Farm animal MSK diseases 2 Flashcards
Outline your approach to the diagnosis of black leg in cattle
- Clinical signs and necropsy findings mostly
- Staining of lesion with specific fluorescent antiglobulins
- Characteristic liver infarcts
- Culture examination likely unrewarding unless fresh tissue
What key differential must be ruled out in a case of sudden death of cattle, prior to necropsy?
Anthrax
Outline the treatment of black leg in cattle
- Only effective if start early
- Large doses of penicillin IV, followed by longer preparations into affected tissue
- Generally slaughter on humane grounds due to subsequent significant muscle loss
How should carcasses resulting from black leg be disposed of?
Burning or deep burial
Outline the prevention of black leg in cattle
- Vaccines
- All animals >6mo should be vaccinated prior to turnout in spring
- Multivalent vaccines covering chauveoi, novyi and septicum
What is malignant oedema in cattle?
Acute wound infection caused by organisms of the genus Clostridium
Outline the aetiology of malignant oedema in cattle
- Many clostridia
- Deep puncture wounds e.g. after operation, parturitiion, injection
- Are soil organisms
- Low O2 tension and tissue damage → rapid multiplication and toxin production
- May get latent infection activation after bruising
Describe the clinical signs of malignant oedema in cattle
- Sporadic
- Signs within 48hours of infection , vary by site
- In all cases: marked anorexia, depression, pyrexia
- Local lesion: swelling (tense, may become emphysematous)
- Lameness, stiffness, muscle tremors
- Usually die within 48 hours
Describe the clinical signs of malignant oedema associated with parturition
- Vulval and perineal swelling
- Blood stained discharge from vulva
- Death within 24-36 hours from onset of signs
Describe the typical pathology of malignant oedema in cattle
- Site of infection surrounded by extensive oedema of subcut tissue and intramuscular fascia
- Oedema fluid appearance varies depending on causative agent
- All body cavities contain bloodstained fluid
- Parenchymatous organs show degenerative changes and PM decomposition
- Thickened uterine and vaginal wall if involved
Compare the appearance of fluid depending on causative agent in malignant oedema (novyi, seticum, sordelli)
- Novyi: fluid clear and gelatinous, little muscle damage
- Septicum: bloodstained frothy oedema, underlying muscle dark red, permeated with gas
- Sordelli: similar to novyi, fluid more bloodstained and foul odour
How is malignant oedema diagnosed?
- Clinical signs and necropsy
- Identify organisms by fluorescent antibody tests or culture
Outline the treatment of malignant oedema
- High dose antibiotics: parenteral penicillin (or tetracyclines)
- Debride and drain wounds, and irrigate with antiseptic solutions
- Supportive treatment with NSAIDs
Outline the prevention of malignant oedema
Trivalent vaccines for chauveoi, novyi and septicum
Outline the aetiology of tetanus in cattle
- Spore forming, mainly inhabit soil and GIT
- Usually enter via puncture wounds, can be genital tract at parturition, surgical wounds, vaccination, other injections
- Tissue damage and lowered O2 tension allows activation and multiplication
- Incubation period can be a few days to 4 weeks or more
Describe the aetiology of idiopathic tetanus in cattle
- Ingested, neurotoxin produced in rumen
- Neurotoxin reaches CNS via peripheral nerve trunks
Describe the clinical signs of tetanus in cattle
- Tetanic paralysis
- prolapse of thrid eyelid
- Rumen tympani
- Unsteady on HLs
- trismus
- Urine retention
- Tetanic convulsions and opisthotonus
- Fatal in 4-5 days in young cattle, within 10 days in older cattle
Describe the pathology that occurs with tetanus in cattle
NO gross or microscopic pathological findings that would confirm tetanus, but should attempt to identify site of infection and culture organism
Outline your approach to the diagnosis of tetanus in cattle
- Distinctive clinical signs
- Rule out other differentials
List the differentials that may present similarly to tetanus in cattle, and explain how these can be differentiated from tetanus
- HypoMg: will have convulsions and tetany but no prolapse to third eyelid or ruminal tympani
- CCN: similar, but no prolapse of TEL and no ruminal tympani
- Lead poisoning: elevated blood and kidney/liver lead levels are diagnostic
- Strychnine: investigation of abomasal contents
Outline the treatment of tetanus in cattle
- Euthanasia considered
- Large doses of penicillin parenterally, continue for at least 7 days
- Irrigate site of infection and topical antibiotics
- Neutralise unfixed neurotoxin
- Induce and maintain muscle relaxation (chlorpromazine or acetyl promazine) until neurotoxin destroyed/eliminated
- Keep in dark, quiet surrounding, soft bedding
How can tetanus be prevented in cattle?
