Guinea Pigs and Hyperthyroidism

Guinea Pigs develop hyperthyroidism and can be treated with i-131.

Signs include hyperactivity and hyperesthesia combined with increased eating but the pets appear thin or are losing weight. Other common but inconsistent clinical findings include diarrhea or soft stool, increased thirst and urination, and a palpable mass in the neck.

Diagnosis can be difficult since thyroxine (T4) levels do not always correlate well with the disease. A T4 level higher than 5.2 mg/dL is considered diagnostic. In cases where the pet is showing hyperthyroid signs (especially a palpable neck mass) and having a normal T4 level, an ultrasound may be beneficial in helping make the diagnosis. Many times the pet is treated based on a presumptive diagnosis of hyperthyroidism.

Therapy can include methimazole but no studies have shown the efficacy of this drug in guinea pigs. Plus methimazole is a daily medication. And it is difficult to monitor on methimazole since a T4 level can be unreliable. At this point, treatment with i-131 seems to be the best option for guinea pigs.

For the latest summary on this disease in guinea pigs, please see the attached PDF article form the Veterinary Clinics of North America.

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