Subject: Do maggots (larvae of Musca domestica and related species) give of toxins?

During my summers of employment at vet hospitals, I have 
experienced the summer plight of animals everywhere, maggots.  
Many dogs have come into the clinics, live, but infected with 
maggots.  Normally, the dog has some sort of a wound of which a 
fly has taken advantage.  I assume that the maggots are larvae of 
musca domestica or related species (horse fly, etc.).  The dogs 
are always lathargic and very sick.  I wonder why this was and 
the vet told me it was because the maggots release a toxin into 
the animal's blood stream.  However, my parasitology professor  
said he did not know of any toxic substance released by larvae of 
musca domestica.  After all, the infestation of live animals by 
m.d. is accidental parasitism, and the release of a toxic 
substance for the purpose of causeing illnes of an animal would 
be unecessary.  My many text books also did not mention any toxin 
release by m.d.  But it seems something is awry if all the dogs 
with meggot infestations are sick.  So my question is, do these 
maggots release a metabolite that is harmful to animals, and if 
so, what is that chemical and how does is specifically cause the 
animal to become sick?

Re: Do maggots (larvae of Musca domestica and related species) give of toxins?