Convulsions and seizures
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Source |
Non-harmful / below threshold / severity degree 0 | Mild / severity degree 1 | Moderate / severity degree 2 | Severe / severity degree 3 |
| Home Office (2014 a) |
. | Focal periodic seizures, or generalised seizures where the animal becomes rapidly unconscious and then does not recover consciousness at any point before death may be considered moderate or even mild. | Longer generalised seizures (in excess of one hour) with recovery will generally be considered severe. | |
| Home Office (2014 a) | Short-term periodic generalised seizures may be considered moderate if animals recover with post-ictal signs being only minor and short-lived and appear normal between episodes. | |||
| Federal Food Safety and Veterinary Office FSVO (2018) |
Convulsion experiments which lead to immediate loss of consciousness (complete convulsion), if the animals do not regain consciousness or are euthanased beforehand Examples: Maximum electroshock. |
Convulsion experiments which do not lead to immediate loss of consciousness, if the animals do not regain consciousness or are euthanased beforehand. Examples: Petit-mal model. |
Convulsion experiments which do not lead to complete loss of consciousness (incomplete convulsions), or if the animals regain consciousness after the cessation of the convulsions. Examples: Administration of spasmogenic doses of PTZ, NMDA, picrotoxin, yohimbine, strychnine or kainate. |
Paralysis
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Source |
Non-harmful / below threshold / severity degree 0 | Mild / severity degree 1 | Moderate / severity degree 2 | Severe / severity degree 3 |
| Home Office (2014 a) |
Paralysis may be considered of moderate severity including the following scenarios. Partial paralysis not preventing movement around the enclosure or other normal activities and where animal has the ability to feed itself when food is given from food hoppers or by other normal presentation. Very short-term (less than 24 hours) total paralysis of hindlimbs only in small rodents, and animals still able to move around the cage. | Paralysis is generally considered severe. Paralysis or hemiparesis in larger species, where the impact is likely to be significantly higher for the individual, would generally be classed as severe. | ||
| Home Office (2014 a) | Conditions leading to limb paralysis (of more than one day duration in rats and mice), or any quadriplegia/paresis for any period and paralysis of any duration when coupled with signs such as marked weight loss or changes in behaviour such as aggression to cage/pen mates is likely to be severe. |
CNS lesions
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Source |
Non-harmful / below threshold / severity degree 0 | Mild / severity degree 1 | Moderate / severity degree 2 | Severe / severity degree 3 |
| Federal Food Safety and Veterinary Office FSVO (2018) |
Suppression of defined nuclei or pathways under anaesthesia, without modification of the animals’ general condition (including feeding/sleeping/social interactions/anxiety). Examples: Genetically-modified animal models of CNS disorders. |
Suppression of defined nuclei or pathways under anaesthesia, with moderate modification of the animals’ general condition (including feeding/sleeping/social interactions/anxiety). Examples: Unilateral 6-OHDA model of Parkinson’s disease (Ungerstedt model). Reversible suppression of brain regions by hypothermia. Viral models of genetic disorders. Lesions of the corticofrontal lobe. Suppression of an efferent motor pathway. Viral models of genetic disorders. Genetically-modified animal models of CNS disorders. Electrically or chemically induced CNS lesions. |
Suppression of defined nuclei or pathways under anaesthesia with impairment of the animals’ general condition (including feeding/sleeping/social interactions/anxiety). Examples: Models with ablation of relatively large areas of the cerebral cortex. |
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| Working Group of Berlin Animal Welfare Officers (2010) |
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Implantation of indwelling catheters in cerebral ventricles or of electrodes in the cerebric, without restrictions on motion. Hypophysectomy with hormone substitution. |
Trauma studies. Models that cause severe, clinically manifest endocrine disorders, e.g. hypophysectomy without hormone substitution. |
Ischaemias
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Source |
Non-harmful / below threshold / severity degree 0 | Mild / severity degree 1 | Moderate / severity degree 2 | Severe / severity degree 3 |
| Federal Food Safety and Veterinary Office FSVO (2018) |
Production of micro-infarcts by established methods, if leading exclusively to short- lasting functional disturbances. Examples: Injection of radiolabelled microspheres (micro-embolism or multi-infarct model). Rose Bengal model with activation by irradiation. |
Production of ischaemias under anaesthesia by established methods, if the animals show no marked functional disturbances after regaining consciousness. Examples: Levin model in the rat. Bilateral carotid ligature in the rat for 30 minutes. Pusinelli model for ≤20 minutes. Short-term normobaric hypoxia in mice. Bilateral carotid ligature in the gerbil for 5 to 30 minutes (depending on the strain). |
Production of ischaemias under anaesthesia, if the animals show considerable functional disturbances after regaining consciousness. Examples: Occlusion of the A. cerebri media in the rat and mouse (MCAO). Permanent unilateral carotid ligature in the gerbil. All models of cerebral ischaemia with ischaemic episodes lasting >15 minutes (unless specially mentioned beforehand). |
Visual system
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Source |
Non-harmful / below threshold / severity degree 0 | Mild / severity degree 1 | Moderate / severity degree 2 | Severe / severity degree 3 |
| Federal Food Safety and Veterinary Office FSVO (2018) |
Electroretinography (ERG) using a circular or filament electrode apposed on the cornea surface of anaesthetised animals. Pupillary light reflex measurement in anaesthetised animals. Imaging (non-invasive fundus visualisation using a scanning laser ophthalmoscope (SLO), retinal camera or optical coherence tomography (OCT)) in anaesthetised animals. Intraocular injection (subretinal or intravitreous) in anaesthetised animals. Laser-induced neovascularisation model. |
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