Tapeworms in Goats
First, let me clarify that I am not a veterinarian. I am not a nutritionist nor a scientist nor a formal researcher. I am just a girl that loves goats. I want to take care of them to the best of my ability, and so I strive to LEARN. I like to share what I learn, but please do check out all the resources provided. This piece was originally written for the KGBA 2020 Spring Newsletter Tapeworms in Goats
Intestinal cestodes, or tapeworms, are normally quite easy to diagnose in small ruminants – the white segments in feces are very visible, as are the occasional ribbon of an intact worm dangling from the south end of a north-bound goat. While tapeworms are not something any goat producer wants to see, the evidence of production or health issues associated with tapeworm infections, especially light burdens, is inconsistent.
Biology of a Small Ruminant Tapeworm Several species of tapeworms are found throughout the world, but the most common species affecting sheep and goats in North America is Moneizia (Moe-knee-zee-ya) expansa. It lives in the small intestine of ruminants and requires a microscopic pasture mite as an intermediate host.Tapeworms are comprised of a head with suckers, called a scolex, and long, flat segmented bodies. Adults can be up to six feet in length; keep in mind the small intestine of an adult goat, depending on the size of the animal, can be sixty to over eighty feet in length. While the size is impressive, the tapeworms are not inert and do not often cause intestinal blockages.
Each section, called a proglottid, is a complete reproductive system. New proglottids are formed directly behind the scolex. As new sections are added and older sections move down the ribbon-like body, the proglottids fill up with eggs. The oldest sections, now full of the triangular-shaped eggs, drop off and are deposited into the environment by fecal pellets – these are the “grains of rice” producers notice. The proglottid disintegrates, and mites consume the tapeworm eggs. If goats consume infective mites, the cycle begins again.
Mites are least active in the winter months,
but tapeworm larvae can overwinter in their intermediate hosts.
While tapeworm eggs might be seen in a fecal float, they do not tell the producer how many tapeworms the goat is harboring – a goat can have a heavy tape worm infection and yet the producer finds no eggs in the float. Eggs are not evenly distributed in manure samples, thus visual appraisal of feces, not fecal egg counts, remains the best diagnostic method.
Occasionally, long tapeworm segments will be expelled from the animal. This might be the result of a natural-occurring death at the end of three or so months or because of a process called “destrobilization,” in which the tapeworms shed all or most proglottids in response to stress, then grows new segments. Clinical Signs and Effects
Goats can be in otherwise excellent health and body condition yet carry a tapeworm burden. Noticeable tapeworm infections usually occur in animals less than six months old, or in animals subjected to poor nutrition or that have additional health issues. Goats tend to develop a natural resistance to infection with age. Proglottids might be visible in normal pellets, soft pellets, or diarrhea. The most common negative consequences of tapeworm infections include ill-thrift and a pot-bellied appearance. Heavy burdens might cause colic and constipation. In extremely rare cases, the intestine may rupture and lead to death.
It must be noted that tapeworms are usually not the only parasite infecting the animal. According to the textbook Goat Medicine, “Attributing disease to tapeworm infections is problematic. It is essential that nematode parasitism, paraphistomiasis (rumen fluke infestation) and liver fluke disease be thoroughly ruled out before clinical disease is ascribed to tapeworms” (Smith and Sherman 469).
As mentioned, formal studies on the impacts of tapeworms have been inconsistent. Some show an increased weight gain in feeder lambs when treated for tapeworms. Others show no difference. In an article entitled “Disgusting Tapeworms,” Dr. Ann Zajac offers a logical explanation:
Why might there be differences in study results? There could be several factors involved: the first is that drugs vary in their efficacy against tapeworms, so in some of the older studies treatment for tapeworms may not have been effective enough to show a treatment benefit. Differences in tapeworm load or timing of treatment may also have an effect. But perhaps more important is that many factors affecting general animal health can influence how much benefit anti-parasitic treatment will have. The results of field research are always strongly influenced by interactions of diet, environment, and other disease problems.
It has been suggested that tapeworm infections can alter the species of bacteria in the gut or slow down the transit time of partially-digested foodstuffs in the gut. It has been hypothesized that animals with heavy tapeworm burdens might be more likely to suffer from enterotoxemia but this has not been formally researched, to date.
If a producer does decide that a significant tapeworm burden is negatively affecting goat health and production, then albendazoles, such as Valbazen® are the most effective chemicals approved for goats in the United States. Fenbendazoles, such as Safeguard® or Panacur®, are also used, but considered less effective. These treatments will only cause the adult tapeworms to lose segments, but will usually not kill the head.
Safeguard® is typically administered 3-5 days and Valbazen® administered once. Please note that Valbazen® is not safe for animals in the first trimester; many producer and veterinarians opt to not use it on any pregnant goat.
Another drug, praziquantel, will kill the tapeworm head, but this drug is not approved for use in goats in the United States. Please consult a small ruminant veterinarian before using drugs off-label.
Additionally, producers should understand that the chemicals available to treat tapeworm infections in goats are also used to treat some stomach worms, most importantly the Barber Pole worm. It is quite possible that Barber Pole worms will exhibit some kind of resistance towards Safeguard® and Valbazen® since these are both from the oldest dewormer class. To avoid selecting for increased Barber Pole worm resistance to these dewormers, producers can combine their tapeworm treatment with their usual effective Barber Pole worm treatment from another class, such as an ivermectin or moxidectin. For further reading on dewormer combos go to https://www.wormx.info/combinations.
For the most up-to-date dosages, please refer to https://www.wormx.info/dewormers - a handy chart has been provided! Additionally, Goat Vet Corner group on Facebook has a file of common dewormer dosages.
The goal of tapeworm treatment, especially because of the potentially unintended consequences concerning Barber Pole worms, is to manage the parasite burden, not focus on eradicating it through chemical means. Tapeworms might be disgusting to many goat owners, but thankfully, do not always warrant treatment.
Smith, Mary C., and Sherman, David M. “Digestive System: Intestinal Cestodiasis or Tapeworms” Goat Medicine Second Edition. Wiley-Blackwell, 2009. P466-469.
Zajac, Dr. Ann. “Disgusting Tapeworms!” ACSRPC, Sept. 2014, https://www.wormx.info/tapeworms.