AN INVESTIGATION INTO THE HEALTH-STATUS AND DISEASES OF WILD DOGS (LYCAON-PICTUS) IN THE KRUGER-NATIONAL-PARK

Many factors have been cited as possible reasons for the decline in th e number of wild dogs (Lycaon pictus), but few studies hav provided su pportive data. Between 1990 and 1993, the dynamics of 10 wild dog pack s in the souther district of the Kruger National Park in south Africa were monitored. Casual observations of the causes of disease and morta lity in the entire population were also recorded. During the same peri od, 46 wild dogs were immobilised, weighed, and subjected to physical examination as well as the collection of blood and faecal specimens. E xternal parasites were collected and blood smears wer prepared. Serum specimens were subjected to routine blood chemistry analyses, hormone and serological assays and formalised blood specimens and faeces were subected to screening for endoparasites. The study population varied f rom 75 in 1990 to 123 in 1993 with a survival rate of 29,9% for pups, 64,5% for yearlings and 69% for adults. Eighty per cent or more of the population were under 4 years of age. The cause of death in all wild dogs in the Kruger National Park could be established only in a small number of cases. Lions were responsible for the death of 20/62 wild do gs and disease caused the death of 6/62 wild dogs. All immobilised dog s were in a good physical condition, but 83% of dogs had one or more s kin leions. Potential life-threathening lesions (bitewounds inflicted by other dogs and lesions inflicted by a snare) occurred in 4 dogs. On e male dog had only one testicle in the scrotum. Twenty-six (93%) bloo d smears were positive for gametocytes of Hepatozoon sp., presumably H . canis, and in 2 dogs trophozoites of Babesia canis were seen. Eighty -six per cent of the specimens were positive for Dipetalonema recondit um. All dogs were infested with ticks and Haemaphysalis leachi, Amblyo mma hebraeum, A. marmoreum, Boophilus decoloratus, Rhipicephalus simus , R. evertsi, R. appendiculatus and R. zambesiensis were identified. C tenocephalides sp. and Echidnophaga larina were also identified. Taeni a sp., Toxascaris canis and Anclostoma canninum were present in faecal specimens. Antibody titres to adenovirus (26/31), B. canis (6/15), ca nine para-influenza virus (21/31), coronavirus (20/31), coxiella burne tti (8/29), reovirus Type 3 (9/31), Rickettsia conorilafricae (27/29), rotavirus (16/31) and Toxoplasma gondii (16/16) were found. The avera ge serum urea concentration was higher (16,4 mmol/l) than that describ ed for captive wild dogs, but other biochemical parameters were genera lly in agreement with values reported for captive wild dogs. Disease c ould not be incriminated as an important cause of death. Our understan ding of the causes of mortality in free-ranging wild dogs is still inc omplete and continued long-term monitoring of selected packs is essent ial. Disease preventive measures should include preclusion of domestic dogs from wild dog habitats and implementation of vaccination and par asite control programmes in domestic dogs in areas surrounding wild do g sanctuaries.