DEHORNING RHINO

The Welfare, Ethics and Behavioral Considerations

 by Karen Trendler

Assessment of the efficacy of dehorning and legal trade in rhino horn

(Diceros  bicornis  and  Ceratotherium  simum ) as  a  deterrent  to  poaching

Endangered Wildlife Trust  EWT Workshop The SA Mint   1-3 March 2011

The ongoing crisis in rhino poaching has opened debates on the:

1. The efficacy of dehorning as a deterrent to poaching
2. The legal trade in rhino horn 

Following the DEA National Rhino Summit in November 2010, the South African government decided to look at the feasibility of legalizing the trade in rhino horn.

This discussion document looks at the ethical considerations around dehorning and proposed legalization of trade in rhino horn.  

The rhino horn issue is a highly complex and controversial one about which not enough is known or understood. More research and a better understanding of the various components and interrelated nature of the issues are needed.

It is critical that decisions are based on well-researched, credible information aimed at reducing poaching and encouraging in-situ rhino conservation.

Misinformation, media hype, well-intentioned but often misdirected anti-poaching campaigns, media reports, corruption, poor law enforcement, economic factors and commercial drives further compound the issues.  

Whilst the workshop focused on the Black rhino (Diceros bicornis) and the White rhino (Ceratotherium simum) poaching, rhino horn and wildlife trade are international concerns with links to organized crime and need to be considered within a global context.  All five species, the single horned Javan and Indian rhino and the double horned Sumatran, Black and White rhino are threatened by demand for rhino horn. Asian rhino are listed as vulnerable to critically endangered and these populations cannot sustain the current poaching pressure. 

Ethics, welfare and behavior

Ethics refers to moral principles of right and wrong, which are guided by societal norms. Ethical decision-making looks at the issue holistically and takes all the factors, implications, and concerned parties into consideration. Simply summarized as Doing the right thing, in the right way, for the right reason.  In order to make ethical decisions we need to be well informed and responsible, and ask the question Does the end justify the means?

Behavior refers to what an animal does and is associated with survival, basic maintenance, reproduction, socialization and how the animal interacts with its environment.

Welfare refers to the health and wellbeing an animal, both physical and mental.  Anything that potentially affects behavior can impact on welfare and consequently on the survival of the individual animal and ultimately on the species.

Structure and composition of Rhino horn

The horn is a tubular, non-bony structure that rests on the nasal and frontal bone protuberances. The horn is composed of modified compressed hair-like fibers containing the protein, keratin. Computerized tomography CT scans reveal that the horn contains a dense inner core of calcium and melanin (similar to horses hooves or birds beaks). Relative proportions and mineral content vary according to region and diet.

The horn grows continuously from a basal growth point at a growth rate of between 5-12 cm per annum, depending on age, sex and health of the rhino. The horn may break, chip, erode and re-grow throughout the natural life of the rhino.

The difference in composition between the inner core and outer sheath, combined with exposure to ultraviolet light, results in differential wear and the tip being worn to a sharp point.

The Dehorning process

The horn is cut off while the rhino is chemically immobilized (anaesthetized). The removal of the horn is a non-invasive, non-surgical procedure, similar to cutting ones hair or nails and should not cause the rhino any pain or injury. Once the antagonist is administered, the rhino can be up and back on its feet within a few minutes.

The risks associated with dehorning include those associated with anesthesia, cutting the horn off too close to growth point and, drugging and handling a very large animal and effects on behaviour. 

There are always risks associated with anesthesia. EtorphineM99, the drug used for immobilizing rhino is procedure is a strictly controlled, high schedule potent opioid. Newer drug combinations and experience have reduced the risks. The current calculated mortality risk for free ranging rhino to  < 1%.  This procedure should only be carried out by a rhino experienced wildlife vet and team using the correct protocols and taking the relevant precautions, should perform the dehorning.  

A Veterinary protocol/ S.O.P  for the dehorning of rhino is currently being compiled by SAVC.

Due to the continual growth of the horn, dehorning may need to be repeated every 18 24 months. Repeated exposure to anaesthesia may contribute to short and long-term health problem; and increases the mortality risk to between 1-2 %. Contradictory opinions were expressed at the workshop. A specialist veterinary aneasthetist confirmed that risks increase with frequency of and repeated exposure to anaesthesia.

Drugging and handling of mega-herbivores carries inherent risks that may include injuries, bruising, overheating, cardiac distress, respiratory depression, increased blood pressure, localized pressure myopathies, miscarriages in pregnant females etc.

The horn should be cut off safely above the germinal growth layer. When the horn is removed too close to the skull, bleeding, injury, maggot infestation, infection, caviations and deformed re-growth can occur. Rhinos have extensive sinus cavities and infection in the sinus cavities following dehorning can have serious and fatal consequences.

Dehorning activities have been linked to green hunting or green darting. This involves payment by a third party (a tourist or paying volunteer) to be involved in or carry out the process. This may increase risks. It should be noted that the South African Veterinary Council SAVC states that green hunting is unethical and no vet may participate in this practice. Department of Environmental Affairs will no longer issue permits for green darting hunting.

The relevant authorizations are required for dehorning and a valid permit is required for possession of horn. The horn once removed must be weighed, measured, micro-chipped permissions and permits must be obtained prior to dehorning and once the horn is and registered with the conservation authorities. 

The impacts of dehorning on behaviour, welfare and survivability need to be considered in evaluating the efficacy and ethical issues around dehorning.

What do rhinos use their horns for ?

Rhino horns play an important role in rhino life history of the rhino and are used for various functions associated with survivalmaintenance, reproduction and social interaction, including:

• Territorial, predator and calf defense
• Dominance and threat displays
• Maintenance behaviors including digging for water, digging soil and mud, foraging, breaking branches, and removing bark.
• Maternal care including breaking branches for calves to eat, moving and guiding calves, and protection

Rhino behavior (territory maintenance and defense, mating, reproduction) involves a combination of factors influenced by size, age, sex, social ranking, and condition and population structure. Vocalizations, olfactory communications, scent marking, horn marking, scraping etc all form part of a range of behaviors thus the impacts of dehorning and horn function need to be evaluated within the complexity of behavior and social dynamics.   

Long-term genetic impacts would also need to be considered.

Does horn removal impact on behaviour?

Dehorning does impact on behaviour but the impact is variabl; and the extent to which this affects welfare and survival of the rhino is not fully understood.

Neutral and negative impacts on behaviour have been reported. The differences in response to dehorning can be correlated to variability in vegetation, visibility, predator type and density, food and territory availability, population stability, area, as well as age, sex and social status.

The negative impacts of dehorning are more severe or problematic in compressed and unstable populations; especially in confined and intensive management situations. There are records of dehorned bulls being injured or killed by horned cows and lesser bulls.  Extensively managed, free-ranging, stable populations displayed minimal or fewer recorded impacts.  

There is insufficient data on the ecological and social impacts of de-horning, and a need for coordinated collection, collation and evaluation of the impacts of dehorning on individual rhino and populations.

Whilst dehorning has proved to be a partial deterrent to poaching, it should not be seen as the only measure and must be utilized as part of comprehensive security management. Dehorning should be combined with other anti- poaching measures (increased security, improved intelligence and collaboration, strategic relocations etc). Dehorning is a crisis measure and should be considered on a case-by-case basis and not as a blanket measure.