bed stain

Question
We have a 2 year old shepard mix who still sleeps with us, (that is not the problem). He has always left rust colored stains on the bed. We have taken him to our vet, who ran urine and stool checks, and everything was normal. We are now discovering black sand under him. I thought it might be iron, but it was not. He seems to be very active and healthy, I just have to wash sheets everyday. What could the stains be from? Also, it seems to be from his bottom end as his head is always up towards us.
Thank you
Kathy Blohm

Answer
Hi Kathy!  This is a bit baffling.  The only thing that I would think that would be a possibility would be that these stains may be caused by his anal glands.  Anal glands are located at 5 abd 7 o'clock around the anus.  They hold a substance that is released during the force of defecation.  The substance then marks their stool with a scent.  This is why dogs always sniff eachother's behinds to say hello, and why dogs always sniff other dog's feces.  It's all about the scent!
When a dog is scared, excited, or extremely relaxed, the glands will release some of this substance.  It usually is not a pleasant smell and ranges from an orange color, to grey to black.  
If tests have been run and he is branded as a healthy dog, this would be the only thing that would come to mind.  
I hope this helps and please keep me posted!
Hilary