Health and Illness.
Alpacas generally maintain good health but as they are stoic, they will try to hide any illness. Knowing your animals makes abnormal behaviour due to illness or injury far easier to identify. Sudden and rapid weight loss is often indicative of health issues so condition scoring or weighing your alpacas on a regular basis is valuable. Moreover, visual clues such as lack energy, spending more time recumbent and reluctance to stand can indicate illness.
Notable in the treatment of alpaca illness is that very few drugs are approved for use in camelids by any national medicines regulatory body. Although a range of safe and effective drugs has now been established for use in alpacas, they are "off label", that is, not specifically tested on them. Vets tend to approximate alpaca dosage rates based on those for sheep.
Following are some of the commoner and relevant conditions affecting alpacas in New Zealand. Veterinary assistance must be obtained if an alpaca owner cannot quickly identify and resolve any illness.
This skin condition is familiar to many livestock owners where it is known by many names: 'cutaneous streptothrichosis' (cattle, goats, and horses), 'rain-scald', ‘mud rash’ or 'mud fever' (horses), 'lumpy wool' (sheep), 'strawberry foot rot' (sheep and cattle) and is a causative factor in 'pastern dermatitis' (horses). It is caused by the bacterium Dermatophilus congolensis and can result in severe skin infections indicated by the formation of crusty scabs containing the microorganism. In alpacas, these lesions are most common on the back and wet, clumped wool may be found that is removable in clumps. The underlying skin is often reddened and weeping.
The bacterium exists in two forms: filamentous and motile zoospores. The zoospore is resistant to heat and being dried out and as it is the dormant phase, it can survive in infected scabs for months. Transmission between animals is known to occur by direct contact but contaminated environments may also be an indirect means.
Veterinary consultation is essential as the treatment will include antibiotics - fortunately the bacterium is sensitive a wide range. Povidone iodine shampoos or chlorhexidine solutions are also is useful in clearing up the disease.
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- Facial Eczema (Pithomycotoxicosis).
Unfortunately there are many livestock owners in New Zealand who have experienced this serious disease as it affects sheep, cattle, red deer, goats and especially camelids. It is caused by a toxin contained in the spores of the fungus Pithomyces chartarum. Although known worldwide, facial eczema is especially common in New Zealand due to the high percentage of toxin producing P. chartarum strains as compared to other countries. Alpacas are more sensitive than sheep to this disease, likely due of a lack of selection pressure in their native environment.
Prevention of facial eczema:
After several days of warm humid weather with nighttime temperatures of over 13°C, the fungus begins growing on the decaying litter at the bottom of the grass sward . On ingestion, the fungal spores release the mycotoxin sporidesmin into the gastrointestinal tract which causes severe liver and bile duct damage. Obstruction of the bile duct may occur which restricts excretion of bile pigments. This results in jaundice and an inability to excrete phylloerythrin, leading to photo sensitization of the skin . Consequently, there is severe skin irritation which the animal tries to relieve by persistent rubbing of its head against objects (e.g. fences, trees etc.) which causes peeling of the skin. There is also restlessness, frequent urination, shaking, drooping and reddened ears, swollen eyes and seeking of shade to avoid sunlight. Veterinary assistance is essential in assessing these animals. An initial diagnosis is made based on these symptoms and behaviours but confirmation requires blood testing for γ-glutamyltransferase (GGT) levels.
Sporidesmin often causes permanent liver damage so support care is needed for any affected alpaca. They should be kept in the darkest area available and receive pain relief, vitamins for liver support and low protein feeds until there is clear recovery. It is notable however that if symptoms are noted then damage to the liver of the animal has already occurred. Moreover, the consumption of spores causes potentiation and subsequent ingestion of small quantities of spores can lead to severe outbreaks.
- Spore counts. There are many commercial and local veterinary services available for determining spore counts in samples taken from paddocks. This method describes the process for taking samples. Samples may be taken to a veterinary practice or farm supply business for sending away to the testing laboratory. Local area spore counts may also be available there. Aggregated counts for areas nationwide are available by e-mail from Gribbles Veterinary during the eczema season. The graphs shown in the reports indicate when the spore counts are climbing and therefore when zinc oxide dosing (see below) must start. Counts in excess of 20,000 spores/g sample are regarded as hazardous to all stock.
- Spraying paddocks with fungicides - ideally, this should be done before the start of the season as the fungicide kills only the vegetative fungus cells, not the spores. Thiabendazole sprays have been shown as effective in controlling sporulation throughout the facial eczema season . Alpacas may graze the sprayed paddock after a number of days as specified in the product description. The treatment provides a level of protection for around 5 - 6 weeks, unless there is significant rainfall. Reapplication will be necessary if spore counts are still elevated.
- Grazing to low level - this must be avoided. Paddocks with minimal remaining grass should be closed off until good regrowth has occurred. Heavy rain helps by washing spores into the ground.
