Worming Alpacas on our Farm

As our herd has increased so have some of the problems associated with this growth. One of the bigger problems has been the Worm or Parasite Burden in our herd.

While some animals are in perfect health, with the odd animal actually being over weight, we still had the problem with a hand-full of the females still being under weight. You might remember me writing an article on this topic last year.

So with the Vets help he put together a Trial to test the efficiency of some of the drenches. We chose Dectomax for a number of reasons but one of the major reasons was that it had a Wide Safety Margin of Error.

You may ask why we used 3mls of Dectomax in the Trial for the adult animals. This came about when Jenny Jackson came to NZ last year to judge the Canterbury & Palmerston North Show. Her Husband George, is a vet and when I was talking to Jenny about Worms in Alpacas and that we used 2mls of Dectomax in NZ, she said “NO” use 3mls, it works much better.

As a result of this we have used 3mls on the adult animals ever since.

The Trial using Dectomax is typed out below in it’s entirety for you to read.

You will also notice at the end of the Trial is a one page set of Guide Lines that Peter Aitken (my new Vet) has typed up after giving us a talk at our Regional AGM. The biggest thing to notice here is that as your Herd Grows so should your Frequency of Drenching”

We now Drench on a much more regular basis and my herd has never looked so good.

Below is a picture of a BMV Inoculating Gun.

I use this gun and can’t recommend them enough. What you may not know is that the normal Needles fit into these guns, so if you are like me and like using a very fine needle, then you still can using this gun.

The AD&E Bottles as well as the 5 in 1 containers just fit right on the top making it very easy to inject a lot of animals very quickly. If you cut off the tip of the needle cover so that only a small part of the needle is poking through then you can’t stick the needle in to far. This stops you putting the needle in one side and then out the other.

The price is only around $30 as well, which makes this an essential tool.

Dectomax™ Drench Efficacy Trial in Alpacas

Aim: To establish the efficacy of injectable Dectomax™ in Alpacas at a dose rate of 0.5mg/kg (approximately 3ml/adult animal) given by sub-cutaneous injection.

Hypothesis: It is believed that Dectomax™ will effectively control gastrointestinal worms seen in Alpacas and will show a greater than 95% reduction in faecal egg counts (FEC).

Rationale: Alpacas are subject to infestation with a number of common intestinal parasites to both Sheep and Cattle seen here in New Zealand.

Along with these they are also subject to some more specific worms such as the relatively recently found Camylid Strongylus (also seen in goats in New Zealand).

Ivomec (ivermectin) is a member of the macrocyclic lactone family of drenches and has been found to be effective in Alpacas for the control of intestinal parasites, a similar member of this family is doramectin, the active ingredient found in Dectomax™, which has a label claim for a high kill rate against sensitive round worms in cattle. Dectomax™ is currently being used by Alpaca owners for the control of worm burdens.

At this point in time, no anthelmintic products are registered for use in Alpacas in New Zealand but it would be reasonable to surmise that a product effective against parasites in cattle would be effective against the same parasite spp. in Alpacas.

This does however make the assumption that the pharmacokinetics of the product are similar across a species gap (i.e. the two compartment model) and those parasites found in Alpacas are not already showing resistance to the macrocyclic lactone family of drenches.


  • Establish a sample population of suitable Alpacas 
    - 10 Crias'
    - 10 Tuis'
    - 10 Adult Females + 5 Adult males
  • Collect faecal samples per rectum from each individual (at least 4gm/animal). Collect samples from all animals on the same day.
  • Individually label each sample and identify it with the animal. 
  • Send all samples for individual FEC on the same day as sampling.
  • Faecal larval cultures should be done on each sample group i.e.
    - Crias'
    - Tuis'
    - Adults
  • Drench all animals in the trial according to weight on the same day as sampling and put onto clean pasture.
  • Resample each animal 10 days post drenching and repeat individual FEC and grouped larval cultures.
  • Analyse results from FEC.

By looking at the results of the FEC and larval cultures it should be possible to state if Dectomax™ is successful at controlling the parasites found within Alpacas. It may reveal certain parasites that are not well controlled by doramectin or if doramectin is not efficacious and another drench should be employed.

