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Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • Biting at the flank, stifle, or chest
  • May be a sign of underlying pathology or behavioral in origin
  • In mild cases, only the hair is bitten; in more severe cases, the skin is torn

Signalment!!navigator!!

  • Almost always a male, usually an intact male
  • The median age of onset is 18 months
  • Arabians and American Saddlebreds are overrepresented

Signs!!navigator!!

  • Biting at the flank or, more rarely, the pectoral area, forelimbs, prepuce, or stifle. The biting may not break the skin, especially if the affected animal is a colt or a gelding, but a stallion may inflict severe injuries to his skin or even underlying tissue
  • Geldings and mares are more apt to rub, roll, and spin than stallions
  • Most horses self-mutilate on both sides, but those that have a side bias turn to the right significantly more often. The horses frequently vocalize and kick out
  • The behavior may occur many times a day or as rarely as monthly. Bouts range from seconds to hours. The median duration is 1–10 min

Causes and Risk Factors!!navigator!!

  • The cause is unknown, but it most often occurs in isolated stallions and sometimes in geldings living in social groups with mares
  • Sometimes aggression is redirected to targets other than the eliciting stimuli. Self-mutilation may be aggressive behavior redirected to the horse itself
  • Horses aroused by the presence of other horses or, in severe cases, by any environmental stimulation may self-mutilate
  • Seasonal changes, excitement, and/or anticipation of food can lead to an increase in frequency

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • It is extremely important to eliminate discomfort as a cause of self-mutilation such as penile, testicular, or urethral lesions, gastrointestinal pain, limb pain, bladder disease, dermatologic problems
  • Any pruritic condition such as external parasites or dermatitis must also be ruled out

CBC/Biochemistry/Urinalysis!!navigator!!

If physical examination warrants.

Other Laboratory Tests!!navigator!!

If physical examination warrants.

Imaging!!navigator!!

Ultrasonography examination of the pelvic area is recommended if the presenting signs and physical examination so warrant.

Other Diagnostic Procedures!!navigator!!

  • A rectal examination and a neurologic examination should be done
  • A skin scraping should be taken

Treatment ⬆ ⬇

TREATMENT

  • Castration of 10 horses was reported as curative in 3, substantially improved in 2, and slightly improved in 2
  • Numerous suggestions have been made, albeit without robust evidence of efficacy:
    • Change in the social environment
    • Allowing a stallion to live with a mare and away from other stallions
    • Donkeys or goats as stall companions
    • Removing mares from a gelding's environment may be helpful
    • Removal of sources of olfactory stimuli such as feces (the stallion's own or another horse's) and skin secretions rubbed onto stall walls have been suggested to help
    • Modifications to the diet and increased exercise can help
    • Blanketing the horse or applying a cradle around the horse's neck can reduce damage to the hair coat and skin but is of questionable ethics. Also, the horse is still able to engage in other behaviors that usually accompany self-mutilation such as vigorous kicking, which can be dangerous to itself and people

Medications ⬆ ⬇

MEDICATIONS

  • An opioid antagonist, nalmefene, has been reported to reduce self-mutilation in a dose-related manner when given IM at doses of 100–800 mg over a 4 day period to an Arabian stallion
  • Amitriptyline, a tricyclic antidepressant, has been used successfully at a dose of 250 mg/day/horse orally to reduce self-mutilation. Its use is contraindicated in patients with cardiac conduction abnormalities, glaucoma, seizures, and urinary and fecal retention problems
  • A wide variety of drugs have been tried therapeutically with mixed results. The sample size of horses treated in reports on the efficacy of medical therapy is small (1–12). Generally, the drugs are used in conjunction with other techniques; if there is a response to drug therapy, it is transitory. Medications reported to have some effect on the behavior are topical applications (antiseptics, shampoos, parasiticides, anti-inflammatory agents, and taste repellents), ulcer medication, antihistamines, steroids, phenylbutazone, flunixin meglumine, synthetic progesterone, acepromazine, and fluphenazine decanoate

Follow-up ⬆ ⬇

FOLLOW-UP

  • Environmental changes should reduce the self-mutilation within 2 weeks
  • Drug therapy may take up to 3 weeks. If there is no improvement in 1 month, another treatment should be tried

Suggested Reading ⬆ ⬇

Dodman NH, Normile JA, Shuster L, Rand W. Equine self-mutilation syndrome (57 cases). J Am Vet Med Assoc 1994;204:1219–1223.

Dodman NH, Shuster L, Patronek GJ, Kinney L. Pharmacologic treatment of equine self-mutilation syndrome. Intern J Appl Res Vet Med 2004;2:90–98.

McDonnell SM. Practical review of self-mutilation in horses. Anim Reprod Sci 2008;107:219–228.

Author(s) ⬆

Author: Katherine Albro Houpt

Consulting Editor: Victoria L. Voith