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1286 Third Eyelid (Nictitating Membrane) Abnormalities Thyroid Hormone Alterations

Third Eyelid (Nictitating Membrane) Thromboembolism
VetBooks.ir Abnormalities Causes of and Predisposing Factors for Thrombosis

Prominent Third Eyelid With Focal Abnormality and Thromboembolism
Curled or scrolled leading edge: excise abnormal cartilage. Vascular Endothelial Damage
Pink, fleshy mass protruding between globe and third eyelid in a young dog Arteriosclerosis
(“cherry eye”): surgically reposition the gland. Atherosclerosis
Pink, fleshy mass protruding between globe and third eyelid in an old dog: Vasculitis
possible neoplasia; biopsy or complete excision of third eyelid. Heartworm disease
Mass within or on anterior surface of third eyelid: biopsy or local excision Catheterization (arterial or venous)
with or without adjunctive therapy; larger masses may require complete Injection of irritating substances
excision of third eyelid. Neoplasia
Generalized Enlargement of Third Eyelid Vascular incarceration/compression
Thickened and depigmented; may have corneal involvement (chronic Hyperhomocysteinemia
superficial keratoconjunctivitis; “pannus”): conjunctival scraping or Feline ischemic encephalopathy
biopsy; treat with topical corticosteroids, cyclosporine. Fibrocartilaginous embolism
Thickened and inflamed with firm, fibrous nodules; cornea, episclera, and Hypercoagulability
bulbar conjunctiva are also often involved: biopsy; treat on basis of breed Infection/sepsis/abscess
and biopsy results (collie: nodular granulomatous episclerokeratitis; other Neoplasia
breeds: ocular nodular fasciitis). Hyperadrenocorticism
Diffuse, generalized enlargement of third eyelid or gland of the third eyelid: Protein-losing nephropathy
aspiration or biopsy; lymphoma or other systemic neoplasia. Protein-losing enteropathy
Prominent Third Eyelid Only Disseminated intravascular coagulation
Nonpigmented leading edge: appears prominent but needs no therapy Thrombocytosis
Secondary to pain: check for corneal ulcer, foreign body, or other source of Platelet hyperreactivity
ocular or intraocular pain. Immune-mediated hemolytic anemia
Horner’s syndrome: look for other signs of miosis, ptosis, and enophthalmos; Parvovirus infection
attempt to localize lesion and treat if needed. Abnormal Blood Flow
Secondary to orbital disease: enophthalmos may lead to passive protrusion Neoplasia
or orbital mass; cellulitis or myositis may displace third eyelid, causing Cardiomyopathy
protrusion. Congestive heart failure
Systemic disease, such as tetanus Endocarditis
Nonpigmented leading edge/margin (seen congenitally as a normal variant): Hypovolemia
appears prominent but needs no therapy Shock
Anemia
From Slatter D: Textbook of small animal surgery, ed 3, Philadelphia, 2003, Saunders.
Polycythemia
Dehydration
Hyperviscosity
Modified from Ettinger S, Feldman E: Textbook of veterinary internal medicine, ed 6, St. Louis,
2005, Saunders.

Thyroid Hormone Alterations

Variables That May Affect Baseline Serum Thyroid Hormone Function Test Results in Dogs
Age Inversely proportional effect
Neonate (<3 months) Increased T 4
Aged (>6 years) Decreased T 4 , increased TSH
Body size Inversely proportional effect
Small (<10 kg) Increased T 4
Large (>30 kg) Decreased T 4
Breed:
Sight hounds (e.g., greyhound), Nordic breeds (e.g., Siberian husky), T 4 and free T 4 lower than normal range established for dogs; no difference for TSH
basenjis, other breeds
Sex T 4 higher in females during diestrus
Time of day No effect
Weight gain/obesity Increased
Weight loss/fasting Decreased T 4 , no effect on free T 4
Strenuous exercise Increased T 4 , decreased TSH, no effect on free T 4

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