Anisocoria

Development of alternating, ipsilateral Horner syndrome and Pourfour du Petit syndrome associated with oesophagostomy tube placement in a cat

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Pourfour du Petit syndrome (PDPS) is a rare disorder that is classically described as reverse Horner syndrome (HS) and results from excessive sympathetic tone to the eye.

In 1727, Francois Pourfours du Petit published the results of his experiments on 3 dogs. The first 2 dogs presented with HS ipsilateral to the lesion of the vagosympathetic nerve trunk after sectioning the intercostal nerve. However, Petit is most famous for his findings observed after sectioning the intercostal nerve on each side of the third dog, which revealed mydriasis rather than miosis. This fact would be later interpreted as irritation or hyperexcitation of the sympathetic nerve chain.

PDPS has rarely been described in the veterinary literature with cases reported in cats with early otitis media. The excessive sympathetic tone to the eye results in pupil dilation, an enlarged palpebral and subtle exophthalmos of the affected side. PDPS can sometime precede HS and be initially confused with internal ophthalmoplegia (parasympathetic denervation).

This report describes a cat where both HS and PDPS occurred ipsilaterally following O-tube placement with spontaneous resolution of all ocular signs after removal of the feeding tube 5 weeks later.