Preventative Medicine 101: Deworming Dairy Goats
by Sue Garvin

Gastro-intestinal parasites are the single most significant problem affecting goat production throughout the world. Internal parasites cause decreased production and even death. A good deworming program seeks to minimize both the damages and the costs associated with GI nematodes. Unfortunately, there is no simple recommendation for a good deworming program. Each herd is unique and every goatkeeper is responsible to evaluate his/her herd and implement an appropriate strategy.

A deworming program is only as effective as the dewormers that are being employed. The current consensus is to rotate dewormers to help reduce resistance. Be certain to dose appropriately. Under-dosing is ineffective, wastes time and money and results in rapid development of resistance. Check for resistance by completing fecal egg counts on several animals before and AFTER deworming. Collect fecal samples the day before deworming and again 10-14 days later. Have a McMaster’s Fecal egg count preformed on the samples. An effective dewormer should reduce the fecal egg count by 90%.

It is essential to realize that an appropriate deworming program can, and most likely will, change from year to year. Age, gestational status, lactation status, management stress factors (nutrition, showing, etc.) and even the weather, all have profound impacts on GI parasites. In all cases, the worst option is to routinely deworm every 21-30 days. Frequent, routine scheduled dewormings are expensive and will result in the rapid development anthelmintic resistance. With a little time, a bit of effort and a lot less money, a better solution is to combine several deworming techniques. The goal is to keep internal parasites under control. It is impossible to eradicate gastrointestinal parasites. The best we can do is control them.

Tactical deworming programs are based on factors that cause surges in fecal egg counts. These factors include stresses such as showing, nutritional problems, illness, introduction of new animals and even the weather. Goats should be treated for GI parasites when facing any of these stress factors. A general rule of thumb for tactical deworming is very appropriate for local goat owners, in the fall: Treat goats 10-14 days after it rains, when there has been a summer dry period/drought prior to the rain.

Strategic deworming programs are implemented when parasites are dormant. However, it is essential to use a deworming product that is effective on the encysted larvae. In our area, during a very cold winter, producers can assume that many of the internal parasites are in a state of arrested development. One way to implement strategic deworming is to treat just before the start of the spring kidding season. Follow the pre-kidding treatment with 2 more treatments at 21 day intervals. This should significantly reduce total parasite burdens on spring pastures.

Pasture, paddock and barn management practices have a tremendous impact on the development of parasite larvae. Overstocking greatly increases the risk of parasitism. ALL feeding (hay and grain) should be done in “above ground” feeders that will discourage fecal contamination. Paddocks and barns should be kept clean and dry. Warm, wet environments will encourage the rapid development of infective larvae. Pastures should to be rotated on a regular basis or at least “cleaned” by horses or cattle. (Goat parasite larvae will die when ingested by horses or cattle.)

We routinely use our horses to clean our pastures. We rotationally graze using electric fencing and netting. We have had a lot of success using pre-kidding strategic deworming followed by 2 treatments during the kidding season. We usually complete a tactical deworming in the fall ten days after a soaking rain. We also implement FAMACHA guidelines to assist us in evaluating our herd.

The FAMACHA system utilizes the coloration of the mucous membranes (of the eyes) as an indicator of anemia. Pale coloration is often an indicator of a heavy parasite load. By examining our goats frequently (every 1-2 weeks in the warm months), we can quickly address any problems that arise in individual animals. It is important to recognize that even a good herd parasite-prevention plan may not suit all the animals in the herd. Some animals may require more frequent treatment due to individual susceptibility. Body condition, fecal egg counts and/or mucous membrane color are all useful in assessing an individual goat’s parasite load. Once susceptible goats are identified, they can be treated individually. Targeting individual animals for treatment (as opposed to treating the whole herd) should help slow the development of resistance in the herd.

Treating goats for “worms” can be problematic. In the United States, very few products are labeled for use in goats, let alone dairy goats. There are three classes of anthelmintics that are routinely used in goats in the US. The macrolides include ivermectin and moxidectin (Cydectin). The most commonly encountered benzimidizoles are Valbazen and Panacur or Safeguard. Morantel and pyrantel fall into a class known as the tetrahydropyrimidines. When rotating dewormers be certain to rotate classes, not just trade name or drug!!!

There has been very little research to determine effective anthelmintic dosages, or milk withdraw times, for goats. It is generally accepted that goats require higher dosages than sheep or cattle. The oral route is often the preferred route of administration. It has been suggested that goats do not properly absorb pour-on and/or injectable dewormers. Inappropriately low absorption could result in more rapid development of resistance. Oral treatment with paste dewormers can also result in unintentionally low dosages for some animals. It is impossible to insure that an anthelmintic is evenly suspended in a tube of paste. When a small portion (of a single tube of paste) is administered, under-dosing or over-dosing can occur. Once again, consistent attention to both overall herd health as well as the individual animals will quickly indicate if treatment was effective. In conclusion, a well managed parasite control program should control internal parasites while controlling costs and minimizing the use of anthelmintics.


References:
Matthews, JG: Diseases of the Goat, ed 2, Oxford, UK, 1999, Blackwell Science Ltd.
Pugh, DG: Sheep and Goat Medicine, Philadelphia, PA, 2002, WB Saunders.
Smith MC Sherman DM: Goat Medicine, Philadelphia, PA, 1994, Lea & Febiger

Anthelmintics (Commonly used in goats)	Oral Dosage*
Albendazole – Valbazen	10mg/kg
Fenbendazole – Panacur	10mg/kg
Ivermectin – Ivomec	0.3mg/kg
Moxidectin – Cydectin	0.5mg/kg
Morantel tartrate – Positive Pellet	10mg/kg
Pyrantel pamoate – Strongid Liquid	25mg/kg

*From Pugh, Sheep and Goat Medicine. Please read label guidelines for milk/meat withdraw information.