Page 1569 - Cote clinical veterinary advisor dogs and cats 4th

790 Pinnal Diseases

Otodectes (primarily affects the ear canal), D. • Basal cell tumor: commonly occurs on the otherwise, a permanent hole will result.
feline pinna
gatoi (cats) Miscellaneous conditions: A small (<0.25 mL) volume of normal
VetBooks.ir • Dermatophytosis (feline > canine) • Aural hematoma (p. 104): hemorrhage within biopsy site on the convex pinna elevates
saline or lidocaine injected under the
Infectious causes:
the skin to protect the cartilage but
or along the cartilage of the pinna. Assess for
• Canine leproid granuloma syndrome: nodules
on convex pinna caused by a novel species
sometimes in the contralateral ear)
dermis.
of mycobacteria with a distinct geographic causes of head shaking (e.g., otitis externa, may result in some distortion of the
distribution • Ear margin seborrhea: pendulous-eared dogs, ○ If direct pressure does not stop bleeding,
• Leishmaniasis (dogs > cats): pinnal scaling particularly dachshunds. Keratinous deposits epinephrine can be applied to the surgical
and alopecia; infected animals are systemi- occur on concave and convex margins; fis- wound with a cotton-tipped applicator.
cally ill sures may form in chronic cases. ○ Suture or allow skin to heal by second
• Pigmented viral plaques: darkly pigmented • Sebaceous adenitis: scaling and follicular casts intention. The latter causes less puckering
macules or slightly raised papules • Acquired folding of feline ear pinnae: associ- of the ear.
Hypersensitivity disorders: ated with iatrogenic hyperadrenocorticism ○ Always include crusts in the biopsy.
• Atopic dermatitis and food allergy: com- (topical or systemic steroid use) Because pinnal biopsies are very thin, place
monly cause pinnal erythema and pruritus • Proliferative and necrotizing otitis externa them on a piece of heavy paper, dermis
• Contact hypersensitivity: most often due of cats: highly characteristic: adherent, dark, side down, before placing in formalin.
to topically applied ear medications (e.g., keratinous debris on the concave aspect of • CBC, serum chemistry profile, thyroid
neomycin, propylene glycol); suspect when the pinna, usually in young cats hormone levels, urinalysis, antinuclear
ear worsens rather than improving with • Canine sterile eosinophilic pinnal furunculosis antibody titers, and other tests as appropriate
treatment despite resolution of infection • Melanoderma and alopecia of Yorkshire • Response to empirical therapy (e.g., Sarcoptes)
on cytology terriers: also affects bridge of nose
• Mosquito bite hypersensitivity (cats): TREATMENT
seasonal; convex pinna is a common site Initial Database
Immune-mediated disorders: Varies, depending on differential diagnoses but Treatment Overview
• Pemphigus foliaceus: may resemble pyo- may include Varies, depending on cause. For aural hemato-
derma, which is rare on the pinna. Common • None; diagnosis may be presumptive (e.g., mas, various surgical and medical techniques
site of lesions in cats aural hematoma, acquired pattern alopecia) are described (p. 104).
• Vasculitis and ischemic dermatopathy: fairly • Skin scrapings (p. 1091)
common cause of pinnal lesions in dogs; this • Pinnal-pedal reflex: ≈82% sensitivity and PROGNOSIS & OUTCOME
diverse group of diseases can be idiopathic, ≈94% specificity for Sarcoptes (p. 900);
hereditary (e.g., Jack Russell terriers), or sensitivity higher than skin scrapings for Varies, depending on cause
iatrogenic (e.g., rabies vaccine induced). this parasite
Ulcerative and crusted lesion, often on the • Cutaneous cytology (p. 1091) PEARLS & CONSIDERATIONS
distal concave pinna; distal extremities and • Wood’s lamp exam, fungal culture
tail tip can be affected • Trichography (demodicosis, color dilution Comments
• Less common, also affecting other sites: alopecia, pediculosis, sebaceous adenitis) • Due to the difficulty of collecting diagnostic
pemphigus erythematosus, discoid lupus • Fine-needle aspiration of nodular lesions skin biopsies from the pinna, seek out and
erythematosus, bullous pemphigoid, cold ○ Acid-fast stain of aspirates if mycobacteria sample other similarly affected areas of skin.
agglutinin disease, alopecia areata, familial suspected • Although both diseases are most common
cutaneous vasculopathy of German shepherd • Skin biopsies in dachshunds, ear margin seborrhea is
dogs ○ Advise clients that pinnal biopsies can characterized by scaling and skin lesions,
• Less common, limited to the pinna: pro- result in permanent cosmetic changes. It is whereas pattern alopecia is not.
liferative thrombovascular necrosis (dogs), not usually necessary to provide cartilage, • Consider empirical treatment for Sarcoptes in
auricular chondrosis (swollen, misshapen, and so full-thickness biopsies are not often dogs with pinnal pruritus, even with negative
painful pinnae) required. skin scrapings and no pinnal-pedal reflex.
Hereditary causes: ○ Procedure often requires general anesthesia
• Acquired pattern alopecia: affects dogs (most because there is very little subcutaneous Technician Tips
commonly dachshunds) before 1 year and space into which to inject lidocaine. The Head shaking greatly exacerbates hemorrhage
progresses to complete pinnal alopecia proximal convex pinna can be an exception. after pinnal biopsies or injury. A gentle technique
• Canine familial dermatomyositis: lesions ○ The pinna can be clipped to help visualize to protect the pinnae from this self-trauma uses
usually manifest by 6 months of age. blood vessels. Close surgical clipping is a surgical stockinette tube placed over the head
• Color dilution alopecia: progressive hair loss not recommended because it can remove and secured to the forehead by surgical tape.
in blue- or fawn-colored dogs diagnostically important material. The stockinette may be used in a single layer
• Other: primary seborrhea, psoriasiform- ○ Pinnal margin lesions or doubled over with loose holes cut out for
lichenoid dermatosis of English springer ■ For a good cosmetic outcome, sample the ears in the bottom layer. The stockinette is
spaniels, exfoliative cutaneous lupus erythe- using a thin shave biopsy of the pinnal placed over the head such that the ears rest in
matosus of German short-haired pointers, margin; using a #15 scalpel blade, shave an anatomically normal position. The stockinette
congenital hypotrichosis, black hair follicular the skin down to the level of the cartilage. must not be tight. The aim is to keep the ears
dysplasia ■ Larger wedges can be removed, leaving from flapping when the head is shaken.
Neoplastic diseases: skin distal to the cartilage for closure.
• Squamous cell carcinoma: most common ■ With extensive pinnal necrosis, affected SUGGESTED READING
in light-colored cats; often preceded by tissue can be excised to create a more Marignac G: Diseases that affect the pinna. In Got-
premalignant actinic keratoses (small areas proximal margin. thelf LN, editor: Small animal ear diseases, ed 2,
of crusting and hyperkeratosis). Pinnal lesions ○ Nonmarginal lesions St. Louis, 2005, Saunders, pp 235-263.
on light-colored cats warrant investigation. ■ Use a biopsy punch (usually 6 mm
• Histiocytoma and sebaceous gland tumor: unless pinna is small). Take care NOT AUTHOR: Kinga Gortel, DVM, MS, DACVD
EDITOR: Manon Paradis, DMV, MVSc, DACVD
commonly occur on the canine pinna to cut through underlying cartilage;
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