Treatment of canine Alopecia X with trilostane

Optimal microneedle length for hair regrowth in hair cycle arrest (alopecia X) in six dogs

BACKGROUND

Hair cycle arrest (HCA) is a chronic alopecic disorder in dogs. Clinical responses vary and are often insufficient. Microneedling (MN) has been used as a successful treatment for HCA in dogs; ideal protocols have not yet been established.

OBJECTIVES

The objective of the study was to compare the efficacy and safety of three needle lengths for MN in dogs with HCA.

ANIMALS

Six unrelated client-owned dogs, including five Pomeranians and one mixed-breed dog, diagnosed with HCA.

MATERIALS AND METHODS

Individual alopecic sites were divided into three sections. For each section, different lengths of needles (1, 2 and 3 mm) were used. Efficacy and safety were evaluated at 1, 3 and 6 months. Treated sections were monitored for 20 months.

RESULTS

Three months after treatment with 3 mm needles, all sections showed hair regrowth. There was no hair regrowth in two of six sections treated with 2 mm needles, and four of six sections did not show a response to treatment with 1 mm needles. Two dogs developed transient pruritus. Five of six dogs had recurrent hair loss between 5 and 16 months of follow-up.

CONCLUSION AND CLINICAL RELEVANCE

Microneedling using longer needles stimulated better hair regrowth in dogs with HCA. Alopecia relapsed in most dogs and minor pruritus occurred in some dogs.

Canine noninflammatory alopecia: An approach to its classification and a diagnostic aid

Noninflammatory alopecia is common in dogs and is a frequent cause to consult a veterinarian. It is also a common reason to take biopsies. Noninflammatory alopecia can be attributed to a decreased formation or cytodifferentiation of the hair follicle or the hair shaft in utero, resulting in congenital alopecia. Congenital alopecia often has a hereditary cause, and examples of such disorders are ectodermal dysplasias associated with gene variants of the ectodysplasin A gene. Noninflammatory alopecia may also be caused by impaired postnatal regeneration of hair follicles or shafts. Such disorders may have a clear breed predilection, and alopecia starts early in life. A hereditary background is suspected in those cases but has not been proven. They are referred to as follicular dysplasia although some of these disorders present histologically like a hair cycle disturbance. Late-onset alopecia is usually acquired and may be associated with endocrinopathies. Other possible causes are impaired vascular perfusion or stress. As the hair follicle has limited possible responses to altered regulation, and histopathology may change during the course of a disease, a detailed clinical history, thorough clinical examination including blood work, appropriate biopsy site selection, and detailed histological findings need to be combined to achieve a final diagnosis. This review aims to provide an overview about the known noninflammatory alopecic disorders in dogs. As the pathogenesis of most disorders is unknown, some statements are based on comparative aspects or reflect the authors' opinion.

The number of mitochondrial DNA mutations as a genetic feature for hair cycle arrest (alopecia X) in Pomeranian dogs

BACKGROUND

Hair cycle arrest (HCA) is a noninflammatory alopecic disease affecting various dog breeds, particularly Pomeranian dogs. This disease is probably a hereditary disorder considering the strong breed predisposition. Despite efforts to identify the pathogenesis of this disease, an underlying specific cause is unknown.

OBJECTIVE

To identify candidate gene mutations for HCA in Pomeranian dogs.

ANIMALS

Four Pomeranian dogs diagnosed with HCA and four unaffected Pomeranian dogs.

MATERIALS AND METHODS

Whole blood was used for DNA extraction. Whole-genome sequencing (WGS) was performed, and variants were analysed using a Genome Analysis Toolkit (GATK) and SnpEff. All reads were aligned to the reference genome, Dog10K_Boxer_Tasha. Sanger sequencing was performed to define the complex mutations.

RESULTS

A total of 113 variants of mitochondrial DNA were found to be effective gene mutations in the eight dogs. The affected dogs showed significantly increased effective mutations (average 57 variants) compared with unaffected dogs (average eight variants; p < 0.05). There was no significant difference in the number of chromosomal DNA mutations between the two groups.

CONCLUSION AND CLINICAL IMPORTANCE

We suggest that an increased number of mitochondrial gene mutations are features for HCA in Pomeranian dogs.