- Alternative feedstuffs - these should be freely available during the danger periods, particularly good quality hay, which reduces the reliance on free grazing.
- Dosing with zinc. Zinc supplementation is used as an effective prophylaxis against sporidesmin toxicity. Evidence indicates that the toxic effect of sporidesmin is due to its ability to generate the highly reactive superoxide radical. Zinc ions appear to interact with the sporodesmin and prevent superoxide radicals being produced.
The incorporation of zinc oxide into alpaca nuts is the only practical way of getting an alpaca to consistently consume adequate zinc. These are widely available from farm stores during the facial eczema season. Putting any zinc salt into the drinking water is ineffective due to the low volume of water drunk per day and the bitter taste of the zinc.
In New Zealand, the facial eczema season usually starts in early January. Given that it takes about two weeks for the blood zinc levels to rise to a protective state, gradual introduction of the zinc-containing nuts (initially with normal alpaca nuts) should begin at New Year. Supplementation with 2g of elemental zinc per 100 kg live weight per day is recommended. Excessive consumption of zinc for extended periods of time in other ruminant species is known to lead to mild pancreatitis and copper deficiency. In sheep and cattle the recommended maximum continuous zinc supplementation period is 100 days. However, there are no studies with alpacas into the maximum dosing period so the same recommendation is followed. The onset and severity of the facial eczema seasons vary so having grass samples tested and keeping a close watch on spore counts is essential. In particularly bad years, extended dosing and feed supplementation may be needed - mild but reversible pancreatitis is a far lower risk to take compared with having a dead animal through liver failure.
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- Ryegrass staggers.
This is a condition caused by the endophyte fungus Epichloë festucae (var. lolii) which is found in the leaf sheath of perennial ryegrass pastures. The endophyte is a deliberate addition to the ryegrass seeds to deter insects, particularly the Argentine Stem Weevil, and increase grass growth rates. The condition is particularly common in New Zealand, possibly to the combination of endophyte-infected ryegrass and the practice of monoculture. This fungus produces several mycotoxins including lolitrem-B, peramine and ergovaline, which when ingested cause neurological symptoms . The disease usually occurs in mid/late summer and autumn or after a drought when new grass is growing quickly. This condition mainly affects animals under 2 years of age but only some are affected and may be permanently so.
In its mildest form, there are slight head tremors or head wobbling but the animal will often appear normal until it becomes excited or agitated. If left untreated, the condition progresses to head shaking, showing a high-stepping gait and a stiffness that can lead to poorly coordinated walking (ataxia). Later there may be complete loss of limb control and the animal will be prone to falling over. Once removed from the pasture, most animals will recover with no apparent residual effects. To achieve this, the patient should be stabled with another alpaca and provided with alternative feedstuffs such as hay, chaff and kibble. The recovery time is between one and three weeks. Veterinary treatment may include an injection with vitamin B1 to eliminate the possibility of polioencephalomacia (thiamine deficiency), which exhibits similar symptoms.
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- Barber’s pole worm (BPW)
The parasitic nematode worm (Haemonchus contortus) infects the C3/abomasum stomach compartment where it attaches and sucks blood from the lining. The female BPW produces thousands of eggs every day which are expelled in the alpaca’s faeces onto the paddock where they hatch, develop into larvae and are ingested during grazing. They then pass into the stomach of the new animal and attach to the stomach wall, thus the life cycle is complete. Infections are serious as large numbers of worms may be present in the abomasum ingesting the blood of the host animal and causing severe anaemia, weakness and ultimately, death.
Symptoms include very pale pink or white mucous membranes of the eye and mouth (gums) - these should be a strong pink colour. Animals are likely to have diarrhoea, show a loss of condition and be lethargic or collapsed due to the anaemia. Treatment involves immediate drenching of the animal or an injectable wormer.
It should be noted that Haemonchus eggs can survive for long periods on the pasture during dry weather. If the alpaca dung is not removed, large numbers of eggs can build up. Warm wet weather (especially in March and April) will cause the eggs to hatch and allow infection or reinfection of an alpaca.
Conventional treatment is by drenching but there is now evidence of resistance to the drugs commonly used . One approach now used is to drench only when an alpaca is shown to have Haemonchus eggs is its faeces. More recently, a vaccine has been developed , prepared from purified Haemonchus intestinal proteins. On injection, the animal’s immune system generates antibodies that circulate in the blood. When the parasite feeds, these antibodies bind to the worm's intestinal lining and block digestion. The parasite starves so produces far fewer eggs to pass into the faeces and ultimately it dies.
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- Fly strike (Myiasis).
In New Zealand, fly strike is well-known as a serious condition in sheep, more commonly seen in regions with summer rainfall. Occasionally it can afflict alpacas when the fleece is short, if there is a skin lesion or the animal has rolled in faeces. An inspection of the animal for cuts is recommended after shearing although skin cuts and abrasions do occur due to vigorous rolling.
