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Flashcards in Farm animal MSK diseases 2 Deck (100)
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1

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

2

What key differential must be ruled out in a case of sudden death of cattle, prior to necropsy?

Anthrax

3

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

4

How should carcasses resulting from black leg be disposed of?

Burning or deep burial

5

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

6

What is malignant oedema in cattle?

Acute wound infection caused by organisms of the genus Clostridium

7

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

8

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

9

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

10

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

11

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

12

How is malignant oedema diagnosed?

- Clinical signs and necropsy
- Identify organisms by fluorescent antibody tests or culture

13

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

14

Outline the prevention of malignant oedema

Trivalent vaccines for chauveoi, novyi and septicum

15

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

16

Describe the aetiology of idiopathic tetanus in cattle

- Ingested, neurotoxin produced in rumen
- Neurotoxin reaches CNS via peripheral nerve trunks

17

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

18

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

19

Outline your approach to the diagnosis of tetanus in cattle

- Distinctive clinical signs
- Rule out other differentials

20

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

21

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

22

How can tetanus be prevented in cattle?

Vaccinations

23

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

24

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

25

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

26

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

27

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)

28

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

29

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

30

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