Goitre and Hypothyroidism (Iodine deficiency) in Angora goatsThursday, 23rd September 2021
By Dr Mackie Hobson
Goitre and Hypothyroidism (Iodine deficiency) in Angora goats
Goitre and hypothyroidism have been reported in the Graaff-Reinet district (Bath et al.) in new-born Angora goat kids whose mothers grazed irrigated fertilised Lucerne pastures during their entire gestation period.
What clinical signs can be seen?
An iodine deficiency results in a lack of thyroid hormone production, and the thyroid gland enlarges. The enlarged thyroid gland is called the goitre. The swelling occurs in the throat area and can be as large as an orange. Goitre is mainly a disease of kids. Goats have a higher requirement for iodine than other livestock.
The Iodine deficiency may result in resorption, abortion or the birth of weak kids showing signs of enlarged thyroid glands, dwarfing, obesity, hair loss, skin changes, skeletal malformations and sluggishness.
Where iodine deficiency has occurred in lambs, they were born hairless, a number died after birth, and many had skeletal deformities such as bent forelegs and overshot mandibles.
What are the causes of Iodine deficiency (Goitre)
- Insufficient intake of iodine from the pasture.
- Diets containing linseed cake, kale, rape and other goitrogenic plants are in the diet of pregnant ewes.
Goitrogens - substances within the feed which inhibit the utilisation of dietary iodine. Goitrogens have been detected in some legumes such as lucerne.
Why does it effect kids more than adult goats?
Thyroid hormones are essential for growth and development of the foetus, particularly the brain, lungs, heart and hair follicles, and contribute especially to survival of the new-born kid.
Adults Angora goats can tolerate fluctuations in iodine supply by using reserves stored in the thyroid gland. This reserve is not available to the developing foetus.
Iodine deficiency makes new-born kids very susceptible to cold, wet weather.
Supplement Iodine during the last two months of their pregnancy.
Treatment of affected kids with iodine or thyroxine tablets is rarely useful, and it is far more effective to ensure adequate iodine nutrition of the foetus.
Plant Poisonings of livestock in Southern Africa, Kellerman, Coetzer, Naude, Botha