Genodermatoses and newly recognized skin diseases (Proceedings) - Veterinary Healthcare
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Genodermatoses and newly recognized skin diseases (Proceedings)


CVC IN WASHINGTON, D.C. PROCEEDINGS


Recognizing breed associated or genetic dermatologic conditions can prove quite challenging on a daily basis. Such conditions are more obvious when multiple animals from a single litter are affected at birth, however clinical signs of many of these conditions are not present until adulthood and many animals have dispersed to new homes. In such cases the genetic link may not be quite so obvious. Pedigree analysis and additional genetic testing have provided much insight as to the mode of inheritance of many of these conditions, however facts regarding pathogenesis of the disease state in most cases remains unclear.

Adult-onset hair loss in Chesapeake Bay retrievers

This coat disorder has been recently reported in the literature. Both intact and neutered animals are affected with a form of adult-onset alopecia. In the cases reported, all animals have been otherwise healthy except for a non-pruritic progressive symmetrical hair loss affecting the axillae, the thorax (lateral to ventral aspects), and the flank region extending to include the caudal dorsum and caudal thighs. The extremities are typically spared with a normal hair coat in these regions. The distribution of hair loss described in this syndrome is consistent with a non-inflammatory (endocrine) pattern of alopecia. The age of onset for clinical signs ranges from 5 months to 4 years and hair loss ranges from thinning in some areas to complete alopecia in others. Routine lab work (CBC, Chemistry panel, urinalysis) results are typically within normal limits; evaluation of thyroid hormones, urine cortisol: creatinine ratios and ACTH stimulation testing fails to reveal significant abnormalities to explain the adult-onset hair loss.

• Diagnosis: Treat and resolve any secondary infections.
Rule out endocrinopathies and systemic illnesses
Submit biopsies for histopathology—Infundibular orthokeratotic hyperkeratosis is a consistent finding along with follicular atrophy.
• Treatment: None reported
• Pedigree analysis: Common ancestors in the sire and dam line of most affected dogs examined.
• Mode of inheritance and pathogenesis unknown; potentially a hair cycle disorder or a type of follicular dysplasia.

Hypotrichosis and alopecia in Irish Water Spaniels

Special coat characteristics are associated with this breed, resulting in the selective breeding of animals possessing such traits. These characteristics include focal areas that are smooth coated interspersed with a mostly curly coat. Recently coat abnormalities have been noted within the breed and include more generalized areas of alopecia and thinly haired regions that extend to include the dorsum, flank region, caudal thighs as well as much of the neck. Both intact and neutered male and female dogs are affected. This is a non-pruritic adult-onset progressive condition affecting middle-aged dogs most commonly. The age of onset ranges from 1-6 years of age, with an onset of 5-6 years of age considered typical. Routine lab work (CBC, Chemistry panel, urinalysis) results are typically within normal limits; evaluation of thyroid hormones, sex hormones (elevated 17-OHP) and ACTH stimulation testing fails to reveal significant abnormalities to explain the adult-onset hair loss.

• Diagnosis: Treat and resolve any secondary infections.
Rule out endocrinopathies and systemic illnesses.
Submit biopsies for histopathology—Infundibular orthokeratotic hyperkeratosis is a consistent finding along with follicular atrophy and pigment clumping within the hair shaft and/or hair follicle.
• Treatment: None reported
• Pedigree analysis: Not reported.
• Mode of inheritance and pathogenesis unknown.

Exfoliative cutaneous lupus erythematosus of German Short-haired pointers

This condition has previously been referred to as a type of lupoid dermatosis and is considered unique to the breed. It is an acquired, adult-onset condition, affecting dogs between the ages of 6 months to 4 years. The predominant clinical sign associated with this disease is an exfoliative, scaling skin disease that will also include alopecia in some cases. It is generalized in distribution and may initially affect the face, pinnae and dorsum and then will progress to involve the remainder of the body. Most dogs have secondary bacterial and yeast infections and are pruritic. Some dogs are systemically ill as well, presenting with pyrexia, peripheral lymphadenopathy and pain or lameness. A stilted or abnormal gait has also been noted. Results of routine lab work (CBC, Chemistry panel, UA) are inconsistent between animals with thrombocytopenia and mild nonregenerative anemia reported in some cases. Lymph node aspiration in some dogs has revealed lymph node hyperplasia.

• Diagnosis: Submit biopsies for histopathology—Lymphocytic interface dermatitis and mural folliculitis with sebaceous adenitis.
• Treatment: Limited success with immunomodulatory drugs (prednisone, cyclosporine, azathioprine) plus topical antiseborrheic treatments.
• Pedigree Analysis: Common ancestor in the sire line for some dogs.
Mode of inheritance currently unknown; autosomal recessive or polygenic recessive mode suggested based on limited pedigree data.
• Pathogenesis: Unknown. Both circulating and tissue fixed antibodies (IgG) detected, thus a cytotoxic T-cell mediated process against basal cells is suggested.


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Source: CVC IN WASHINGTON, D.C. PROCEEDINGS,
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