Infectious causes of lameness Flashcards
What is the primary pathogen in footrot in sheep, and what are its virulence factors
DIchelobacter nodosus
Virulence factors: type IV fimbrae for adherence to tissue, proteases critical for initial separation of hoof from tissue, outer membrane proteins (phase variation), 10 serogroups
What strains of D. Nodosus are there
VIrulent strain: serious, persistent, severe necrotic damage, 10% production loss
Benign strain: mild lameness, moderate interdigital dermatitis, may self cure
What epidemiological factors contribute to transmission of footrot in sheep
-Warmth, moisture about 10 degrees C
-source: chronic carriers in diseased feet
-D. Nodosus survives less than 7 days in environment
-Breed (Merino)
-Age
What is the treatment and control for footrot in sheep
Treatment: parenteral antibiotics as early as possible
Control: footbathing to destroy organisms before damage to hoof wall. Either 5% CuSO4, 10% ZnSO4, 10% formalin
How do you prevent footrot in sheep
Footbathing carried out correctly, isolate bought in animals, immediate isolation of affected animals, vaccination, breed replacements from never-lame ewes, cull
Why is eradication of D. Nodosus possible but not F.necrophorum
F necrophorum is: more successful in drier climates, is a commensal in the GIT flora so can’t be gotten rid of by depopulation
What is interdigital dermatitis caused by in sheep vs in cattle
Sheep: F. Necrophorum, Dichelobacter nodosus
Cattle: F. Necrophorum, Prevotella spp., Dichelobacter nodosus
What is contagious ovine digital dermatitis caused by and where do the lesions start
Caused by: treponemes, D. Nodosus, and F. Necrophorum
Lesions start: at the coronary band
How is CODD treated
Amoxicillin or macrolides
What are the risk factors of CODD
-presence of footrot
-Lowland pasture
-lush and poached pasture
-Buying in sheep
-Presence of cattle with DD
-Time of year (late summer/early autumn)
What causes digital dermatitis in cattle
-anaerobic spirochaete- Treponema species
What is the source, risk factors, and treatment of digital dermatitis of cattle
Source: rectal carriers
Risk factors: high prevalence in heifers, high correlation with heel horn erosion, hoof trimming equipment, not widely present in environment
Treatment: topical treatment
What causes interdigital phlegmon (foul of the foot) in cattle and what is this called in the US
-Causes: F. Necrophorum +/-other organisms suck as Porphyromonas levii and Prevotella intermedia prior to injury to the skin
-Called footrot in the US
What causes thrush of the frog (digital necrobacillosis) in the horse
-F. Necrophorum
Which bacteria are found in foot abscesses of cattle, sheep, and pigs, and what causes the defect in the foot
Bacteria: F. Necrophorum and T. Pyogenes
Causes of defect: white line disease or solar hemorrhage which allow invasion of infection which may break out at the coronet
