Update on hypothyroidism in dogs | Vets & Clinics

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Update on hypothyroidism in dogs

This post provides an update on the latest developments in hypothyroidism in dogs. We will analyse four recent abstracts available on the Vets Affinity page, plus a few more about other pathologies. 

Veterinary medicine and care

1. The effect of experimentally induced hypothyroidism on the isoflurane minimum alveolar concentration in dogs. Berry SH et al. Vet Anaesth Analg 2014 

The aim of this study was to assess the effect of experimentally induced hypothyroidism on the minimum alveolar concentration (MAC) of isoflurane in dogs. The authors looked at 18 adult female mongrel dogs, with hypothyroidism induced in half of them. The results were analysed 9–12 months after inducing the hypothyroidism in dogs.

The results were as follows:

  • The mean isoflurane MAC was 0.98 ± 0.31% in dogs with hypothyroidism versus 1.11 ± 0.26% in euthyroid dogs.
  • No statistically significant differences were found between mean isoflurane MAC in dogs with hypothyroidism and euthyroid dogs (p = 0.3553).

The authors concluded that the MAC of isoflurane in dogs did not change due to experimentally induced hypothyroidism and therefore hypothyroidism in dogs is not an indication for isoflurane dose reduction.

2. Efficacy of cefpodoxime with clavulanic acid in the treatment of recurrent pyoderma in dogs Sudhakara RB et al. Vet Sci 2014 

This article investigated disorders associated with recurrent pyoderma. These included demodicosis, Malassezia dermatitis, flea infestation, hypothyroidism and keratinisation disorders (seborrhoea).

Treatment consisted of cefpodoxime with clavulanic acid plus the concurrent medications necessary to treat any underlying associated conditions.

 In all cases, the response to treatment was excellent, with an improvement at 9 to 19 days in cases of recurrent superficial pyoderma and at 17 to 21 days for recurrent deep pyoderma.

However, one dog suffered a relapse after 45 days due to associated hypothyroidism. 

3. Exogenous thyrotoxicosis in dogs attributable to consumption of all-meat commercial dog food or treats containing excessive thyroid hormone: 14 cases (2008–2013)Broome MR et al. J Am Vet Med Assoc 2015; 246: 105-111 

Clinical findings in dogs with exogenous thyrotoxicosis due to the consumption of dog foods with a high thyroid hormone content. It was a retrospective study of just one case, with 13 more cases then being analysed prospectively.

The animals’ serum thyroid hormone levels were measured before and after eating commercially available foods. Thyroid tissue was also assessed by scintigraphy in 13 out of 14 subjects before the suspected food was discontinued and in 1 out of 13 dogs thereafter.

Serum thyroxine concentrations were high in all dogs initially. Scintigraphy revealed a decreased uptake in the gland in 13 out of 13 dogs examined.

4. Gallbladder sludge in dogs:ultrasonographic and clinical findings in 200 patients Cook AK et al. J Am Anim Hosp Assoc. 2016 Mar 23 

This study assessed whether the observation of echogenic material in the gallbladders of dogs has any pathological significance. The gallbladders of 200 dogs were examined through ultrasound and the results assessed in combination with their clinical data.

The authors reported the following results:

  • 66.5% of dogs had some hyperechoic material in the gallbladder.
  •  Dogs with > 25% biliary sludge were older than those with minimal sludge.
  • Dogs with spontaneous hyperadrenocorticism or hypothyroidism were more likely to have > 25% biliary sludge (odds ratio: 5.04).
  • The presence of > 25% biliary sludge was associated with an increase in gallbladder volume, suggesting that some changes in its function or contractility might affect the formation of biliary sludge in dogs.

Four weeks after discontinuing the suspected diet, total concentrations returned to normal in all dogs and any signs associated with thyrotoxicosis had disappeared.

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