Information and advice from the RVC Farm Animal Clinical Centre on alpaca parasite control

Camelids are very susceptible to gastro-intestinal parasitism and this is probably one of the most common cause of illness we see as veterinarians, yet it is mostly preventable by employing some basic strategies.

Alpacas have little natural resistance to parasites due to a lack of parasites in the climate and environment of the South American Andes. This poses a problem under the more intensive systems in which they are kept in the UK, where typically gastro-intestinal parasites are highly prevalent in all farmed species and on our pastures.

Basic management

There are some important basic management tools we should utilise to minimise the levels of parasites to which alpacas are exposed and decrease their risk.

These include not overstocking pastures; ideally there should be no more than 5-7 alpacas per acre of good quality grazing. Pasture should be rested so that animals can be moved onto clean uncontaminated pasture at least once a year.

Removing dung piles regularly will decrease the parasite load on the pasture and create more grazing space as animals will not graze these areas.

Newly bought in animals should be quarantined for several weeks before introduction and during that time tested for parasites and treated as necessary so as not to introduce new infections to the existing animals.

All animals should be body condition scored or weighed on a monthly basis and recorded so that trends in both individuals and groups of animals can be addressed as the most common cause for weight loss is parasites.

It is important to work with your veterinarian when devising a worming programme as this should include a plan for testing animals as well as treating them.

Testing

Testing for gastro-intestinal parasites is performed on faecal samples which you can collect and send off through your vet.

There are some basic rules to adhere to when testing to ensure the results are representative of any problems present.

Samples should be taken from individual animals and the samples labelled so you know who it came from; although this can be appear more costly than pooling samples it is necessary as alpacas are susceptible to low numbers of parasites and so a positive sample from one animal may be diluted and appear negative if mixed with a sample with no parasites, creating a false negative test result.

When choosing which animals to test, 10% of all animals or 10 total animals whichever is greatest is ideal; alpacas which are thin or sick should be tested, otherwise animals aged 6-18 months of age as these are a good barometer for the others on farm.

It is important to collect a large enough sample (we require at least 3 gram of faeces for each animal) and perform a specific test called a Modified Stolls faecal egg count, this is a technique different to that used routinely for other large animals as it measures a smaller number of eggs, important as alpacas are susceptible to smaller numbers than sheep for example.

It may also be prudent to re-test animals after treatment to ensure the treatment has been successful; this is called a faecal egg count reduction test and is typically performed 2-3 weeks after treatment where we are looking for a 90% or greater reduction in numbers, with more resistance to wormers developing this can be important.

Worms

There are two main families of worms which infect alpacas: Strongyles and trichostrongyles, the latter of which includes Haemonchus contortus and Nematodirus.

These are all tested for in the Modified Stolls faecal egg count and require treatment.

parasitic worm
A barbers-pole worm (Haemonchus contortus) taken from the 3rd compartment of an affected alpaca.

I cannot emphasise enough how important it is to discuss treatment plans with your vet. There are many pitfalls and one of the biggest emerging problems is resistance to wormers, this happens when wormers are used poorly, such as when the wrong drug is chosen, or it is incorrectly dosed or they are given when they are not needed. The ‘latest’ product or one that seems most advanced is not necessarily the correct choice as when resistance develops we have nothing left to treat them with, a major problem.

The barbers pole worm (Haemonchus contortus) is a potentially very damaging dangerous worm for alpacas as it causes profound blood loss internally, leading to severe and often life threatening anaemia. The worms attach to the lining of the 3rd compartment (stomach) and suck blood. These worms are very prolific in the warm damp conditions in the UK and lay large numbers of eggs very quickly. Any alpaca which is weak or dull should be examined for signs of anaemia. It is useful to look at the colour of the mucous membranes around the eyes or gums and see how pale the animal is.

There is a scoring system, called the FAMACHA™ method where a score of 1 is given to a healthy animal with pink membranes which requires no treatment up to a score of 5 where the membranes are white and completely lacking colour and immediate treatment is needed. Blood transfusions may also be needed in profoundly affected animals. If this parasite is present on the farm, your vet should advise you on further testing and treatment. There are several different treatment options and what may be right on one farm may not fit another so it is vital you liaise with your vet. No precise treatment recommendations will be made here for that very reason, that each situation is individual and requires a specific tailored plan. The only mention I will make is that dectomax (doramectin) is often used on farms, but should be used with caution as it can be very ineffectual as a treatment for gastrointestinal parasites.

Coccidia

Coccidia is a different type of parasite, a protozoa, which typically affects young alpacas and is often, but not always, associated with overcrowding and poor hygiene.

It is also diagnosed when the faecal egg count for worms is performed by identification of the coccidia eggs (oocysts) in the faeces. These eggs directly damage the small intestine, causing diarrhoea which may be bloody and prevents nutrients from being absorbed leading to poor growth and weight loss. It is possible for alpacas to simply have the weight loss or poor growth, without diarrhoea.

The routine de-wormers do not kill this parasite so if it is present, specific treatment with toltrazuril or diclazuril will be needed.

Prevention of future infections includes cleaning and disinfection of contaminated areas where youngstock are housed and your vet may also recommend a preventative drug treatment called decoquinate.

Infected animals should also be isolated from others.

Liver fluke

Alpacas are susceptible to infection with fluke (Fasciola hepatica) which can cause a spectrum of signs from sudden death and acute illness such as weakness, reduced appetite and anaemia, to more subtle chronic signs of ill thrift.

two adult liver flukes
Adult liver flukes (Fasciola hepatica)

The liver fluke is ingested while grazing and the small fluke burrow through the intestine and migrate to the liver where they move through damaging the liver before laying eggs in the bile ducts. Eggs are then hatched and passed in the faeces where they find their way into water snails in which their life cycle continues before they are eaten again.

Diagnosis is not always straightforward, partly as it depends on the time of the year as to whether you can find fluke eggs in the faeces; a negative faecal egg count does not necessarily mean fluke is not a problem. This is a different faecal test to the worm tests mentioned above and needs to be requested separately.

Bloodwork taken by your vet may be helpful in showing changes in the liver parameters and protein levels. Routine de-wormers also do not treat fluke. Treatment is further complicated by the fact that some treatments target the adult flukes only and there is only one treatment (triclabendazole) which treats all stages.

It is important again to consult your vet if you are concerned about fluke.

Conclusion

In conclusion, it is important that owners and vets work together and that each farm or holding has a specific tailored and targeted parasite control program, which uses appropriate testing as well as treatment.

Resistance developing to wormers is a real threat and has already occurred in other species, such as sheep.

It should also be noted that the routine de-wormers do not treat coccidia or liver fluke.

With good use of basic management strategies as well, parasites are a controllable problem.


Dr Alex McSloy wrote an article on this subject for Alpaca Magazine, which is produced by the British Alpaca Society. This Fact File includes the information submitted to the magazine.

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