hyperpigmentation in chihuaha

I have a 5 lb chihuaha that just got spayed and within a week developed dark pigmented skin on her underside. I took her to the vet and had a skin test done for food allergies. This test came back negative. Should I be concerned? she also has what appears is a irratation on the tips of both her ears. She had this when I got her at 2 months old. I thought it would go away but she is now 7 months old and it remains the same. Thanks

[ddeiman]

There could be a few things going on here. Thyroid should be checked along with regular blood panel but there are types of Alopecia X that could be it. Sometimes related to sex hormones or adrenal issues. First make sure you have a good vet or specialist like a dermatologist. Or ask you vet to call and consult with a vet dermatologist so he or she knows exactly which tests you need and what treatment to use. Reg vets are good for a lot of skin issues but their knowledge only goes so far and them guessing could wind up costing you money for unnecessary things. Has your vet done any skin scrapes and looked under a microscope at them? Simple things like bacteria, fungal or mange can be ruled out this way. Bloodwork can rule out the thyroid and some adrenal possibilities and lastly a biopsy sent away to a pathologist could give a definite answer. Some dogs just have a melatonin deficiency. The ears make me think possible autoimmune which also you need blood tests. Good luck!

[chihuawa10]

Many of our chihuahuas tummies change to a darker color as they get older. On another note,
Chihuahuas are know to get a condition that the blood does not flow to the tips of their ears which cause sores at the tips. There are meds you can get a the vet derm. specialist. but we have found that after many specialist visits... it not really a big issue unless they are bleeding often.
Serena
Chihuahua Rescue