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petplan pet insurance presents a closer look at hyperthyroidism in cats


For our next discussion, let’s first paint a very brief picture:


Imagine an older cat, a little cranky, thinner than he used to be, but with a great appetite. Perhaps he vomits or has diarrhea a little more frequently, and he isn’t grooming himself nearly as well as when he was younger. You notice that he is more likely to find that sunny spot in the window to warm himself, and maybe you are cleaning bigger or more numerous clumps out of his litter box… 

Many of us would attribute these signs to old age, just being a cat, or perhaps we wouldn’t even notice these behaviors as being any different because they came on so gradually. Even more likely, your older cat may only be exhibiting one or two of these changes. What does it all mean? Well, as you can imagine, these are very non-specific signs (especially each on their own), but when we put them all together, with a thorough physical exam, we might find that we are dealing with hyperthyroidism. 

What is hyperthyroidism? In short, it is the overproduction of thyroid hormones. It is a disease seen often in cats, particularly seniors over 10 years of age, but rarely in dogs (who are much more prone to the converse condition, hypothyroidism), so for today we’ll focus on our feline friends.

Hyperthyroidism, in most cases, is relatively easy to diagnose and treat, and cats generally respond very well to treatment. (Here comes the however…) However, hyperthyroidism can lead to and hide a variety of other diseases, which can be more difficult to manage, and costly without the peace of mind of cat insurance from Petplan pet insurance.

But let’s not get ahead of ourselves. Let’s first discuss hyperthyroidism itself, and then in the next blog we will discuss these associated diseases.

As mentioned, hyperthyroidism is seen most commonly in older cats, and the clinical signs often include all or some of the following:

  • Weight loss
  • Ravenous appetite: These are the cats that suddenly start waking you up to feed them, or attack your ankles every time you walk by their food dish to “convince” you to give them another scoop-full.
  • Unkempt hair coat: Remember when kitty had that beautiful, shiny, lustrous hair coat?  Now it’s greasy, clumpy, and brittle.
  • Increased thirst (polydipsia)/increased urination (polyuria): Usually pet parents notice a water bowl that suddenly needs to be filled more often, or a litter box that has gotten heavier/needs to be scooped more frequently.
  • GI upset: vomiting and/or diarrhea
  • Heat intolerance:  These cats look for the warmest spot in the house
  • Restlessness, aggression, nervousness

Pet parents may not realize that there is anything out of the ordinary, because the signs can develop slowly over time. Oftentimes, these subtle changes are discovered at your cat’s annual wellness exam, and your veterinarian may notice one or more of the following during a physical examination (in addition to those changes noted above):

  • Tachycardia (increased heart rate)
  • Heart murmur that was never before appreciated
  • Goiter (enlargement of the thyroid gland felt on palpation of your cat’s neck): This is oftentimes referred to as a “thyroid slip”
  • Generalized muscle loss
    rthyroidism is with blood work. Your vet will likely recommend a chemistry panel, a complete blood count (CBC), and a T4 (thyroid hormone). Depending on these results, it may be necessary to add on another test, called a free T4, to more definitively diagnose hyperthyroidism. Don’t be surprised if your vet also recommends a urinalysis and takes blood pressure measurements (more on this next time).

Fortunately, a diagnosis of hyperthyroidism is not, in itself, a cause for excessive worry. In an upcoming blog, we will discuss the treatment options your vet will likely discuss with you and the follow-up care you can expect. We will also discuss the aforementioned “other diseases” that hyperthyroidism can hide and/or cause.

To more waggin’ and purrin’. rwkj

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Chris AshtonCo-Founder and Co-CEO of Petplan Pet Insurance
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Visit your vet at least once a year to keep your pet protected from preventable diseases.