Deslorelin Implant Treatment for Hair Cycle Arrest (Alopecia X) in Two Intact Male Keeshonden

Alopecia in dogs occurs secondary to a variety of underlying inflammatory and noninflammatory conditions. Hair cycle arrest (alopecia X) is a noninflammatory alopecia that is frustrating to diagnose and treat due to lack of understanding of disease pathogenesis. A variety of therapies for hair cycle arrest have been described with inconsistent efficacy in different dog breeds and sexes; no definitive treatment is available. This report describes the use of a deslorelin acetate implant in two sexually intact adult male keeshonden, both diagnosed with hair cycle arrest. The dogs had progressive alopecia of the trunk that spared the head and distal limbs present for at least 2 yr. Diagnosis of hair cycle arrest was made based on clinical features, dermatohistopathology, and lack of systemic abnormalities. Treatment with a single subcutaneous 4.7 mg deslorelin acetate implant resulted in profuse hair regrowth within 3.5 mo that endured for at least 14 mo. Deslorelin implantation is a management option that is safe, affordable, and appears effective for sexually intact male keeshonden with hair cycle arrest.

Microneedling as a successful treatment for alopecia X in two Pomeranian siblings

BACKGROUND

Alopecia X (hair cycle arrest) is a relatively frequent hair growth disorder in Pomeranians and several other breeds, characterized by symmetrical, noninflammatory alopecia without systemic signs. The cause and pathogenesis remain unknown. Previously reported treatments with various topical and systemic drugs have been variably successful.

HYPOTHESIS

We hypothesized that superficial mechanical skin trauma applied with a microneedling device would induce long-term hair regrowth at treated sites.

ANIMALS

Two neutered female Pomeranian siblings with histologically confirmed alopecia X. Previous treatments with deslorelin, melatonin and topical minoxidil had failed to produce significant hair regrowth.

METHODS

The dogs were anaesthetized and the skin was punctured with a microneedling device. Dogs were followed over a period of 12 months.

RESULTS

Five weeks after microneedling hair regrowth started, followed by a reduction in hyperpigmentation of affected skin. After 12 weeks there was a 90% improvement in coat coverage at previously alopecic areas. Twelve months after the procedure, coat conditions remained stable. No adverse effects were noted.

CONCLUSIONS AND CLINICAL IMPORTANCE

This is the first report of microneedling to induce hair regrowth in dogs affected by alopecia X. Long-term studies with microneedling in a larger number of dogs with alopecia X will need to be performed to confirm these preliminary results and to further evaluate if hair-regrowth is permanent.

Trilostane in dogs

Over the last 10 years, trilostane, a competitive inhibitor of steroid synthesis, is being widely used for the treatment of canine hyperadrenocorticism. Trilostane causes a significant but reversible decrease in cortisol production and a concomitant improvement in clinical signs in most dogs with this common condition. Side effects, though infrequent, can be serious: dogs treated with this drug require regular monitoring. This review summarizes current knowledge of the use of this drug with particular emphasis on its efficacy, safety, adverse reactions, and effects on endocrine parameters. Brief mention is made of its other uses in dogs and other species.

Serum 17alpha-hydroxyprogesterone concentrations during the reproductive cycle in healthy dogs and dogs with hyperadrenocorticism

OBJECTIVE

To determine concentrations of 17alpha-hydroxyprogesterone (17OHP) in serum of healthy bitches during various stages of the reproductive cycle and in bitches with hyperadrenocorticism and to compare the dynamics of 17OHP with those of progesterone.

DESIGN

Prospective evaluation study.

ANIMALS

15 healthy sexually intact bitches and 28 spayed bitches with hyperadrenocorticism.

PROCEDURES

11 healthy bitches were evaluated during estrus, nonpregnant diestrus, and anestrus (group 1); 4 other healthy bitches were evaluated during pregnancy and after ovariohysterectomy (group 2). Cycle stages were determined via physical examination, vaginal cytologic evaluation, and serum progesterone concentration. Bitches with hyperadrenocorticism were evaluated once at the time of diagnosis (group 3). Serum hormone concentrations were determined with immunoassays.

RESULTS

In group 1, the serum 17OHP concentration was significantly higher in diestrus (median, 1.8 ng/mL) than in estrus (median, 1.1 ng/mL) and anestrus (median, 0.2 ng/mL) and higher in estrus than in anestrus. Changes in serum progesterone concentrations accounted for 22% (estrus) or 23% (diestrus) of the variation in serum 17OHP concentrations. In group 2, 17OHP and progesterone concentrations were significantly higher during pregnancy than after ovariohysterectomy. The serum 17OHP concentration in group 3 was significantly lower (median, 0.2 ng/mL) than in group 1 in estrus and diestrus and in group 2 during pregnancy (median, 0.7 ng/mL) but was not different from 17OHP concentrations in anestrus or after ovariohysterectomy (median, 0.2 ng/mL).

CONCLUSIONS AND CLINICAL RELEVANCE

Serum 17OHP concentrations in healthy bitches increased during estrus, diestrus, and pregnancy and at those times were higher than in spayed bitches with hyperadrenocorticism.

