Tuesday, February 21, 2012

Ask the Vet: Dogs Who Love Bugs

by Mark Nunez, DVM
© Oblivion9999 via Flickr.com
Facial Swelling
Common in Bug Bites & Ingestion
Dear Dr. Mark: Skipper likes to eat bugs. Are there any bugs Skipper shouldn't be eating? All Summer long I had to watch him because of the bees. Lucky we did not have any bees for snacks. Today Skipper was out chasing a bug and he managed to catch it for his snack. Spiders are another thing he wants to snack on...Help! I don't want Skipper to get sick.

Sharon G.
Hello Sharon,

This is a good question.  Most bugs are not toxic in the sense that they will cause liver and/or kidney damage if ingested, but there are a few notable ones that I will discuss.  The main problem is the same problem that people have, anaphylaxis (allergic reactions) to stinging insects.  

Fortunately, for our canine friends, their immune cells are distributed a little differently as compared to ours and they do not have the issue of their throats swelling shut like we do.  Their faces swell (angioedema), they break out in hives, they get very itchy, and could also have vomiting and diarrhea.  Occasionally, the diarrhea can be very bloody.  The good news is that they usually respond very well to Benadryl and corticosteroids (Prednisone).  Eating caterpillars with spines or non-venomous hairs can cause a localized itchy response due to mechanical irritation and foreign body that can result in hives, drooling, difficulty swallowing and tongue, lip and oral irritation.
The notable mentions that can cause major problems are listed here with images at the links:
  • Monarch butterfly caterpillars.  These guys feed on milkweed which contains cardiac glycosides so they can be toxic to the heart. Some caterpillars have stiff spines or hairs that can do physical trauma and cause oral and GI irritation.
  • The puss or asp caterpillar, flannel moth larvae (Megalopyge opercularis) is considered the most dangerous caterpillar in the US (Primarily SE) although over 40 genera worldwide are reported to cause problems.
  • The slug caterpillar, or saddleback, is in North America and is a stinging caterpillar. They have 2 horns with spines. The hag moth, or monkey slug, also stings and is primarily east coast and SE NA. The gypsy moth (New England) can envonmate (inject poisonous material) as well; lots of others as also.
  • Probably the absolute worst is the Lonomia species (Brazil, etc). It can cause deaths, coagulopathies ,etc. 
It can be very difficult to stop your dog from eating bugs.  Usually a good sting is motivation enough.  Fortunately, most dogs are not allergic and should learn their lesson once they experience the unpleasantness of a sting, or a bad taste as well :-).
© courtesy m.n.
Dr. Nunez

Dr. Nunez is a practicing veterinarian while also assisting patients through The Balanced Canine blog and his own online veterinary pharmacyHave a question for Dr. Mark? Send it to AllThingsDogBlog@gmail.com. You can also follow Mark on Twitter.

Want to read more from Dr. Mark? Try these, or visit his archives:

The Dangers of Animal Bones
Tuberculosis and Dogs
Timing of Feeding
Arthritis Treatment and Prevention

Dr. Nunez's advice does not replace an actual exam with a veterinarian.


Kolchak Puggle said...

Felix is a world-class bug catcher. He sits perfectly still and waits and waits and then...SNAP! Right out of the air he will catch a fly (and then try to open mouth kiss me.) It's gross as woof, but I don't think I could ever stop him. He's too fast!

Rose Montagne said...

Hi thanks for the info! I am just wondering are just the catipillars poisonous in all of these cases or also the moth/ butterflies?? My boy loves to chase and eat moths which are hard to tell apart!!

Anneke Vrieling said...

Hi Rose,if the caterpillar is toxic then the resulting moth/butterfly would be toxic, too. Most are harmless and even actually quite nutritious (rich in protein) so not to worry.
In general, most toxic insects can be recognised by 'warning colours' like red, yellow, black, whereas edible ones would have natural, camouflaged colours and patterns.
Dogs are just domesticated wolves and wolves would eat some invertebrates and plants alongside their main staple of ungulates (elk, deer, etc). So it's quite natural for your dog to eat some insects.

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