Distal limb necrosis in Cows (Bovis) | Vetlexicon
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Distal limb necrosis

ISSN 2398-2993

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Synonym(s): leg necrotic septicaemia septicemia lameness lame salmonella fescue foot mould mold fungal toxin toxic toxicology poison poisonous poisoning ergotism salmonellosis

Introduction

  • Cause: a deficit in local circulation. Most common causes are ergotism, poisoning by tall fescue grass or septicemia (particularly salmonella).
  • Signs: cold, dry, discolored skin in distal limbs +/- tail and ear tips.
  • Diagnosis: clinical examination.
  • Treatment: removal of causal agent, antibiotics if infective cause, supportive therapy until necrotic skin sloughs off and is replaced by healthy tissue.
  • Prognosis: guarded, slow recovery, often need euthanasia on welfare grounds.

Presenting signs

  • Animal may be bright and well.
  • Swelling of lower limb for example, pastern-hock area, in 1 or more limbs.
  • Hindlimbs more commonly affected than forelimbs.
  • Lameness with or without pain.
  • Dry, leathery, discolored, sunken, cold skin in affected area.
  • May see a line of sharp demarcation of healthy and diseased skin between coronet and fetlock .
  • Ear tips or tail may also be affected .

Acute presentation

  • Necrotic skin eventually sloughs but this may take a long time.
  • If prolonged, may lead to joint involvement with separation of phalanges from metatarsal/metacarpal.
  • In extreme cases, the digit may even slough off.

Geographic incidence

  • Worldwide.

Age predisposition

  • Calves and young animals are more susceptible to Salmonella septicemia Salmonellosis; therefore, distal limb necrosis is more commonly seen in the young.

Seasonal predisposition

  • Incidence of ergotism Ergotism is more common in wet, humid, warm climates.
  • Fescue foot is more likely to occur in autumn - grass toxins (Festuca arundinacea) are higher in autumn and it is more readily seen 7-10 days after turnout to affected pasture in cooler weather Plants associated with nitrate poisoning.
  • The cold weather causes low blood flow to the feet and distal extremities, which exacerbates the problem.

Breed/Species predisposition

  • Cattle showing Bos indicus ancestry are more likely to lose their tails if affected.

Cost considerations

  • Veterinary costs: drugs and supportive treatment.
  • Possible death/euthanasia of the affected animal(s).
  • Lowers conception rate in breeding animals.
  • Cost of treating affected pasture (see Prevention below).

Pathogenesis

Etiology

  • Caused by agents that damage or occlude arterioles leading to local damage to the skin in the distal extremities.

Fungal toxins

  • Parasitic fungus Claviceps purpurea (ergotism) Ergotism .
  • Fungal endophytes (ergovaline) in tall fescue; ‘fescue foot’.
  • Less commonly, Aspergillus spp Aspergillus spp and mushroom poisoning.

Secondary to general septicemia

Predisposing factors

General

  • Not common due to the improvement in modern management systems.
  • Although rye grass is widespread in distribution, it is rare that sufficient quantities are eaten in large amounts during the toxic stage to induce poisoning.

Specific

  • Grazing high risk pastures during periods of cooler weather conditions.

Pathophysiology

  • Distal limb necrosis is DRY gangrene; it is unrelated to WET gangrene:
    • Dry gangrene: arterioles damaged/occluded, venous drainage intact, sterile.
    • Wet gangrene: lymphatic/venous vessels obstructed, no drainage, putrefaction +/- infection.
  • Distal limb necrosis is caused by interference with local blood supply, namely arterioles – either damaged by trauma, pressure or toxins or obstruction by microemboli or spasm.
  • Lymphatic drainage and venous return vessels remain patent.
  • Lack of oxygen and nutrients to tissue results in necrosis of the dermis, epidermis and sub-cutaneous tissue.
  • Dead tissue then sloughs away. Underlying tissue is granulation tissue.
  • If prolonged, epiphyseal osteomyelitis, polysynovitis and arthritis may occur.
  • In extreme cases, the digit may slough off.

Timecourse

  • Distal limb necrosis is a chronic disease; skin sloughing may take several days/weeks.
  • Treatment will necessarily be prolonged.

Epidemiology

  • May affect several animals if all are exposed to a common causal agent, but generally single animals in a group are affected.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Loeb E, Toussaint J M, Rutten P M G & Koeman J P (2006) Dry gangrene of the extremities in calves associated with Salmonella dublin; a possible immune-mediated reaction. J Comp Pathol 134 (4), 366-369 PubMed.
  • Baker I (1995) Ergotism. In Pract 17 (7), 317.
  • Holliman A & Barnes J (1990) Ergotism in young cattle. Vet Rec 127 (15), 388 PubMed.

Other sources of information

  • Osweiler G D (2014) Fescue Poisoning. In: MSD Manual - Veterinary Manual. Website: www.msdvetmanual.com.
  • Radostits O M, Gay C C, Hinchcliffe K W & Constable P D (2006) Veterinary Medicine. 10th edn. Saunders Elsevier, USA. pp 666, 909, 1902-1903.
  • Science Direct (online) Festuca Search Results. Website: www.sciencedirect.com.