Breath weapons for furry friends?

[Ranged Ranger]

Is there any way in the rules that adds breath weapons to a familiar, animal companion, special mount, or similar creature? I'd like a cat with a 5' cone breath weapon, and am wondering if there's an existing way to get there before resorting to complete homebrew...

[Celestia]

Several dragon-based templates grant breath weapons. The Dragonfire Adept gets a breath weapon. There are probably some dragon-based feats for breath weapons, too.

[Biffoniacus_Furiou]

You can use Share Spells with the spell Dragon Breath (SC), which is a personal range buff that gives you (or your companion you've shared it with) a breath attack usable every 1d4 rounds for the duration. It only lasts a round/level, but being personal range you can use Persistent Spell with it.

[Thurbane]

Metabolic Fire graft (Races of the Dragon, p.129).

For a familiar, it may be eligible to undergo the ritual to get the Dragonborn template (Races of the Dragon, p.8).

[Zaq]

AFB, but I'm pretty sure at least one soulmeld gives you something that either is a breath weapon or else looks like a breath weapon but doesn't officially have the "breath weapon" designation, and then there's a feat to share soulmelds with your familiar.

The devil may be in the details, here. I'm not sure if that soulmeld requires a bind, and if it does, I forget if Share Soulmeld grants the effects gained from binding melds. I may have to check later.

[ShurikVch]

Drakken Familiar ACF (Dragon Magic) - familiar got Dragonblood subtype; 15' cone of fire 1/hour (instead of Deliver Touch Spells); and Speak with Dragons (http://www.d20srd.org/srd/typesSubtypes.htm#dragonType) (instead of Speak with Animals of Its Kind)


AFB, but I'm pretty sure at least one soulmeld gives you something that either is a breath weapon or else looks like a breath weapon but doesn't officially have the "breath weapon" designation, and then there's a feat to share soulmelds with your familiar.Dissolving Spittle
Also, Dragonfire Mask with Chakra Bind (Throat)

[Dimers]

Have the [[companion]] wear an item with a continual or usable-at-will spell effect. Plenty to choose from there.

Though if you want exactly 5-foot breath weapon rather than at least 5-foot, you're going to be much harder pressed to find a match, regardless of the method.