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564 Iron Toxicosis

to insert on adjacent iris, lens, or cornea. • Synechiae: anterior forms typically arise from PROGNOSIS & OUTCOME
When they insert on the lens or cornea, base of iris or pupillary margin; posterior: • Prognosis for anterior uveitis depends on
VetBooks.ir PPMs are a developmental defect that terior aspect of iris; often result in dyscoria severity at presentation, individual variation
opacification of these structures may occur.
forms arise from pupillary margin or pos-
(abnormal pupil shape)
in severity and frequency of recurrences,
may have a heritable component in some
underlying cause, and client compliance.
breeds.
Initial Database • Primary intraocular neoplasia usually carries
DIAGNOSIS • Complete ophthalmic exam (p. 1137) a poor prognosis for saving the eye but good
• Variable depending on underlying condition. prognosis for systemic health.
Diagnostic Overview • Ocular melanosis has a varied rate of progres-
The diagnosis is generally suspected because of Advanced or Confirmatory Testing sion and usually carries a poor prognosis
the chief complaint or emerges as an incidental • Varies, depending on underlying condition. for saving the eye if secondary glaucoma
finding on ophthalmic exam. Characterization • Ocular ultrasound (differentiates uveal develops.
of an iris problem is based on a careful exam neoplasm from cyst) • Uveal cysts and PPMs rarely cause problems
of the anterior chamber and iris surface with with vision or ocular comfort.
magnifying head loupes and diffuse and focal TREATMENT
light sources. PEARLS & CONSIDERATIONS
Treatment Overview
Differential Diagnosis Treatment of iris abnormalities varies widely, but Comments
Discoloration of iris: fortunately, diagnosis and subsequent treatment • Most iridal abnormalities can be readily
• Increased pigmentation decisions are usually straightforward based on diagnosed on the basis of clinical signs.
○ Uveal melanoma: variable appearance in clinical signs. • Anterior uveitis requires immediate thera-
dogs (focal) vs. cats (mainly diffuse); solid peutic intervention.
tissue; may cause dyscoria (misshapen/ Acute General Treatment
distorted pupil) and/or anisocoria (unequal • Directed at underlying condition, when Prevention
or asymmetrical pupils) possible Avoid breeding affected or closely related dogs
○ Ocular melanosis of cairn terriers • PPMs do not generally require treatment predisposed to breed-related iris abnormalities.
○ Uveal cyst: round to ovoid, single or unless there is substantial corneal and/or lens
multiple, often translucent opacification. Technician Tips
○ Chronic anterior uveitis ○ Iris-to-cornea PPMs may cause significant • Intraocular pressures should be checked in
• Depigmentation corneal edema, which may benefit from any cloudy eye.
○ Chronic anterior uveitis topical 5% hypertonic saline ophthalmic • Pupillary light reflexes should be evaluated
○ Uveal neoplasm solution or ointment q 6-12h; continued and documented before dilation with
• Reddening long term if clinical improvement noted. tropicamide.
○ Rubeosis iridis; indicates chronic change ○ Iris-to-lens PPMs can lead to cataract
○ Iridal hemorrhage formation; if cataract is causing vision SUGGESTED READING
○ Uveal neoplasm impairment, cataract surgery may be Hendrix DVH: Diseases and surgery of the canine
Iris mass: warranted (p. 147). anterior uvea. In Gelatt KN, editor: Veterinary
• Uveal neoplasm ophthalmology, ed 5, Ames, IA, 2013, Wiley-
• Uveal cyst Possible Complications Blackwell, pp 1146-1198.
Iris strands: • Varies, depending on underlying condition AUTHOR: Steven R. Hollingsworth, DVM, DACVO
• PPMs: arise from iris collarette; typically fine • Cataracts and corneal edema associated with EDITOR: Diane V. H. Hendrix, DVM, DACVO
strands PPMs are rarely progressive.

Iron Toxicosis Client Education
Sheet

BASIC INFORMATION RISK FACTORS ○ Second stage (6-24 hours): latent period,
• Concurrent ascorbic acid (multivitamin) apparent recovery, may be very short stage
Definition ingestion may increase iron absorption. ○ Third stage (12-96 hours): lethargy, GI
Iron toxicosis occurs when absorbable forms • Availability of multivitamins (notably effects, acidosis, shock, hypotension,
of iron are ingested, resulting in severe prenatal vitamins), iron-based snail/slug tachycardia, liver failure, coagulopathy,
gastrointestinal (GI) effects and shock, followed baits, instant hand-warmers, heat patches kidney injury
by acidosis, central nervous system (CNS) or wraps, fertilizers, desiccants, and some ○ Fourth stage (2-6 weeks): possible scarring
depression, hepatic necrosis, and possibly birth control pills and stricture formation as GI ulcers heal
kidney injury.
Clinical Presentation PHYSICAL EXAM FINDINGS
Epidemiology HISTORY, CHIEF COMPLAINT • Signs of hypovolemic shock (poor pulse
SPECIES, AGE, SEX • History or evidence of ingestion of iron- quality, delayed capillary refill time, severe
Dogs are most commonly involved, but containing agent lethargy, tachycardia)
all species, ages, and both sexes can be • Mostly presented as an acute toxicosis • Signs of dehydration
affected. ○ First stage (0-6 hours): vomiting, diarrhea • Evidence of abdominal pain
(possibly severe/bloody), lethargy • GI bleeding

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