Animal models of stroke are procedures undertaken in animals intending to provoke pathophysiological states that are similar to those of human stroke to study basic processes or potential therapeutic interventions in this disease. Aim is the extension of the knowledge on and/or the improvement of medical treatment of human stroke.
Classification by cause
The term stroke subsumes cerebrovascular disorders of different etiologies, featuring diverse pathophysiological processes. Thus, for each stroke etiology one or more animal models have been developed:
Delay: Whereas in animal studies the time of incidence onset is known and therapy can be started early, patients often present with delay and unclear time of symptom onset
“Age and associated illnesses: Most experimental studies are conducted on healthy, young animals under rigorously controlled laboratory conditions. However, the typical stroke patient is elderly with numerous risk factors and complicating diseases ”
Morphological and functional differences between the brain of humans and animals: Although the basic mechanisms of stroke are identical between humans and other mammals, there are differences.
Evaluation of efficacy: In animals, treatment effects are mostly measured as a reduction of lesion volume, whereas in human studies functional evaluation is commonly used. Thus, therapies might reduce the size of the cerebral lesion, but not the functional impairment when tested in patients.
Ethical considerations
Stroke models are carried out on animals which inevitably suffer during the procedure. These encumbrances are e.g. social stress during single or multiple animal caging, transport, animal handling, food deprivation, pain after surgical procedures, neurological disabilities etc. Thus, according to general consensus, these experiments require ethical justification. The following arguments can be produced to give reason for the conduction of animal experiments in stroke research:
Stroke is the leading cause of permanent disability in the developed countries.
Yet there is no effective treatment available for the majority of stroke patients.
Currently there are no in vitro methods that could satisfactorily simulate the complex interplay of vasculature, brain tissue, and blood during stroke, and thus could replace the greater part of animal experiments.
During animal experimentation the following prerequisites have to be fulfilled to maintain the ethical justification :
Reduction: Animal numbers have to be kept as little as possible to draw scientific conclusions.
Refinement: Experiments have to be best planned and to be conducted by trained personnel to minimize the suffering of animals on the one hand and to gain as much knowledge as possible out of the utilized animals.
Replacement: Whenever possible animal experiments have to be replaced by other methods.
