Abstract
On pages 400–416 of this issue we present the 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism (FHT). The disease occurs throughout the world and in the US affects about 10% of feline patients over 10 years of age. It emerged as a new problem in cats just over 35 years ago and, although our understanding of the disease has evolved significantly, we still have many questions. Several excellent recent reviews of the history, pathogenesis, epidemiology and incidence of FHT are available, so we chose specifically to emphasize clinical aspects of disease management.
Today we less commonly see the ‘classic’ hyperthyroid cat that is hyperactive, losing weight in spite of a ravenous appetite and has a prominent mass in its neck. Instead we diagnose more cases at an early stage in disease progression, often before the cat shows overt clinical signs; this is largely because feline geriatric screening panels now routinely include serum thyroxine (T4). And because age is a risk factor for the disease, we have realized that FHT case presentations and diagnostic testing results may be ambiguous due to the presence of other age-related comorbidities such as heart disease, diabetes mellitus, gastrointestinal dysfunction and chronic kidney disease (CKD).
These newer clinical presentations seem to fall into six categories, and we have developed a diagnostic and management strategy for each. This has allowed us to answer such questions as how to recognize the health significance of early presentations of the disease, how early to treat the disease, and whether to treat FHT when comorbid conditions are present, especially CKD and cardiac disease.
In addition to the novel approach of viewing FHT from a clinical presentation standpoint, we have chosen to refute many of the myths that surround aspects of the disease and replace them with an evidence-based narrative that veterinarians and their practice teams can apply to feline patients and communicate to their owners.
Most importantly, because FHT is life-threatening, we recommend treatment of all hyperthyroid cats, with concurrent management of any comorbidity. We outline the currently available treatments for the disease, offer suggestions to help guide treatment selection and summarize expected outcomes. We have also developed two client handouts; one explaining disease management in general (pictured), and one outlining the advantages and disadvantages of the four common therapeutic modalities.
Our Advisory Panel included primary and referral clinicians in both feline-exclusive and canine–feline practices. Their vast knowledge and experience with current clinical aspects of FHT allowed us to create this novel approach to case management. We greatly appreciate their enthusiasm about their goal of ensuring treatment for each hyperthyroid cat and for eliminating the myths that have prevented treatment of cats that could have lived longer, healthier lives. We also thank Dr Ed Kanara and Mr Mark Dana who skillfully guided the process.
FHT is a disease of senior cats that, more often than not, we can cure or successfully manage thanks to better awareness, routine screening tests and a variety of readily available treatment options. It is our hope that these AAFP Guidelines will help clinicians accomplish this goal.