[attrition] Diagnosing Figlet - An Overview of Hyperthyroidism in Guinea Pigs

[security curmudgeon]

http://attrition.org/~jericho/gpigs/case-figlet.html

Diagnosing Figlet - An Overview of Hyperthyroidism in Guinea Pigs
Thu Feb 4 09:37:27 UTC 2010

Summary

"Hyperthyroidism is a condition in which the thyroid gland is overactive, 
and makes too much thyroid hormone (called thyroxine and 
triiodothyronine). Hormones are substances that affect and control many 
important functions in the body." [1]

While many animals have significant differences from humans and each 
other, many aspects of hyperthyroidism are the same across species. In 
guinea pigs (Cavia porcellus), this condition is thought to be extremely 
rare. Recent anecdotal evidence suggests that it may be more common than 
many veterinarians previously believed. Hyperthyroidism can cause serious 
problems with other parts of the body such as the heart, kidney and lungs. 
When diagnosing guinea pigs, problems in these organs are not always 
thought to be systemic. Given poor breeding habits and the fragile guinea 
pig body, when a kidney or lungs develop serious issues, there is often 
little hope for the animal. Doing further investigation to determine why 
the organs are failing is rarely done for a variety of reasons, primarily 
the perception of guinea pigs as 'just rodents' and the high cost of 
medical procedures on an animal that is likely near death.

I recently lost a guinea pig, Figlet, to hyperthyroidism, but learned a 
lot about it during the process. Because it is often difficult to obtain a 
definitive diagnosis, and because of the lack of information available on 
the condition as found in guinea pigs, I am publishing my observations and 
the case history of Figlet. This article is targeted toward guinea pig 
owners, but will contain a good deal of technical information that will be 
of interest to veterinarians. I am in a relatively unique position to 
write this article. First, confirmed diagnosis of hyperthyroidism is very 
rare in guinea pigs, as was the case for Figlet. Second, I happen to live 
in the same state as one of the very few doctors who have specifically 
studied this condition in guinea pigs. Third, I have a strong desire to 
help educate other guinea pig owners as they often care deeply for their 
animals, but suffer with the rest of us due to a lack of in-depth 
knowledge about guinea pig health.

Guinea pigs who develop hyperthyroidism may exhibit several symptoms that 
help diagnose this condition. These symptoms are not specific to the 
condition and may manifest to varying degrees or not at all. If you have a 
guinea pig that exhibits many of these systems, consult your veterinarian. 
These are described in more detail, as pertained to Figlet later:

     * Excessive and frequent urination -- Often difficult to observe, 
especially in a multi-pig cage.
     * Enlarged thyroid nodules -- Early development may be impossible to 
detect. Advanced cases may be as large as a pea and easily felt during 
palpation by owner or vet.
     * Excessive energy / very active -- May seem to sleep less, run around 
more, exhibit more energy in or out of cage.
     * Increased appetite and thirst for water -- May be difficult to 
observe in a multi-pig cage.
     * Weight loss -- Even if eating more than usual, an observed steady 
weight loss.
     * Higher temperature and/or heat intolerance -- Guinea pig may seek 
cool surfaces, avoid warm fleece and be warmer to touch than other pigs.

If your guinea pig exhibits these symptoms, consult a veterinarian. Be 
warned, many vets do not specialize in "exotics" (the term used by vets to 
describe most rodents, reptiles and birds). They will likely have no 
experience with hyperthyroidism in guinea pigs and will rely on their 
knowledge of the condition as pertains to cats. There is only a single 
test (nuclear scintigraphy) that can definitively diagnose the condition 
in guinea pigs, and it may be costly or not available from most vets. 
Blood work can only give an 'indication' and palpation of the thyroid 
gland may not reveal the mass until the condition has progressed. If left 
untreated, hyperthyroidism can lead to serious problems in the heart, 
kidney, lungs, spleen and possibly other organs. Surgery to remove the 
mass is possible, but very expensive and rarely performed.

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