Lecture 22 3/27/25 Flashcards
What are the two types of horn cells in the hoof?
-tubular horn cells that give strength to the horn
-non-tubular horn cells that hold the horn together
What is intercellular cement?
a lipid-rich extracellular matrix
Which vitamins and minerals are essential for hoof health and maintenance of the intercellular cement?
-biotin
-zinc
-copper
What are the characteristics of vertical wall cracks?
-also known as sand cracks
-more common in beef cattle
-start in the intercellular cement
-occur with vitamin/mineral deficiency
-can originate from the coronary band, center, or weight bearing surface (most common)
What are the predisposing factors for vertical wall cracks?
-decreased foot strength/horn quality
-abnormal claw shape/abnormal stresses
-horizontal grooves from laminitis
-deficiencies in copper, zinc, selenium, and molybdenum
-deficiencies in biotin and vitamin E
-high BCS
-high sulfate, iron, and nitrate in water
-abrupt diet changes
-dry environments
Where to vertical wall cracks most commonly occur?
-dorsal wall
-abaxial-axial wall junction
How do partial/incomplete thickness cracks differ from full/complete thickness cracks?
-animals with partial thickness cracks are often not lame
-animals with full thickness cracks often are lame
-full thickness cracks often have protrusion of corium and granulation
What are the characteristics of vertical wall crack treatment for both complete and incomplete cracks?
-be careful not to make crack deeper
-do corrective trimming to prevent packing of dirt/material
-use grinder/dremel as needed
-provide stability to the crack with acrylic and/or wire
-apply wooden block to opposite claw
-blend margins of crack with adjacent hoof wall
-do rechecks and corrective trimming as needed
What is the average growth rate for hoof wall?
5 mm per month
What are the treatment steps for incomplete vertical wall cracks?
-pare a “V” shape to the depth of crack
-make horizontal grooves at one or both ends of crack
-stabilize with wire if wide
-fill defect with epoxy; do not contact corium
What are the treatment steps for complete vertical wall cracks?
-regional IV anesthesia
-thin horn around protruding corium to relieve pressure
-remove corium to level or pared horn
-apply mixture of dexamethasone and oxytetracycline powder to trimmed protruding tissue
-apply claw block to opposite
What are the characteristics of the granulation response seen with vertical wall cracks?
-follows inflammation
-helps with healing when it occurs in a normal amount
-excessive granulation delays healing
What is the use of topical steroids in vertical wall cracks?
to dampen the inflammatory response
What are the characteristics of oxytetracycline?
-lipid soluble antibiotic that penetrates intracellularly and inhibits protein synthesis
-decreases MMP activity
-inhibits neutrophil function
What should be done if a crack goes all the way to the coronary band?
-trim close to the coronary band but do not actually traumatize the coronary band
-allow hoof to grow out before removing the remainder of the crack
How are vertical wall cracks prevented?
-nutrients
-proper BCS
-select for good claw conformation
-concentrate on balancing heels when trimming
-look for other signs of subclinical laminitis
What are the characteristics of interdigital fibroma?
-producers call it a “corn”
-affects many ruminant species
What can cause interdigital fibroma?
-interdigital dermatitis
-foot rot
-foreign body
-other infection
What is the treatment for interdigital fibroma?
if ulcerated:
-remove it in surgery to the point it is flat and then burn the remainder with a hot iron to prevent recurrence
if not causing issues:
-benign neglect
What are the main infectious diseases of the claw?
-digital dermatitis
-heel erosion
-foot rot
What is the prevalence of digital dermatitis?
-more common in dairy cattle than beef cattle
-70 to 95% of dairy farms affected
-higher prevalence in confinement housing than pasture-based systems
Which cattle are at greatest risk for digital dermatitis?
-early lactation cows
-heifers
What is the effect of digital dermatitis on reproduction?
-increased open days
-reduction in milk production
What is the most common etiology of digital dermatitis?
Spriochete bacteria, especially Treponema
Where is digital dermatitis typically located?
