ABSTRACT OF THE WEEK

Veterinary dermatology
Volume 25 | Issue 6 (December 2014)

Deslorelin for the treatment of hair cycle arrest in intact male dogs.

Vet Dermatol. December 2014;25(6):519-22, e87-8.

Francesco Albanese¹, Eleonora Malerba, Francesca Abramo, Vincenzo Miragliotta, Federico Fracassi

¹ Private Practitioner, Via Giovanni da Verrazzano 19, 52100, Arezzo, Italy.

Abstract

BACKGROUND:Hair cycle arrest (alopecia X) refers to a canine alopecic condition of unknown pathogenesis, characterized by symmetrical, nonpruritic and noninflammatory alopecia that spares the head and distal extremities.

HYPOTHESIS/OBJECTIVES:The objective of this study was prospectively to evaluate the efficacy of a 4.7 mg deslorelin implant in the treatment of intact male and neutered female dogs affected by hair cycle arrest.

ANIMALS:Ten Pomeranian dogs (eight intact males, two neutered females), four Italian spitz (three intact males, one neutered female), three miniature poodles (two intact males, one neutered female), two Siberian huskies (both intact males) and one intact male chow chow dog with confirmed hair cycle arrest were included in the study.

METHODS:Each dog was treated with a subcutaneous sterile implant containing 4.7 mg deslorelin. Responder dogs were re-implanted 6 months after the first implant in order to obtain a 1 year pharmacological exposure and 1 year of follow-up.

RESULTS:Hair regrowth was visible within 3 months in 12 of 16 intact male dogs (75%); no hair regrowth was noted in any neutered female dogs. The overall response to therapy was 60%. No adverse effects were noted.

CONCLUSIONS AND CLINICAL IMPORTANCE:These findings suggest that deslorelin may be a treatment option for intact male dogs with idiopathic hair cycle arrest. Deslorelin is an alternative to current therapies and castration.

Companion Notes

Prospective report on the efficacy of deslorelin for hair cycle arrest in intact male dogs and neutered female dogs

Study design

- introduction on hair cycle arrest (alopecia X) in the dog

- non-inflammatory alopecic disorder of unknown pathogenesis

- presentation is similar to other endocrine disorders (hyperadrenocorticism)

- symmetrical, nonpruritic, non-inflammatory alopecia of the following

(head and distal extremities usually unaffected)

- neck

- tail

- perineum

- caudal thighs

- trunk

- ‘plush-coated’ dogs most commonly affected

- neutered and intact male and female young adult dogs affected

- reported treatments have variable efficacy and include the following:

- none of the following is known as the most effective and safe:

(may result in either partial or complete hair regrowth)

- growth hormone

- methyltestosterone

- mitotane

- trilostane

- melatonin

- fulvestrant (estrogen receptor antagonist)

- medroxyprogesterone acetate

- neutering

- often the initial treatment of choice for intact males

- complete or partial hair regrowth occurs in 60-83.3%

- deslorelin; long-acting gonadotrophin-releasing hormone agonist

- causes prolonged positive feedback on the pituitary gland

- this desensitizes and down-regulates pituitary receptors

- specifically, gonadotrophin-releasing hormone pituitary receptors

- this initially stimulates gonadotrophin production/release

- then it inhibits gonadotrophin production/release

- so far no adverse effects reported in dogs

- except for follicular cysts and prolonged estrus in a sex:F dog

- reversible mode of action reported in recent study on stopping deslorelin

- testes and prostate gland histology and endocrine variables assessed

- these completely recover after deslorelin stopped in male dogs

- as does semen production

- used for the following:

- control of reproduction

- sex hormone-dependent diseases

- reversible chemical castration in dogs

- hyperestrogenism in ferrets

- study population:

- dogs with confirmed hair cycle arrest

- 10 pomeranian dogs (8 intact sex:Ms, 2 neutered sex:Fs)

- 4 Italian spitz (3 intact sex:Ms, 1 neutered sex:F)

- 3 miniature poodle dogs (2 intact sex:Ms, 1 neutered sex:F)

- 2 Siberian husky dogs (2 intact sex:Ms)

- 1 intact sex:M chow chow dog

- inclusion criteria included all of the following:

- predisposed breed with dense undercoat

- history of progressive, non-inflammatory alopecia

- no concomitant systemic signs

- normal thyroid and adrenal function tests

- lesion distribution characteristic of hair cycle arrest

- progressive truncal hair loss and/or woolly coat quality

- with or without hyperpigmentation

- normal CBC, chemistry and urinalysis

- no physical and microscopic signs of infectious microorganisms/parasites

- that would require topical or systemic treatment

- histopathology consistent with hair cycle arrest

- history & signalment

- median age at first consultation: 6.1 years of age with a range of 1.7-14

- median duration of clinical signs of hair cycle arrest: 19.4 months

- procedure:

- subcutaneous sterile 4.7 mg deslorelin implant, all dogs

(Suprelorin^®; Virbac, Carros, France) using a single-use implanter

- responders were re-implanted 6 months after first implant

- assessment methods

- physical examination after 3, 6 and 12 months

Results

- visible hair regrowth within 3 months, 12 of the 16 intact males

- at 6 months these 12 had full hair regrowth

- non-responders included the following:

- 2 of 8 pomeranians

- 1 of 3 Italian spitz

- 1 of 2 Siberian huskies

- no hair regrowth, all the neutered females

- adverse effects: none noted

- hematology was unremarkable in all 20 dogs

"As deslorelin acts via inhibition of gonadotrophin production and release, and none of the neutered females enrolled in this study responded to the treatment, one could speculate that hair regrowth in our cases was mediated by inhibition of gonadal hormones, obviously not present in neutered animals."

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