Many species kept in zoological collections live longer than they would naturally in the wild.4 These older animals can be described as being elderly, ageing or geriatric and will present with a variety of clinical conditions which require treatment and management.1-3 Clinical conditions such as osteoarthritis, spondylitis and dental disease are painful and debilitating, which may not become apparent to keepers/caregivers until significantly progressed. This presentation will outline the model of a proactive ageing zoo animal care programme that can be applied across all taxa.
The programme was designed to include monitoring of both behaviour and clinical health. Animals were classified as ‘ageing’ by being 75% through their natural longevity. Longevity data from the wild was used, but where this information was not available, data pertaining to the longevity in captivity was used. Once identified, the individual’s behavioural, reproductive and clinical histories were reviewed. Two methods of assessment were used: ‘hands off’ and ‘hands on’ methods to create a database of information to feed into an overall welfare assessment. Initially, animal’s behaviour was discussed with the keepers and any specific health concerns identified (e.g., stiff movement, poor appetite). Training needs were identified (e.g., crate training, weigh scales training, injection training) and plans put in place.
Methods of ‘hands off’ included behavioural observations; the use of positive reinforcement training; collection of biological samples; weight and body condition scoring; and thermal imaging. Behavioural observations included keeper daily records and veterinary observations. Basic behavioural ethograms were used to assess various aspects including social interactions, enclosure use, gait analysis and response to medication. These ethograms were repeated after periods of time to monitor change or following a course of medication. Video footage was also used especially for gait analysis and nighttime data. Goals of training included the ability to weigh individuals, closely inspect or examine the animal and the collection of biological samples (e.g., blood, urine). Training was also used to ensure individual dosing of medications. Diagnostic tests were performed through training and clinical follow-up achieved through training in some individuals. Visual body condition scoring was used in conjunction with body weights to monitor health. Thermal imaging was a useful tool for identifying areas of inflammation, monitoring progress of conditions and response to treatment.
A ‘hands on’ health assessment included a weight and body condition score; clinical examination including detailed dental examination; collection of biological samples (e.g., blood, urine, faeces); diagnostic tests (e.g., radiography, ultrasonography); and treatment as appropriate (e.g., dental extractions).
Following health assessments, the clinical findings and results of tests were discussed with the appropriate animal managers and treatment options outlined and implemented. This information was fed into an overall welfare assessment which was carried out in conjunction with veterinary and animal staff. At this point, timelines for clinical followup were agreed upon, and criteria for euthanasia were developed in some cases. Training needs were also discussed, as were any enclosure modifications or dietary alterations which could be beneficial for the animal. Animals were not isolated for treatment and always managed within their social groups.
Creation of clear, written criteria for euthanasia was carried out in certain cases where appropriate. The euthanasia procedure was discussed in detail with regard to the wellbeing of the animal, management of the other animals and also the keepers. The practicality of the postmortem procedure was included in the planning. A thorough postmortem examination including detailed histopathological assessment of tissue samples allowed identification of the cause of clinical findings and the presence of subclinical diseases.
The majority of individuals assessed were mammals, but reptiles and birds were also included in the programme. As an example, over a 12-month period, 47 ageing primates and apes and 19 non-primate mammals were assessed. Forty-two percent of each category were found to have clinical conditions which had not been previously diagnosed and required treatment/management.
Zoo animals can be challenging from a clinical perspective, as they often hide symptoms of disease until the disease process has progressed significantly. This model of ageing animal care proved that clinical conditions were found following proactive health assessment which had not been apparent to keepers prior to the examination. Examples included osteoarthritis, spondylosis and dental disease. Treatment and management of these conditions led to improvement in individual welfare and cases were followed up appropriately to ensure ongoing monitoring. Welfare was improved as painful conditions, such as dental disease and osteoarthritis, were diagnosed, treated and managed appropriately. Keepers reported improved activity, demeanour and appetite in many such cases. The use of positive reinforcement training was a key element to the programme. Keeper attitudes changed over time to embrace the programme. Initially sceptical, the team became supportive after seeing the benefits to the animals under their care. Involving the keepers in health assessments, decision making around euthanasia and postmortem examinations also improved teamwork and understanding. Overall, this approach led to the implementation of a positive and proactive programme for assessing the welfare of ageing animals on a regular basis.
The authors would like to thank the keepers involved for their commitment to management, treatment and training of the aging animals under their care.
1. Baine K. Management of the geriatric psittacine patient. Journal of Exotic Pet Medicine. 2012;21:140–148.
2. Longley L. A review of ageing studies in captive felids. International Zoo Yearbook. 2011;45:91–98.
3. Paré JA, Lentini AM. Reptile geriatrics. Veterinary Clinics of North America: Exotic Animal Practice. 2010;13:15–25.
4. Tidière M, Gaillard JM, Berger V, Müller DW, Lackey LB, Gimene O, Clauss M, Lemaître JF. Comparative analyses of longevity and senescence reveal variable survival benefits of living in zoos across mammals. Scientific Reports. 2016;6.