418 DISEASES/DISORDERS
CLINICAL FEATURES
Early symptoms are nonspecific: slow progression of clinical signs often delays
diagnosis.
Systemic symptoms primarily associated with decreased metabolic function.
Initial symptoms:
Malaise
Mental dullness; rare seizures, ataxia, coma
Exercise and cold intolerance
Behavior change
Obesity
Intact animals may demonstrate reproductive dysfunction (e.g., decreased fertil-
ity, failure to cycle).
Nondermatologic symptoms reported with moderate frequency:
Peripheral neuropathy (occasionally acute)
Cranial nerve deficits (Horner’s syndrome)
Generalized myopathy (weakness)
Megaesophagus
Laryngeal paralysis
Corneal lipidosis
Recovery with supplementation may be rapid for neuropathy and myopathy but
is not consistent with megaesophagus or laryngeal paralysis.
Dermatologic changes:
Hair coat changes seen in greater than 40% of cases:
Dull, brittle hair coat (Figure 28.3)
Change in coat quality – preferential loss of primary guard hairs, leaving
the fine undercoat more visible and giving the appearance of a “puppy”
coat (Figure 28.4)
Easily epilated hairs
Failure to regrow hair coat after clipping; seen initially as loss of coat in
areas of friction or pressure (e.g., collar, lateral elbows, lateral hocks) (Fig-
ure 28.5)
Reduced hair coat growth following shedding; hypertrichosis has been
described in boxers and Irish setters due to retention of dead hair coat
Hair coat color change (most often lightening), especially at the tips of the
hair
Initial alopecia may be patchy and asymmetric. Advanced cutaneous symptoms:
Bilaterally symmetric alopecia; usually truncal, sparing head and extremities
(Figure 28.6)
Pinnal alopecia and scaling
Alopecic or “rat” tail (Figure 28.7)
Edematous appearance to skin (myxedema and mucinosis) (Figures 28.8, 28.9)