The use of remote thermography to assess physical and behavioral aspects of maggot masses present in goat carcasses (Capra hircus aegagrus L.) killed by ivermectin overdose

One factor that has been little explored by researchers and can be very important in the development dynamics of immature muscoid flies, is the maggot mass and their physical parameters during the development of these insects. Studies indicate that the heat produced by the maggot mass is directly correlated to its size and development time, so, study on such behavior can help to achieve a more reliable Post Morten Interval (PMI).

Considering that the development of insects is closely related to biotic (ex: anatomy and physiology of the carcass) and abiotic (ex: temperature and presence of drugs or toxins) factors, these must be taken into account for a more effective expertise. An important aid that thermography provides for forensic studies is the location of the maggot mass, since drugs tend to have a higher concentrations on specifics organs, the distribution of the maggot masses along the carcass, can lead to evaluate the cause of death. In Brazil, is increasing the reports of animal deaths due to intoxication by ivermectin, an antiparasitic drug widely used in both pets and cattle breeding. Thus, the demand for knowledge to solve these cases is also increasing.Four goats was used in the experiment: Two killed by concussion, one exposed in a shady spot (Carcass I) and one exposed to incidence of sunlight (Carcass II); The other two were killed by overdose of ivermectin, one being exposed in a shady spot (Carcass III) and the other exposed to incidence of sunlight (Carcass IV). Thermographic images of the carcasses were made every 12 hours.There was a significant difference in the temperature, size and distribution pattern of the maggot mass between the Cascass III and the others Carcasses. In this Carcass maggot masses had a small size and its colonization was limited to the head until the tenth day of exposure, while others already had a mass in the head and another in the region close to the anus on the second day of exposure. This can be explained by the pharmacodynamics of the drug, which has the largest concentration in the intestine region, thus preventing the development of larvae in this anatomical site. Recent studies showed that light incidence and high temperatures are the main factors involved in the degradation ivermectin, thereby justifying the results found in Carcass IV, resembling carcasses without the presence of the drug. Furthermore, the Carcass III took 6 days longer to complete the decomposition, thus demonstrating the importance of the maggots on the decomposition process and the  influence that this drug has on the development rate of this insects.