Rat EAE Scoring

Typically, EAE is scored on scale 0 to 5. Most researchers also give rats "in-between" scores (i.e. 0.5, 1.5, 2.5, 3.5) when the clinical picture lies between two defined scores.

In most cases rats are scored daily, starting 7 days after immunization (Day 7) and continuing until Day 20.

We recommend the following scoring guidelines for rats:

Rat EAE scoring

Score Clinical observations
0.0

No obvious changes in motor function compared to non-immunized rats.

When picked up, the tail has tension and some movement when finger runs along the tail.

0.5

Tip of tail is limp.

When picked up, the tail has tension except for the tip. When walking, the tip of tail is dragged on the cage bottom.

1.0

Limp tail.

When picked up, the whole tail is limp. The walk is not affected.

1.5

Limp tail and hind leg inhibition.

When picked up, the whole tail is limp. Walking is very slightly wobbly.

2.0

Limp tail and weakness of hind legs.

When picked up, legs are held close together. When the rat is observed walking, it has a clearly apparent wobbly walk. One foot may have toes dragging, but the other leg has no apparent inhibitions of movement.

2.5

Limp tail and dragging of hind legs.

Both hind legs have some movement, but both are dragging at the feet (rat trips on hind feet).

  - OR -

No movement in one leg/completely dragging one leg, but movement in the other leg.

3.0

Limp tail and complete paralysis of hind legs (most common).

  - OR -

Limp tail and almost complete paralysis of hind legs. One or both hind legs are able to paddle, but neither hind leg is able to move forward of the hind hip.

  - OR -

Limp tail with paralysis of one front and one hind leg.

3.5

Limp tail and complete paralysis of hind legs.

Rat is moving around the cage, but when placed on its side, is unable to right itself. Hind legs are together on one side of body.

4.0

Limp tail, complete hind leg and partial front leg paralysis.

Rat is minimally moving around the cage but appears alert and feeding.

Often euthanasia is recommended after the rat scores 4.0 for 2 days. However, with daily s.c. fluids some rats can recover. When the rat is euthanized because of severe paralysis, a score of 5.0 is entered for that rat for the rest of the experiment.

4.5

Complete hind and partial front leg paralysis, no movement around the cage. Rat is not alert.

Rat has minimal movement in the front legs. The rat barely responds to contact.

Euthanasia is recommended. When the rat is euthanized because of severe paralysis, a score of 5.0 is entered for that rat for the rest of the experiment.

5.0

Rat is found dead due to paralysis.

  - OR -

Rat is euthanized due to severe paralysis.