foot lesions

Question 1

foot lesions are split into what causes? name the 4 most common foot lesions and tell me what their general cause is.

Answer 1

Digital dermatitis - infection

sole ulcer - claw horn

sole hemorrhage - claw horn

white line dz - claw horn

Question 1

what is the cause of digital dermatitis?

Answer 1

Treponema spp (3 groups) + opportunistic/secondary bac t

Question 2

what are the risk factors for digital dermatitis?

Answer 2

group of cattle housed together

unsure of transmission, maybe direct and fomites, maybe genetic component too

Question 3

what is the main and possibly only reservoir of digital dermatitis?

Answer 3

lesions on infected animals

Question 4

what are the C/S of digital dermatitis?

Answer 4

• mild-severe lameness
• interdigital area behind heel bulbs
• small circular moist browny grey exudative areas of epidermal liquefaction
• matting of surrounding hair
• raw dermal granulation tissue if diphtheritic debris cleaned (painful!)
• occasionally skin above 1 heel bulb only
• interdigital space b/t claws, coronary band at front of foot, around accessory digits
• papilliform or hairy warts

Question 5

how is digital dermatitis classified? briefly explain it

Answer 5

M scale

M0 = healthy, normal
M1 = early, small, <2cm
M2 = acute, active, bright red/granulomatous, >2cm
M3 = healing stage w/i 1-2d after topical tx, where acute lesion has covered itself with a firm scab
M4 = late chronic lesions (dyskeratotic)
M4.1= chronic lesion w/ subacute components

Question 6

how do you dx digital dermatitis?

Answer 6

clean and examine –> C/S

Question 7

how do you tx digital dermatitis?

Answer 7

clean/dry, topical Ab (oxytetracycline) or bandage w/ Abs

Question 8

what are the other names for sole ulcer?

Answer 8

pododermatitis, circumscripta

Question 9

what are the causes of sole ulcers?

Answer 9

• movement of P3, claw overgrowth, external pressure –> pinching of corium & germinal epithelium b/t P3 and hoof capsule
• pinching around bony protrusion where flexor tendon attaches (caudal edge of pedal bone)
• changes in structure/function of digital cushion –> poor/inadequate cushioning and formation of new bone on P3 (exacerbates problem)

Question 10

tell me about mild, moderate, and severe sole ulcers

Answer 10

mild: blood in horn as sole is produced = sole hemorrhage

mod: partial/intermittent interruption of horn production at sole ulcer site

severe: horn production completely stops at sole ulcer site for long time

Question 11

what are the C/S of sole ulcers/sole hemorrhage?

Answer 11

• slight-severe lamenss
• often both hind feet (one worse than the other)
• predominantly on lateral claw of hindfeet, medial claw of forefeet
• hemorrhagic discolouration to complete cessation of horn prod. at ulcer site
• possible secondary infection
• deep digital sepsis in extreme cases

Question 12

how do you dx sole ulcers?

Answer 12

clean/trim foot, C/S are pathognomonic

Question 13

how do you tx sole ulcer/sole hemorrhage?

Answer 13

corrective trimming + reduce height of affected claw and dish site

remove underrun horn and granuloma if present

apply foot block to sound claw + NSAIDs

parenteral ABs if infection

place on deep straw if severe

want to decrease pressure on pinched corium

Question 14

what is the px of sole ulcers/sole hemorrhage?

Answer 14

good if simple, poor if multiple claws affected/severe/deep digital sepsis is present

Question 15

tell me the pathogenesis of white line dz.

Answer 15

• junction of sole + wall = area of weakness
• causes similar to sole ulcers –> initial hemorrhage in white line, which may then separate
• separation exacerbated by standing on concrete, dirt/stone impaction –> infection through to corium
• white line seals over –> infection trapped –> pus produced expands within potential space –> under sole pain!
• abscess forms under sole, infection can tract up wall, eventually pus breaks out, usually at heel or less commonly at coronary band

Question 16

what are the C/S of white line disease?

Answer 16

• mod-severe lameness
• lat claw more commonly affected
• swelling = advanced ± large abscess
• leg abducted to bear weight on medial claw
• always on white line, more frequently on abaxial wall closest to heel, then going to tip of claw to axial side

Question 17

how do you dx white line dz?

Answer 17

• pain if “tweak” claw
• white line impaction and abscess when trimming/exploration
• small pin prick sized holes to large areas of impaction on white line (ALWAYS BLACK)

Question 18

how do you tx white line dz?

Answer 18

• trim/balance both claws
• explore impacted white line
• drain abscess
• remove underrun sole
• if tracked ip wall, remove entire section of wall
• Ab dressing (max 48h)
• foot block sound claw + NSAIDs
• parenteral Abs if necrotic corium found

Question 19

in bovines, 90% of lameness is in the ____, and 90% of those lesions are in the ____.

Answer 19

foot, hind feet

Question 20

what is the other name for foot rot?

Answer 20

interdigital necrobacillosis

Question 21

what is the cause of interdigital necrobacillosis?

Answer 21

acute necrotising inflammation of interdigital skin –> F. necrophorum ± T. pyogenes, Strep AND damage to skin

Question 22

what are the C/S of interdigital necrobacillosis?

Answer 22

• sudden onset
• mod-sev lameness
• swelling of ST above/around coronary band and between digits (digits forced apart)
• swollen/hot/enflamed/painful
• split in interdigital space which discharges pus/necrotic tissue
• F. necrophorum SMELLS

Question 23

how do you dx foot rot?

Answer 23

C/S

Question 24

how do you tx root rot?

Answer 24

check interdigital space for FBs, wash/flush, debride, topical ABs, parenteral ABs (3-5d)

Question 25

what are the 2 tx options for septic arthritis?

Answer 25

amputation
facilitated ankylosis