Mastitis 'Blue Udder' 'blou-uier'
By Dr Mackie Hobson BSc(Agric),BVSc

1. Diseases

Severe cases can result in death of the ewe or result in starvation of the kid, but more losses occur from premature culling, and reduced performance of kids.

Causes of infection:

The term ‘blue udder’ is used to describe infections caused by:

1. Pasteurella haemolytica, now called Manneheimia haemolytica
2. Staphylococcus aureus
3. Corynebacterium pyogenes (name changes to Actinomyces pyogenes and Acranobacterium pyogenes and now known as Trueperella pyogenes. Corynebactrium pseudotuberculosis has also been implicated.

The condition is seen more in late lactation.

Environmental contamination is an important source of infection. Intensive conditions will lead to greater occurrence of the infection and warm moist conditions allow better survival of the bacteria. Trauma caused by vigorous and suckling by kids predisposes the udder to infection. Kids from infected ewes often try to suckle from other ewes and so transmit the infection.

Clinical signs:

Up to 5 % of ewes can be affected. In severe cases, blood supply to the udder is affected and a blue discoloration may result, hence the name "blue udder." Ewes affected with mastitis become feverish, go off feed and become depressed. They may hold their rear foot up, as if they are lame, and refuse to allow their kids to suckle. A watery, flocculent exudate may be expressed from the teat.

Ewes can die 2-3 days after infection or may develop into an abscess.

Ewes with sub-clinical mastitis usually appear quite healthy, but there is a reduction in their milk supply and development of lumps (scar tissue) in their udders, hence the name "hard udder." This is probably the most "serious" form of mastitis to the producer, since it often goes undetected.  

Gangerous mastitis is often caused Staphlococcus aureus.

Hardening of the udder is often caused by Pasteurella haemolytica

Abscessation of the udder is often caused by Corynebacterium spp.

Diagnosis:

Diagnosis is made on clinical signs and examination but to distinguish the bacterial cause the taking sterile samples from udder for culture is required.

Treatment:

Unless treatment started within a day the udder is unlikely to be saved.

• Antibiotics (Tetracyclines), injection or inframammary
• Stripping of the glands
• Use of oxytocin to promote milk let down
• Anti-inflammatory injections
• Staph mastitis is difficult if not impossible to clear up because the organism forms micro abscesses. It is sometimes difficult to identify because of intermittent shedding thus one negative culture does not mean absence of infection.

Control:

• Vaccination (Blue udder vaccine- Pasteurella haemolytica 2,7,9 and toxoid from Staphylococcus aureus)
• Vaccinate twice. The 1^st injection is given 6 weeks and 2^nd 2 weeks before kidding. A single booster 2 weeks before kidding is then given each year.
• Reduce feed intake dramatically 3 days befoe weaning.
• Prophylactic intra-mammary antibiotic preparations.
• In outbreak separate infected ewes and kids
• Teat spraying reduces the incidence of mastitis in outbreaks. Products which have been tested include 0.5% iodine (betadine) and 0.5% chlorhexidine.
• The udders of ewes should be examined after weaning and before breeding. Ewes with hard lumps in the udders should be culled, as these ewes will become increasingly poor producers of milk. Ewes that can only nurse one lamb should be culled from the flock. There is some evidence as to a genetic component to mastitis.

Reference:

J.Coetzer –Infectious Diseases of livestock

Bath –Kleinvee-siektes

Terry C. Gerros, DVM,MS,DACVIM