Epidemiology and Causation of Lameness Flashcards
what are some obstacles to diagnosing and providing care for lameness cases in cow-calf operations?
- struggle to identify lameness
2 different thresholds for identifying problems
- lameness has no effect on animal
- facilities/inability to examine animal
what are the most common lesions seen in cow-calf lameness?
- most commonly in foot!
- more common in hind limb
- lateral claw more commonly affected
non-infectious:
1. screw claw
2. vertical fissures
3. sole ulcer
4. interdigital fibroma
5. hoof overgrowth
6. foot rot is also very common!!! but is not usually referred to larger hospitals (it is most of the lamenesses)
what are the most common lesions seen in feedlot lameness? describe feedlot lameness trends
a common welfare concern in feedlots! (decreases eating decreases growth)
diagnosed commonly after 57 days on feed (increased diet and can increase risk)
- upper limb lameness
- septic joint or deep digital sepsis
- foot rot
trends:
1. lameness more common in winter
2. toe ulcers or abscesses earlier in days of feed
3. heel warts diagnosed later in days on feed
4. 40% of animals diagnosed as lame died or were euth due to lameness
5. infectious disorders most common: foot rot, septic arthritis
describe lameness trends in dairy (5)
- 97% in foot (92% of those in hind limbs, 65% of those in lateral claws)
- most common diagnoses: sole ulcers and white line disease, digital dermatitis, foot rot, and toes ulcers
- lesions differ by lactation number:
-infectious lesions more common in heifers than mature cows (less immunity built up)
-non-infectious lesions most common in mature cattle: white line disease, sole ulcer, and toe ulcer - there is an increasing prevalence of digital dermatitis in dairy herds (1st lactation animals): esp showing and stocking animals
- majority of lameness non-infectious
what is the most common cause of lameness in large scale production systems? how are these usually treated? how prevent?
non-infectious disorders
cattle are commonly given antimicrobials to address clinical signs; this may actually delay appropriate diagnosis and allow lesions to progress to irreversible stage
routine trimming important to restore normal weight bearing and eliminate lameness; can use claw growth patterns as a selection tool and reduce incidence of common and more complicated infectious disorders
describe sole ulcers; include background, where occur, predisposing factors/pathogenesis, clinical signs, and treatment
- most common cause of lameness in cow-calf and dairy; can be related to housing and nutrition, foot trimming and claw care practices, and pre-existing conformational issues
- occur most commonly in lateral claw of rear foot, commonly bilateral with a high rate or recurrence
- predisposing causes result in increased mechanical loading and enzymatic changes, failure of suspensory system of P3, and compression of corium between P3 and sole
-mechanical pathogenesis: hard walking surface, biomechanics, or calving can cause overgrowth or disproportionate growth that causes the compression of solar corium between P3 and sole, which alters blood flow and leads to ischemia, interrupting horn proliferation and growth eventually leading to an ulcer
-enzymatic (inflam or noninflam) changes from calving or grain overload kick off pathways that result in breakdown/stretching of 3 supportive structures and result in ulcers
- clinical signs
-moderate to severe lameness (grade 3-4)
-alterations in foot placement:
–sole ulcer = affected foot out to offload lateral claw
–heel ulcer: shifting weight to toes to offload heels - treatment:
-corrective trimming and application of block on sound claw to relieve weight bearing on affected claw to allow pain control and tissue healing
-paring of loose and necrotic hoof horn away form ulcer bed at 45 degree angle, leave only normal corium
describe toe abscess/toe ulcers
- localized horn destruction that penetrates the claw capsule leading to exposure/infection of the corium, common in feedlot; often affect both toes on the same foot!
