Paraphimosis

Introduction

Paraphimosis is the inability to retract the erect penis back within the prepuce. This usually occurs in dogs following sexual stimulation. The pathogenesis is not understood.

Signalment

The condition is most commonly see in dogs. It may be caused by hair constricting the penis at its base, phimosis - which is a congenital narrowing of the preputial orifice, trauma, a short prepuce, circumferential foreign bodies around the base of the penis, priapism - secondary to neurological abnormalities or inflammation.

Diagnosis

Diagnosis can be made based on the history and clinical exam findings.

Treatment

Paraphimosis should be treated as an emergency requiring prompt treatment. The penis should be cleaned and lubricated and then returned to the prepuce. If the penis is oedematous, hyperosmolar fluid, cold packs or warm packs can be used to reduce the size of the penis before attempting to replace it.

If the condition is caused by phimosis either the prepucial opening should be enlarged surgically or partial penile amputation should be performed. Any hair or foreign object constricting the base of the penis should be removed. The dog may require sedation or general anaesthetic.

If the penis is not immediately replaced it will dry out and become painful - secondary to this self-trauma, ulceration, urethral obstruction, necrosis and gangrene may occur. Should any of these things occur, partial penile amputation may be necessary. The dog should be catheterised if there is any risk of urethral obstruction.

Further treatment is limited but the following have been used in men and horses: Injection of alpha-adrenergic drugs or benztropine, and anticholinergic drugs, into the corpus cavernosum penis to induce detumescence; and the creation of a communication between the corpus cavernosum penis and the glans penis surgically - which can be attempted in breeding animals.

Prognosis

If paraphimosis is recognised early and treatment instigated immediately then prognosis is very good. However the longer the vascular supply to the penis is compromised the worse the prognosis.

References

Gilson, SD (1998) Self-Assessment Colour Review Small Animal Soft Tissue Surgery Manson