Hello and thank you for writing in.
Can you tell me if you have noticed any fleas on him?
Is he licking the area that is changing color?
Is it a yellow or more of rust color?
Ok, thank you for the information.
When animals lick their fur more then normal it oxidizes on the fur and will turn the white fur a rust or red color over time.
This was most likely due to his licking from the fleas. Now that you have the fleas under control you could try a bluing shampoo(most pet stores and groomers carry this) which should remove the red color and turn it back to white. Once he stops licking the fur should in a short time return to normal. If you would like to try the shampoo I would recommend waiting until the night before your next flea application to be sure you do not remove the Advantage.
This is nothing to worry about and is quit normal when fleas are present and the pet has white fur. This is often the first sign to medical personal that an animal is licking or chewing a certain area.
I hope this has eased your mind. Please feel free to reply back if I can be of further assistance.
Candy
Technician
Practicing Veterinary Technician for 23 years. Veterinary Practice Owner, Technician Trainer