This should interest people who are into horror movies! The pet is a dog but it could easily have have been a cat.
The picture is published here with the express permission of the Cuyahoga Falls Veterinary Clinic in Cuyahoga Falls. It is published on their Flickr page; a highly instructional photostream if not a bit grizly. I am not sure I could have been a veterinarian despite being concerned about animal welfare and having studied biology at school.
If you’d like to read more about this fly larva and how it enters the the body of cats and dogs and moves around inside coming to rest just under the skin where it makes a breathing hole…click this link, where you’ll see one being pulled out of a cat. This has to done with skill. The vet who took the picture said he gets about two cases a year during the summer.
A “warble” is a small lump in the skin. When I first heard the word I thought it was another word for fly maggot.