Editing Hyperthyroidism (section)

==Other animals==

===Cats===
{{main|Feline hyperthyroidism}}
Hyperthyroidism is one of the most common endocrine conditions affecting older domesticated [[cat|housecats]]. In the United States, up to 10% of cats over ten years old have hyperthyroidism.<ref name="AAFP 2016">{{cite journal | vauthors = Carney HC, Ward CR, Bailey SJ, Bruyette D, Dennis S, Ferguson D, Hinc A, Rucinsky AR | title = 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism | journal = Journal of Feline Medicine and Surgery | volume = 18 | issue = 5 | pages = 400–416 | date = May 2016 | pmid = 27143042 | doi = 10.1177/1098612X16643252 | doi-access = free | pmc = 11132203 }}</ref> The disease has become significantly more common since the first reports of feline hyperthyroidism in the 1970s. The most common cause of hyperthyroidism in cats is the presence of [[benign tumors]] called adenomas. 98% of cases are caused by the presence of an adenoma,<ref>Johnson, A. (2014). &nbsp;Small Animal Pathology for Veterinarian Technicians. Hoboken: Wiley Blackwell.</ref> but the reason these cats develop such tumors continues to be studied.

The most common presenting symptoms are: rapid [[weight loss]], [[tachycardia]] (rapid heart rate), [[vomiting]], [[diarrhea]], increased consumption of fluids ([[polydipsia]]), increased appetite ([[polyphagia]]), and increased urine production ([[polyuria]]). Other symptoms include hyperactivity, possible aggression, an unkempt appearance, and large, thick [[claws]]. [[Heart murmurs]] and a [[gallop rhythm]] can develop due to secondary [[hypertrophic cardiomyopathy]].  About 70% of affected cats also have enlarged thyroid glands ([[goiter]]). 10% of cats exhibit "apathetic hyperthyroidism", which is characterized by anorexia and lethargy.<ref name=Gra2014>{{cite journal | vauthors = Vaske HH, Schermerhorn T, Armbrust L, Grauer GF | title = Diagnosis and management of feline hyperthyroidism: current perspectives | journal = Veterinary Medicine: Research and Reports | volume = 5 | pages = 85–96 | date = August 2014 | pmid = 32670849 | pmc = 7337209 | doi = 10.2147/VMRR.S39985 | doi-access = free }}</ref>

The same three treatments used with humans are also options in treating feline hyperthyroidism (surgery, radioiodine treatment, and anti-thyroid drugs). There is also a special low iodine diet available that will control the symptoms providing no other food is fed; Hill's y/d formula, when given exclusively, decreases T4 production by limiting the amount of iodine needed for thyroid hormone production. It is the only available commercial diet that focuses on managing feline hyperthyroidism. Medical and dietary management using methimazole and Hill's y/d cat food will give hyperthyroid cats an average of 2 years before dying due to secondary conditions such as heart and kidney failure.<ref name=Gra2014/> Drugs used to help manage the symptoms of hyperthyroidism are methimazole and carbimazole. Drug therapy is the least expensive option, even though the drug must be administered daily for the remainder of the cat's life. Carbimazole is only available as a once daily tablet. Methimazole is available as an oral solution, a tablet, and compounded as a [[topical medication|topical gel]] that is applied using a [[finger cot]] to the hairless skin inside a cat's ear. Many cat owners find this gel a good option for cats that don't like being given pills.{{cn|date=July 2024}}

Radioiodine treatment, however, is not available in all areas, as this treatment requires nuclear radiological expertise and facilities that not only board the cat, but are specially equipped to manage the cat's urine, sweat, saliva, and stool, which are radioactive for several days after the treatment, usually for a total of 3 weeks (the cat spends the first week in total isolation and the next two weeks in close confinement).<ref>{{cite web| vauthors = Little S |title=Feline Hyperthyroidism |url=http://www.winnfelinehealth.org/Pages/Feline_Hyperthyroidism_Web.pdf |year=2006 |publisher=Winn Feline Foundation |access-date=24 June 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090509070957/http://www.winnfelinehealth.org/Pages/Feline_Hyperthyroidism_Web.pdf |archive-date=9 May 2009}}</ref> In the United States, the guidelines for radiation levels vary from state to state; some states such as Massachusetts allow hospitalization for as little as two days before the animal is sent home with care instructions.{{cn|date=July 2024}}

===Dogs===
Hyperthyroidism is much less common in [[dog]]s compared to cats.<ref>{{cite book| vauthors = Ford RB, Mazzaferro E |title=Kirk & Bistner's Handbook of Veterinary Procedures and Emergency Treatment|date=2011|publisher=Elsevier Health Sciences|location=London|isbn=978-1-4377-0799-1|page=346|edition=9th}}</ref> Hyperthyroidism may be caused by a thyroid tumor. This may be a thyroid [[carcinoma]]. About 90% of carcinomas are very aggressive; they invade the surrounding tissues and [[Metastasis|metastasize]] (spread) to other tissues, particularly the lungs. This has a poor [[prognosis]]. Surgery to remove the tumor is often very difficult due to [[metastasis]] into [[arteries]], the [[esophagus]], or the [[windpipe]]. It may be possible to reduce the size of the tumor, thus relieving symptoms and allowing time for other treatments to work.{{Citation needed|date=April 2010}} About 10% of thyroid tumors are benign; these often cause few symptoms.{{Citation needed|date=April 2010}}

In dogs treated for [[hypothyroidism]] (lack of thyroid hormone), iatrogenic hyperthyroidism may occur as a result of an overdose of the thyroid hormone replacement medication, [[levothyroxine]]; in this case, treatment involves reducing the dose of levothyroxine.<ref name=HypoT>{{cite web|url=http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/40602.htm|title=Hypothyroidism|publisher=Merck Veterinary Manual|access-date=27 July 2011|url-status=live|archive-url=https://web.archive.org/web/20110526152610/http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm%2Fbc%2F40602.htm|archive-date=26 May 2011}}</ref><ref>{{cite web|url=http://usa.leventa.com/Vet/label.asp|title=Leventa-Precautions/Adverse Reactions|publisher=Intervet|access-date=27 July 2011|url-status=live|archive-url=https://web.archive.org/web/20120114181242/http://usa.leventa.com/Vet/label.asp|archive-date=14 January 2012}}</ref> Dogs which display [[coprophagy]], the consumption of feces, and also live in a household with a dog receiving levothyroxine treatment, may develop hyperthyroidism if they frequently eat the feces from the dog receiving levothyroxine treatment.<ref name="Shadwick 2013">{{cite journal | vauthors = Shadwick SR, Ridgway MD, Kubier A | title = Thyrotoxicosis in a dog induced by the consumption of feces from a levothyroxine-supplemented housemate | journal = The Canadian Veterinary Journal | volume = 54 | issue = 10 | pages = 987–989 | date = October 2013 | pmid = 24155422 | pmc = 3781434 }}</ref>

Hyperthyroidism may occur if a dog eats an excessive amount of thyroid gland tissue. This has occurred in dogs fed commercial dog food.<ref name="Broome 2015">{{cite journal | vauthors = Broome MR, Peterson ME, Kemppainen RJ, Parker VJ, Richter KP | title = Exogenous thyrotoxicosis in dogs attributable to consumption of all-meat commercial dog food or treats containing excessive thyroid hormone: 14 cases (2008-2013) | journal = Journal of the American Veterinary Medical Association | volume = 246 | issue = 1 | pages = 105–111 | date = January 2015 | pmid = 25517332 | doi = 10.2460/javma.246.1.105 | doi-access = free }}</ref>