lameness 2 Flashcards
important infectious disease of the bovine foot
- Foot rot
- Digital dermatitis
- Heel horn erosion
important non-infectious disease of the bovine foot
- Sole hemorrhage / ulcer / abscess
- White line disease
- abnormal hoof growth
bovine foot rot
- other names
- pathogenesis
- timing, environment
- A.k.a. pasture foot rot or interdigital necrobacillosis
- Abrasion of interdigital skin > entry of Fusobacterium necrophorum + other pathogens
- Pastured cattle in wet weather and feedlot cattle during spring thaw; sporadic in housed dairy cows with wet floors
- Injury to skin between claws required
– Ice, stones, mineral deficits, etc. - Wet conditions increase risk but not sufficient cause
<><><><> - = cellulitis of the pastern
foot rot signs, general presentation
- = cellulitis of the pastern
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Signs
– More common in hind limbs, usually one foot
– Necrosis (split) of interdigital skin > foul smell
> May involve deep tissues if not treated
– Symmetrical circumferential swelling of the pastern
– Claws spread apart
– Acute onset of lameness (typically grade 4/5)
– May be febrile and partially anorexic
– No claw horn lesion
Foot Rot
- Treatment, efficacy
- control
Treatment
– F. necrophorum is very sensitive to antibiotics
* Penicillin (3 days)
* Ceftiofur (Excenel) – dairy (no milk withhold)
* 1 dose of long-acting oxytetracycline – feedlot & pastured cattle
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* Prompt treatment = rapid cure
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Control
– Antiseptic footbath – e.g. 5% copper sulfate
– Clean, dry floors and stalls; drainage in yards, lanes and pastures
Digital Dermatitis
- other names
- pathogens
- lesions, location
- A.k.a. “hairy heel wart”, “strawberry foot rot”, or Mortellaro’s disease
- Contagious–spirochete bacteria (Treponema spp.)
> Appear to require anaerobic conditions e.g. thin layer of wet or dry manure - Superficial inflammation of epidermis proximal to caudal interdigital space
- Ranges from 1-2 cm circular red erosion to proliferative lesion above the heel
> Occasionally seen between claws, on dorsal aspect or coronary band
Digital Dermatitis
* Signs
– Not swollen
– Usually a single rear limb
– Resting or shaking foot when standing still
– Variable degree of lameness (Grade 2 to 4)
– Circular 1-4 cm reddish granulation tissue (“strawberry” ) or papillomatous mass of long, fine tendrils (“hairy wart”) on plantar surface just above interdigital cleft
– No claw horn lesion
Digital Dermatitis
* Transmission
– Cow to cow – common in heifers when added to herd
– Fomites
– Foot trimming equipment
digital dermatitis treatment
– Topical oxytetracycline: powder or injectable liquid applied on a bandage (gauze square + VetWrap) or as a paste without a bandage (175 ml glycol, 175 ml vinegar, 150 g oxytet)
– Bandages must be removed in 3 days
– Paste is equally effective and therefore preferred
– Cure rate is very high, but so is relapse rate in high prevalence herds
Digital Dermatitis
* Control
– Clean, dry floors and feet
– Footbath medicated with oxytetracycline > 0.1 – 0.8% oxytetracylcine solution in water
– Spraying feet with oxytet solution (?)
– Disinfect hoof instruments between herds
– Regular hoof trimming
Heel Horn Erosion
- other names
- cause?
- pathogen and pathogensis
- A.k.a. “stable foot rot” or interdigital dermatitis
- Chronic exposure to moisture/ manure
- Infected with Dichelobacter nodosus
- Erode soft heel horn – Pitting > erosion & fissures
Heel Horn Erosion
* Signs?
* co-exists with what other condition?
– Cleft of black necrotic heel bulb tissue
> Deep ‘V’ groove across heels
– Fissures and necrosis at junction of skin and horn of heel; not penetrating the corium or skin
– Unilateral lameness but bilateral lesions
> Always examine the non-lame foot
– Variable degree of lameness (typically grade 2- 3)
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* Can co-exist with digital dermatitis
– Recent data suggest they be associated
Heel Horn Erosion
* Treatment and control
- Treatment:
– Functional trim of entire foot to take pressure off heel
– Trimming (debridement) of necrotic tissue to ‘open’ the cleft
– No antibiotics or wraps
<><><><> - Control:
– Clean environment
– Formalin or copper sulfate footbaths
– Regular hoof trimming
Sole Hemorrhage/Ulcer/Abscess
- pathogenesis
- Laminitis ???
- loss of support for P3 > Increased activity of matrix metallo-proteinases around calving may
contribute - sinking of P3
- hemorrhage and pressure necrosis of corium and sole > Mechanical stress of standing on
concrete ± lack of lying time contribute - full-thickness break in epidermis = ulcer
- bacterial involvement = abscess
<><><><> - damage is from the inside out! generally
Laminitis - pathogenesis
- Inflammatory response to e.g., rumen acidosis or toxic mastitis > systemic release of vasoactive chemicals
- causes temporary constriction of capillaries in foot (sensitive laminae)
- Ischemic necrosis
- Re-opening of capillaries & flooding with blood
- Inflammation, pain, separation of laminae
<><><><> - Excellent story, but… the balance between
– laminitis
– increased proteinase effects at calving
– mechanical effects of excessive standing (on concrete) are not well worked-out
