IACUC Policy 012: Murine Ulcerative Dermatitis (MUD)

1. Purpose: Some laboratory mouse strains [e.g., C57BL/6(B6)], are predisposed to developing severe ulcerative dermatitis.  This has been well documented in the literature and is currently considered idiopathic in some strains.  This condition can progress quickly and cause lesions over large parts of the body.  Areas primarily affected are the neck, head and axillary regions of the limbs.  This condition does not typically respond well to treatment and can become debilitating, if not addressed.

2. Policy:

2.1 Laboratory Animal Resources (LAR) staff or any other caretakers that detect the beginning stages of ulcerative dermatitis are required to document the presence of the condition on the cage card, and to alert the protocol Primary Investigator (PI) of the malady.  The PI is responsible for assuring that the following policy is adhered to, including any necessary treatments.

2.2 Early Treatment Murine Ulcerative Dermatitis: 

2.3 Upon diagnosis, all mice exhibiting early symptoms of ulcerative dermatitis must be placed on a treatment program immediately (and the treatment recorded on the cage card) and the Attending Veterinarian must be notified.  Alternatively, project PI may elect to euthanize the mouse at this time.

2.4 In mice that exhibit patches of ulcerative dermatitis with total area on the body less than the area of a 10 mm circle must: Have their rear toenails trimmed immediately and at least every 10 days thereafter.

2.5 Mandatory Euthanasia:

As the ulcerative dermatitis progresses mice must be euthanized if any of the following apply:

1.  There is a single ulcerative lesion greater than 10 mm in diameter, or

2.  There are multiple ulcerative lesions that total 10 mm in diameter, or

3.  There are any ulcerative lesions exhibited with additional signs of morbidity.

4. The lesions are not resolving within 14 days of starting treatment.