Toy Poodle Discoloration

Question
Hello There:  I have a toy poodle who is now 9 yrs old.  He used to an apricot and changed to a very light beige color which is fine.  But,...just in the last month he has a very large "S" shaped (reddish brown) spot down his back and it is quite large.  

I am confused here as to what caused it.  I did take little Reno into the veterinarian and he did not now either what was wrong and ran blood test which told us nothing.

Reno's hair in the spot is growing back but, it totally different in color.  

My question is:  There was one day I took Reno with me to Coeur d' Alene Lake where we had a picnic and it was sunny, but most of the time Reno was in the shade or just under my chair.  Could he have been sunburned?  This was around the first two weeks of June 08 that I had gone to the lake.  Most of the time he is inside but goes outside too and runs around and chases squirrels.  Ha!

Well, he does not seem affected by it at all, but it sure looks funny!

Sandy

Thanks for your advice here!

Answer
Hello Sandy and Reno,
Reno's initial color change from an apricot to the lighter color he is now is due to the fact that his color is due to a fading gene.  This causes his color (however slowly) to lighten as he ages.  
The color change on his back is abnormal though and can be due to a number of things.  Injury, Medication, Sun Damage to the skin, Fleas (the dog scratches the flea bites making Hot Spots), Allergies, or the dye used in lower quality dog foods.  
Any of these things can cause your dogs hair to grow back in a different color  
Actually I say it grows in a different color, but what really happens is that it grows back in the orginal color that the dog was from birth.  
For instance, I have a Silver Std Poodle.  When he gets an injury to his skin, his hair grows back Black because Silver puppies are born black.  As he continues to age, the black spot becomes more Silver in color just like the rest of the hair did from birth.

Your dog could very well have gotten Sunburn on his hair, but I wouldn't think that it would cause damage enough to change his hair color.  You will most likely have that spot on him for a year or more until it starts to lighten enough to blend with his current hair color.  

I hope this helps you some.  If you have other questions about Reno or comments for me, please feel free to ask.

Thanks for using AllExperts.com,
Kim