Are persistent organic pollutants important in the etiology of feline hyperthyroidism? A review

Abstract

Feline hyperthyroidism is a rather new disease, first reported from the North American east coast in 1979. The prevalence is increasing, especially in older cats, and hyperthyroidism is now reported worldwide as the most common feline endocrinopathy. Several studies have been performed trying to identify important etiological factors such as exposure to persistent organic pollutants, and especially brominated flame retardants, have been suggested to be of importance for the development of the disease. Recent studies have shown higher concentrations of these contaminants in serum of hyperthyroid cats in comparison to cats with normal thyroid status. However, other still unknown factors are most probably of importance for the development of this disease.

Feline Comorbidities: Balancing hyperthyroidism and concurrent chronic kidney disease

“…5,12,16 Raised awareness of the condition, widespread availability of diagnostic tests and ageing of the cat population may all be playing a role; however, environmental, genetic, hereditary and goitrogenic risk factors, such as dietary components, additives and pollutants, could also be contributing factors. 1,5,8,[17][18][19] Chronic kidney disease (CKd) is prevalent in older cats, with over 80% having evidence of the condition by 15 years of age 20 and over 30% of cats in this age group having azotaemic CKd. 21 A number of risk factors for developing CKd have been identified, including frequent vaccination, 22 the presence of dental disease, 22,23 a thin body condition and a history of a cystitis episode or a general anaesthetic within the previous 12 months.…”

“…5,12,16 Raised awareness of the condition, widespread availability of diagnostic tests and ageing of the cat population may all be playing a role; however, environmental, genetic, hereditary and goitrogenic risk factors, such as dietary components, additives and pollutants, could also be contributing factors. 1,5,8,17–19…”

Per- and polyfluoroalkyl substances (PFASs) in Swedish household dust and exposure of pet cats

“…In addition, cats have an increasing prevalence of developing hyperthyroidism, an endocrine disorder also increasing in humans, and associations have been found between elevated levels of certain polybrominated diphenyl ethers (PBDEs) in hyperthyroid cats compared to levels in healthy cats (Norrgran et al 2015 ). Feline hyperthyroidism is manifested as a disturbed upregulation of the thyroid hormone (TH), thyroxine (T4) concentration, and downregulation of thyroid stimulating hormone (TSH), with clinical consequences such as weight loss, polyphagia, polydipsia, hyperactivity, aggression, diarrhea, vomiting, and tachycardia (Jones et al 2019 ; Peterson and Ward 2007 ).…”