Suspicious moles on my dog’s rectum

Hi vets! Thank you in advance for your time, and I apologize for the “up close and personal” pictures! My dog Brody (chihuahua mix, aprox. 5-6 years old) has a couple of moles that are concerning me (on his anus). The largest one has been there for at least 6 months but has gotten much bigger (probably doubled in size in the last few months). The one towards the upper left is new! At his last exam our vet told us the large one is not something to be concerned about but I just wanted an additional opinion. Is it odd that they are growing in size/that a new one has appeared? Would you recommend seeking out a dermatologist to look at these? He does have very fair/pink skin with a few moles in other places. My apologies if I’m just an over-worried dog mom in this case! Note: He has no health issues (aside from minor allergies that cause some itchiness). Thank you SO MUCH.

Hello!  These brown splodges are in a very delicate place - removing or sampling such 'moles' could affect the muscle of the sphincter and thereby cause faecal incontinence, but on the other hand if the lesion may be sinister, it would arguably be useful to identify it (some mast cell tumours for example, may be treated to some extent with medication if identified).  There is a sampling technique called a Fine Needle Aspirate, a less helpful but less invasive test than a biopsy that may help to identify some kinds of lesion, but the pitfalls of this technique might also have to be appreciated. However, the problem is that I haven't seen this mark in context and know nothing about it, so your vet has much more experience of it than me.  Do they think it may be sinister?  Good questions for them, include, 'could this be something sinister / how do you know that it is not a sign of disease / is any kind of sample necessary / might you have got this wrong / should we refer to a skin specialist?' Vets don't mind being asked this sort of question outright as we are all just trying to work with you to get the best outcome we can for the patient.  If they are not asked how they arrived at a conclusion, they may not realise that you need more information.

Thank you for your reply! I only just now saw it. I will ask some follow up questions.