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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A 48-yr-old captive white rhinoceros ( Ceratotherium simum ) was euthanized due to old age, pododermatitis, and progressive laminitis of the middle toe of the left fore- and hindlimbs. Severe chronic necrotizing periodontitis and dental loss was diagnosed, although food intake prior to death had not decreased. In addition, extensive ulceration of the tongue was noted. Histologically, squamous cell carcinoma of the tongue was diagnosed with chronic severe ulcerative glossitis. Metastatic lesions were not detected. Clinicians should monitor the oral health of aging rhinoceros due to the occult nature of these lesions.

Providing for infants nutritionally via lactation is one of the hallmarks of mammalian reproduction, and infants without motivated mothers providing for them are unlikely to survive. Mothers must maintain regular contact with infants both spatially and temporally while utilising their environment to forage, avoid threats and find shelter. However, mothers can only do this and maximise their reproductive success with some degree of cooperation from infants, despite their developing physical and cognitive capabilities. The neuropeptide hormone oxytocin (OT) triggers proximity-seeking behaviour and acts in a positive feedback loop across mother-infant bonds, stimulating appropriate pro-social behaviour across the pair. However, data on infant OT levels is lacking, and it is unclear how important infants are in maintaining mother-infant associations. The bottlenose dolphin (Tursiops truncatus) is a mammalian species that is fully physically mobile at birth and has multi-year, but individually variable, lactation periods. We investigated OT concentrations in mother-infant pairs of wild individuals compared to other age and reproductive classes. An ELISA to detect OT in dolphin plasma was successfully validated with extracted plasma. We highlight a statistical method for testing for parallelism that could be applied to other ELISA validation studies. OT concentrations were consistently elevated in calves up to at least 4 years of age with lactating mothers (12.1 ±0.9 pg/ml), while all mothers (4.5 ±0.4 pg/ml) had OT concentrations comparable to non-lactating individuals (5.9 ±0.5 pg/ml). Concentrations within infants were individually variable, and may reflect the strength of the bond with their mother. The OT system likely provides a physiological mechanism for motivating infants to perform behaviours that prevent long-term separation from their mothers during this crucial time in their life history. Elevated infant OT has also been linked to energetic and developmental advantages which may lead to greater survival rates. 3 Environmental or anthropogenic disturbances to OT release can occur during bond formation or can disrupt the communication methods used to reinforce these bonds via OT elevation. Variation in OT expression in infants, and its behavioural and physiological consequences, may explain differences in reproductive success despite appropriate maternal behaviour expression.

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