Farm Animal Information - Alpacas
Alpacas are becoming very popular on lifestyle blocks around the Waikato. Alpacas are members of the South American camelid family, the same family as llamas, but alpacas (70 to 90 kg) are smaller than a llama (100 to 200 kg). Their original habitat was the unforgiving mountainous regions of the Andes. Alpacas are prized for their fibre, which is stronger and more resilient than merino sheep wool. Alpacas are generally hardy animals, but like most domestic animals may be susceptible to some conditions.
Anaemia in Alpacas
We have seen a few cases of anaemia in alpacas in 2012 which seem to be associated with the worm called Barber’s Pole (Haemonchus contortus). In severe cases, animals have pale eyes and gums, are weak and often suffer significant body condition loss. In 2012, summer – autumn, we had a period of perfect conditions for Haemonchus to multiply and thrive, with warm weather and regular rainfall. Animals pick up the larvae from the pasture, and the larvae grow into adult worms in the third stomach and intestines. They can even arrest their development and survive in the stomach till the following season, when the conditions suit larval survival better. Haemonchus are blood suckers and also cause seepage of blood and protein. Thousands of eggs are then shed in the faeces to further contaminate paddocks. Frustratingly, this disease often occurs about the same period as facial eczema, leading to potential confusion over the cause of the problem. Accurate diagnosis is essential if they are to respond to treatment. Some may need a blood transfusion as well as drenching and nutritional support, but this disease can be a killer. More worm resistance to anthelmintics (worm drenches) is being seen in sheep and cattle, and it is quite likely to rear as a problem for alpacas at some point. There are several combination drenches on the market now which contain two or three ingredients and get around the problem of resistance to a single active. Whilst seeing no eggs under the microscope does not guarantee no worms in the alpaca, it is recommended good husbandry practice to get faecal egg counts done before drenching to see if it is necessary (thus avoiding the cost of excessive drenches, and increased risk of developing resistance), and after drenching to see if the drench is effective.
- Monitor spores by spore counting during danger periods. Remembering the spore levels deemed to be safe for other classes of stock are probably not safe for alpacas. Long term consumption of low levels of spores may be just as damaging as short term high levels.
- Fungicide spraying of the pasture is effective in killing the fungus, but not the spores, and can give protection for up to 8 weeks depending on the product used and application rates.
- Remove animals from toxic pasture and feed supplementary feed during the danger period.
- Zinc salts are effective in reducing liver damage by interfering with the enzyme pathway that produces the damage. Alpacas are not big consumers of water, so treatment of troughs with zinc sulphate is ineffective, plus the zinc sulphate is not very palatable. Zinc oxide can be provided in capsule form [Time Capsules] to sheep and cattle but the coating appears to be rapidly broken down by alpacas so it is ineffective. Zinc oxide can therefore be drenched every 3 to 4 days or more easily the zinc oxide can be added to the feed with molasses to disguise the taste.
- Clostridial diseases affect most domesticated animals, with diseases such as enterotoxaemia, botulism, tetanus, blackleg and malignant oedema. Fortunately vaccination gives good protection.
- Few clostridial infections have been reported in alpacas but use of a clostridial vaccine is advised. There are no vaccines (or medicines and worm drenches for that matter) specifically developed for alpacas in this country, so any useage is off label. However their efficacy in other domestic animals is high in preventing disease, and so they are being routinely used in alpacas.
- In the absence of any other information, I would recommend vaccination of pregnant dams at least 2 months prior to due date of giving birth, followed by a booster shot 3 to 4 weeks later.
- The immune system of the cria lacks maturity and may not respond to vaccination at an early age, however it may be prudent to vaccinate in the first month of life and again a month later and at weaning.
- This disease is widespread in farm animals but has so far not been reported in alpacas.
- A family of organisms seen worldwide, that cause diseases such as TB and Johnes disease that usually develop slowly.
- There are only rare reports of natural cases of TB in alpacas in South America, so they do not appear to be particularly susceptible.
- TB testing of Alpacas is not compulsory in NZ, since neither alpacas nor their by-products are consumed. However, the Alpaca Association requires animals going to shows, be Tb tested within 2 months of going to a show, or come from a herd where a regular testing programme is in place. Animals going to a stud for mating may also be required to be tested.
- