From 2004 until 2016, 21 Père David's deer (Elaphurus davidianus) have died for unknown reason at Zoo Duisburg. These deer, also known as milu, have succumbed from a myopathy that occurred seasonally in autumn and in spring. The clinical signs shown by the animals closely resembles those of a disease called equine atypical myopathy (EAM), which is formerly known in horses. The cause for EAM in Europe was found in the ingestion of hypoglycin A, contained in samaras and seedlings of the sycamore maple tree (Acer pseudoplatanus). To test the hypothesis that the mortality of milus was caused by ingestion of hypoglycin A, 79 sera from all zoos and wildlife parks that have kept milus in Germany and Austria, including 19 diseased and 60 healthy animals, were used. Selected biochemical values and additionally hypoglycin A, methylenecyclopropyl acetic acid-carnitine (MCPA-carnitine), and acylcarnitines, which have been found in horses suffering from EAM, were determined. The results showed greater values of serum activities of creatine kinase (P < 0.001) and aspartate aminotransferase (P < 0.001) in diseased milus comparing to healthy ones confirming a myopathy in affected animals. Moreover, hypoglycin A and MCPA-carnitine were found in the blood of Père David's deer and thus, hypoglycin A intoxication was considered to be a potential cause for the myopathies by ingestion of sycamore maple samaras that were present in the enclosure of the affected animals. Hypoglycin A values were greater in diseased animals (P < 0.01) as well as MCPA-carnitine levels (P < 0.05). Additionally, affected milus showed greater C5-OH-carnitine (P < 0.01) and C6-carnitine (P < 0.001) values. Until now hypoglycin A intoxication was only known in the family of Equidae, in humans, and in laboratory rats, and it has not been previously described in other zoological families. Comparing to horses, ruminants do have a different digestive tract and it will need further investigation to find out if several factors are involved to trigger an outbreak in ruminants.

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The hearing sensitivity of 18 free-ranging and 10 captive harbour seals (Phoca vitulina) to aerial sounds was measured in the presence of typical environmental noise through auditory brainstem response measurements. A focus was put on the comparative hearing sensitivity at low frequencies. Low- and mid-frequency thresholds appeared to be elevated in both captive and free-ranging seals, but this is likely due to masking effects and limitations of the methodology used. The data also showed individual variability in hearing sensitivity with probable age-related hearing loss found in two old harbour seals. These results suggest that the acoustic sensitivity of free-ranging animals was not negatively affected by the soundscape they experienced in the wild.

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