Vaccinations
What is downer cow syndrome?
Pathology that develops secondary to prolonged recumbency as a result of muscle and nerve damage, can occur within 6 hours
Outline the prognosis for downer cow syndrome
- Depends on history and clinical presentation
- Depends on extent to which farm staff are prepared to nurse the recumbent animal
- Some may need euthanasia immediately
Outline the treatment and management of downer cow syndrome
- Rapidly and effectively address the initial cause of recumbency
- Limit effects of downer cow syndrome until the animal is able to rise unassisted
- Asses the animal back to its feet if necessary
- Ensure comfortable while recumbent
- NSAIDs
- Physiotherapy, massage and limb manipulation to encourage blood flow
- Rolling regularly
- Barriers to restrict cow onto soft surface
- Lifting
What are the complications that may occur from prolonged lying in cattle?
- Nerve damage in lower back, Hl, Fl
- Muscle damage from compression of major muscle groups
- Bed sores
- Mastitis
- Pneumonia
- Hip dislocations
Give examples of how a downer cow may be encouraged to stand
- Tail lift
- Nets, slings, cradles and harnesses
- Bagshaw hoist
- Inflatable bags (difficult to use)
- Flotation tank (rarely available)
What are the key advantages and disadvantages of the tail lift method for lifting a recumbent cow?
- Ad: straightforward, cheap
- Disad: only suitable for mildly affected cows
What are the key advantages and disadvantages of using nets, slings, cradles and harnesses for lifting a recumbent cow?
- Ad: relatively cheap and straighforward
- Disad: can be difficult to fit, must be fitted correctly, cow must be accessible to lifting machinery
What are the key advantages and disadvantages of the Bagshaw hoist for lifting a recumbent cow?
- Ad: relatively cheap and straightforward, easier to fit than nets, slings, cradles and harnesses
- Disad: must be tightened properly to avoid injury, potential welfare concerns, cow must be accessible to lifting machinery
What are the key advantages and disadvantages of inflatable bafs for lifting a recumbent cow?
- Ad: do not require cow to be accessibe to lifting machinery
- Disad: difficult to use effectively, time consuming
What are the key advantages and disadvantages of a flotation tank for lifting a recumbent cow?
- Ad: probably best, most appropriate and cow friendly system
- Disad: very expensive, very time consuming
Discuss the risks of lifting down cows
- Only to be used if cow is trying to stand effectively, must be able to take some of her own weight
- Lifting may cause damage through pressure from lifting devices causing swellings and pain
What methods can be used to move a down cow?
- Load onto a carry all on back of a tractor and secure effectively
- Load into a front end loader bucket on front of a tractor
- Carry in a sling
- Hip clamps only over short distance, with belt or strap supporting under her chest
What methods for moving down cows should be avoided?
- Hip clamps alone
- Dragging
Discuss the monitoring of down cows
- Assess response to treatment at regular intervals
- Non-alert cows rechecked within 2-4 hours, then again in 6-8 hours
- For alert cows reassess within 8-12hours
- Assess at least once a day after first day of being down
- Assess repsonse to treatment, original diagnosis, treatment of secondary damage, nursing protocols, lifting, consider euthanasia
What is the time limit for a downer cow?
No time limit on nursing downer cow as long as welfare is not compromised
List the indications for euthanasia of a downer cow
- Incurable conditions e.g. fracture, tendon rupture
- Lack of response to treatment of primary condition in reasonable time
- Alert becomes non-alert
- Pain, suffering
- Unable/unwilling to maintain sternal recumebncy
- Anorexia, adipsia
- Obvious bed sores/swollen joints/limbs
- Insufficient staff/facilities to provide nursing care
Describe the aetiology of sole ulceration in cattle
- Movement of P3 +/- claw overgrowth +/- external pressure leads to pinching of corium and germinal epithelium between P3 and hoof capsule
- changes in structure and function of digital cushion may lead to poor cushioning
- Formation of new bone on P3 may exacerbate problem
Where do sole ulceration lesions typically occur in cattle?