- risk factors:
-thin soles
-hard, abrasive, or irregular walking surfaces (new load of gravel, use hotshots to make cattle move faster)
-subclinical laminitis can contribute
-poor animal handling
-extended transportation time - can lead to necrosis of soft tissues and pedal bones or pedal osteitis
- treatment: open toe capsule to relieve pressure
describe white line disease
- second most common non-infectious cause of lameness in commercial cattle populations; group of lesions affecting sole-wall junction; associated with fissure, hemorrhage, and/or abscessation
- there are differences in origin and heterogenous nature of horn within different zones of white line, leading to the white line being a point of weakness in cattle that is worsened by disease or conditions that result in production of poor quality hoof horn that is less resistant to physical forces of weight bearing, leading to compaction of foreign material and colonization with bacteria
- treatment:
-if diffuse hemorrhage of white line or sole: is associated with laminitis and/or nutritional management, transfer to soft flooring surfaces and change diet to facilitate recovery
-of other forms suspected: functional claw trimming and removal of wall surrounding white line defects
-topical treatment: contraindicated and provide no benefit inmost cases, usually just delay healing and promote excess granulation tissue formation
-bandages and wraps: ONLY benefit is to control hemorrhage or treatment of digital dermatitis, only use for protection when excessive amounts of corium have been exposed, will delay healing of sole ulcers and apply pressure to already sensitive areas of hoof and can promote bacterial growth and retention of moisture
-block toe????? check powerpoint
describe factors associated with white line disease (4)
- compression and expansion of digital cushion during weight bearing: at site of heel strike during locomotion
- confinement on hard, poorly maintained flooring surfaces: increased shearing forces on axial and abaxial walls
- excessive lateral or medial movement when feet placed firmly: like in milking parlor holding areas
- subclinical laminitis/inferior horn quality with chronic overfeeding of energy and protein
describe treatment of white line disease
- if diffuse hemorrhage of white line or sole: is associated with laminitis and/or nutritional management, transfer to soft flooring surfaces and change diet to facilitate recovery
- if other forms suspected: functional claw trimming and removal of wall surrounding white line defects
- topical treatment: contraindicated and provide no benefit inmost cases, usually just delay healing and promote excess granulation tissue formation
- bandages and wraps: ONLY benefit is to control hemorrhage or treatment of digital dermatitis
-only use for protection when excessive amounts of corium have been exposed
-will delay healing of sole ulcers and apply pressure to already sensitive areas of hoof and can promote bacterial growth and retention of moisture - block application and removal of all loose, necrotic tissue is the MOST EFFECTIVE therapy in majority of cases
-reassess after 35 days, removal or retrim
-if not fully healed, replace block post trim and reassess in 3-5 weeks
describe interdigital fibromas; include clinical signs, diagnosis, and treatment
- result from hyperplasia of interdigital skin
- can be from irritation of skin due to stubbly pastures, poor environmental hygiene (subclinical, or recurrent footrot), or claw overgrowth leading to trapping of manure and debris and friction between skin and overgrown hoof tissue
- clinical signs:
-none if lesions are small
-mild to moderate (2-3) lameness with larger lesions putting mech stress on digits
-moderate (3-4) lameness with ulcerated or infected fibromas - diagnosis: evaluation of foot
-response to digital pressure on lesion
-response to compression across both claws (pinching) - treatment:
-small or incidental lesions: may be found during routine trimming and not cause lameness, no specific therapy
-larger lesions causing lameness and sensitive to digital pressure: surgical resection of hyperplastic tissue
in what subclasses of production are infectious causes of lameness more common? what are these common infectious causes?
feedlot, dairy youngstock, and 1st calf heifers
footrot and heel warts, septic arthritis in feedlots
footrot and heel warts in youngins
describe footrot
- infectious disorder of interdigital skin and subcutaneous tissues; superficial skin defect that progresses to a septic cellulitis; widespread geographic distribution; more common in dairy and feedlot populations
- diagnosis:
-examination of the foot, pick foot up
-differentials: laceration of ID space, ID fibroma, foreign body penetration - clinical signs:
-symmetric swelling in interdigital space and around coronary band - risk factors: suggest a role for immune system in development of disease
-production stage: early lactation
age: younger
-environment and management: warm and moist, increased rainfall, rocky pastures, etc.
describe diagnosis, clinical signs, and risk factors of foot rot
diagnosis:
-examination of the foot, pick foot up
-differentials: laceration of ID space, ID fibroma, foreign body penetration
clinical signs:
-symmetric swelling in interdigital space and around coronary band
risk factors:
1. production stage: early lactation
age: younger cows as opposed to mature cattle (suggest a role for immune system in development of disease)
- environment and management:
-warm and moist (enhanced bacterial survival and maceration of skin)
-increased rainfall
-rocky pastures, ice, crop stubble, twigs, rough or frozen ground
describe the pathogenesis/etiology of foot rot (4)
- bacterial infection strongly influenced by environmental and management factors; but not much evidence to suggest contagious
- results from fecal contamination of interdigital skin
- primary etiologic agents are fusobacterium necrophorum!! and bacteroides melaninogenicus: require scar or disruption of epi barrier; can’t breach intact tissues (gram negative anaerobes!)
- other organisms work synergistically with F. necrophorum and contribute to development of disease
