Iodine-restricted food versus pharmacological therapy in the management of feline hyperthyroidism: A controlled trial in 34 cats

The standards of reporting trials in pets (PetSORT): Explanation and elaboration

Well-designed randomized controlled trials (RCTs) provide the best evidence of the primary research designs for evaluating the effectiveness of interventions. However, if RCTs are incompletely reported, the methodological rigor with which they were conducted cannot be reliably evaluated and it may not be possible to replicate the intervention. Missing information also may limit the reader's ability to evaluate the external validity of a trial. Reporting guidelines are available for clinical trials in human healthcare (CONSORT), livestock populations (REFLECT), and preclinical experimental research involving animals (ARRIVE 2.0). The PetSORT guidelines complement these existing guidelines, providing recommendations for reporting controlled trials in pet dogs and cats. The rationale and scientific background are explained for each of the 25 items in the PetSORT reporting recommendations checklist, with examples from well-reported trials.

Radioiodine treatment in hyperthyroid cats: insights into the characteristics of owners and their cats, and owner motivation and perceptions

OBJECTIVES

Radioiodine (131I) therapy is the most appropriate treatment option for many hyperthyroid cats, as it is minimally invasive and often curative. Nevertheless, 131I treatment is not always pursued by owners. Hence, it is important to obtain more insight into owner satisfaction during and after 131I treatment, and their decision-making process. In this study, we describe the characteristics of owners and their hyperthyroid cats referred for 131I therapy, and determine owners' motivation and how they experienced the 131I treatment of their cat.

METHODS

A survey was sent to owners whose cats underwent 131I therapy (n = 1071) between 2010 and 2017 at Ghent University. The survey contained 35 questions with tick-box or free-text answer options concerning family situation, pet insurance, previous therapy, comorbidities, motivation for 131I therapy and owner perception of this treatment.

RESULTS

In total, 438 owners completed 94% or more of the questionnaire. Over half of the cats (55%) had received previous medical, dietary or surgical treatment. Motivations for changing the initial therapy to 131I therapy included difficulties in administering medication (31%), insufficient improvement in clinical signs (23%), side effects (16%) and following the referring veterinarian's advice (16%). Almost a fifth of owners (18%) were not informed about the existence of 131I therapy by their veterinarian and found information on 131I treatment online or through friends. Hospitalising their cat was very distressing for 17% of owners. Most owners (92%) were satisfied with the treatment. Reasons for dissatisfaction were insufficient communication, iatrogenic hypothyroidism, persistent hyperthyroidism and comorbidities post-treatment.

CONCLUSIONS AND RELEVANCE

Our study stresses the importance of communication regarding the possible outcome of 131I treatment, the importance of managing underlying comorbidities before treatment and anticipating the stress of owners during their cat's hospitalisation period. The results of this study could help in improving client communication when advising on 131I treatment.

The Prevalence, Magnitude, and Reversibility of Elevated Liver Enzyme Activities in Hyperthyroid Cats Presenting for Iodine-131 Treatment

Objectives

The primary objective of this study was to report the prevalence and magnitude of elevated liver enzyme activity in feline hyperthyroidism using a large cohort of cats presenting for iodine-131 treatment. The secondary objective was to determine if elevated liver enzyme activity was a reversible process following successful iodine-131 treatment.

Methods

Cases that presented for a single iodine-131 treatment were retrospectively reviewed. Short-term and long-term follow-up clinicopathologic data was then reviewed for the secondary objective.

Results

Two hundred seventeen hyperthyroid cats met the inclusion criteria for the primary objective. In total, 123/217 (56.7%) of the cats had at least one liver enzyme elevation on their chemistry panel, with alanine transaminase activity being the most common. All cats who were successfully treated with iodine-131 had liver enzyme activity within the reference range at short-term follow-up and long-term follow-up points.

Conclusion and Relevance

Our study demonstrates that elevated liver values are common in cats presenting for iodine-131 treatment. Additionally, our study demonstrates that even when liver values are markedly elevated prior to treatment, the liver enzyme activity will return to normal after successful resolution of hyperthyroidism using iodine-131 treatment. Investigation into hepatobiliary disease and liver function tests for cats with a diagnosis of hyperthyroidism may be unnecessary as the liver values will likely return to normal with successful iodine-131 treatment.

Hyperthyroidism in Cats: Considering the Impact of Treatment Modality on Quality of Life for Cats and Their Owners

In cats, hyperthyroidism can be treated in 4 ways: medical management with methimazole or carbimazole, nutritional management (low-iodine diet), surgical thyroidectomy, and radioactive iodine (¹³¹I). Each form of treatment has advantages and disadvantages that should be considered when formulating a treatment plan for the individual hyperthyroid cat. Medical and nutritional managements are considered "reversible" or palliative treatments, whereas surgical thyroidectomy and ¹³¹I are "permanent" or curative treatments. The author discusses how each treatment modality could be the optimal choice for a specific cat-owner combination and reviews the advantages and disadvantages of each treatment option.