Bovine Orthopoedics and sudden death Flashcards
Where is digital dermatitis usually seen?
Just above interdigital cleft, between heel bulbs
Often erected hair around lesion
How is digital dermatitis diagnosed?
Clinical signs only, no diagnostic tests
What are the stages of digital dermatitis?
M0- normal
M1- early lesions, <2cm, ulcerative
M2- classical ulcer >2cm, painful
M3- scab formation after topical treatment
M4- chronic lesion, dyskeratosis, proliferation
M4.1- same as M4 but also has an ulcerative area
What does ‘acute’ digital dermatitis mean?
There is an ulcerative lesion
How do you treat digital dermatitis?
Put cow in crush Clean and dry the lesion Topical antibiotics (oxytetracycline) Trim foot while waiting to dry, look for other lesions Repeat daily for at least 3 days
What causes interdigital necrobacillosis (foul in the foot/foot rot)?
Fusobacterium necrophorum (biotypes A and AB) Enters through an interdigital lesion
How is interdigital necrobacillosis diagnosed?
Clinical exam
Typically only one foot affected, can be swollen
Swelling above the claws/characteristic odour
Lesions between the 2 claws
How do you treat interdigital necrobacillosis?
Cow in crush Check for foreign body Clean lesion Remove necrotic tissue Systemic broad-spectrum antibiotics for 3 days
What causes interdigital dermatitis?
Dichelobacter nodosus
Where is interdigital dermatitis seen?
Milder infection of interdigital skin, can spread across heels (heel horn erosion)
Give some controls for digital dermatitis
Footbaths
Good hygiene measures
How do you treat heel horn erosions?
Foot trimming, topical antibiotics
Give 3 non-infectious foot lesions
Sole haemorrhages/bruising
Sole ulcers
White line lesions
All associated with subclinical laminitis/ SARA (weakening of suspensory apparatus)
Describe sole haemorrhage/bruising
Contusion of the corium
Pressure from pedal bone (abnormal decent/movement)
External pressure (eg from stones), esp if soles are thin
Describe sole ulcers
Exposure of the corium
Disrupted sole horn production
Mainly caused by trauma/contusions of the corium from the pedal bone
How do you treat sole haemorrhages/ulcers?
Put cow in crush
Functional trimming (Dutch method)
Block unaffected claw
NSAIDs
Describe white line disease/abscess
Caused by stones/separation/manure
Associated with shearing/sideways forces on the feet
Can have abscess formation
How do you treat white line lesions?
Put cow in crush Functional trimming (Dutch method) Explore impacted white line, drain abscess, remove detached horn/under run sole Block unaffected claw NSAIDs
Give some possible causes of interdigital hyperplasia
Chronic skin irritation (eg digital dermatitis)
Hereditary?
What causes digital dermatitis?
Treponema spp, various strains
Identified in hair follicles and sebaceous glands
How do you treat interdigital hyperplasia?
Surgical removal under regional anaesthesia if causing lameness
Toe ulcers/necrosis are associated with what?
Overwear or over-trimming of the toe sole
Can get infected
How do you treat toe ulcers/necrosis?
Trim/block unaffected claw
Partial or full digital amputation
How do you treat a vertical wall crack?
Trim
Can block unaffected claw
Can stabilise hoof wall
How does deep digital sepsis occur?
Untreated foul in the foot, complicated sole ulcers, untreated white line abscesses, puncture wounds
How do you treat deep digital sepsis?
Amputation?
Arthrodesis?
Euthanasia?
Where do retroarticular abscesses form? What do they look like?
Above heel bulb
One claw, extensive painful swelling of the heel on a single digit
How do you treat retroarticular abscesses?
Surgery
Digital amputation
What is a corkscrew claw?
Dorsal edge of claw wall deviates from a straight line
Laminitis is associated with what?
Grain overload SARA Weakening of suspensory apparatus/ poor horn quality Endotoxins Increased activity of MMPs
How long do cows lie down for in a day?
12-14 hours
If a cow is sitting ‘half in half out’ of a cubicle, what does this mean?
Cubicle is too short -> more pressure on back legs -> risk factor for lameness
What is the best bedding choice for cow cubicles and why?
Sand:
Inert (lack of bacterial growth), cushioning, comfortable
What features must a cubicle have?
