Evaluation of causes of mortality and morbidity in captive wild animals...

... and proffering system of amelioration in Ibadan, Nigeria

by Adetunji E. Veronica, Department of Veterinary Public Health and Preventive Medicine, Aquatic and Wildlife Medicine Unit, University of Ibadan, Nigeria

in WDA-AME Newsletter 2021, Vol.5, issue 1

The reports of high mortalities in captives and free-living wild animals have become major concerns among conservationists, and zoological facilities are expected to play a major role in conservation (Russel, 2006). According to Fox’s report, necropsies performed in more than 6,000 captive mammals and birds at the Philadelphia Zoo was said to be the first publication on causes of mortalities in zoo animals (Fox, 1923; Aguirre, 2009). Smith, 2009, identified and described 110 diseases of the zoo and exotic animals. Mathision and Huw (1998) observed that mortalities in wild animals could be due to infectious agents like parasitic, bacterial, fungal, viral and rickettsial or non-infectious causes like injuries, poisoning, congenital abnormalities, neoplasm and malnutrition.

Study 1

A retrospective study conducted between 2007 and 2012, on the causes of mortalities in wild animal species kept at University of Ibadan zoological garden, Agodi zoological garden, Ibadan and some wild animals kept in private homes in Ibadan, Oyo State, Nigeria. The study was carried out by collecting data of post mortem examination of wild animals at Mokola Veterinary Hospital, Ibadan and the University of Ibadan Veterinary Teaching Hospital. An overall total of 127 deaths was reported during the study period. Annual increases in mortalities were reported while the majority of the deaths occurred during the rainy season. There was a significant positive correlation between monthly mortalities and average monthly rainfall for Ibadan (r=0.62, P<0.05). The highest mortalities were reported in avians (29.13%), followed by reptiles (27.56%), primates (16.53%), carnivores (13.39%), rodents and ruminants (each with 6.30%) and porcine (0.79%). Causes of mortalities were unknown in more than 17% of the cases. The known major causes include, injuries (23.62%), gastroenteritis/helminthosis (14.96%), invasion by soldier ants (9.45%), transportation stress (8.66%), old age (7.87%), malnutrition (6.30%), paralysis (3.15%), drowning (2.36%) and others (6.32%). It was therefore concluded that to achieve a significant reduction in mortalities of captive wild animals, managers of zoological gardens should adopt proper housing and feeding, routine vaccination, deworming, hygiene and sanitation and seek prompt veterinary attention when animals are sick or they sustained injuries

Study 2

A study of wild animal’s demography in zoological gardens in the southwestern, Nigeria using structured questionnaires and zoo records was conducted. This study reported the avians, reptiles and primates constituted 35%, 26% and 21%, respectively. The study also reported a total of 108 mortalities (annual mean of 36) during a three year period. Causes of mortalities include: transport stress (18%), senility (12%), drowning (10%) and unknown causes (35%). The sex skewed demographic profile showed that there were more male (25%) than female (21%) animals in these zoos. It was advocated that to promote wild animal conservation, routine screening of animals, good nutrition, post-mortem examination of dead animals to ascertain causes of death and also strategies aimed at improving the reproductive capacity of wild animals like artificial insemination should be considered to balance zoo animal demography and reduce mortalities.

Study 3

Studies conducted in 2018, on the use of a drug to manage Capture or exertion myopathy (CM) in two ostriches (Struthio camelus), was evaluated. This work was carried out to restrain and immobilize two ostriches in a bid to facilitate their clinical examination and transportation from one location to another, without subjecting the birds to capture myopathy that arises from the stress and exertion associated with physical restraint and capture. Two ostriches, male and female, weighing 120kg and 105kg respectively, were requested to be immobilized for relocation over a distance of 15 kilometres in Oyo State, Nigeria. The birds have fasted for 16 hours overnight and at the initial stage fed little amounts of feed mixed with diazepam at 3mg/kg which accomplished mild sedation after one hour followed by intramuscular injection of ketamine. There was complete recovery 3 hours post administration of ketamine. We, therefore, conclude that the diazepam and ketamine combination is safe for use in the restraint and transportation of ratites and can also prevent the risk of capture myopathy. We suggest that the current dose of diazepam might be increased if the oral route is to be employed in order to shorten the onset of sedation and increase the depth of sedation.

Study 4

A study was conducted to determine the levels of infestation of gastrointestinal parasites in 36 non-human primates (NHP) and 19 zookeepers at the University of Ibadan Zoological Garden (UIZG) and Agodi Zoological Garden (AZG) in Ibadan, Nigeria. Freshly passed faecal samples were collected from NHP, zookeepers, and apparently healthy individuals (control). The faecal samples were processed using standard parasitological techniques. Twenty-two (61.1%) out of 36 NHP at UIZG and AZG were infested with gastrointestinal parasites. Infestations at UIZG and AZG were 61.3% and 60%, respectively. All the red patas, mangabey and mandrill monkeys and 90.9% (10/11) of the green monkeys were infested. There were higher infestation rates in young NHP than in adults (P<0.05). The infestation rates in males and females were the same (61.1%). The most prevalent gastrointestinal parasites were Trichuris trichiura,(47.2%), Strongyle spp (13.9%), Entamoeba spp (13.9%) and Stronglyloides spp (5.6%). Six (27.3%) of the infested NHP had mixed infestations. Only one of the 19 zookeepers screened was infested with Ascaris lumbricoides and two (15.4%) of the 13 members of the control group (garden workers) were infested with Ancylostoma duodenale. There was no evidence of cross-transmission of gastrointestinal helminths between the NHP and the zookeepers.

System of amelioration of morbidity and mortality in captive wild animals in Ibadan, Nigeria

Proper housing and adequate feed and adoption of effective biosecurity measures are very germane. In addition routine tests, deworming and prompt treatment of injured and sick inmates. Dead animals should be subjected to post-mortem examination to determine the causes of death which will enable the institutionalization of diseases preventive mechanisms. The amendments of relevant local laws in Nigeria to further protect wild animals from overexploitation was recommended. To ameliorate the risk of capture myopathy in ratites oral administration of diazepam accompanied by intramuscular administration of ketamine can provide excellent restraint mechanisms and also reduce injury.