Back of the foot
Describe the development of sole ulcer lesions in cattle as a result of the underlying aetiology
- Mild: incorporation of blood into horn as sole is produced
- Moderate: partial/intermittent interruption of horn production at sole ulcer site
- Severe: horn production completely arrested at sole ulcer site for a prolonged period
Outline the clinical signs and presentation of sole ulcers in cattle
- Slight to severe lameness (does not relate to severity of lesion)
- Often both hind feet, one usually worse
- Usually lateral claw of HF and medial claw of FF
- Haemorrhagic discolourisation
- Possible secondary infection
Explain why a normal trim may not identify sole ulcer lesions
- Corium needs to grow to point where can be seen
- If lame but nothing seen on trim, go back and check again in a few weeks
How are sole ulcers diagnosed in cattle?
Pathognomic once inspected and trimmed
Outline the treatment of sole ulcers in cattle
- Corrective trimming (reduce height of affect claw, dish site)
- Remove underrun horn and granuloma if present
- Apply foot block to sound claw
- Administer NSAIDs for 3 days
- Administer parenteral antibiotics if infected (not routine)
- Place on deep straw if severe
Discuss the prognosis of sole ulcers in cattle
- Good in simple cases
- Poor if multiple claws affected, severe, deep digital ulcer present
- High risk of going lame again
What are the risk factors for the development of sole ulcers in cattle?
- Walking and standing for long periods on hard surfaces esp. post-calving
- Hoof overgrowth
- Periparturient period (increased movement of pedal bone)
- Loss of BCS (leads to loss of fat from digital cushion)
Discuss the control measures that may help prevent sole ulcers in cattle
- Reduce walking and standing time on concrete (cubicle training, fresh cow groups, rubber matting)
- Improve cubicle comfort to increase lying time
- Regular foot trimming to prevent overgrowth
Discuss the potential consequences of deep digital sepsis in cattle
- May track up into flexor tendon or joint
- Occasionally get osteomyelitis, more commonly infection of DIP joint
Discuss the treatment of deep digital sepsis in cattle
- Surgical interventions may result in long term best prognosis, but short term has significant impact on welfare
- Can take up to 1 year to heal
Discuss the aetiology of digital dermatitis in cattle
- Mutlifactorial infectious bacterial disease (3 groups of spirochetes - Treponema)
- Unsure of mechanism of entry
- Lesions on infected animals are main and possibly only reservoir for pathogen
- Thought to transmit in slurry or hoof knives
- Usually manifests when cattle are housed together
Outline the clinical signs of digital dermatitis in cattle
- Mild lameness, becomes severe if not treated
- Interdigital area behind heel bulbs normally affected
- Small circular moist browny grey exudative areas of epidermal liquefaction and matting surrounding hair/crusty lesion with matted hair
- Raw dermal granulation tissue
- Hairy warts can form
Give the 3 groups of spirochaetes implicated in digital dermatitis in cattle
- Group 1: Treponema medium/vincentii like
- Group 2: Treponema phagedenis like
- Group 3: Treponema pedis
Describe the “M0” digital dermatitis classification
Normal digital skin without any signs of DD
Describe an “M1” digital dermatitis lesion
- Early, small circumscribed red to grey epithelial defect <2cm diameter that precedes acute M2 stage
- Usually not lame, not too uncomfortable
- may be found whilst looking for other lameness lesions
Describe an “M2” digital dermatitis lesion
- Acute, active ulcerative (bright red) or granulomatous (red-grey) digital skin alteration >2cm diameter
- Toe touching stance, hold foot up, shaking feet when walking
- Very painful
Describe an “M3” digital dermatitis lesion
- Healing stage within 1 or 2 days after topical treatment
- Acute lesion has covered itself with firm scab like material
- Crust thicker, redness disappears
- Firmer crust than M2 lesion
Describe an “M4.1” digital dermatitis lesion
- Chronic lesion with subacute components
- May relapse back to acute infection
Discuss the importance of the digital dermatitis cycle with regards to the M classifications
- When trying to control DD, try to reduce M2 lesions by treating these
- This will reduce the number of lame animals and the reservoir for infection
- Most footbaths etc. are aimed at reducing the number of M4s
Discuss the 3 types of digital dermatitis animals
- Type 1: does not develop M2 lesions, but can show M1 and M4
- Types 2: single episode of M2 followed by prolonged period (months - years) of absence of acute DD
- Type 3: repeat episodes of acute M2 lesions (interval between episodes can be as short as 10-14 days)
How is digital dermatitis diagnosed?
