Dryland Distemper, Hematoma, Pigeon Breast ?

What do you think?  

Look below for information that will lead you to the diagnosis.

An abscess is a localized pocket of pus in a cavity which is comprised of tissue decomposition and debris.  It indicates infection and must be drained and treated with antibiotics.  

A hematoma is a localized collection of clotted blood or serum due to a break in a blood vessel or vessels.  

Dryland distemper?  We did have a case of that here in November 1999.  Although it usually appears in the pectoral muscles of the chest, it can manifest in the udder, sheath, neck, so why not the forearm?  

Abscess?  6 weeks ago, Sherlock received a small abrasion on his forearm (probably from racing through the brush near the spring) about 4 inches from the site of this swelling.  But it required little treatment and healed quickly.  However one is always suspicious of a connection between a wound and a later swelling.  But 6 weeks later?  

Hematoma?  One of the most common causes of a hematoma in horses is a kick but since Sherlock is turned out in his own pasture, being kicked was not an option unless it was from a mule deer!  Yet, he could have crashed into a rock, tree or post when playing - and he does play hard!  

The only way to find the answer is to probe the swelling with a needle.  This needs to be done by a competent veterinarian.  The site must be surgically prepared so no bacteria is introduced into the site with the probe.  Once clipped, the site is scrubbed three times.  Then a needle is inserted into the center of the swelling (usually there tends to be a central soft spot).  If a thick greenish or yellowish substance begins to drip from the needle, it is probably an abscess which means the veterinarian might decide to open up the site to allow free drainage.  He/she might want to culture the drainage to determine what bacteria are present and to determine the antibiotic to be used.  In the case of pigeon breast, the bacteria would be corynebacterium pseudotuberculosis.   

If the drainage from the needle is "clean" red blood or clear blood serum, it is likely a hematoma which will heal on its own in 2-4 weeks.  The horse's body will absorb the fluid and the swelling will do down. There is a small chance the hematoma could become infected.  Often the horse is put on antibiotics as a precautionary measure.  

Sherlock's swelling drained clear serum.  After a 7 day antibiotic regimen, the swelling is down 85%.  We are keeping a watchful eye on it.  

It is important to give prompt attention to any swelling, especially around a joint.