Needs a metre of forward lunge space to be able to stand up
Good to not be against a wall
Want defecation to be done outside cubicle (ie cubicle not too long)
Why does cubicle bedding need to be dry?
Once wet, increased bacterial load -> increased risk of mastitis
What is ‘green bedding’ for cubicles?
Dried faecal matter
Give some negative factors of using green bedding in cubicles
Potential for disease spread as increased bacterial load
Potential risk of antibiotic resistance
Kit is expensive to buy
Potential public health risk -> bugs on bed could end up in milk
Not to be used for cows <12 months old
Give some negative effects of using sand as bedding in cubicles
Needs topping up as cows dig it out
Clogs up drainage systems
Increases wear on machinery
Why is over-crowding a problem in housed areas?
Increased standing times -> increased risk of white line disease
More aggressive interactions between cows
How many cubicles should a farmer provide?
One per cow = bare minimum
5% extra (DEFRA)
20% spare for freshly calved cows
How much feed barrier space should a cow have?
76cm yokes, one per cow
At least 70cm per cow (if not using yokes)
Up to 1m for transition cows
A BCS less than what increases the risk of lameness?
< 2.5
What are the 4 mobility scores?
0 = sound 1 = abnormal gait but not identifiably lame 2 = slightly lame 3 = severely lame
When should we foot trim?
At drying off (60 days before calving)
60-100 days in milk
How big of a lying area should transition cows have?
What about feed space?
10-15 square metres per cow lying area
75-100cm per cow feed space
What BCS should a cow be at calving?
3
Which part of the pain pathway do NSAIDs affect?
Level of inflammatory mediators, possibly some central action aswell
Which part of the pain pathway do local anaesthetics affect?
Nociceptor stimulation
Give some clinical responses to pain
Impaired rumen function Activities aimed at minimising pain eg lying down Increased HR, RR, temp Dull, depressed Vocalisation Facial expression Decreased food intake and bodyweight
Give some clinical signs of lameness
Arched spine Hanging/nodding head as they walk Shortened stride length Adducting/abducting HLs Paddling/shuffling of feet Unwilling to walk Reduced weightt-bearing of affected limbs Decreased milk yield
How are hock lesions caused?
Excess pressure on joints
Inadequate bedding, poor cubicle design
Give some effects of lameness on fertility
Delayed cyclicity and oestrus behaviour
Increased calving to 1st service
Increased calving to conception
Increased number of serves per conception
How can you manage pain in lame cows without drugs?
Reduce standing times at milking
Reduce walking times
Increase comfort in cubicles/yards eg straw yards
Increase foot hygiene
How do you calculate cow comfort quotient?
No of cows using cubicles correctly
divided by
No of cows interacting with cubicles
Give a problem with using deep straw bedding in cubicles
Increased risk of bacterial growth eg Streptococcus uberis (mastitis risk)
How big should a passageway be?
3-4.5m
Give some factors which contribute to hygiene of cubicles
Cubicle length (not too long -> faeces in cubicles) Frequency of scraping out Passageway width (3-4.5m) Bedding plus lime Ventilation and drainage Frequent disinfection Foot bathing
What are the 3 scores for cow cleanliness?
0= no dirt/ minor fresh dirt/ dried splashing 1= an area of dirtiness at least palm size 2= am area of dirtiness at least forearm length
What size should floor slat widths be?
140-160mm for mature dairy cows
Spacing of 35-40mm
Reduce the spacing for smaller breeds/heifers
Give some indications for doing a digital amputation/arthrodesis surgery
Deep digital sepsis/septic arthritis of DIP joint
Complications associated with sole ulcers, white line abscesses, foul in the foot, penetrating injuries
Retroarticular abscess
Non-healing wall lesions
Toe necrosis (amputation)
What is the method of choise for digit amputation?
Disarticulation at proximal interphalangeal joint (method 1)
What nerve block should be used when doing digit amputation/arthrodesis?
Intravenous regional block
20-30ml LA (eg lignocaine, procaine)
19-21G butterfly catheter
Why is method 2 of digital amputation not recommended?
Involves cutting through 2nd phalanx
Disruption of blood supply to part of 2nd phalanx that is left/prolonged recovery
When bandaging a foot after digital amputation, why are the 2 accessory digits left out of the 1st softban layer?
