Cellulitis

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Cellulitis

Cellulitis is the inflammation of the superficial tissue layers beneath the skin, caused by a bacterial infection. It usually occurs secondary to a wound or infection of the deeper tissues. Wounds may even be superficial and small, however anything that breaks down the skin barrier provides a pathway for bacterial organisms to enter the body. Moderate to severe cases of rainrot can sometimes cause cellulitis in horses, due to secondary invasion by bacteria.

Cellulitis usually starts around the immediate area of the infection, such as the wound or joint, etc. However it will quickly spread downward and sometimes upward in the affected leg. Horses with cellulitis may also be lame. Horses that develop cellulitis as a result of a superficial wound are usually mildly lame however if it develops as a result of a deeper tissue infection, such as septic arthritis at a joint, lameness is usually moderate to severe.

Cellulitis is distinguishable from 'stocking up' through noting the temperature of the swollen area, as cellulitis will feel warm to the touch, as opposed to stocking up, which feels normal or slightly cool. Horses with stocking up also will have bilateral swelling--in that both legs will be swollen. Horses with cellulitis may sometimes have both legs swollen if they have an infection in both legs, but it is more likely that it will be usually be associated with one leg, not both.

Every time cellulitis occurs, it caused lymphatic inflammation and possibly some permanent damage. Severe or repeated episodes of cellulitis can lead to lymphedema.

Symptoms

Hot, painful soft tissue swelling
Pitting when pressure is applied to skin
Acute onset of severe lameness
Fever

Diagnosis

  • History
  • Clinical signs
  • Complete blood count
  • Serum chemistry profile
  • Radiographs
  • Ultrasound - reveals accumulation of subcutaneous fluid, and in some cases fluid, or gas deep within fascial planes.

Treatment


TreatmentDetails
Treatment of underlying cause
Antibiotics
Supportive careCold hosing the affected leg, support bandaging with stall rest
Anti-inflammatories
Topical poulticeApplication of diclofenac with or without a solution of 10% DMSO and 1% amikacin to the entire limb, avoiding any open wounds, incisions, or areas of full-thickness skin defects. Gloves should be worn when applying these substances to the limbGetman et al., 2013
In severe casessurgical drainage may be required.

Prevention

  • Carefully clipping long hair on the legs and keeping them clean and dry
  • Avoid frequent bathing of the horse
  • Properly treat all wounds

Prognosis

It depends on the cause, if it is caused by a superficial wound it is usually a pretty good prognosis as opposed to a result of a deeper tissue infection.

Scientific Research References

Good Overviews

Risk Factors

  • Horses with a prior history of cellulitis
  • Any abrasion, laceration and injection - as they create a portal of entry for bacteria to enter.