-found on rare feet in 90% of cases
-most commonly at the plantar interdigital cleft
-can be seen at dorsal aspect or corium
What is the common term for digital dermatitis affecting the corium and why?
hairy attack, because it leads to hair-like projections at the site of the lesion
Which level on the digital dermatitis scoring system is considered the “classic” lesion?
M2
Which level on the digital dermatitis scoring system has potential to be life-threatening?
M4
What are the characteristics of digital dermatitis in beef cattle?
-anecdotal reports
-seems to be more common now
-identical lesions to start; thought to progress more severely
What are the risk factors for digital dermatitis?
-muddy/wet conditions
-host genetic factors
-not washing hoof trimming equipment between cows
-outside hoof trimmers
-presence of other infectious disorders
-chronically infected cows/reservoir cows
-purchase of infected cattle
How is digital dermatitis treated at the individual level?
-clean lesions with soap and water
-apply topical antibiotic; oxytetracycline under a bandage
How is digital dermatitis treated at the herd level?
-clean with water under pressure
-foot bath with formaldehyde, copper sulfate, and/or antibiotics
What is important regarding bandages as part of treatment for digital dermatitis?
bandaged animals heal best, but bandages can be hard to manage
How is digital dermatitis prevented?
-foot baths
-improved environmental hygiene
-automatic washing of hooves
-biosecurity
What are the characteristics of copper sulfate foot baths?
-not fully effective if manure is present
-negative impact on environment
What are the characteristics of formaldehyde foot baths?
-still effective in 20% manure
-conc. higher than 5% can cause chemical burns on skin
-not commonly used due to worker safety
-poor activity at low temps
What are the advantages of using foot baths?
-good access to lesions in interdigital space
-convenient
What are the disadvantages of using foot baths?
-cost
-inefficient
-environmental concerns
What are the characteristics of spray on treatment for digital dermatitis?
-must spray all feet, including heels, toes, and lesions
-typically done with oxytetracycline
-done once daily for 5 to 7 days, then once daily on lesions
-must teach producers to avoid the mammary glands
What are the advantages of spray on digital dermatitis treatment?
-less copper content waste
-cheaper
What are the disadvantages of spray on digital dermatitis treatment?
-labor intensive
-poor access to interdigital space
-risk of milk contamination with antibiotics
What is the prognosis for digital dermatitis?
-most animals respond to treatment
-positively affected by good leg cleanliness and early treatment
-negatively affected by presence in multiple limbs
-54% have recurrence within a year
Why is it difficult to produce a vaccine against digital dermatitis?
there are several different treponema phylotypes associated with the disease
What are the characteristics of interdigital dermatitis?
-different than digital dermatitis!
-superficial dermatitis of interdigital skin; does not invade deeper
-often found with digital dermatitis and heel horn erosion/slurry heel
-may be painful to touch, but does not cause lameness
-more common on rear feet
-prevented with foot baths and good hygiene
What are the potential consequences of interdigital dermatitis?
-predisposes to overgrowth of the heel
-associated with interdigital hyperplasia development
What is the treatment for interdigital dermatitis?
-regular hoof trimming
-removal of hard ridges and underrun horn
-topical antimicrobials in severe cases
What are the characteristics of foot rot?
-common
-interdigital necrobacillosis
-“foul” in the foot
-mixed bacterial infection of soft tissues
-can lead to ascending infections; esp. affects tendons and joints
What are the characteristics of Fusobacterium necrophorum?
-normal GI flora of cattle
-enters defect in interdigital skin to cause foot rot
-virulence factors include leukotoxin, endotoxin, hemolysin, and dermonecrotic toxin
Which factors can predispose to foot rot?
-wet conditions
-loose-housed cows
-trauma
-contaminated environment (organism survives 1 to 10 months)
What is the treatment for foot rot?
-debride and clean interdigital space
-parenteral antibiotics
-provide dry and clean environment
How is foot rot prevented?
-foot bath
-good corral and free stall hygiene
-reduce fecal contamination
-vaccines available; not proven efficient
What are the characteristics of super foot rot?
-rapid onset
-does not respond to single dose of antibiotics
-some are resistant to antibiotics
-unilateral joint involvement may benefit from digit amputation
-prognosis depends on structures involved
