Unlike conventionally farmed animals, deer have not been (extensively) selectively bred for domesticity, with the exception of some populations of reindeer. Within the Arctic Circle, some groups of reindeer have been domesticated for 2000 years or more. Deer entered intensive farming systems relatively late and after the development of handling facilities for the safety of the animals and their human handlers. This lack of selection means that even managed farm deer are more akin to their wild compatriots than they are to other farmed livestock. This behavioural proximity to wild deer dictates that handling must be carefully planned. Deer across the world are prey species, whose evolution has led them to be flight animals. For deer, catching is much the same as predation, meaning they will act accordingly by attempting to escape and live for another day.

No matter the urgency required for deer capture, considerable planning and expertise are required to maximise the likelihood of a successful outcome, irrespective of the capture methodology. The knowledge, equipment and patience required should not be underestimated. Whilst plans frequently change, the initial planning phases are paramount for minimising risk to handlers and the deer.

Capture myopathy is a well-documented condition that can affect a wide variety of animals. In deer, it is a recognised potential complication of any iatrogenic stressful events, including anaesthesia, capture and/or translocations (Paterson 2014). Capture myopathy was reported in the initial formation of deer farms in New Zealand, where wild deer were either darted, netted or rounded up into pens, with significant numbers of the original stock within deer farms being affected (Pollard and Wilson 2002). Capture myopathy is commonly associated with rhabdomyolysis, although the exact aetiology is not fully understood.

Capture myopathy may occur within 24–48 hours of the original initiating cause; however, it can be weeks after the event that clinical signs may be manifest. The presentation often includes recumbency with an inability to stand due to paresis or full paralysis. This may be generalised or localised to a single limb. Muscular pain may be associated with recumbency, death can occur relatively swiftly.

Non-natural stressful events are most commonly the initiating trigger for capture myopathy. Species more prone to responding stressfully to situations (e.g. roe deer) are more predisposed (Montané et al. 2002). Attention should be placed on minimising stress to reduce the risk of myopathy developing. Even so, relatively low-stress events may still lead to myopathies. Predisposing factors may include age, gender, concurrent disease and nutritional status (particularly Vitamin E/selenium) however, no firm linking factors have been identified (Krauer 2024).

Different forms of capture myopathy have been recorded, including capture–shock syndrome, ataxic myoglobinuric syndrome, ruptured muscle syndrome and delayed peracute syndrome (Paterson 2014). These are generally approached in a similar manner by most clinicians when dealing with wild or park deer. Analysing muscle enzymes, including creatine kinase, aspartate aminotransferase and lactate dehydrogenase, may aid the diagnosis (Montané et al. 2002), although no link has been established between any biochemical markers at the time of capture and the risk of development of myopathy.

Once manifest, treatment should focus on analgesia and supportive therapies, which is most feasible in a zoological collection setting (trying to avoid further stress to the deer). The prognosis is generally poor and few recover; euthanasia on welfare grounds may be the most practical outcome.

The prevention of capture myopathy centres on minimising the stress of animals being handled, reduction in anaesthetic times, minimising anaesthetic hypoxia, using anxiolytic agents in protocols and reducing exertional activities.

The legal status of deer is covered in other chapters in this book. Free-roaming deer within deer parks are considered ‘wild deer’ under UK law. Deer within parks are covered by the Deer Act (1991), Section 4, which details the prohibition of the use of traps, nets and darts when taking deer alive. These activities must be licensed by Natural England (NE) or Natural Resources Wales for England and Wales; no license is required in Scotland. General licenses can be sought for the catching of park deer; however, usually, individual operations are licensed through the submission of an A32 licensing form. Under the Deer Act (1991) licensing, wild deer may only be caught for translocation, scientific research or other purposes deemed appropriate by the licensing body.

Muntjac in the United Kingdom are identified as an invasive species in The Invasive Alien Species (Enforcement and Permitting) Order (2019) and this prohibits their release into the wild. Historically, rehabilitation licences for release could be sought from NE; however, at the time of writing (January 2025), such licences are not available. Muntjac may be released into enclosures, constructed with specifications outlined by NE (Natural England 2020). Hence, indiscriminate catching operations (e.g. wild netting) should consider the possibility of catching muntjac and other prohibited species and plan for such circumstances accordingly.

The possession and use of devices for remote chemical injection are controlled under the Firearms Act (1968). This states that ‘any weapon of whatever description designed or adapted for the discharge of any noxious liquid, gas or other thing’ is a restricted firearm and is only legally able to be possessed under a firearms licence. This applies to dart rifles and pistols, any blow-pipe (purpose-built or home-fashioned) and any other equipment for the delivery of darts, as well as the darts themselves. All darting equipment falls under Section 5 of the Act; the most restricted class of firearm and the most registered firearm dealers (RFD) are not permitted to hold, handle or sell such equipment.

Under UK law, the administration of an intramuscular injection to a farmed animal is permitted by exemption under Schedule 3 of the Veterinary Surgeons Act (VSA 1966). Since park deer are classed as wild deer and not farmed deer, performing an intramuscular injection on these animals is, therefore, an act of veterinary surgery with no exemption granted under the VSA. Consequently, the darting of any deer outside of a farm must be performed by a veterinarian registered with the Royal College of Veterinary Surgeons (Boyes et al. 2021).

Irrespective of species or origin (farm, park or wild), deer are considered to be food-producing animals. Consequently, only medicines with an established maximum residue level are permitted for use in deer species. These medicines are outlined in the European Union (EU) regulation 2010/37 (EU Regulation 2010/37). Since all medicines used in deer fall under the cascade, suitable meat withdrawal limits should be applied. All treated deer should be identified (such as by an ear tag) for recording medicine administration and to observe withdrawal periods.