Several species of blowfly may lay eggs around the wound or faeces and on hatching (12-24 hours), the maggots start to degrade and liquefy the underlying tissues. Toxins released by the decomposing tissues and ammonia secreted by the maggots are absorbed into the animal’s bloodstream causing systemic illness, possibly leading to death. Once flystrike has started, the smell of decomposition attracts further flies to the infection site. Regular inspection of the herd will identify abnormal numbers of flies around any animal.
Immediate veterinary treatment is essential as appropriate insecticides and antibiotics will be required.
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Alpacas can be infected by mites with three species causing specific skin conditions, Sarcoptes, Chorioptes and Psoroptes.
The mange mite (Sarcoptes scabiei) is likely the most serious of these parasites and causes sarcoptic mange, otherwise known as scabies. The mite burrows into the skin of the less hair covered areas such as the legs, ears and belly and these develop bald spots, show flaking and crusting. The skin may become thickened as the disease develops and the alpaca shows intense itching (pruritus). Scabies may be a significant zoonotic risk , i.e. it can spread to other animal species including humans.
Chorioptes mites live their entire three week life cycle on the surface of the skin where they feed on dead cells. When caused by C. bovis, they are found particularly on the legs, feet and tail with symptoms of mild pruritus, alopecia and scaling of the feet and tail base resulting. Species identification is based on morphology (shape). Insecticidal sprays (eg. fipronil) are used in alpacas for eliminating Chorioptic mites as on contact it kills them within two hours and the treatment lasts up to one month.
Psoroptes mites can infect alpacas causing crusting weeping lesions but these are more confined to the ears. The animal exhibits head shaking and scratching. The Psoroptes mite affecting alpacas may be the same species that causes sheep scab.
In all cases, skin scrapings are taken from the affected areas and examined under the microscope. The morphology of any mites seen is used to diagnose the condition. Treatment of these mite conditions is by veterinary prescribed insecticides and it should be noted that all animals in the herd may need examination and treatment to prevent reinfection.
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- Tuberculosis (Tb).
Tuberculosis is an infectious disease caused by the bacterium Mycobacterium bovis. It affects a wide range of animals in New Zealand but cattle and deer are most at risk of contracting the disease. The common brushtail possum (Trichosurus vulpecula) is the main wildlife vector (carrier) of bovine Tb in New Zealand. The usual route of infection is through the inhalation of droplets expelled from the lungs an infected vector.
The TBfree programme (through OSPRI) aims to eradicate bovine Tb from New Zealand through targeted control. As part of the process, the country is divided into Tb control areas with each having specific testing frequency and movement control measures, depending on the risk of Tb transmission from an infected vector. As it is now established that camelids are susceptible (if resistant) to this disease, the Alpaca Association of New Zealand (AANZ) has set up a procedure for testing and reporting of camelid herd Tb status. The scheme is voluntary but all owners are strongly recommended to take part. Moreover, it is a condition of attendance at A&P shows that alpacas are tested and have valid certificates. All herd members over 6 months old must be tested to gain a “Whole Herd” status.
The single tuberculin test (STT) is approved for use as a primary Tb test for alpacas. An accredited vet will be needed to apply the test to an area of skin either at the neck site (about level with the animal’s back) or behind the foreleg. The neck site is the AANZ preferred and recommended site. Examination of the test site is made two or three days later for any skin reaction.
A detailed Tb reference card can be downloaded from the AANZ archive.
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Most of the literature below can be accessed by clicking on the highlighted link. Some links will access the appropriate web page from which the article can be downloaded but others will immediately start downloading the full reference.
4. Boyd, E. (2016). Management of Facial Eczema. M.Vet. Stud., Massey University.
5. Philippe, G. (2016). Lolitrem B and Indole Diterpene Alkaloids Produced by Endophytic Fungi of the Genus Epichloë and Their Toxic Effects in Livestock. Toxins (Basel), 8(2): 47. DOI: https://doi.org/10.1038/ncomms2516
20. Foster, A., Jackson, A. and D´Alteiro, G.L. (2007). Skin diseases of South American camelids. Practice, 29: 216–223.
21. Sinclair, D.P. and Howe, M.W. (1967). Effect of thiabendazole on Pithomyces chartarum (Berk. & Curt.) M. B. Ellis. N.Z. J. Ag. Res., 11(1): 59-62. DOI: https://doi.org/10.1080/00288233.1968.10431634
22. Mitchell, K. J., Thomas, R. G. and Clarke, R. T. J. (1961). Factors influencing the growth of Pithomyces chartarum in pasture. N.Z. J. Ag. Res., 4(5-6): 566-577. DOI: 10.1080/00288233.1961.10431614
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