A Lump in the Throat

                                                                          

 

            In all my thirty-two years as a veterinarian, I don't recall ever seeing any kind of animal with a goiter. Then I received a phone call from a Boer goat raiser named Joel. He had just started kidding, and several of his first kids were born dead with odd lumps in their throats. Photographs he sent showed the classic bilaterally symmetrical swellings in the location of the thyroid gland. They could have been textbook photos of goiters.

            From the tone of his voice, I could tell Joel was quite concerned.       If he's not the most conscientious goat breeder I know, he is at least in the top two. His herd management  has always been top-notch. So why was he having this problem? And why now?

            Joel couldn't think of anything he was doing that was different. He was feeding the same grain mixture and minerals he had used for the last few years. Furthermore, the moms that were producing the kids with goiters were his older does who never had any issues like this before.

            A goiter is an enlargement of the thyroid gland. Typically in goats, it occurs as the result of an iodine deficiency. The thyroid gland utilizes iodine in the production of thyroxine, or thyroid hormone. If iodine levels are low, thyroxine cannot be produced, thus causing the "master gland of the body"- the pituitary, to produce thyroid stimulating hormone, which is sent to the thyroid gland. This prompts the thyroid gland to work extra hard to try to produce it's hormone, and almost like a muscle lifting weights, it will enlarge. 

            In addition to low levels of iodine in the diet as a cause of goiters, there are certain plants which are termed "goitrogenic." These plants interfere with the uptake of iodine in the thyroid gland, and include cabbage, broccoli, kale, cauliflower, Brussels sprouts, soybeans, and turnips. I discussed these plants with Joel, but it was kind of a moot point. His goats ate none of those things.

            I heard from Joel again about three weeks later on a Friday afternoon. His report was not good. Twenty-one kids had been born dead with goiters, including a set of twins that morning. He inquired about having them necropsied, the animal version of an autopsy.

            Fridays are not the best day of the week for collecting tissue samples, because they have to sit over the weekend before being shipped off on Monday. I asked Joel if he would be willing to drive the kids down to the Ohio Department of Agriculture Lab in Reynoldsburg that afternoon. He had no problem with that. Like I wrote before, he is conscientious.

            When I spoke to the pathologist who worked on Joel's kids, he confirmed the goiter diagnosis. He also told me this: "Boer goats are more susceptible to goiters than any other breed." I didn't know that, and I see a lot of Boer goats. The pathologist then told me that goiter development usually occurs between the first and second month of a goat's five month gestation.

            When I relayed this information to Joel, he had a revelation for me. He found out the clover hay he had purchased, which he fed for the first couple of months of his does' pregnancies, was harvested from a field that had a cover crop of turnips on it the winter before.

            Cover crops are becoming more popular in this area for a variety of soil improvement reasons. Turnips, by virtue of their large bulbs and deep root systems,  help to decrease soil compaction and open the soil for worms and nutrient penetration. However, as they decompose, apparently some of those goitrogenic properties can be taken up by growing clover plants.

            In Joel's herd, it was only the older does who had the affected kids. Even though they were fed the same clover hay, his younger does were supplemented with a grain ration that did contain some iodine. It wasn't a large amount, but evidently it was enough.

              So goat breeders, before the next kidding season arrives, make sure there is adequate iodine levels in your feed and mineral mixes, or supplement the herd with iodized salt. Then, hopefully, the only lump in the throat you have to deal with is the one in your own. The source, of course, coming from the pride you feel when you see your beautiful new kids.

 

By Dr. John H. Jones