Difference between revisions of "Bacterial skin infections - Pathology"

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*'''[[Contagious Footrot]]'''
 
*'''[[Contagious Footrot]]'''
  
*'''Necrobacillosis''' of the foot
+
*'''[[Necrobacillosis]]''' of the foot
**Usually caused by [[Fusobacterium|''Fusobacterium necrophorum'']] with other bacteria
 
**In sheep:
 
***'''Ovine interdigital dermatitis'''
 
****Acute necrotising dermatitis similar to benign footrot
 
***'''Foot abscesses'''
 
****Bulbular or lamellar
 
****Mostly in wet conditions and in heavy sheep
 
**In cattle:
 
***'''Interdigital dermatitis and cellulitis'''
 
***Caused by ''F. necrophorum'' and [[Bacteroides|''Bacteroides melaninogenicus'']]
 
***Predisposed by trauma
 
***Grossly:
 
****Fissures, necrotic swollen edges in interdigital spaces
 
****Inflammation may spread to joint spaces
 
  
 
===Systemic bacterial infections===
 
===Systemic bacterial infections===

Revision as of 11:18, 30 June 2010


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()Map INTEGUMENTARY SYSTEM (Map)
SKIN INFECTIOUS



Cutaneous bacterial infections tend to be called pyodermas. They are superficial, deep and are common in dogs, but less common in other species.

Superficial pyoderma

Superficial pyoderma in a dog (Courtesy of Bristol BioMed Image Archive)
  • Affects epidermis and upper infundibulum of hair follicles
  • No scarring when healed
  • Grossly:
  • Microscopically:
    • Intraepidermal pustular dermatitis
    • Superficial suppurative folliculitis
    • Bacteria commonly not seen

Impetigo

Dermatophilosis

Greasy pig disease

Ovine Fleece Rot

Equine Pastern Folliculitis

Deep pyoderma

Staphylococcal Folliculitis and Furunculosis

Subcutaneous abscesses

Bacterial granulomatous dermatitis

  • Usually due to saprophytes
  • Grossly:
    • Diffuse or nodular lesions
    • May ulcerate and form drainage fistulas
  • Microscopically:
  • Mycobacterial granulomatous or pyogranulomatous lesions
    • Usually caused by Mycobacterium lepraemurium (feline leprosy) or other Mycobacteria
    • Most commonly lesions appear on head, neck and legs
  • Botryomycosis

Bacterial pododermatitis

Systemic bacterial infections

  • Salmonellosis
    • Capillary dilatation and congestion -> cyanosis of external ears and abdoman
    • Thrombosis -> necrosis of extremities
  • Erysipelas in pigs
    • Caused by Erysipelothrix rhusiopathiae
    • Vasculitis, thrombosis, ischaemia -> cutaneous lesions - firm, raises, rhomboidal pink to dark purple areas
  • Clostridium novyi
    • Severe cellulitis, toxaemia and death of young rams during breeding season (due to traumatised heads) - 'big head'
  • Streptococcus equi
    • In horses
    • Immune complex vasculitis -> purpura