Diagnosis of Drowning and the Value of the Diatom Test in Veterinary Forensic Pathology

Abstract

The detection of diatoms into the organs is considered an important “biological marker” for the diagnosis of drowning in human pathology, but it still has a high possibility for false positive results. The aims of this study were: (1) to evaluate the contribution of pathological examination in drowning cases and (2) to investigate the differences in the number and location of diatoms between animals who died in drowning and non-drowning conditions. For these purposes, 30 dead adult dogs were selected for the study and subdivided into five groups. The group A comprised six cadavers dead for drowning; the group B comprised six control animals; the groups C, D, and E comprised six animals dead for causes other than drowning and subsequently immersed in water for 24, 48, and 72 h, respectively. On each animal, a complete macroscopic and histological examination and diatom test were performed. Diatoms test and quantification were also performed on drowning mediums. Pathological findings of the animals in the group A showed pulmonary congestion, oedema, and hemorrages in the lung. However, similar injuries were also observed in control and experimentally submerged cadavers. In contrast, we observed a statistically differences between drowning animals and all experimentally submerged groups and control animals regarding diatom numbers recovered from organ tissue samples (p < 0.05). Therefore, these findings suggest that the number of diatoms may be used as a valid tool to differentiate animals who died in drowning and non-drowning conditions, even if the latter were found in an aquatic environment.

Challenges in the Assessment of Bycatch: Postmortem Findings in Harbor Porpoises (Phocoena phocoena) Retrieved From Gillnets

“…48 A study on drowned and nondrowned dogs concluded that pulmonary congestion, edema, and hemorrhages in the lung were present in both groups and therefore was deemed an unreliable indicator of drowning. 50 In addition, changes in reticulum fiber structures in lung tissues as a histological criteria for death by drowning 28,53 could not be confirmed in later investigations, 15 nor in this study. Hyphema in cetaceans was significantly related to drowning by others 1,13 and was observed in 5 of the 11 confirmed bycatch cases.…”

“… 38 In our study, no sign of foreign material was observed in histological sections of lung, although no further attempt was made to specifically assess the presence of diatoms. This method has proven to be informative on the diagnosis of drowning in dogs 50 and terrestrial wildlife, 10 but less useful in animals that live in the marine environment and have fish in their diet, like otters, 10 cetaceans, and sea turtles. 55 Its applicability for marine species therefore requires further investigation.…”

Use of the international classification of diseases (ICD)-11 method applied to veterinary forensic pathology for coding the cause and manner of death in wildlife

“…In the case of a fox, a coypu and a mink, the samples of the drowning medium confirmed the presence of the same populations of diatoms found in the organs examined. As demonstrated by Piegari et al the number and presence of diatoms in certain districts, such as the sternal medulla, can be considered as a valid tool in the definition of death by drowning ( 26 ). To confirm the diagnosis, the diatom test was applied to target tissues of a coypu and a mink, dead from causes other than drowning, with negative results (absence of diatoms).…”

Characterization of Suspected Crimes against Companion Animals in Portugal

“…The frequency of animal drowning is unknown, and the literature addressing this topic is sparse [ 40 , 41 ]. A drowning diagnosis in animals is even more complex than in humans due to the different anatomophysiological respiratory system specificities of the species, and it remains a challenge both for human and veterinary forensics [ 42 ]. There are no pathognomonic drowning necropsy findings; therefore, drowning remains an exclusion diagnosis based on the circumstances of death and nonspecific findings of the necropsy [ 43 ].…”

“…There are no pathognomonic drowning necropsy findings; therefore, drowning remains an exclusion diagnosis based on the circumstances of death and nonspecific findings of the necropsy [ 43 ]. As in humans, in suspected cases, the presence of diatoms can be investigated [ 42 ], although this was not found necessary in the only case present in this study.…”