Mountain gorilla veterinary care started in the Parc National des Volcans in 1986 (Foster 1993). The main reason for veterinary assistance was to remove snares from gorillas that accidentally got trapped. If not removed, snares often result in the loss of a limb and sometimes death due to infection leading to gangrene.
The Morris Animal Foundation, together with the Office Rwandais du Tourisme et des Parcs Nationaux (ORTPN), established what is now known as the Mountain Gorilla Veterinary Centre. Ten years later, in January 1996, another veterinary unit was set up by Uganda Wildlife Authority (UWA) to provide veterinary care for the mountain gorillas in Uganda, catering to the Bwindi Impenetrable National Park population and the gorillas of the Mgahinga National Park, which are part of the Virunga gorilla population. The UWA veterinary unit has received technical and financial support from International Gorilla Conservation Programme (IGCP) and Dian Fossey Gorilla Fund (DFGF), UK, among others.
Since 1986 veterinary interventions have extended beyond snare removals to dealing with disease outbreaks where there were a few deaths of gorillas. These include a suspected measles outbreak in the Virungas in 1988 (Hastings et al. 1991) and a scabies outbreak in Katendegyere tourist gorilla group in Bwindi Impenetrable National Park in 1996 (Kalema et al. In press). There is speculation that both these disease outbreaks were human related.
Minimising Disease Transmission
Owing to the close genetic relatedness, gorillas can get the same diseases that humans get. Wild gorillas, however, are often naive to human pathogens which can therefore have devastating effects on the gorilla population. To minimise the risk of disease transmission from humans to gorillas health rules for tourists and guides have been developed. The rules include a minimum 5 metre distance when viewing gorillas; burying faeces when defecating in the forest; turning away to cough or sneeze; not allowing sick people to visit the group; not allowing children under 15 years old to visit gorillas as they carry childhood diseases like measles (Macfie 1992). Veterinarians and field staff monitor disease in the population by observation, non-invasive methods like faecal and urine examination, and gorilla necropsies (Sleeman 1998).
Policies for Medical Intervention
The policy from Mountain Gorilla Veterinary Project (MGVP) in the Virunga Mountains is that medical interventions are justified only if the gorilla’s condition is human induced or life threatening. The purpose of these restrictions is to minimise behavioural disturbance and interference with natural selection (Foster 1993, Sleeman 1998). The policy was later updated to allow sampling of one healthy gorilla at a time during a disease outbreak.
The stress induced in an intervention can be quite significant, as it involves immobilising a gorilla, and chasing the group away to treat it. The silverbacks are normally very protective, especially if the victim is an infant or juvenile and will sometimes charge several times. Therefore a cost/benefit analysis is made. The benefits of the procedure to be carried out on the gorilla must outweigh the costs of the great behavioural disturbance during an intervention and the risk of anaesthesia.
Veterinarians in the field face many dilemmas. A frequent example is when two silverbacks fight and one is very severely injured. While the condition can be life threatening, medically treating the injured male would be interfering with the natural process of male-male competition and leadership succession, integral factors of the gorilla’s social system.
There tends to be a lot of political pressure to intervene with wildlife, especially high profile species like the mountain gorilla. In the Mgahinga Nyakagezi gorilla group, in 1998, I received a lot of pressure from the rangers and warden to treat the older silverback, Bujingo, as the younger silverback, and most likely his son, Mark, was trying to take over the group. Bujingo had many fighting wounds and was getting weak so the tourists were upset. I resisted intervening, and a few months later, I visited the group and Mark was now the leader of the group, while old Bujingo trailed at the back. Clearly it was time for another, younger, fitter silverback to take over the group, and not intervening allowed this to happen smoothly. In this case conservation of a species and its natural behavior took priority over the welfare of one individual.
Case Histories of Intervention
In 1998 I had to carry out two medical interventions on mountain gorillas in Uganda, of a very different nature. One was not straightforward while the other one was. I was called to a case of a mountain gorilla that had a rectal prolapse and another one that had a snare.
Rectal prolapse surgery in Bwindi mountain gorillas
On 1st June 1998, I was called to attend to a very sick female juvenile mountain gorilla in Mubare tourist group. The animal, called Kahara, had a rectal prolapse. This is a condition where the rectum comes out of the anus. Frequent causes in people and animals are enteritis, constipation, and tumours, among others. Children born with weak rectums tend to develop prolapses, a condition thought to be congenital ( Cain 1980). This indicates that there could be a weak genetic component.
On Wednesday 3rd June, I did a health check on the gorilla with Dr. Ken Cameron, MGVP vet. Judging from the reports of the ranger guides and trackers the female juvenile gorilla seemed to be improving. I did not want to rush to intervene because we had seen a similar case in October 1997 for the first time and the prolapse cured itself spontaneously without any treatment, much to our surprise.
