22.5.1: Lameness in calves Flashcards
What causes White muscle disease?
- Vitamin E/ selenium deficiency
- These two nutrients come as a pair
White muscle disease is also known as nutritional muscular dystrophy
When do animals present with signs of White muscle disease? Which animals are affected?
- Affects young, fast growing animals
- Most commoly calves <6 months, has been reported up to 2 years old
- Lambs and kids can be affected too
- Often following sudden expectation of exercise e.g. reared indoors then turned out at 6-8 weeks old; also reported in housed animals
Clinical signs of White muscle disease
- Recumbency and difficulty standing -> inability to stand for more than a few minutes
- Stiff, trembling limbs, weakness elsewhere (e.g. neck)
- May rotate distal hindlimbs from hocks if able to walk
- Gluteal, shoulder and dorso-lumbar musculature palpably enlarged and firm
- Other signs related to (striated) muscle affected e.g. intercostal muscles -> dyspnoea; myocardium -> cardiac arrhythmias; tongue -> inability to suckle
Which of the following is a poor prognostic indicator in White muscle disease?
* Dyspnoea
* Cardiac arrhythmias
* Inability to stand
Cardiac arrhythmias
Diagnosis of White muscle disease
- Clinical exam and history -> known deficient pastures
- Urinalysis: myoglobin = muscle injury
- Biochemistry: elevated creatine kinase (CK) and aspartate aminotransferase (AST)= muscle injury/ myocyte damage
- Biochemistry (at lab): low selenium or glutathione peroxidase
- Liver biopsy: low selenium and Vitamin E
What is glutathione peroxidase and why would it be low in a calf with White muscle disease?
Glutothione peroxidase (GSH-Px)
* Delayed increase in response to selenium administration (4-6 weeks)
* GSH-Px is a selenium protein
* Collect sample in lithium heparin (green) or EDTA (purple) tube (check with lab)
* This is the preferred test for WMD in the UK
Treatment of White muscle disease
- Vitamin E/ selenium - single dose usually sufficient but can be repeated after 2-4 weeks; poorer prognosis if myocardial involvement
- NSAIDs as needed
Prevention of White muscle disease
- Ensure adequate selenium intake of dams during late pregnancy
- Provide supplementation to dams if deficient pastures e.g. long acting injection, intraruminal bolus, oral dosing, addition to ration
- Can supplement calves
How do Vitamin E and selenium pass from dam to calf?
- Vitamin E - colostral transfer
- Selenium - transplacental and colostral transfer
Causative agent of Blackleg
Blackleg = clostridial myositis
* Causative agent: Clostridium chauvoei
Clinical signs of Blackleg
- Sudden death☠️
- Can look like White muscle disease but Blackleg is typically unilateral
- Lameness and upper limb muscle swelling
- Often die soon after clinical signs appear (12-36hrs)
Aetiology of clostridial myositis (Blackleg)
- Soil-borne infection that enters through lesions of the skin or mucosa
- Calving/ lambing injuries, fresh navel etc. are risk factors
- Causes severe necrotising myositis
Diagnosis of clostridial myositis (Blackleg)
- ⚠️Take care at PM exam - anthrax is a ddx!⚠️
- Once anthrax is exposed to oxygen, starts to sporulate -> must test first before cutting it open
- Blackleg: affected muscles are dry and dark on cut surfaces
Treatment of clostridial myositis (Blackleg)
- High dose penicillin
- Double dose every 12-24hrs
Prevention of clostridial myositis (Blackleg)
- Vaccination: monovalent and multivalent vaccines available
- Initial course at 3-6 months old followed by annual boosters
- Vaccines are cheap so definitely cost-effective even if one animal lost to Blackleg