Dectomax™ Trail Results.

Results: See attached Laboratory results.

Alpaca Name
Faecal Egg Count (eggs/gm faeces)
17/04/04 27/04/04  
Selena 0    
Cilla 0    
Franjelica 0    
Dark Angel 0    
Harlequin Pudding 300 0  
Janies Desire 0    
Fancy Nancy 900 0  
Sleeping Beauty 0    
Chiqueta 200 0  
Jenie 0    
Chance 100 0  
Princess 100 0  
Bambi 0    
David and Judes' Girl 100 0  
Coco 0    
Dianna 400 0  
Brutus Cria 0    
Ginger Spice 0    
Fergie 0    
Claudia 0    
Cinnabar 900 0  
Ashley 0    
Wizard 200 0  
Robbie 200 0  
Gladiator 0    
Inca Gold 200 0  

From the initial animals sampled according to the original proposal, insufficient animals with elevated worm burdens were available to complete the study as planned. Those animals with FEC of 0 were excluded from the study.

A composite group was then made of all those animals that had FEC >0 (11 animals) which was enough to satisfy requirements for a simplified drench efficacy check. Following the second round of faecal sampling, detailed statistical evaluation of the data was not required as basic calculations showed the arithmetic mean reduction in egg counts to be 100%.


The above data would support the conclusion that Dectomax™ (at 0.5mg/kg) is an effective drench for the control of gastrointestinal parasitism in Alpacas.

In turn certain assumptions as to the mode of action/distribution and length of duration of activity could be made, however these would only be assumptions as no studies into the pharmacokinetics of the product in Alpacas have been made nor have any with-holding periods been established and as such it is still an unregistered product for use in this species.

No side effects were noted at the above dose rates.


Alpacas are subject to infestation with a number of common intestinal parasites to both Sheep and Cattle seen here in New Zealand. Along with these they are also subject to some more specific worms such as the relatively recently found Camylid Strongylus (also seen in goats in New Zealand).

There have been few published studies done to look at the extent of parasitism and its effects on Alpacas here in New Zealand so it is not easy at this stage to state with confidence which of the common parasites found here are the most detrimental or prolific within the New Zealand Alpaca population.

Different areas of New Zealand are subject to different worm problems, the dry warm conditions found around Canterbury for example could be expected to result in fewer worm problems than in the Manawatu or further north; conditions further north being wetter and more humid.

Of those papers that have been published, they would suggest that Alpacas are slightly less susceptible to parasitism than sheep, however, the broad range of worms found with in the Alpaca faeces would suggest they can play host to both cattle and sheep parasites.

When considering gastrointestinal worms, it is quite common to think of the worms within the animal as being the problem, and to a point they are. Worms within animals are responsible for the visible clinical problem; resulting in what is seen as scouring alpacas, loss of condition and failure to thrive. 

However, the worms that are causing the damage within the animals are only about 10% of the total worm population.

Where is the other 90% of the population then? 
They can be found in the pasture on which the animals are grazing, either as eggs, or the more dangerous stage three infective larvae. They hide in the pastures waiting to be taken up by the unsuspecting animals as they graze.

It would be easy to assume that if they are on the pasture and not actually in the animals themselves then what harm can they do? The harm comes from the rate at which they are ingested following drenching and the speed with which the gut can become repopulated with worms after the ‘annual’ or ‘biannual’ drench.

It can take as little as 10 days before worm burdens within the gut have started to cause damage to the gut lining again, even following an effective drench! If the pasture that the Alpaca has been grazing, post drenching, has a high level of contamination with infective larvae, a 10 day respite is all the drench has achieved.

It is therefore paramount that, together with regular drenching, appropriate management techniques are employed to control pasture contamination levels and thereby get the most out of your drench.