Clean and examine foot for pathognomic lesions
Discuss the treatment of digital dermatitis in individual cattle
- Clean, remove matted hair and scab to exposie lesions
- Dry, apply topical antibiotic oxytet spray, repeat for 3 days
- OR bandage with antibacterial products e.g. copper sulphate powder (off licence)
- Parental antibiotics effective but may not be cost effective or justifiable
- Care re spread of infection to other animals on foot trimming equipment
Discuss the treatment of digital dermatitis in cattle at herd level
- Antibiotic footbaths but now considered unacceptable use of ABs
- Targeted topical treatment following identification of animals with lesions in milking parlour is better
Discuss the prognosis for digital dermatitis in cattle
- Good except if lesions on front of food
- Newer presentations of super-infection onto other claw horn lesions may be more difficult to treat
Explain why digital dermatitis lesions on the front of the food have a worse prognosis
- Cause damage to the periople
- Impairs production of wall
- Leads to underunning
Identify the risk factors for digital dermatitis in cattle
- Housing (cf. pasture)
- Wet and dirty conditions
- Automatic scrapers
- Herd expansion/poor biosecurity
- Younger cows
- High production
Discuss the prevention of digital dermatitis in cattle
- Maintain clean environment and foot trimming equipment
- Routine/regular disinfectant foot baths
Outline the aetiology of white line disease in cattle
- Junction of sole and wall is area of weakness
- Movement of P3, environmental risks, problems with digital cushion leading to initial haemorrhage of white line which may then separate
- Standing on concrete, direct and stones impaction exacerbates separation
- White line seals over, trapping infection, pus produced expands within potential space under sole causing pain
- Infection can track up wall
Outline the clinical signs of white line disease in cattle
- Moderate to severe lameness
- Lateral claw more common
- Swelling
- Leg abducted to bear weight on medial claw
- Small black dots along white line
Outline how white line disease in cattle is diagnosed
- Pain if tweak claw
- White line impaction and abscess if trimmed and explored
- Small pin prick size holes to large areas of impaction on the white line
- Can cut down to expose tract (but difficult for horn to grow back after this)
Outline the treatment of white line disease in cattle
- Trim and balance both claws
- Explore tract, drain abscess, remove under run sole
- Remove section of wall if tracked up
- Antibiotic dressing for max 48hours
- Block on contralateral claw
- NSAIDs
When would the administration of parenteral antibiotics be justified in the treatment of white line disease in cattle?
If necrotic corium is found
Discuss the prognosis for white line disease in cattle
- Good if simple sole abscess
- More difficult if tracks up
- may progress to deep digital sepsis
Outline the risk factors for white line disease in cattle
- Periparturient increase in movement of pedal bone
- Loss of fat from digital cushion
- Poor underfoot conditions
- presence of small sharp foreign bodies in environment e.g. flint stones
- Turning sharply on concrete surfaces
Discuss the control of white line disease in cattle
- Improve cow tracks
- Improve underfoot conditions
- Reduce bullying and improve cow flow
- Addition of 20mg/cow/day of biotin to diet
What is interdigital necrobacillosis in cattle also known as?
