Autoimmune polyendocrine syndrome in a standard poodle with concurrent non‐endocrine immune‐mediated diseases

Case Report: The potential association with polyglandular autoimmune syndrome in a dog following long-term oclacitinib therapy

A 12-year-old spayed female Maltese dog had been receiving oclacitinib, a Janus kinase (JAK) inhibitor, for 7 years to manage chronic pruritus due to atopic dermatitis. During this treatment, the dog was diagnosed with primary hypoadrenocorticism and hypothyroidism based on history, physical examination, and hormonal analysis. This case was initially suspected to be polyglandular autoimmune syndrome (PAS) based on long-term treatment of oclacitinib. To confirm the diagnosis of PAS, the presence of autoantibodies was tested. 21-hydroxylase autoantibodies (21-OHAb) were detected, but negative for thyroglobulin autoantibodies (TgAA). Considering the potential of oclacitinib to induce autoimmune diseases, we examined to identify the association of interleukin-10 (IL-10) in PAS of the dog. This case suggests a potential association between prolonged oclacitinib administration and the development of PAS in a dog. Regular hormonal monitoring and careful dose adjustments of oclacitinib during long-term therapy of atopic dermatitis are recommended to minimize the risk of autoimmune disease development. To the best of our knowledge, this is the first case report suggesting that PAS could be induced by oclacitinib.

Longitudinal assessment of thyroid function in dogs with hypoadrenocorticism: Clinical outcomes and prevalence of autoantibodies

BACKGROUND

Knowledge about primary hypoadrenocorticism coexisting with immune-mediated thyroiditis (Schmidt's syndrome) in dogs is limited.

OBJECTIVE

To evaluate thyroid function in dogs with naturally occurring hypoadrenocorticism before and during treatment.

ANIMALS

Sixty-six client-owned dogs.

METHODS

Measurement of canine thyroid stimulating hormone (cTSH), total thyroxine (T4), free thyroxine, and autoantibodies against thyroglobulin, T4, and total triiodothyronine.

RESULTS

Thirty-eight dogs were assessed before and 28 during treatment. Follow-up data were available for 24/38 and 17/28 dogs, with median follow-up duration of 3.8 years (range, <1.0-8.8 years) and 4 years (range, 1.1 weeks to 10.5 years), respectively. Canine thyroid stimulating hormone was above the reference range at the time of diagnosis of hypoadrenocorticism in 10 of 38 dogs but decreased into the reference range in 7 for which follow-up data was available. Hypothyroidism was confirmed in 5 dogs at a median age of 11 years (range, 7-15 years). In 4 dogs, the condition was diagnosed after a median treatment duration of 5.75 years (range, 2.6-10 years), while in 1 dog, the diagnosis was made concurrently. One dog had detectable thyroid autoantibodies.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypothyroidism occurs as a rare concurrent condition in dogs with hypoadrenocorticism, potentially at any phase of treatment. Close monitoring of cTSH levels in these dogs could be beneficial, as early changes might indicate the onset of hypothyroidism. The low prevalence of detectable thyroid autoantibodies suggests that nonimmune mechanisms might contribute to thyroid dysfunction.

Hypothalamic-pituitary-adrenal axis recovery after intermediate-acting glucocorticoid treatment in client-owned dogs

BACKGROUND

In dogs, duration of hypothalamic-pituitary-adrenal (HPA) axis suppression after systemic glucocorticoid treatment is reported to vary from a few days to up to 7 weeks after glucocorticoid discontinuation. These data are derived mainly from experimental studies in healthy dogs and not from animals with spontaneous disease.

HYPOTHESIS AND OBJECTIVE

To determine the timeline for recovery of the HPA axis in a group of ill dogs treated with intermediate-acting glucocorticoids (IAGCs).

ANIMALS

Twenty client-owned dogs that received IAGC for at least 1 week.

METHODS

Single-center prospective observational study. An ACTH stimulation test, endogenous ACTH concentration, serum biochemistry profile, and urinalysis were performed at T0 (2-6 days after IAGC discontinuation) and then every 2 weeks (eg, T1, T2, T3) until HPA axis recovery was documented (post-ACTH cortisol concentration > 6 μg/dL).

RESULTS

The median time of HPA axis recovery was 3 days (range, 2-133 days). Eleven of 20 dogs showed recovery of the HPA axis at T0, 6/20 at T1, and 1 dog each at T2, T5, and T9. Dose and duration of treatment were not correlated with timing of HPA axis recovery. Activities of ALT and ALP were significantly correlated with the post-ACTH cortisol concentration (rs = -0.34, P = .03; rs = -0.31, P = .05). Endogenous ACTH concentration was significantly correlated with pre (r = 0.72; P < .0001) and post-ACTH cortisol concentrations (r = 0.35; P = .02). The timing of HPA axis recovery of the dogs undergoing an alternate-day tapering dose was not different compared to dogs that did not (3.5 vs 3 days, P = .89).

CONCLUSION AND CLINICAL IMPORTANCE

Most dogs experienced HPA axis recovery within a few days after IAGC discontinuation. However, 2/20 dogs required >8 weeks.

[Polyendocrine syndromes in dogs]

The autoimmune polyendocrine syndrome (APS) refers to a combination of autoimmune endocrine disorders. It is rarely described in dogs. The most common combinations are hypoadrenocorticism and hypothyroidism, followed by diabetes mellitus, and less often hypoparathyroidism and orchitis. The diagnosis of the APS is based on the diagnosis of each endocrinopathy, as is the therapy, which involves the substitution of deficient hormones. If a patient was previously stable under treatment and is showing further signs (e.g. polyuria, polydipsia, or weight loss), the development of additional endocrinopathies like hypoadrenocorticism or diabetes mellitus should be considered. The diagnosis of the initially diagnosed endocrinopathy should also be critically questioned. This article summarizes some cases of our own animal hospital and selected cases published in the available literature.

Histopathological evaluation of the adrenal glands in a cat with primary hypoadrenocorticism and multiple endocrine disease

Case summary

A 6-year-old male neutered domestic longhair cat was referred for investigation of weight loss, hyporexia, vomiting and diarrhoea. The cat was diagnosed with primary hypoadrenocorticism, exocrine pancreatic insufficiency, cobalamin deficiency and a chronic enteropathy, and started on therapeutic treatment. Diabetes mellitus developed 4.5 months later, and the cat was started on insulin therapy. The cat was euthanased 10 months following the diagnosis of hypoadrenocorticism due to the development of status epilepticus, which was not associated with glucose or electrolyte abnormalities. Histopathological assessment of the adrenal glands at post-mortem examination documented lymphoplasmacytic adrenalitis, with the lymphocytic population being predominant. Immunohistochemical staining classified the lymphocytic infiltrate as T-cell rich, supportive of the cat's hypoadrenocorticism being due to autoimmune disease.

Relevance and novel information

This case documents the novel use of immunohistochemical staining in combination with histopathology to further assess the adrenal glands in non-neoplastic-associated primary hypoadrenocorticism in a cat. This identified similar pathological changes to those previously described in dogs with autoimmune primary hypoadrenocorticism. Additionally, this is the first report of a cat with multiple endocrine disease that included primary hypoadrenocorticism and highlights that monitoring for the development of additional endocrine disease should be advised in these cases.