“Tail Necrosis”

Definition

A lesion or annular constriction of the tail resulting from the lack of hydration in the skin of the tail.

Clinical Signs

May see the following:

• A circular ring at the base of the tail if an infant rat, or an oozing sore at the base of the tail in adult rats.
• Swelling, inflammation, or necrosis of the portion of the tail below the annular constriction.
• The partial loss of tail.

Etiology

Tail necrosis, or ringtail as it is more commonly called because of the annular lesions or constrictive rings that are seen, can occur in all ages of rats but primarily occurs in infant or suckling rats.

The condition may first appear with inflammation, edema, and lesions. Necrosis may then develop causing sloughing of the tail distal to the lesion or constriction. If predisposing factors aren’t corrected early on amputation may be required if healing does not occur.

In cases where the condition is mild, and the predisposing factors are corrected, few or no annular constrictions may be seen.

Factors which predispose or contribute to this condition are: a low humidity environment of less that 20%; poor temperature regulation in the vessels of the tails in infant/suckling rats in response to surrounding environmental temperature changes; overly absorbent bedding or litter (e.g., corn cob type litter); blood lab draws from tail veins, or dietary deficiencies of essential fatty acids.

Prevention plays a key role in correcting some of these factors before the condition develops such as: maintaining humidity of 50% in the rat’s environment, using humidifiers not only in the drier parts of the country but in winter months when homes are being heated, paying attention to the type of diet being given, and using recommended litter/bedding such as Aspen, or CareFRESH just to name a couple.

Figures

Case Histories of Ringtail

• Fig. 1: Ringtail in adult rat
• Fig. 2: Ringtail in a baby rat
• Fig. 3: Partial tail loss due to ringtail in two 10-week-old female rats (Story and Nubs)

Diagnostics

Recognition of presenting signs.

Obtain history of husbandry practices, including type of cage, temperature of the environment, type of litter used, type of diet.

Treatment

Correction of predisposing factors:

• Increase humidity in rat room to at least 50% or higher with the aid of a humidifier.
• Change to less absorbent litter. For recommendations and listings see Litter.
• Change to a more nutritious diet. For recommendations and listings see Diet.
  
  *Note: adding unsaturated fats (i.e., 5% corn oil), or essential fatty acids (i.e., omega-3 fatty acids) may be beneficial.¹

Application of topical moisture such as olive oil, or lanolin daily^2,3.

If severe infection or necrosis develops amputation of the area proximal to the constriction may be required. However, in uncomplicated cases and when at all possible, it is preferred to let the tail slough of its own in order to permit the remaining tissue to heal covering the exposed bone.

Nursing Care

• Assess condition of the tail daily.
• Maintain treatment until resolved.
• Maintain clean cage environment. Use bedding and litters as recommended. For more information on types of litter and bedding, see the Care section of the Rat Guide.
• Evaluate and maintain adequate temperature and humidity in rat room.
• Maintain healthy diet to include fresh water daily. Include juicy types of fruits to encourage adequate hydration.
• Seek the attention of a veterinarian if condition becomes worse.

Outcome

• Condition reversed if mild
• Necrosis of tail prevented
• Infection prevented
• Tail healed

Prevention

• Use cages where there are solid bottoms.
• Avoidance of hygroscopic (overly absorbent) litters.
• Addition of a humidifier in dry climates or during winter months when homes are being heated.
• Maintenance of a healthy diet, that includes essential fatty acids for weaned rats and in does that are still suckling young.

References

1. Brown, C., & Donnelly, T. (2012). Rats: integumentary system. In K. Quesenberry, & J. Carpenter, (Eds). Ferrets, rabbits, and rodents: clinical medicine and surgery (3rd ed., p. 362). St. Louis: W.B. Saunders Company
2. Taylor DK, Rogers MM, Hankenson FC. (2006). Lanolin as a treatment option for ringtail in transgenic rats J Am Assoc lab Anim Sci. 2006; 45:83-87. Retrieved April 5, 2012, from http://www.ncbi.nlm.nih.gov/pubmed/16539341
3. Flynn, R.J. (1967). Note on rintail in rats. In: Husbandry of Laboratory Animals (M.L. Conalty, ed.) Academic Press, New York NY 1967; 285-288.