There are already articles on our website pertaining to goat health and goat nutrition.  However, because deworming goats is essential to the health of our goats, we decided to write a separate article pertaining to deworming them.
_____________________________________________________

There is no getting around it.  Goats, in general, are very susceptible to internal parasites, especially stomach and intestinal worms.  These worms feed on blood and if left untreated cause anemia and death.  Infection typically reaches highest levels in summer when most grazing occurs.  Goats are browsers like deer.  They eat plants from the top down.  Therefore, one management technique to suppress worms is to allow pastures to grow tall before grazing.  The closer the goat grazes to the ground, the better chance it will ingest worm larvae.  Another effective management technique is to utilize multiple pastures rotating goats from one to the next and allowing grazed pastures to rest and regrow.  We utilize three main pastures that can be expanded in additional pastures if we need to.

Treating goats that show signs of internal parasites is not as straightforward a task as you might have hoped.   Why?  The same deworming products for goats have been on the market for years which is a bit problematic since worms can easily become resistant to medications used over and over.  That means simply administering deworming medications does not guarantee that your goats will be rid of the worms that affect their health, production, and overall well-being.   We utilize a worm control approach that includes natural herbal dewormers and rotational grazing for adequate suppression of worms loads.   Then, as a last resort, we administer chemical dewormers.   One note – a worm control program cannot rely totally on using deworming medications that are “listed for goats” because there are very few.

This article describes what we have found to be useful in controlling parasites in our herd.  So, let’s begin.  We only use orally administered dewormers.  Worms are predominantly located in the stomachs and intestines of goats.  So, oral administration of deworming meds kills more worms than injectables.  Some dewormers are available in multiple formulations including oral, injectable, or pour-on formulations.  However, as I stated above, the best way to control parasites of goats is through oral administration since the medication goes right to the problem.  Side note – we do not like to use dewormers that you feed in a ration due to the possibility that the goat may not ingest enough medication.

Administering Treatment

There are several effective methods to administer dewormer meds.  We use a plastic syringe (no needle) with volumetric markings on the tube, place it in the back of the throat with the goats head above horizontal, and administer as fast as the goat will swallow to avoid spillage.  Make sure you do NOT underdose due to spilling or spitting meds out or you run the risk of causing worm resistance to the meds.  We always make sure the goats are slightly overdosed to ensure that an appropriate amount of dewormer is ingested. 

Prior to dosing make sure that you know the actual weight of each goat and administer the correct amount based on the known weight rather than an estimated weight (we seem to underestimate our goats’ weights).    We utilize a digital scale to weigh our goats.  Again, underdosing can result in development of resistant worms.  With few exceptions most dewormers are quite safe and overdosing slightly will not affect the health of the goat.  

Correct Dosage

Here is where it gets a bit complicated.  Goats metabolize dewormer medications more rapidly than sheep (for example) so goats require higher doses of dewormers.  As a general rule, the dewormer dose is typically doubled for goats compared to sheep (exception – Levamisole – use 1.5 times the dosage of sheep).  Ok, enough, right?!  Let’s make a complicated topic a little easier.  We utilize a “Dewormer Chart for Goats” developed by Ray Kaplan, DVM, PhD, University of Georgia. You can download the chart at wormx.info (https://docs.wixstatic.com/ugd/aded98_c7a6cc3b624043aeaefe8693f9f13c71.pdf).   Make sure you use the latest chart as there are several versions floating around the internet.  And, make sure you read all the notes below the chart before you begin dosing!

Ten days after initially dosing we administer another round of deworming meds.  Worms thrive in various stages within a goat.  We re-dose so that there is a higher total percentage of worms killed.

Combination Dewormers

As I mentioned earlier, the procedures we use as described above, will eventually result is worm resistance due to the fact that there are only 4 major groups of deworming medications.  Similar to chemical weed control, if you use the same pesticide(s) year after year, weeds will eventually become resistant.  It is the same with deworming medications – worms will eventually become resistant to the deworming meds.  As the effectiveness of the dewormers decreases, it provides less and less benefit to your goats.  Wormers were highly effective when they were first introduced (>99%).  Once the efficacy of a wormer falls to about 50% it is no longer useful as a sole treatment. 

Given the fact that resistance will happen and the fact that new goat dewormers are not being developed in the US to keep pace with needs, what is the best approach for using dewormers?  We used to think that simply rotating between dewormers would prevent resistance.  However, according to Dr. Ray Kaplan, Professor of Parasitology at the University of Georgia, “rotating between dewormers will not prevent resistance from worsening and is no longer recommended”.  Research now shows that the best approach is to use several different dewormers at the same time as a combination treatment. 

According to Dr. Kaplan, there are two major benefits to using goats deworming drugs in combination:

1. There is an additive effect with each drug used, making the combination treatment more effective with additional drug used, and
2. Higher efficacy means that there are fewer resistant worms that survive treatment but also results in fewer total worm population.

So, the sooner you start your combination treatment program the better off you will be.  Why?  Here is an easy example:  If two drugs each with 90% efficacy are used in rotation (like we used to do), each time the goats are treated 10% of the (resistant) worms survive.  In comparison, if you use the same two drugs in combination at the same time, efficacy increases to 99%.  The math is simple – the first drug kills 90%, the second drug kills 90% of the remaining 10% [90% + (90% x 10%) =99%].  That means efficacy achieved is 10X greater and yields 10X fewer resistant survivors. 

If that is not good enough, consider that there are fewer resistant worms deposited on your grazing lands.  This greatly slows the development of drug resistance in the overall worm populations on your farm.

Precautions.

1. Unlike New Zealand or Australia where there are products that already contain a combination of dewormers so one product can be administered, the USA does not have any combination dewormer formulations (yet).   This means the meds have to be bought and administered separately.  And you can’t just mix the drugs together because they are chemically incompatible.  You must administer each drug separately one immediately after the other.
2. All dewormers must be administered at the full recommended dose.
3. Meat and milk withdrawal time is the longest of the drugs used.
4. Treat goats only when needed (FAMACHA method can be used to determine).
5. All safety precautions that exist for any one drug will also exist when used in combination. However, there are currently no known additional risks using more than one dewormer.

Note:  It is possible that you will not notice a large difference in response if your dewormers are at >80% efficacy.  However, the impact on further development of resistance could be large.

______________________________________________________________________________

1. To view Dr. Ray Kaplan’s article in its entirety: “Combination Dewormers: The Time is Now”, American Consortium for Small Ruminant Parasite Control, Timely Topics, January 2017.
2. Disclaimer:  The following is what we have found to be effective for our herd of Nigerian Dwarf goats.  We are not veterinarians.  The deworming methods we describe are our methods.  We strongly encourage consulting your local veterinarian for deworming products and procedures.