How do we check the health of our primates?

10 Dec 2018 | Back to News, Publications and Annual Reports

BPRC has an excellent reputation when it comes to knowledge, colony management, and accommodating and looking after its animals. We apply sophisticated methods so as to minimise the discomfort experienced by the animals to the maximum extent possible, and we have a transparent policy with regard to animal welfare. On that basis, we are happy to tell you more about our annual animal health checks, executed under the supervision of our four vets.

Three main duties

One of these vets is Jaco, who has been with us since 2002. Jaco and his colleagues in the veterinary team have three main duties: monitoring animal health, facilitating experiments and providing education. Animal health is monitored primarily by way of the annual health checks (more about that later) and by treating health problems that may occur from time to time.

'We are home to a relatively large group of primates, particularly compared to zoos. The majority, around one thousand, live in breeding groups. Breeding groups allow them to display their natural behaviour. The downside is a number of naturally occurring problems, such as challenges to the hierarchy and diarrhoea. These issues require an adequate response on the part of vets, who always need to make a comparative assessment between the benefits of treating an individual and the impact of such a treatment on the group as a whole.'

The group vs the individual

Jaco is aware that the need for such an assessment may not be immediately obvious to outsiders. 'If you want to treat an individual primate, you always need to take the composition of the group into account. With primates, small cuts heal of their own accord. Under such circumstances, why run the risk of increasing the stress level of the whole group by removing a single individual? Another thing to consider is that primates do not simply come to you for treatment. Whenever we need to make such an assessment, we consult a behavioural expert, who knows exactly what position the primate concerned occupies in the hierarchy. If treatment is necessary, we will obviously provide it; but when you know that a problem will sort itself out and an intervention will mainly cause stress, the best course of action is to do nothing. Moreover, primates generally make a speedy and complete recovery.'

Facilitating experiments and providing education

The members of the veterinary team facilitate experiments by executing the biomedical procedures of primate studies, such as injecting the lungs with infections for the purpose of tuberculosis research and removing biopsies (bits of tissue) for microscopic examination. This responsibility also covers animal welfare activities, such as providing pain relief for arthritis. The vets' main duty of providing education mainly involves organising tours and presentations for students. 'I gave a presentation for PhD candidates of Utrecht University only last week. We usually do so in-house, so they can visit the primates at the same time.'

Annual health checks

Once a year, the vets check the overall health of the breeding colony by administering a check-up to each individual primate. 'We check one complete breeding group at a time. Such a group comprises between 25 and 40 animals. We execute this check once a year at most, unless an animal is selected for an experiment, in which case we execute a more comprehensive health check. After all, studies require the use of previously healthy animals.'

Step 1: Narcosis

Before any biotechnical procedures can be executed, the animals must be anaesthetised. This process must be done when their stomachs are empty. As most procedures are executed in the morning, this fact means that animals receive no food or drink after 17:00 the day before. Jaco: 'This situation does not disrupt their normal routine, as part of which they receive their last meal of the day around 16:00. If they feel hungry afterwards, they can help themselves to whatever might be left. As a result, there is no change to the normal feeding schedule. The one difference is that we empty the feeding troughs completely at 17:00. However, the animals continue to have access only to drinking water.'

The next day, the keepers lead the primates out of the enclosure through the hatches. 'They have been conditioned to walk in a certain direction, so they file out of the enclosure one by one. The next step is to anaesthetise them.'

Step 2: Identification

'As each primate is different, it is important for the vets to know with which individual they are dealing. Our primates have been chipped, similarly to cats and dogs, so they can be identified by scanning the chip with a reader. Special read-outs specify to which procedures each primate is submitted. Once identified, they proceed to the surgery room, where multiple keepers are present at all times. As the law stipulates multiple means of identification, each primate who does not already have one is administered a readily legible chest tattoo (under sedation). We also paint a mark on one of their arms or legs in order to identify them more easily from a distance once they are back in the enclosure, where tattoos can be difficult to spot.'

Step 3: Blood sampling and clinical examination

The vets take blood samples for health checks and genetic research. This clinical examination comprises checks of the animal's weight, body temperature, condition and teeth, an auscultation (i.e. examination with a stethoscope or Pinard horn) of the heart and lungs, a kidney check and a pregnancy check. Jaco: 'We also take hair samples to measure their cortisol values, allowing us to gauge an animal's stress level. Hair samples are a useful way of assessing long-term stress levels. By taking hair samples every year, we can establish a baseline value for each individual primate and take action when they are suffering from chronic stress. We also administer the Mantoux test to check for signs of tuberculosis. This procedure involves a brief prick in the eyelid. We can observe the result from a distance rather than forcing the animal to be put under narcosis again.'

Step 4: Recovery

Making primates wake up from narcosis in their own enclosure is tricky, as Jaco admits. 'Animals that come out of narcosis can behave unpredictably. For instance, some may try to walk even though they are not yet fully awake. You may see them stumble and occasionally fall. It is not a pretty sight. However, in over 16 years as a vet here, I have never seen a single accident: no broken arms or legs, not even a concussion. They suffer nothing more serious than the odd graze. You have to realise that these animals are both wild and social. If you let them wake up separated from each other in small cages, their stress levels go through the roof. The way that we do it causes relatively less stress and allows them to wake up together in familiar surroundings. For us, there is no reason to deviate from this procedure. We deem this method of recovery to be in the best interests of the animals.'

Animal welfare challenges

Nevertheless, Jaco is aware that there are ways to improve animal welfare, not just at BPRC but during biomedical research in general. 'The first thing that comes to mind is a scorecard to assess the level of pain relief which an animal requires. Unlike humans, primates are unable to grade their pain on a scale of 0 to 10. As a result, we can only make an educated guess when it comes to their pain level. It would be great if we had a scorecard that would allow us to gauge when a primate is experiencing pain and the chosen pain relief method is either or not effective. This process is a work in progress. Something similar exists for mice; the position of a mouse's ears and whiskers says something about its emotional state. BPRC is keen on contributing to methods that are currently under development for primates. In addition, we would like to adopt more modern means of narcosis that would allow us to anaesthetise animals more quickly, keep them under for less time and let them wake up more rapidly. We are keeping a close eye on the latest developments and have the aim of contributing to improvements as much as we are able.'