Page 136 - Cote clinical veterinary advisor dogs and cats 4th

46 Alopecia, Cat

Differential Diagnosis Initial Database • Abdominal ultrasound/thoracic and abdomi-
nal radiographs (paraneoplastic, thymoma)
Congenital (all nonpruritic): • Comprehensive ectoparasite examination • Histopathologic evaluation of skin biopsies
VetBooks.ir • Hereditary hypotrichosis (affected individuals ○ Trichography: examination of hair tips to may be helpful in the diagnosis of endocri-
(flea combing, skin scrapings, trichograms)
• Alopecia universalis (affected individuals born
without hair)
nopathy, neoplasia, paraneoplastic syndrome,
determine whether hair loss is self-inflicted
born with a thin hair coat progressing to
(fractured hair shafts)
alopecia) • Fungal culture (in-house dermatophyte test mural folliculitis, and follicular dysplasia.
Findings consistent with normal skin support
• Follicular dysplasia (ongoing hair thinning medium or external lab) (pp. 247 and 1091) a behavioral diagnosis but are not pathog-
progressing to alopecia) • Anal sac expression (anal sac disease may nomonic; behavioral cause (psychogenic
Acquired: elicit excessive self-grooming; monitor long- alopecia) is a diagnosis of exclusion.
• Pruritic term response to anal sac expression)
○ Parasitic (flea, D. gatoi, Cheyletiella, TREATMENT
Otodectes, Notoedres, Sarcoptes [rare in cats], Advanced or Confirmatory Testing
Trombicula, Felicola subrostratus) Tests are selected based on information gathered Treatment Overview
○ Fungal (e.g., M. canis) to date and feasibility of testing with each case. Correct underlying cause of alopecia.
○ Food allergy • CBC: eosinophilia may support a diagnosis
○ Atopic dermatitis of a hypersensitivity/parasites. Acute and Chronic Treatment
• Nonpruritic: • Fecal evaluation may reveal an external para- • Depends on underlying cause
○ Fungal site such as a flea, Demodex, or Cheyletiella. • Specific parasiticide or broad-spectrum
○ Telogen/anagen effluvium • Serum biochemical profile: metabolic disease antiparasitic therapy:
○ Feline degenerative mural folliculitis • Urinalysis: metabolic disease, ventral ○ Ectoparasiticide response trial (broad-
○ Inflammatory bowel disease abdominal alopecia (cystitis) spectrum parasiticide for 6-8 weeks,
○ Cystitis • Thyroid hormone evaluation +/− fluralaner or lime sulfur dips for D.
○ Anal sacculitis • An 8-12 week strict elimination dietary trial gatoi)
○ Endocrinopathy (hyperthyroidism; • Response to steroid therapy is supportive of ○ Express anal sacs (if ventral abdominal/
hypothyroidism: iatrogenic, spontaneous a pruritic cause. tail head alopecia)
[very rare]; hyperadrenocorticism: iatro- • Intradermal and/or serum allergy testing ○ Elizabethan collar to differentiate self-
genic, acquired [rare]) is supportive but not conclusive that hair trauma from hair loss
○ Neoplasia (cutaneous T-cell lymphoma, loss is due to environmental allergies. A
paraneoplastic syndrome, thymoma, negative test result does not eliminate the PROGNOSIS & OUTCOME
hypereosinophilic syndrome) possibility.
○ Behavioral: compulsive, anxiety • Feline leukemia virus and feline immuno- Uncomplicated disorders carry a better prog-
○ Neurologic: hyperesthesia deficiency virus testing (should be performed nosis for control (atopic dermatitis) and possibly
○ See algorithm for feline alopecia (p. 1401). before cyclosporine use) cure (fungal, parasitic, food allergy), but many
cases can involve more than one cause. In these
cases, the prognosis depends on the complete-
ness of diagnostic testing and on client and
patient compliance.
PEARLS & CONSIDERATIONS
Comments
• A normal skin biopsy does not rule out
pruritus as a cause of self-trauma.
• A large percentage of cats that self-traumatize
have multiple, concurrent causes, emphasiz-
ing the need for a complete workup.
• Food allergy should be ruled out in all
nonseasonally pruritic patients.
• Absence of parasites on physical examination
does not preclude their presence. Perform
empirical parasiticide therapeutic trials.
Technician Tips
Skin scrapes performed in regions difficult to
groom (back of neck) may increase likelihood
of finding D. gatoi.

SUGGESTED READING
Mecklenburg L, et al: Hair loss disorders in domestic
animals. Ames, IA, 2009, Wiley-Blackwell.
ALOPECIA, FELINE Self-induced alopecia on the abdomen due to intense pruritus in a 4-year-old Birman AUTHOR: Stephen Waisglass, DVM, DACVD
cat with Demodex gatoi infestation. (Copyright Dr. Manon Paradis.) EDITOR: Manon Paradis, DMV, MVSc, DACVD

www.ExpertConsult.com