Hypothyroidism in Dogs

Canine Hypothyroidism - ‘Szadee'

szadee before treatmentSzadee is a 3 year old female Staffy who was seen at our clinic after her owners noticed her activity levels had decreased and she had put on weight. Despite a strict calorie-controlled diet Szadee had not lost weight, in fact she had gained over a kilo! Szadee had also developed hairloss and dandruff along her flanks and a ‘tragic' facial expression. Canine hypothyroidism was strongly suspected and a blood test confirmed the diagnosis.

Szadee was started on twice daily thyroid hormone supplementation and her owners noticed a dramatic improvement. She became more active, her haircoat improved and she now has a happy facial expression rather than a tragic one! She also before treatment  right sidebegan to lose weight. A follow up blood test confirmed her thyroid hormones were now within normal range. Szadee will require lifelong medication and regular monitoring but her owners are very happy at her improvement.

Canine hypothyroidism is a common hormonal disease caused by destruction of the thyroid gland. It is most common in middle-aged dogs and certain breeds are more commonly affected, including Golden Retrievers, Boxers and Miniature Schnauzers. Thyroid hormones are involved in the regulation metabolism so a deficiency of these hormones causes a variety of different signs. The most common signs are:

      • weight gain
      • lethargy
      • weakness/exercise intolerance
      • skin abnormalities such as hair loss (often symmetrical and on the flanks), dandruff or skin infections
      • development of a ‘tragic' facial expression due to swelling of the tissues of the face

As you can see, Szadee presented with all these changes, but many dogs will only have one or two, making the diagnosis more challenging. Using blood tests to diagnose the condition can also present issues, again in this case Szadee was relatively straightforward but there is no test for hypothyroidism that is 100% accurate and a frustratingly large number of dogs will have ‘equivocal' results, meaning additional testing may be needed.

happy dog with thyroxineOnce diagnosed, treatment for hypothyroidism involves giving replacement thyroid hormones for life. The dose is initially estimated based on the dogs weight and a follow up blood test used to check the dose, usually adjustments will need to be made to avoid over- or under-dosing. Regular monitoring is then required as dose requirements may change.

Hypothyroidism is generally a very rewarding disease to treat for both owners and vets as the improvement is usually so pronounced. Generally improvement in activity levels and weight loss occur first, skin and coat changes may be slower.