Follicular dysplasia of the adult doberman pinscher

This paper presents the case of an adult female, red Doberman pinscher affected by permanent hypotrichosis, limited to the dorsolumbar region and sides of the trunk. The hypotrichosis began at approximately the age of 2 years and progressed slowly with no skin hyperpigmentation. The clinical and histopathological characteristics are of an uncommon form of follicular dysplasia.

Oestrogen receptor antagonist and hair regrowth in dogs with hair cycle arrest (alopecia X)

An oestrogen receptor pathway that regulates the telogen-anagen hair follicle transition in mice has been described. The purpose of this study was to investigate whether fulvestrant, a pure oestrogen receptor antagonist, would cause hair regrowth in Pomeranian dogs with hair cycle arrest (alopecia X). Eleven Pomeranian dogs with hair cycle arrest were randomly assigned to receive two intramuscular injections of either 10 mg kg(-1) fulvestrant (n = 6) or an equal volume of saline (n = 5) 1 month apart. Complete blood count, chemistry panel, and urinalysis were monitored prior to the first injection and monthly for 2 months. Dogs were evaluated each month for degree of hair growth, percentage of body affected, and quality of new hair growth. Three control dogs received fulvestrant after the completion of the study. In addition, one control dog and one treatment dog received two subcutaneous injections of 20 mg kg(-1) fulvestrant 1 month apart. No dogs that received 10 mg kg(-1) fulvestrant had any evidence of hair regrowth. The control dog that received 20 mg kg(-1) fulvestrant had substantial hair regrowth 1 month after the first injection. No adverse effects from the treatment were noted. Fulvestrant does not appear to be a feasible treatment for dogs with hair cycle arrest (alopecia X) when administered intramuscularly at 10 mg kg(-1). A higher dose of fulvestrant requires more investigation but may be cost-prohibitive.

Cortisol, aldosterone, cortisol precursor, androgen and endogenous ACTH concentrations in dogs with pituitary-dependant hyperadrenocorticism treated with trilostane

Trilostane is thought to be a competitive inhibitor of the 3beta-hydroxysteroid dehydrogenase (3beta-HSD), an essential enzyme system for the synthesis of cortisol, aldosterone and androstenedione. Due to its reliable clinical efficacy, trilostane is increasingly used to treat dogs with pituitary-dependant hyperadrenocorticism (PDH). The objective of our study was to investigate the effect of trilostane on precursor concentrations located before (17alpha-OH-pregnenolone, dehydroepiandrostenedione) and after (17alpha-OH-progesterone, androstenedione, 11-deoxycortisol, 21-deoxycortisol) the proposed enzyme inhibition, on end products of steroid biosynthesis (cortisol and aldosterone) and on endogenous adrenocorticotrophic hormone (ACTH) concentrations in dogs with PDH. Hormones of the steroid biosynthesis pathway were evaluated in 15 dogs before and 1h after injection of synthetic ACTH prior to (t(0)), in weeks 1-2 (t(1)) and in weeks 3-7 (t(2)) of trilostane treatment. Endogenous ACTH concentrations were measured at the same time points before performing the ACTH stimulation test. During trilostane treatment baseline and post-stimulation cortisol concentrations decreased significantly. Baseline serum aldosterone levels showed a significant increase; post-stimulation values decreased. Baseline and post-stimulation 17alpha-OH-pregnenolone and dehydroepiandrostenedione concentrations increased significantly. 17alpha-OH-progesterone and androstenedione levels did not change. Post-stimulation 21-deoxycortisol concentrations decreased significantly, baseline 11-deoxycortisol concentrations increased significantly. Endogenous ACTH levels showed a significant increase. The significant increase in 17alpha-OH-pregnenolone and dehydroepiandrostenedione concentrations confirms an inhibitory effect of trilostane on the 3beta-HSD. Since 17alpha-OH-progesterone concentrations did not change, but cortisol concentrations markedly decreased, trilostane seems to influence additional enzymes of the hormone cascade, like the 11beta-hydroxylase and possibly the 11beta-hydroxysteroid dehydrogenase.

The Use of Trilostane for the Treatment of Alopecia X in Alaskan Malamutes

Three Alaskan malamutes with hair loss and slightly elevated blood concentrations of 17-hydroxyprogesterone after stimulation with adrenocorticotropic hormone (ACTH) were treated with trilostane. Trilostane, an inhibitor of 3 β-hydroxysteroid dehydrogenase, was given twice daily at a dose of 3.0 to 3.6 mg/kg per day orally for 4 to 6 months. Routine ACTH stimulation tests were performed over 8 months to evaluate the degree of adrenal function suppression. Treatment with trilostane led to complete hair regrowth in all three dogs within 6 months. No adverse effects associated with trilostane were recognized.