Ichthyosis

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The pelage of a Golden Retriever with nonepidermolytic ichthyosis, showing the large, white, and loosely adherent scales[1]
Nonepidermolytic ichthyosis in an American Bulldog[2]

Ichthyoses is a genetic skin disease characterized by faulty formation of the outer layer of the epidermis, the stratum corneum, with resultant scaling[3].

A number of forms are recognized in dogs including epidermolytic (ichthyosiform dermatosis) and non-epidermolytic ichthyosis.

Ichthyosiform dermatosis (epidermolytic ichthyosis) is reported exclusively in Cavalier King Charles Spaniels, characterized by a congenitally abnormal (rough/curly) coat with concurrent keratoconjunctivitis sicca (dry-eye curly-coat syndrome)[4] and sometimes episodic falling.

Non-epidermolytic ichthyosis have been identified in the Norfolk Terrier[5], Jack Russell Terrier[6], American Bulldog and Golden Retriever breeds[7].

In ichthyosiform dermatosis, persistent scale along the dorsal spine and flanks with a harsh frizzy and alopecic coat is evident in the first few months of life. The ventral glabrous skin is often hyperpigmented and rough, similar to sandpaper[8]. Affected pups are usually smaller than littermates.

Footpads are often hyperkeratinized from young adulthood with nail growth abnormalities and intermittent sloughing[9].

Clinical symptoms of ichthyosiform dermatosis are often associated with dental disease, primarily tartar formation and gingivitis, with some dogs requiring tooth extractions[10].

Diagnosis is based on exclusion of other causes of generalized nondermolytic ichthyosis such as follicular parakeratosis, atopy[11], underlying metabolic/endocrine abnormalities and/or bacterial infections[12].

Disease management of ichthyosiform dermatosisis difficult, with many owners opting to euthanize affected puppies on welfare grounds.

Non-epidermolytic ichthyosis is relatively nonpathogenic and can be managed with regular medicated sebolytic shampoos.

References

  1. Mauldin EA et al (2008) The clinical and morphologic features of nonepidermolytic ichthyosis in the golden retriever. Vet Pathol 45(2):174-180
  2. EwKab
  3. DiGiovanna JJ & Robinson-Boston L (2003) Ichthyosis: etiology, diagnosis, and management. Am J Clin Dermatol 4:81–95
  4. Forman OP et al (2012) Parallel mapping and simultaneous sequencing reveals deletions in BCAN and FAM83H associated with discrete inherited disorders in a domestic dog breed. PLoS Genet 8(1):e1002462
  5. Credille KM et al (2005) Mild recessive epidermolytic hyperkeratosis associated with a novel keratin 10 donor splice-site mutation in a family of Norfolk terrier dogs. Br J Dermatol 153:51–58
  6. Credille KM et al (2009) Transglutaminase 1-deficient recessive lamellar ichthyosis associated with a LINE-1 insertion in Jack Russell terrier dogs. Br J Dermatol 161:265–272
  7. Grall A et al (2012) PNPLA1 mutations cause autosomal recessive congenital ichthyosis in golden retriever dogs and humans. Nat Genet 44(2):140-147
  8. Guaguere E et al (2009) Clinical, histopathological and genetic data of ichthyosis in the golden retriever: a prospective study. J Small Anim Pract 50(5):227-235
  9. Hartley C et al (2012) Congenital keratoconjunctivitis sicca and ichthyosiform dermatosis in Cavalier King Charles spaniel dogs. Part II: candidate gene study. Vet Ophthalmol 15(5):327-332
  10. Barnett KC (2006) Congenital keratoconjunctivitis sicca and ichthyosiform dermatosis in the cavalier King Charles spaniel. J Small Anim Pract 47:524–528
  11. Terada Y et al (2011) Clinical comparison of human and canine atopic dermatitis using human diagnostic criteria (Japanese Dermatological Association, 2009): proposal of provisional diagnostic criteria for canine atopic dermatitis. J Dermatol 38(8):784-790
  12. Scott DW et al (2001) Muller and Kirk’s Small Animal Dermatology. 6th ed. Philadelphia, PA: WB Saunders. Keratinization defects. pp:1022–1054