Riding Dog-Animal Companion - Poisonous bite

[Yogibear41]

Is there anyway to give a riding dog animal companion a poisonous bite? Looking to optimize a Fiendish Riding dog (lawful evil) as an animal companion for a high level (lawful evil) planar ranger. Figured using venomfire on it would be the best way to up his damage, also being able to harvest the poison to poison my own weapons would be nice. Already have my effective animal companion level boosted to my actual level using various options, and I plan on training him as a warbeast. I don't plan on riding it (were both medium), just want the role play of using a dog.

[Thurbane]

A Snake-Dog (https://www.wizards.com/dnd/article.asp?x=fr/fx20011025a) has a poisonous bite by default, but I don't think it's eligible as an AC.

I was looking for items that give a bite attack (Fanged Mask etc.), but can't find any with poison.

The Spider Bite feat (PGtF) might work, but a riding dog would struggle to meet the reqs.

Bebilith Blessing spell (DotU) will give a poisonous bite for the duration.

[The Viscount]

What kind of limitations are we dealing with?
The monstrous beast template from Savage Species can add poison, though it doesn't discuss character options for AC.

[Yogibear41]

What kind of limitations are we dealing with?

I want it to be a dog based creature, doesn't necessarily have to be a riding dog(although they are the best option I have found), needs to be something that would make sense on a LE character, I know there is an abyssal heritor feat that can give limited poison, but that wouldn't really fit with the LE theme(basically devil ancestry is appropriate, other fiendish ancestory is not), I want it to be medium sized. Needs to be legal to use as an animal companion. Patron Deity Lloth doesn't fly, better to have on deity requirement.

One of the main benefits to using a dog is the ability to be able to take it into towns/cities without people freaking out. Tigers/bears/etc. don't really fit, but I could swing a dog, even a fiendish one.

[NotASpiderSwarm]

There's a couple mundane items that will let you poison a bite attack, but they're all 1-time use and not viable for Venomfire etc. Similarly, spells that give a poison attack aren't common and would be a DM ruling if they work (only one I know is minute/level from Book of Vile Darkness).

Worst-case, take a Fleshraker and put a Hat of Disguise on it?

[daremetoidareyo]

Share soulmeld. There's a cloak thingy that grants a poison bite. Phase cloak I think. You need two levels of totemist tho

[SirNibbles]

Yuan-ti Poison Fangs Graft (Serpent Kingdoms, page 154); initial/secondary damage are both 1d6 Con, with a Fortitude save (DC 10 + 1/2 HD + Con Mod) to negate.

[Thurbane]

Yuan-ti Poison Fangs Graft (Serpent Kingdoms, page 154); initial/secondary damage are both 1d6 Con, with a Fortitude save (DC 10 + 1/2 HD + Con Mod) to negate.

^^ Great find! This is probably going to be the simplest solution...

[Noxangelo]

Collar of Venom from BoVD. gives all natural attacks an additional poison. is pricey at 50k gp for a fort DC:14 and its big brother the Collar of Virulent Venom is 138K for a DC:20

[PoeticallyPsyco]

Not poison, but the Feral Animal Companion feat gives it a diseased bite, in addition to some stat boosts.