Tuesday, October 30, 2007

Toxicology Tuesday, October 30

Once again this week, I took a wrong turn in the grocery store and got lost in the produce section. While I tried to find my way out, I wondered whether these avocados* were

Toxic or Not?

*(Here, we are talking about the flesh of the fruit only, not the bark, leaves, rind, or pit.)


Toxic, to birds, particularly psittacines (parrots)

OK, I’ll confess. This post was a bit sneaky. First of all, everybody should know by now that KatDoc doesn’t do bird medicine, so you are forgiven if you didn’t think “avian” when you read this one. Secondly, the people who noted that I specified only the fruit recognized there was some trick to this question.

The point I wanted to make with this week’s quiz is to help you become discriminating researchers when you look up toxic plants on the Internet or in various pet publications. Most of these sources just run a list of plant names, without specifying what part or parts are toxic, what species may be affected, and whether the toxicity is limited to mild GI distress or is more severe.

In this week’s case, avocado bark, leaves, rind, and pits have all been implicated in various toxicities in a number of different species. Dogs may experience vomiting and diarrhea. Horses, physically unable to vomit, develop colic, which can be fatal. Goats have been reported to develop mastitis (inflammation of the udder) from eating avocado leaves. Cattle, rabbits, rodents, cats and fish are also among the listed species affected by the plant parts, but only birds seem to be severely affected by eating the fruit.

Respiratory distress, congestion and fluid accumulation in the tissues around the heart can lead to death in several avian species. My various sources listed parrots, budgies, cockatiels, canaries, and ostriches specifically. The toxic agent is a fatty compound called persin. No treatment was mentioned, nor could I find a toxic dose.

Here’s an interesting fact: The Guatemalan type of avocado (Persea americana) is toxic, but the Mexican variety (P. dryminfolia) apparently is not. According to my reading, the most commonly available avocados in the US are of the Guatemalan variety.

Finally, critically evaluate your source before freaking out when Fido steals the guacamole. All the legitimate references I checked (ASPCA’s Animal Poison Control Center, U of Penn, Wikipedia) reported nothing more than GI signs in dogs, but one unnamed site called avocados “highly toxic” and “deadly” for dogs, without citing their source or giving any data. Question everything you read (including this blog!) before jumping to conclusions on the safety of anything your pet eats.

Charlie, aka "Chuckles,"
a 21 year old Chestnut-fronted Macaw,
says, "Don't eat avocados!"

photo by Charlie's human mate, Julie Zickefoose
[Thanks, Zick!]


Lisa said...

It's GREEN, it must be toxic!

Anonymous said...

You excluded the bark, leaves, rind, and pit. That's got to mean the flesh of the fruit is NOT TOXIC.

Or was that a trick?

Kathy said...

No research...avocado flesh is toxic for pet birds for sure...so I'll go out on an avocado limb and say it is toxic for cats and dogs as well.

KGMom said...

Hazarding a guess here--not.
Otherwise, what can you give your dogs with their Doritos--without guacamole?

Mary C said...

Hi Kat Doc - here's hoping the flesh is NOT toxic. I have a couple of cats who have really liked licking avocados. And here in California, avocados are used in our salads frequently.

nina said...

I'll guess toxic--just to be different.
I always think of avocados as somewhat exotic--it seems those types have hidden dangers?

Julie Zickefoose said...

Science Chimp soooo wants to say something, but will keep quiet until tomorrow

eee eee eee...Boo!

KatDoc said...

Finally, after 20-some Tox Tuesdays, I got you all guessing a bit!

This was a trick question, as Anon noted. Kathy is right, that avocados are toxic to birds, but fell for the classic blunder of assuming they would be toxic to dogs and cats, too. I thought more people might go there.

Lisa knows I don't eat anything green, except green M&Ms, so played the "race card." Gotcha sis! And, guess what? I DID eat guacamole, when it was made fresh right before my eyes by the Science Chimp. (Yeah, Zick, I was embarrassed to let you know what a picky eater I really am. I ate fresh tomato salsa, too. Unprecedented!)

Mary C., let your cats be your guides. If they lick the avocados and don't vomit, you're OK. Just don't let them lick the ones in your salad; remember, they licked their butts first!

Donna, if you are worried about guac for your dog's Doritos, try salsa instead. Lower fat content, and Lisa' Rott, Murphy ate a whole jar with no side effects, so it should be safe.

Nina - In rural SW Ohio, avocados are pretty exotic, aren't they? For our Cal. friends, they are probably standard fare.


Julie Zickefoose said...

Oooh, I mean EEEE...I love this post, not just because my psittacine mate is featured. I have a neat story from Costa Rica, where the tropical ecologist Dan Jantzen (sorry if I misspelled his name) has worked for many years. He and his colleagues were speculating wildly about what animals might disperse avocados. The animal in question would ideally devour the fruit whole and pass the pit somewhere else. They speculated that perhaps the avocado was a dinosaur-dispersed species that survived the demise of its disperser! Monkeys tend to eat them right in the tree, and drop the pit beneath the tree--not exactly effective seed dispersal. The flesh is toxic to birds, so parrots are ruled out as possible dispersal agents. And so these tropical Science Chimps set up a motion-sensitive camera in front of an avocado tree. And guess what showed up, eating the fruit whole and walking away, presumably to pass the pits (OW!) later? Jaguars!
Avocado flesh is high in protein, and jaguars love them, and they're the only animals big enough to eat them whole without damaging the seed. So jaguars are the dispersal agent for avocados. Cool, huh?
I would really like to see jaguar scat with avocado pits in it. I would keep in mind that wild avocados have MUCH smaller pits than the ones in the grocery bin. They'd better!

Eee! Eee! OW!

KatDoc said...

WOW! A Toxicology Tuesday first! The Science Chimp gives us a bonus lesson on avocado dispersal. Thanks, Julie - you're the best. That really is cool. And thanks again for sharing the photo of Charlie, doing his Cover Bird pose.

No wonder Mary C's cats love to lick her avocados: they are reverting to their jaguar ancestry. (Careful, Mary; they will drop down out of the jungle some night. l;and on the back of your neck, and all we will hear are the screams .....

Lisa said...

A correction: he ate all of the salsa, but only part of the jar [jk].

Who knew avocados were high in protein?! Another excellent reason for me to eat them!

Kathy said...

So nice to see Charlie's picture and get the story about the seed dispersal. I went out on the limb, and it broke with me. Maybe next week I'll have the right answer!