Why didn't deworming improve FAMACHA© scores?
Dr. Steve Hart
Extension Goat Specialist (retired)
Langston University
Deworming animals with FAMACHA© scores of 4 or 5 should result in the improvement of FAMACHA© scores by at least one when checked two weeks later. What if it doesn’t? There are several reasons why deworming small ruminants may not improve their FAMACHA© scores. We will start with the most common and go to the less likely items.
First, if you are deworming lactating animals, the nutritional competition between milk production and making blood may keep the animals anemic until they are in late lactation or until their young are weaned. Protein is necessary for immune system functioning as well as making blood as are some minerals, particularly iron, copper, zinc and cobalt. Heavy pasture contamination (lots of infective larvae on pasture) can also cause animals to become wormy quickly. Animals should be rotated to a new pasture.
This is often a problem with hobby farmers who have only one pasture. When there is a lot of summer rain, infective larvae accumulate on pasture. The producer needs to find some other place to put his/her goats on for at least two months while infective larvae die off. Maybe, he/she can find an overgrown pasture that a neighbor owns. The best thing is to cruise the neighborhood and look for an overgrown area that has chain link or other fencing that will keep goats in; seek to access it.
Then, we need to think about dewormer resistance as a possible cause. We use FAMACHA© to reduce the rate of development of dewormer resistance. However, dewormer resistance can still develop. The most common source of dewormer resistance is new animals: the new elite doeling or ewe that you acquire. The seller wouldn’t admit that she is carrying worms and surely wouldn’t tell you they were highly resistant worms, even if he/she knew. Resistant worms will spread despite FAMACHA©, but at a slower rate than if everything was blanket dewormed. It is very important to deworm new animals coming onto your place with different classes of dewormer and check the fecal sample a week or two later to make sure that you have killed all the worms.
Liver flukes are parasites that eat their way through the liver, consuming blood and causing bleeding and persistently high FAMACHA© scores. Most dewormers do not kill liver flukes, with the exception being Valbazen® which kills adult liver flukes and the Clorsulon in Ivermec Plus which kills immature and adult liver flukes. Fluke eggs are generally not found in the feces until the infection has been going for awhile. Also, the traditional fecal flotation methods will often not detect fluke eggs. There are specialized tests for detecting fluke eggs. Your local veterinarian will know whether flukes are common in your
area (liver flukes affect virtually all livestock species and humans) and should be able to advise on the best method to control them in your area.
Sucking lice can also cause anemia, especially in young animals. The dewormers Ivomec®, Eprinex® and Cydectin® will control sucking lice if they are used. Coccidiosis can also cause anemia. Without a fecal examination, it is difficult to determine if diarrhea is caused by worms or coccidia or both. Wormy animals are susceptible to coccidiosis and animals may need to be treated for coccidiosis to recover from worms.
A lesser cause of persistent anemia is Johne’s disease, a chronic bacterial disease that causes animals to waste away. The incidence seems to be increasing in goats, maybe because we are more aware of it and looking for it. The disease is most common in dairy cows with lower incidence in other animal species. The major symptom of the disease is a skinny animal that has anemia that continues to lose weight and stay anemic until they die. The animals often eat well but have a rough hair coat and flaky skin. This is an infectious disease caused by a bacterial organism. More information can be found at http://www.johnes.org/goats/faqs.html.
This article was originally written Augusts 2015. It was reviewed and updated November 2024 by the author.