https://www.vetsurgeon.org/f/clinical-questions/20738/hair-loss-in-a-guinea-pig Weird case of a Guinea Pig that I haven&#39;t seen before. 4y 2m FE seen last Jan for a lump removal under the axillae. Fine since then, This Saturday I saw her for hair loss. No itching/scratching, otherwise fine. NAD on exam apart from slight weight lossen-USTelligent Community 10https://www.vetsurgeon.org/thread/124695?ContentTypeID=1Tue, 18 Nov 2014 19:35:55 GMT146601cc-3922-4be7-9974-7e1d4e45a66b:3010ccac-d682-4ea7-91b1-53ba9543f750Marie Kubiak<p>I wouldn&#39;t 100% rule out ovarian cysts for the dorsal patch but as you say the distribution is far from typical. Dermatophytosis and barbering from a companion would be possibilities, as would be self-trauma for the dorsal lesion. I saw a very similar lesion to the larger one in a GP with discospondylitis that was chewing at the area overnight but the head lesion would be difficult for a GP to inflict on itself.</p> <p>I&#39;d start with a dermatophyte culture (Woods lamp assessment isn&#39;t much good&nbsp; in rodents as Trichophyton mentagrophytes is usually responsible and doesn&#39;t fluoresce) and discuss with the owner if a companion is potentially a cause.</p> <p>Marie</p><div style="clear:both;"></div>