Ulcerative Dermatitis

Objective Measurement Within the LAR Vivarium

Last Review Date: June 6, 2018

I.  Purpose/Scope

The purpose of this Standard Operating Procedure (SOP) is to outline the procedure to objectively score Ulcerative Dermatitis (UD) within the mouse colonies of the LAR Vivarium.

II.  Policy

It is LAR policy to meet or exceed all federal, state and local regulations and guidelines and to comply with all institutional policies and procedures as they apply to the use of animals in research. Personnel must attend any applicable training in animal care and use, occupational health and safety, equipment operation and SOP’s prior to performing activities outlined in this SOP or work under the direct supervision of trained LAR personnel.

III.  UD Scoring System

The UD scoring system provides an objective measure with which to determine if a mouse is unresponsive to therapeutic treatments by using parameters that increase with disease severity. This scoring system is easy to perform and interpret and provides an objective measure with which to make decisions regarding euthanasia and affected mice that are refractory to therapeutic treatment.

The UD scoring system is based on a 0 to 100 scale, with 100 being the most severe score. A threshold score of 75 should initiate contact between the LAR staff member and the Attending Veterinarian and Investigator of Record (IR) for a recommendation to euthanize the affected mouse. 

A.  Scratching Number

The affected mouse is observed for 2 minutes. Each time a paw is raised to scratch itself it is counted.

Scratching Number


B.  Characterization of the Lesion (COL)

      Describing the appearance of the lesion and its associated score value.





No lesion present 

Excoriations only or one,

    small punctate crust (< 2 mm)

Multiple, small punctate crusts

    or coalescing crusts (>2mm)

Erosion or ulceration





C.  Length of Lesion (LOL)

     Length of the lesion is determined by measuring the longest diameter of the largest lesion identified. This measurement should involve the lesion only and not cross over clinically normal skin.


LOL                                 Score

0 cm                                 0

<1 cm                               1

1 cm - 2 cm                     2

>2 cm                              3


D.  Region Affected (RA)

     This is a description of the area on the body that is affected. See Figure 1. 


Regions Affected                    Score

None                                            0

Region 2 or 3                               1

Region 2 and 3                           2

Region 1 +/- other affected
    regions                                    3



Figure 1. Regions Affected on the Mouse

mouse regions

Region 1:  The head cranial to the point of ear

                  attachment and/or lesions affecting the
                   mandible cranial to the sternum

Region 2:  Inner and outer ear, dorsal cervical region
                  audal to the ear attachment, dorsal and
                  ventral thorax, and thoracic limbs

Region 3:  Any region caudal to the ribcage


Once all of the above values are scored the formula to calculate the Severity Score Formula is as follows:  (A + B + C + D)/ 12] x 100

IV.  Severity Score Assigned to the Affected Animal

Once a Severity Score is calculated for the affected animal the score is recorded in the Animal Health Records for future reference. If or when the Severity Score reaches the threshold score of 75 the Attending Veterinarian and the Investigator of Record are alerted and the recommendation of euthanasia will be made.

V.  Reference

Hampton AL, Hish GA, Aslam MN, Rothman ED, Gergin, IL, Patterson, KA, Naik M, Paruchuri T, Varani J, Rush HG. 2012. Progression of Ulcerative Dermatitis Lesions in C57BL/6Crl Mice and the Development of a Scoring System for Dermatitis Lesions. Journal of American Association of Laboratory Animal Science 51(5); 586-593.