- Foul
- Foul in the foot
- Claw ill
- Lewer
Discus the aetiology of interdigital necrobacillosis
- Acute necrotising inflammation of interdigital skin
- Fusobacterium necrophorum +/- secondaries
- damage to skin e.g. FBs, rough underfoot conditions
Outline the clinical signs of interdigital necrobacillosis
- Sudden onset moderate to severe lameness
- Swelling of soft tissues above and around coronary band and between digits (digits spread apart)
- Swollen, hot, inflamed, painful
- Split in interdigital space which discharges pus and necrotic tissue
- Characteristic foul smell
- Swelling can track into tendon sheaths
- Anorexia, drop in milk yield, weight loss, pyrexia
How is interdigital necrobacillosis in cattle diagnosed
Signs are pathognomic once foot is examined
Outline the treatment of interdigital necrobacillosis in cattle
- Check interdigital space for FBs
- Wash and flush with plenty of clean water
- Debridement of necrotic tissue if present
- Apply topical ABs
- Parenteral antibiotics 3-5 days
- e.g. oxytet, penicillin/pen+strep, suphamethoxypyridazine
Discuss the prognosis of interdigital necrobacillosis in cattle
- Good if treated early
- Deep digital sepsis can result in aggressive cases or if left untreated
Discuss the risk factors for interdigital necrobacillosis in cattle
- Poor (rough/sharp) underfoot conditions
- Unhygienic underfoot conditions
Discuss the control measures that can be used against interdigital necrobacillosis in cattle
- Improve underfoot conditions
- Foot bathing
Explain what is meant by superfoul in cattle
- More aggressive and severe form of interdigital necrobacillosis
- Quickly invades deeper structures of foot
Discuss the treatment of superfoul in cattle
- Early aggressive therapy require
- Clean, debride and flush (use IVRA to provide analgesia for flushing)
- Pack with antibiotic and bandage (e.g. oxytet?)
- Systemic antibiotics until signs resolve e.g. pen/pen+strep
Outline the aetiology of sole haemorrhage/bruising in cattle
- Traumatic damage to corium between pedal bone and sole leading to blood being incorporated into sole horn as it is produced
- Can occur as a result of movement of the pedal bone and inadequate cushioning from digital cushion
Outline the clinical signs of sole haemorrhage in cattle
- Low grade lameness/tenderness
- Sole contains areas of bruising (may take weeks to become visible as sole grows out)
Outline the diagnosis of sole haemorrhage in cattle
- Usually visible
- If not reached weight bearing surface, may only not pain when area is percussed/pinched or by exclusion of other causes
Discuss the treatment of sole haemorrhage in cattle
- Depends on degree of lameness, severity of lesions
- Trim overgrown feet
- Apply block to unaffected claw
- Course of NSAIDs
- Keep on straw for 1-2 weeks if no block
How can sole bruising in cattle be prevented?
Ensure optimal underfoot conditions, encourage lying
What are the possible consequences of foreign body penetrations into the feet of cattle?
Carry infection through sole to corium which then establish infection and abscesses in a similar way to white line disease
Describe the clinical signs of foreign body penetrations into the feet of cattle
- Similar to white line disease
- Lameness often peracute in onset
- Severe if FB still in sole
- Black tracks in the sole leading to sub-sole abscess (diagnostic)
Discuss the treatment and prognosis for foreign body penetrations into the feet of cattle
- Treatment: open lesion and allow to drain, open enough to prevent re-impaction of affected area with debris from the environment
- Prognosis: good as for WLD, occasionally may penetrate deep and cause deep digital sepsis
Outline the aetiology of heel horn erosion in cattle
- Aka slurry heel
- Standing in wet corrosive slurry causes erosion of soft horn of heel forming pits and fissures in heel
- Heel eventually disappears completely if severe or untreated
Outline the treatment of heel erosion in cattle
- Trim away loose and fissured horn, spare healthy heel
- Corrective trimming to increase angle of front wall to ground to reduce the pressure on the sole ulcer site
Discuss the prevention of heel erosion in cattle
- Regular formalin foot bathing through winter to harden feet
- Improve underfoot conditions
- Avoid standing in slurry
Discuss the prognosis of heel erosion in cattle
- Good if treated before complete destruction of heel
- If destroyed, foot rotates backwards and get shallow hoof angle
- Pressure exerted by caudal palmar edge of pedal bone increases which can lead to pinching of corium and development of sole haemorrhage and eventually sole ulcers
Discuss the aetiology of vertical fissure (sand cracks) in cattle
- Damage to periople or underlying wall producing corium
- Common causes are digital dermatitis lesions on front wall of foot, and trauma, very hot dry sandy conditions in summer
Outline the clinical signs of vertical fissures in cattle
- Often asymptomatic
- If underlying laminae involved, or crack infected, severe lameness can ensue
Discuss the treatment of vertical fissures in cattle
- Crack opened and underlying abscess exposed and allowed to drain
- If granulation tissue develops following opened crack, resect granulation tissue and apply block to sound claw
