Laboratory indicators of hypothyroidism and TgAA-positivity in the Eurasian dog breed

Abstract

Background Hereditary hypothyroidism represents a concern for dog breeders; thus, surveillance programs have been established for several dog breeds. Methods Thyroid profiles (total thyroxine (TT4), thyrotropin (thyroid stimulating hormone (TSH)), and thyroglobulin autoantibodies (TgAA)) collected as part of a breed surveillance program in Eurasians (2009–2017) were retrospectively analyzed. The study included data from 1,501 Eurasians from a German breeding club. Classification was exclusively based on laboratory data. Hypothyroidism was defined as a combined decrease in TT4 and increase in TSH in serum and was classified as TgAA-positive and TgAA-negative hypothyroidism. Thyroglobulin autoantibodies (TgAA) independent of the concentrations of TT4 and TSH were determined. The overall prevalence of hypothyroidism, TgAA-positive hypothyroidism, TgAA-negative hypothyroidism and TgAA-positivity was assessed when the dogs entered the program. Follow-up laboratory data was available for 324 dogs without hypothyroidism on initial examination. Results The initial screening was performed at a median age of 18 months (interquartile range (IQR): 15–29). The overall prevalence of hypothyroidism was 3.9% (n = 58; 95% CI: 2.9–4.8%) and the prevalence of a positive TgAA status was 7.9% (n = 118; 95% CI: 6.6–9.3%). The prevalence of TgAA-positive and TgAA-negative hypothyroidism was 1.7% (n = 26; 95% CI: 1.1–2.4%) and 2.1% (n = 32; 95% CI: 1.4–2.9%), respectively. 22.0% of dogs with positive TgAA status (26/118) were already hypothyroid on initial examination. Overall, 42.5% (17/40) of TgAA-positive dogs on initial examination developed hypothyroidism on follow-up. Conclusion The results of this study demonstrate that the Eurasian dog breed exhibits a relevant risk for hypothyroidism and presence of TgAA. The predictive value of TgAA for hypothyroidism or developing hypothyroidism was high in this breed. Further investigations with longitudinal studies in individual dogs are warranted.

Juvenile primary acquired hypothyroidism in a dog with suspected renal dysplasia

“…At first presentation, 26/118 TgAA-positive dogs were found to be hypothyroid (defined as low serum tT4 and high TSH) without reported clinical signs. 7 The median and mean ages of TgAA-positive hypothyroidism in this cohort were 1 and 2.23 years, respectively. With the absence of clinical signs reported in this group, this may further support that clinicopathological changes of hypothyroidism can pre-date typical clinical disease.…”

“…3 Diagnosis of lymphocytic thyroiditis can be achieved through documentation of a positive TgAA titre, although a negative titre may be seen in later stages of disease. 7 Renal dysplasia is a developmental disorder of the kidneys, which can lead to early-onset azotaemia and progressive renal dysfunction. While histopathology of affected kidneys is required for definitive diagnosis, [8][9][10] in cases with appropriate signalment and clinicopathologic abnormalities, ultrasound findings are often deemed adequate, 11 and reportedly corroborate with severity on histopathology.…”

Alterations in serum concentrations of visfatin and betatrophin in dogs with hypothyroidism

“…Thyroid evaluation included measurement of free thyroxine (FT4) and thyroid stimulating hormone (TSH; Canine Free T4 and Canine TSH, Diagnostic Products Corporation Immulite, Siemens, New Jersey). [22][23][24][25] The referring veterinarian of each newly diagnosed hypothyroid dog identified at the referral laboratory was contacted and with the dog's owner consent, the medical record was reviewed and a fasted pretreatment serum sample was collected. Dogs were included in the study group if the following inclusion criteria were met: (1) a combination of decreased serum FT4 concentration (reference range, 0.6-3.0 ng/dL) and increased TSH serum concentration (reference range, 0.03-0.40 ng/mL), 22,24 The control group included healthy dogs selected from the population of client-owned dogs from veterinary practices served by the referral laboratory during the same time period that were approximately matched by sex to the hypothyroid dogs, and their ages and BCS (1-9 scale) 26 were within similar ranges of those of the hypothyroid dogs.…”

Polyendokrine Syndrome beim Hund

“…An der großen Altersspanne wird deutlich, dass Hunde in jedem Alter weitere Endokrinopathien entwickeln können. Eine aktuelle Studie von Schlipf et al [30] zur Hypothyreose bei Eurasiern zeigte, dass diese häufig schon im Alter von 2 bis 4 Jahren erkranken. Das mittlere Alter bei Diagnose der ersten Endokrinopathie betrug bei Blois et al [4] 7,9 Jahre, wobei der jüngste Hund 3,1 Jahre alt war.…”

“…Im letzten Stadium, der nicht-entzündlichen atrophischen Hypothyreose, sind sie auf Grund des Rückgangs der Entzündung nicht mehr oder nur noch in geringen Mengen vorhanden [19,37]. Eine aktuelle Studie von Schlipf et al [30] beschrieb ein erhöhtes Risiko für eine Hypothyreose und TgAA bei Eurasiern, zu denen auch die Hündin aus Fall 1 gehört. Außerdem konnten die Autoren der zitierten Studie einen hohen positiven Vorhersagewert für TgAA zur Entwicklung einer Hypothyreose nachweisen.…”