactose, NAGase)

Advantages �� Accurate, rapid, precise�� Low cost

�� Some counters have good correlation with FC�� Performed on-farm�� Some available for on-line detection

�� Practical, rapid, simple, user-friendly �� Performed on-farm�� Minor equipment needed�� Low cost�� Available for on-line detection

�� Relatively inexpensive�� Performed on-farm �� Most commonly used method for on-line detection during each milking

�� Low cost�� Potential for on-line adaptation

* Gold standard.

w

DIAGNOSIS

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Somatic cells (SC) Changes in milk composition

Disadvantages �� False positives (colostrum, early or late lactation, sudden drop milk production)�� Must send to lab for analysis�� Results not available immediately

�� See false positives for FC�� On-line system uses composite milk sample�� High cost, need counter and cartridges (expiration date)

�� See false positives for FC�� On-line system uses composite milk sample�� Correlation with FC is low�� Subjective scoring system may vary between individuals�� Scores based on range of SC in sample and not on actual count

�� False positives as ionic concentration is also affected by inflammation�� Ionic concentration may also be affected by milk sample physical characteristics (viscosity, temperature, fraction)�� Sensitivity and specificity for this method can be improved with consistency of sampling or by combining with production data

�� Accuracy might fluctuate and thus the need for routine calibration�� Time required to complete assay�� Mostly used as a research tool

Diagnosis5

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Bovine mastitis

a cb

Figure 22. Proper method to collect a milk sample from a cow for bacteriological culture. (a) The opening of the teat canal is cleaned with an alcohol swab; (b) strip teat 2-3 times to remove the fore milk; (c) aseptically collect milk sample into sterile tube taking care to not contaminate the lid or the edges of the tube. Courtesy of Mr. Mark Lewis.

DIAGNOSIS

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Figure 23. Bacteriological culture of milk sample. (a) Blood plate agar demonstrating Streptococcus aglactiae colonies. Courtesy of Mr. Mark Lewis. (b) Antibiogram. Courtesy of Dr. David Bemis.

a b

Treatment6

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Bovine mastitis

» Goals:

» Curing the infection.

» Speeding the recovery to a clinical cure.

» Saving the affected quarter and the cow.

» Severity of each case will dictate the order in which these goals are prioritised.

» When possible, therapy should be based on culture results as there are no other methods that ac-curately predict aetiology. This would ensure appropriate therapy towards a specific pathogen(s) of those cases that need it, resulting in the overall reduction of the use of antimicrobials and decrease chances of residue violations. Cultures should be available within 24 hours to be of benefit.

TREATMENT

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Table 8. Intramammary (IMM) therapy for clinical mastitis based on severity.

Severity Mild Moderate Severe

Frequency 60-90 % 10-30 % 10-15 %

Presentation Abnormal milk Abnormal milk and/or quarter + one systemic sign

Abnormal milk and/or quarter and more than one systemic sign

Treatment �� Culture-based decision to treat�� Not an emergency

�� ± Wait for culture results�� Examine again later on. If worse, then start treatment

�� Treat immediately�� Do not wait for culture results

IMM antibiotics* �� Only treat culture-positive cases with approved products�� Most products are effective against Gram+ pathogens. Their use enhances clinical cure and prevents spread and/or chronic infections�� Regarding Gram-, ceftiofur is approved for E. coli but mild infections will probably self-cure. Klebsiella sp. can become chronic so treat�� No effective treatment for Mycoplasma, Prototheca and yeast

Use best judgment. Most severe cases are due to Gram- but Gram+ are capable as well

* Use approved products: amoxicillin, ampicillin/hetacillin, ceftiofur, cephapirin, cloxacillin, erythromycin, novobiocin, penicillin and pirlimycin.

Control and prevention7

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Bovine mastitis

a b

CONTROL AND PREVENTION

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c ed

Figure 28. Udder preparation for milking process. (a) First a pre-dipping solution is applied to the each teat and allowed to remain for 30 seconds. (b) Next, the milker wearing clean gloves, cleans and dries each teat with disposable towels. (c) Then each teat is stripped to check for abnormalities in the milk. (d) If everything is normal, the milking cups are properly attached. (e) After the cow is done milking, a post-dipping teat disinfectant is evenly applied to each teat, ensuring that it covers the whole teat. Courtesy of Mr. Mark Lewis.

8

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Case investigation Bovine mastitis8

Identify cows by SCC2 or CMT3

Clinical mastitis outbreak

Milk culture

SCC mature cow, early lactation = dry cow management problem

� Reflects equipment problems � Identify by SPC1

Bacterial count in bulk tank

� Reflects subclinical mastitis � Bull tank SCC values may be affected by season, region, herd size and could be normal despite mastitis levels �Must use routinely for surveillance

Bulk tank SCC

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CASE INVESTIGATION

Figure 30. Common case scenarios that would require an investigation at the problem farm.

1 SPC = Standard Plate Count.2 Most reliable aid to estimate prevalence, incidence and evaluate efficacy of mastitis control measures. Most obtain monthly from testing service.3 The only reliable, user-friendly, economical, cow-side test for detecting subclinical mastitis. Read results within 15 seconds.

Environmental:

� Inadequate milking routine � Defective milking equipment

Cull or treat cows

Contagious:

� Infected cows are the main source

Identify pathogens

Identify cows by SCC or CMT

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