Clinical aspects of voluntary therianthropy. Common risks of shapeshifting.

Biology of magical creatures


Voluntary therianthropy is the ability of a human being to transform into another animal species. Unlike other forms of therianthropy, often associated with infectious diseases (for example lycanthropy), during voluntary transformation the shapeshifter performs directed input of considerable magical energy and undergoes significant anatomical and physiological changes. As such, voluntary therianthropy is also a risky event that may lead to serious injuries, or other unpredictable complications, summarized in this article.


First of all, we should clearly define what therianthropy is and what the difference between voluntary one and other forms is. In a broad sense, this is the ability of human beings to transform into an animal. The most common case is the well-known werewolves, who suffer from an infectious disease called lycanthropy. Werewolves among other similar creatures do not take the animal form or shapeshift on will, which excludes them from the voluntary therianthropes. Some humans also could take an animal form, but by using animal skin or, are transformed into animals by a magician and therefore are also excluded from the present definition. According to it, voluntary therianthropy is the ability of a human being, through the means of magic power to transform himself into an animal, which is not differing from an ordinary specimen of the same species. In simpler words, a shapeshifter must be able to turn himself into a wolf, which even other wolves do not recognize as something different, whenever he wants.

As we will see below, voluntary therianthropy is a difficult task and a rare magical skill. The animagi, for example, are considered so powerful and potentially dangerous, that they should register themselves or otherwise could be subject to punishment [1]. Another type of magical shapeshifters, the beast-masters, are so specialized in therianthropy, that they barely possess any other magical skill [2]. Usually, animagi could take a single animal form, while beast-masters, if very skillful, might be able to transform into three or even more different animals [2]. There are few, indeed, magicians, so powerful to be able to take any animal form on will and even unleash this skill in such an immature occupation as a wizards’ duel [3].

Practical difficulties of shapeshifting

Why is shapeshifting so difficult? A short overview of available evidence of magic leads us to the conclusion that this is a kind of energy, overcoming the laws of thermodynamics and physics in general. With magic you can lift and move objects, you can change shape and you can annihilate or create matter out of apparently nothing. The latter, however, is not true at all, as what you do is transform the atoms and molecules of the air into atoms and molecules of something else. If you want to produce an apple, you can do it by transforming a certain part of the air into a complex structure, made of carbohydrates, proteins, secondary metabolites, etc. It is thermodynamically a nightmare, because what you do is to skip the complex mechanisms of nitrogen fixation, photosynthesis, protein translation and virtually any kind of intracellular process, and it will take an enormous energetic input to get a simple apple. Still, it is not so bad, because you have all the chemical elements of the apple in abundance everywhere around.

How about shapeshifting? It seems easier because the magician just needs to re-arrange all his body, including the skeleton, internal organs, etc. It is less difficult when the new form is also a mammal and of the same size as the human form. Let’s imagine, however, that the magician turns into a mouse. This means that a body of 70-80 kg will transform into a body of less than 50 g (0.05 kg) and an enormous amount of organic matter should disappear somehow. Then, when the magician wants to turn back into his human form, this organic matter should be materialized, which will require a significant input of magical power. Early therianthropes experimented with the condensation of matter, thus enclosing their entire body weight into the body of the animal. This approach, however, proved unsuccessful, as a 45 cm mouse, weighting 80 kg is extremely difficult to maintain as matter and these magicians tended to explode spontaneously. Therefore, it took centuries until the first true animagus invented the amorphous parallel aniplasma. What this does mean is that the magician transforms the excess of organic matter into an amorphous substance, temporally stored in a magic-sustained parallel space and could quickly summon it to retrieve his human form. Similarly, the transformation into a larger animal, also involving a large amount of organic matter in excess requires this matter to be stored in the same form of aniplasma.

Table 1. Comparative figures of various parameters are needed for a single transformation into another animals species. *based on a human, weighting 80 kg; **depends on many variables, including biomass of the aniplasma, anatomical and physiological transformations and phylogenetical proximity. The maximum theoretical value is 1 (human-to-human transformation) and decreases for more complex transformations (0 if transformation is considered impossible).

Another serious inconvenience of the transformation into another biological species is the need for extensive training in controlling the new body. Imagine that you suddenly turn into an owl. Your brain will face the serious challenge to adapt to the different perceptions of light, the inability to handle tools, and most importantly, you will need to learn how to fly. Accordingly, transformation into a wolf will seriously overload your brain with information from different scents, a snake body will pose serious problems in moving and percept thermal information, etc. Therefore, therianthropes need years to adapt to an animal body and this is the main reason the majority of them could transform into a single or few species.

Common medical risks of shapeshifting

Transformation failures

Let us go back to the human-to-mouse transformation to explain this serious complication. During the simultaneous reshaping of the whole body sometimes individual organs or systems may transform in the wrong way. Therefore, if a single bone does not turn into a mouse one, it will lacerate through the body and lead to serious trauma or even death. In the same case, during the opposite transformation, a similar bone transformation failure may result in a limb turned dysfunctional, or other serious complications.

Acquired animalistic features 

In this common complication the animagus, especially if spending large periods in the animal form will accumulate various animalistic features of both anatomical and behavioral character. A typical example, Peter Pettigrew, spent so much time in the form of a rat that his facial appearance and behavior started resembling this creature [1]. In certain cases, this may even reflect the preferred diet and result in raw meat preferences, etc.

Systemic autoimmune responses

Our immune system is finely tuned to recognize external biological material and to not recognize our cells and tissues. In this way, it can effectively discriminate between our cells and infectious agents such as bacteria. During therianthropy, being an acquired skill, small populations of the animal cells may remain non-transformed and trigger an immune response, leading to inflammation and other serious complications. It is why most of the animagi do have symptoms, similar to the autoimmune diseases Lupus erythematosus or arthritis.

Animal-specific diseases

In its animal form, an animagus faces a wide spectrum of parasites and infectious diseases, otherwise not common for humans. For example, the canine distemper, a viral disease caused by Canine morbillivirus may be caught in a wolf form. It normally does not affect humans, but if the animagus is already infected, it may result in different, even life-threatening symptoms in his human form.

The aniplasmic ghosts 

Usually, if an animagus is killed in its animal form, this leads to a release of the aniplasma in what is known as an aniplasmic ghost. Unlike ectoplasmic ghosts, these are amorphous flesh masses, roaming due to residual magic. Their lifespan does not exceed several weeks due to exhaustion of the magical power and the growth of different bacteria.



  1. Joanne K. Rowling. 1997 – 2007. Harry Potter. Bloomsbury Publishing.
  2. Tim Daniels. 1993. The Beast master. 1994. The Three Stones of Destiny. Astrala Publishing.
  3. Wolfgang Reitherman. 1963. The Sword in the Stone. Walt Disney Production.

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