These techniques can include:

  • Moving animals onto clean* pasture following drenching. (this can encourage worm resistance)(* Clean pasture is considered that which has not been grazed recently (i.e. up to 6 months by any stock), has been shut up and cut for hay/silage or been recently re-sown with new grass or crops.)
  • Ensuring that correct and adequate drenching doses* are used (check that drench guns for oral drenches are delivering the required dose by squirting a ‘dose’ into a measuring cylinder, check it for five consecutive doses).(*Doses will vary depending on products used but as a general rule should be at least 1.5 times the sheep dose rate.)
  • After drenching hold the animals penned for around four to six hours to allow the drench to start to take effect before release onto clean pastures. This is more important with injectable drenches and free access to clean water should be available while being held off feed.
  • Drenching should be done at regular intervals which under intensive stocking rates could be as frequent as every 6 weeks (needs will vary depending on numbers of alpacas)
  • Pick up the faeces in a paddock after the animals move on. In summer harrow the paddock to break up the faeces and allow for desiccation of the larvae (this may facilitate spread of worms over the cooler winter months or when rain is frequent so restrict it to the drier summer months).
  • Quarantine any animals being introduced to a mob. Drench them as soon as they arrive on a property irrespective of when they were last drenched. Keep them separate from other animals for at least a week (by doing this it is possible to observe for any additional health problems and prevent rapid spread to the existing animals).
  • Bringing animals in and yarding them for a period of 3-4 hours prior to using an oral drench may help to increase the efficacy of the drench used, again, access to clean water while in the yard is essential.
  • If using an oral drench that requires a high volume, split it into two doses (if a 10ml dose is required give two doses of 5ml) this may help to prevent it being spat back out at you!

But what Drench do I choose?
Choice of drench is limited to injectable and oral drenches at this stage. As a general rule it is important to choose a drench that will work!

Pour on drenches are not recommended for Alpacas as Alpacas have a skin that is thicker than the animals for which pour on drenches were devised therefore they do not penetrate effectively and results can be quite variable.

That leaves oral and injectable drenches. If using an oral drench the ones to be cautious of are those containing Levamisole (‘clear drenches’).This is due to the low safety margin of this product at normal dose rates which would be lower still at the 1.5x dose rate. They do work well but care in administering them at accurate dose rates must be taken.

Injectable products must all be given subcutaneously (SQ). Ivomec as a product tends to sting the most when administered. 
The aforementioned faecal egg count reduction test (drench efficacy trial) undertaken in the Manawatu showed that Dectomax™ (Pfizer) at a dose rate of 0.5mg/kg was effective at eliminating worm burdens in a mixed age group of Alpacas.

This dose rate was equivalent to 3ml/adult animal (previous recommendations of 2ml). Although quite a high dose, this product is believed to have a wide safety margin in most species, a definitive safety margin however has not been established for Alpacas.

It is important to remember that no animal health products available for the treatment of Alpacas in New Zealand are registered for use in this species; therefore all use is strictly off label and subject to owners consent.

Gastrointestinal Parasite control in Alpacas

Some Guidelines
May 22nd 2004

1. Choose an effective drench (not all drench products are created equal!)

2. Drench all animals on the property at the same time.

3. Drench all animals correctly according to body weight at 1.5x the recommended dose for sheep. (or as otherwise recommended by your veterinarian)

4. All new stock being brought onto the property should be quarantined in a special paddock/pen used solely for that purpose for 1-2 days. These animals should be drenched as soon as they arrive on the farm.

5. No animals on the property should graze the quarantine paddock at any stage other than when being introduced to the farm for the first time.

6. Drenching intervals will depend on numbers of Alpacas and how intensively grazed they are. As a rule of thumb the following is an approximation based on numbers of animals. (these recommendations will also vary with the type of drench used)

No. of Alpacas Drench Frequency
· 1-3 every four to six months
· 3-8 every three to four months
· >8 may need to be done as frequently as every 6 weeks

7. An annual faecal egg count reduction test (FECR test) to assess worm burdens and the effectiveness of the drench you are using is advisable.

8. It is important to remember that requirements will vary for each individual farm. For example some properties may have minimal parasite numbers and not require much in the way of drench use. It is therefore wise to consult with someone on the appropriate strategy for you!

Peter Aitken BVSc
Awapuni Veterinary Services 
PO Box 4000
Palmerston North