Severe (Toxic) mastitis in sheep

Question 1

Acute mastitis in sheep (cf dairy cows)

Answer 1

• Clinical mastitis events in sheep may be under-reported and may be missed, but the incidence is generally a lot lower than in dairy cow herds
• Acute mastitis in sheep is recognised and can be very severe in affected ewes

Question 2

Acute mastitis in sheep - CS

Answer 2

• may be ill
• on her own
• depressed
• anorexic
• may appear lame (painful udder)
• udder hot and swollen
• udder may also be cold and discoloured (‘black bag’) (red to purple to black)
• gangrenous appearance in sheep (much more common than in cattle)
• lambs not feeding
• if ewe survives the black necrotic tissue will slough off with lengthy healing
• euthanasia on welfare grounds to be considered

Question 3

Acute mastitis in sheep - causative pathogens

Answer 3

• The major causative bacterial species for mastitis in sheep are Staphylococcus aureus, Mannheimia haemolytica, E. coli and CNS species
• S. aureus is one of the most frequently detected species responsible for acute mastitis

Question 4

Acute mastitis in sheep - risk factors

Answer 4

• Mis-match of milk supply (nutrition of ewe) and milk demand (ewes with triplets)
• Inadequate nutrition of ewe
  – Protein – hungry lambs and teat trauma
  – Energy – poor immune function
• Poor anatomy
  – teat placement
• Chilling of the udder (bad weather, lack of shelter, excessive “crutching” [removal of the fleece - so lots of exposure of the udder)
• Teat lesions
  – Orf, S. aureus, traumatic (lambs)
• Hygiene at lambing and environment management

Question 5

Acute mastitis in sheep - tx

Answer 5

• Systemic antibiotic
  – Amoxicillin or Oxytetracycline
  – Tilmicosin (Cat C) carries a specific indication for treatment of acute mastitis in sheep but beware risk of self-injection (anaphylaxis is reported in humans)
• NSAIDs
  – Not licensed for any conditions in sheep
  – Use on the cascade