Differentials and diagnostics

Podcast: LA Masses overview  (< 9 min)

The main differentials for masses in large animal species are:

Diagnosis

             The first step in diagnosing a mass is starting broadly (common causes of masses) and then narrowing your differential list based on a good history and physical examination. These principles cross species. History of injury may point you toward abscesses, hematomas, granulomas and hernias. Fever is associated with abscesses and neoplasia. Cardinal signs of inflammation (heat, pain, swelling, redness, and loss of use)  are typically usually identifiable with abscesses and sometimes with neoplasia.  Ultrasound and other imaging studies can be useful to determine the type of tissue or cellularity of fluid, extent and size of the mass, infiltration (neoplasia) or capsules (abscesses) and to find foreign bodies. Typically the most useful diagnostic tool is fine needle aspirate – stick a needle in it. In most cases, this is safe and effective. There are exceptions! Needle sticks through contaminated regions (vagina, rectum, oral cavity, prepuce) or contaminated tissues (cellulitis) can easily create an abscess and should not be attempted.

Resources

Skin diseases in horses, VCNA 31(2): 359-376, 2015 – discusses sarcoids, granulomas, lymphomas, SCC and more