However the animal’s condition worsened. On Saturday 6th June, during the tourist visit I re-examined Kahara and saw that she walked with very great difficulty and there were very many flies in her night nest from the rotting prolapse. So after the tourist visit I anaesthetised and treated the gorilla, assisted by a team of 2 ranger guides and 4 trackers, some porters, and the warden-in-charge, Chris Oryema. I removed the rotten portion of the rectum which was full of maggots, and put back and stitched the viable portion to the body wall. I also gave antibiotics to treat the severe infection, and anti-parasitics in case the cause of the prolapse was a high parasite burden causing straining. At the time the damage to the rectum was so great that I ended up removing 10 cm of rectum. The prognosis was not bright and I wasn’t sure whether Kahara would survive.
Kahara recovered well from the anaesthetic and was carried to the rest of the group who had already moved a long distance across the river because the operation took 2 hours. She was accepted very well back into the group. The next day when I checked on her she was still weak but looked brighter. I received reports the next few days on her condition and, amazingly, she steadily improved. The next week, Drs. Liz Macfie (IGCP) and Ken Cameron found Kahara playing and eating, which was great news. A few weeks later I went to check on Kahara and she was playing and baby-sitting her younger brother, Rugaba. After some time she went tumbling down the hill towards her mother, showing us just how well she was!
There was a lot of controversy over whether or not I should intervene because rectal prolapses do not appear to be human caused, and we may be interfering with the normal natural selection process and promoting bad genes in an already endangered population. However for various reasons, I decided to treat the animal. These are in no particular order of importance: 1) welfare, 2) to reduce visitor distress, 3) political pressure by the park management, 4) research to find out what caused the prolapse, 5) conservation, since mountain gorillas are so endangered that every breeding female counts. I preserved some of the rectum tissue for genetic analysis to see if there is a genetic predisposition, and the information we shall get from this case will guide us for future rectal prolapse cases in the mountain gorillas.
Kahara, being female is part of the breeding stock of gorillas, and it is important to see if her offspring develop rectal prolapses. Intervening with Kahara could have been a case of individual welfare taking priority over conservation, but only time will tell.
Snare Removal in Mgahinga mountain gorilla
In November 1998 I received word that a mountain gorilla in Mgahinga Nyakagezi tourist group had a wire snare on the hand. Working with the MGVP veterinarians, Drs. Tony Mudakikwa, Ken Cameron and Mike Cranfield, the next day we successfully removed the snare from a three year old infant male gorilla called Majembere. However because the rangers called me out too late, we found that two of the fingers were going to fall off and therefore presumed that the snare had been on for at least one week. We treated the infection successfully and he was returned to the group which had been quite disturbed during this intervention with both silverbacks greatly resisting the treatment team. At the time we felt that though Majembere would lose 2 fingers at least he will not lose his hand or his life from infection. A health check 2 months later revealed that Majembere lost 2 full digits and the top third of another, but otherwise was bright alert and active again.
Conclusion
From these cases, I feel that there is a need to update the present policy for mountain gorilla veterinary interventions. The most important is when there is a disease outbreak that can cause the loss of many gorillas. In order for scientific investigations to be carried out thoroughly, samples have to be taken from sick, dead and healthy animals to establish the cause. Once the cause is established then the disease can be controlled strategically. For example if it is a viral cause then a rise in antibody titer detected by taking two blood samples of healthy and sick animals and comparing the serum from the blood, would confirm the viral diagnosis. However, the present policy only allows sampling of gorillas whose lives are threatened and makes allowances for only one healthy gorilla to be sampled at a time. This limits the potential for diagnosis, making it almost impossible to investigate a disease outbreak and therefore carry out appropriate measures to control it.
As an example, the possible measles outbreak in 1989 was not investigated thoroughly and even up to this date, it is not fully confirmed that it was measles, as the virus was seen in only 1 out of 6 gorillas that died during that time. A small number of carefully timed immobilization for sample collection would have probably yielded more useful data (Hastings et al 1991). Although the gorillas stopped showing signs of respiratory disease after being vaccinated against measles, it is impossible to determine whether this was a result of the vaccine or if they got better naturally (Hastings et al 1991).
In contrast, when two gorillas fight, the condition may be life-threatening, but it is a totally natural part of gorilla life and does not warrant an intervention that would interfere with the important social process of group succession. If a condition is unusual like the rectal prolapse and we are not sure if it is human caused, it may be justified to intervene and find out as a guide for future cases. For example, epidemiologically an animal with a rectal prolapse could be an indicator of something gone wrong in the population like exposure to a human parasite causing unnatural straining leading to a prolapse. We must realise, however, that by intervening, we may be promoting bad genes in an already highly endangered population.
To intervene or not to intervene. Veterinarians in the field faced with a sick gorilla have to make tough decisions as they are often pressurised by both camps. The current policy largely ignores the welfare of individual animals which goes against our training as veterinarians. However as veterinarians involved in wildlife conservation, we have had to learn new principles as it is often the case that conservation ends up being a priority over welfare even in such a highly endangered high profile species like the mountain gorilla. Having a clearer intervention policy will make it easier for veterinarians, wildlife managers, researchers and other people involved in mountain gorilla conservation.
Credit: GLADYS KALEMA, Bvet Med, MRCVS , Veterinary Officer, Uganda Wildlife Authority, P.O. Box 3530, Kampala, Uganda. January 1999.