So that when the next bandage layer is applied, they are being pressed against a soft bandage rather than skin (which could cause necrosis)
How should the foot be treated before doing an arthrodesis/digital amputation?
Washed and disinfected
What post-op care should be carried out after an arthrodesis/digital amputation?
Dressing changes
Antibiotics
Analgesia
What can go wrong after a digital amputation/arthrodesis?
Poor post-operative care
Problems with remaining claw (after amputation)
Ascending infections
Chroninc pain
Failure to achieve ankylosis of the joint (after arthrodesis)
What does it mean when cows ‘dog-sit’ in cubicles?
Poor cubicle comfort
How much space should cows have in a straw yard?
At least 10 square metres of resting area per cow
How would you identify a weight-bearing lameness?
Shortened stride of the sound leg
Head position at point of weightbearing: head up if front leg affected, head down if back leg affected
How do you treat contracted tendons in calves?
If you can manually extend feet so calf can stand plantigrade, splinting should be sufficient
If not: tendonectomy
How do you treat upward patellar fixation?
Cut the medial patellar ligament on both legs
Give some clinical signs of osteodystrophies
Stiffness/recumbency
Bone distortion
Long bone fractures
Swelling joints
How do you diagnose osteodystrophies
Joint fluid analysis
Bloods: increased AlkPhos, decreased calcium
PM, histopath
What causes white muscle disease?
Vit E and selenium deficiency
How would you identify white muscle disease in a cow?
‘Flying scapula’ (scapula appears to be raised above the body)
What would you see in the serum of the blood of a cow with white muscle disease?
Decreased vit E and selenium
Increased AST and CK (muscle enzymes)
How would you recognise hip dysplasia?
Stifle is rotated outwards, hock is rotated inwards
How do dislocated hips occur in cows?
Connected with oestrus or calving (slackening of ligaments)
How can you treat hip dislocation?
Closed reduction: sedate, lie cow on side, extend leg as much as possible, push stifle down and hock up.
Must be done within 24 hours, before a blood clot has formed
Give a cause of a spontaneous fracture in a cow
Hypophosphataemia
Can you splint a fracture above the elbow and stifle?
NO
Must be able to splint up to a joint above the fracture
How do you treat septic arthritis?
Conservative: aggressive ABs, anti-inflammatories
Surgical: lavage, arthroscopy, arthrotomy (opening the joint)
When does the Food Hygiene (England) Regulations 2005 state that emergency slaughter can be used?
An otherwise healthy animal must have suffered an accident that prevented its transport to the slaughterhouse for welfare reasons
Which criteria must a cow fit in order to be sent for slaughter at a slaughterhouse?
Likely to be fit for human consumption
Clean
Free from residues
Properly identified with at least one official eartag and passport
Fit to be transported to a slaughterhouse
When may a cow be slaughtered on farm and the body sent to a slaughterhouse with a veterinary certificate?
If it is otherwise healthy but has suffered an accident preventing transport
When may a cow be slaughtered on farm and have its body disposed of as fallen stock?
Not fit for human consumption
Not properly identified eg no ear tags
Not fit to be transported to a slaughterhouse
Is on-farm burial permitted for cows that die on the farm?
No
What must happen to cows that die on farm that are aged over 48 months?
Tested for BSE
Give some differentials for sudden death in cows
Haemorrhage (eg calving injury) Plant toxicity (eg yew) Lightening Electrocution Hypomagnesaemia Hypocalcaemia Toxaemia Bloat Blackleg (Cl chaevoei) Blacks disease (Cl novyi type B) Anthrax
What would you see in a cow that has died of anthrax?
No rigor mortis, blood not clotted- black and tarry
Who is authorised to do anthrax tests?
OV
What must happen if a farmer suspects anthrax on their farm?
Farmer informs vet of sudden death
Vet telephones local APHA office
Out of hours can do the test first, but must telephone next working day
Given a reference number if DEFRA want the test
You may do a private investigation, without telling the Ministry of a negative finding, but you will not be paid
APHA will tell the police and Local Authority if positive
(Don’t move the animal until tested negative)
How do you test for anthrax?
Thick blood smear from dead cow, stained with methylene blue
