Morgan Murphy

Cellulitis in Horses

Swollen legs, lameness and reluctance to move the hind of the body can indicate one of a number of different conditions. However, if these symptoms are accompanied by an extreme, subcutaneous infection with the formation of seeping pus, it is likely your horse has contracted cellulitis.

What is cellulitis?

Cellulitis can affect any horse

Also called septic cellulitis or phlegmon, cellulitis is a disease that, in equines, predominately affects the back legs. It normally begins with bacteria entering the dermal layers of an exposed wound and embedding into the deeper tissue.  Once inside the soft connective tissue, the bacteria multiply and quickly spread throughout the limb, forming pus which can seep from the skin as a visible discharge.  The initial wound can be caused by a variety of factors, from parasites through to mud fever lesions, and there is some evidence to suggest that prolonged exposure to dry grounds such as sand can contribute to the occurrence of wounds through long-term irritation.  The extent of the infection varies from horse to horse and it can extend to the surface of the skin. Please note that the size of the initial wound does not affect its severity


What are the signs of cellulitis?

You may not initially suspect cellulitis as the combination of symptoms could represent any one of a number of different conditions. Therefore, if you notice a combination of the following symptoms you should contact your veterinarian for an appropriate diagnosis:

  • swelling of the leg
  • heat in the leg
  • the leg seems painful to the touch
  • fever
  • lameness
  • depression and change of demeanor
  • pus draining from the skin (in advanced cases).

It is important to note that cellulitis can develop very quickly, progressing from a very minor cut to severe infection over only a few short hours. In very severe cases, it can develop into more severe complications such as necrosis (where the skin tissue dies and breaks away) and so it is vital to seek veterinary attention as soon as possible.

How is cellulitis diagnosed and treated?

As yet, the causes of cellulitis and the factors determining the severity of infection are relatively unknown. There are, however, certain elements which are believed to contribute to its development, such as poor wound management, poor hygiene, weakened immune response and compromised circulation.  There do not appear to be any breed or type predispositions but there does seem to be a high rate of reinfection following the initial episode.

Your veterinarian will normally treat the horse with a combination of antibiotics and pain relief medications (including a non-steroidal anti-inflammatory drug to bring down any inflammation).  Depending on the state of the wound it may also require draining, bandaging and nursing for some time afterwards until healing is complete.

Can cellulitis be prevented?

It is impossible to completely protect your horse from illness and injury but taking a number of measures can limit the risk of the infection becoming more severe:

  • Thoroughly check your horse over daily – this is vital to ensure you identify any new wounds to his body.
  • If there are wounds on your horse, ensure you clean these thoroughly, removing any residue or dirt which might contribute to an infection. Use a disinfectant such as chlorhexidine to prevent infection forming in the wound.
  • Keep your horse in hygienic surroundings: if he is stalled, make sure his stall is cleaned twice daily to remove wet bedding and droppings. If he is out at grass, remove droppings from the field regularly.
  • Keep legs clean and dry. If the legs are sweaty and hot after exercise, you may think about cold hosing or cleaning them prior to drying off. In muddy conditions try to remove all the mud and keep your horse’s legs as dry as possible.
  • Keep a regular exercise program which promotes circulation and ensures fitness is constant and well maintained.
  • Practice excellent fly control – pests landing and feeding on a wound will quickly spread infection. Reducing exposure to adult flies can keep the horse and his environment more hygienic. Use Spalding Fly Predators prior to fly season/adult flies hatching to prevent your horse from being irritated by these pesky insects.

Just as with any infection, cellulitis can have a number of complications. With good management you can certainly help to limit the repercussions.

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