5 ms·

Thanks! Apologies for taking this so far down the rabbit hole, but if dogs are unable to metabolize theobromine, then how does it leave their system?

by elhudy 8y ago

nneonneo 8y ago
"Can't" isn't quite accurate - what it really means is that the rate of metabolism is significantly slower. Dogs can (and will) eventually metabolize and eliminate theobromine, but the rate is slow enough that the compound can build to toxic levels quickly following ingestion. In general, mammals are capable of metabolizing and/or eliminating nearly any foreign organic compound over a long enough timespan, thanks to the mechanisms of xenobiotic metabolism. The liver contains a large number of enzymes of the Cytochrome P450 (CYP) family, which are able to catalyze reactions with a wide variety of compounds as the first (and most critical) step of metabolism. These reactions typically make the compounds hydrophilic, making it possible for the kidneys to pick them up and eliminate them. However, different animals express the various CYP enzymes at different levels; some are much more effective at metabolizing certain compounds (e.g. theobromine) than others. So, if an animal lacks a certain CYP enzyme (or it is expressed at a very low level), they will also metabolize certain compounds much slower (other enzymes, which are less efficient, will have to do the job). So, basically: dogs lack certain enzymes in their liver which means that they metabolize theobromine much slower than humans - but that doesn't mean they don't metabolize it at all.
- cknoxrun 8y ago
  Just to tack on to this, this is the cause of almost all drug-drug interactions and many adverse drug reactions. CYP450 is an incredible family of enzymes.
dspillett 8y ago
> if dogs are unable to metabolize theobromine They can, just not very well. We can too, but not perfectly. To get a lethal dose of theobromine a healthy human adult would need to eat about 10Kg of milk chocolate in a very short space of time (less for dark chocolates). For most small dogs a normal ~40g bar is enough to cause concern, if an even smaller dog (i.e. breads that are sometimes called "toy" dogs) consumes a standard bar you should take it to the vet immediately as that could likely be quickly fatal.
- elhudy 8y ago
  My ~25lb dog once consumed half a bar of 80% dark. I gave her ~4 Tbs of hydrogen peroxide per the internet's suggestion and she basically drank it like water, without issue >.> I like to believe her excessive food consumption throughout her life was training for this moment where she would need to metabolize poison.

Thanks! Apologies for taking this so far down the rabbit hole, but if dogs are unable to metabolize theobromine, then how does it leave their system?

by elhudy 8y ago

Thanks! Apologies for taking this so far down the rabbit hole, but if dogs are unable to metabolize theobromine, then how does it leave their system?

nneonneo 8y ago

"Can't" isn't quite accurate - what it really means is that the rate of metabolism is significantly slower. Dogs can (and will) eventually metabolize and eliminate theobromine, but the rate is slow enough that the compound can build to toxic levels quickly following ingestion. In general, mammals are capable of metabolizing and/or eliminating nearly any foreign organic compound over a long enough timespan, thanks to the mechanisms of xenobiotic metabolism. The liver contains a large number of enzymes of the Cytochrome P450 (CYP) family, which are able to catalyze reactions with a wide variety of compounds as the first (and most critical) step of metabolism. These reactions typically make the compounds hydrophilic, making it possible for the kidneys to pick them up and eliminate them. However, different animals express the various CYP enzymes at different levels; some are much more effective at metabolizing certain compounds (e.g. theobromine) than others. So, if an animal lacks a certain CYP enzyme (or it is expressed at a very low level), they will also metabolize certain compounds much slower (other enzymes, which are less efficient, will have to do the job). So, basically: dogs lack certain enzymes in their liver which means that they metabolize theobromine much slower than humans - but that doesn't mean they don't metabolize it at all.

cknoxrun 8y ago
Just to tack on to this, this is the cause of almost all drug-drug interactions and many adverse drug reactions. CYP450 is an incredible family of enzymes.

dspillett 8y ago

> if dogs are unable to metabolize theobromine They can, just not very well. We can too, but not perfectly. To get a lethal dose of theobromine a healthy human adult would need to eat about 10Kg of milk chocolate in a very short space of time (less for dark chocolates). For most small dogs a normal ~40g bar is enough to cause concern, if an even smaller dog (i.e. breads that are sometimes called "toy" dogs) consumes a standard bar you should take it to the vet immediately as that could likely be quickly fatal.

elhudy 8y ago
My ~25lb dog once consumed half a bar of 80% dark. I gave her ~4 Tbs of hydrogen peroxide per the internet's suggestion and she basically drank it like water, without issue >.> I like to believe her excessive food consumption throughout her life was training for this moment where she would need to metabolize poison.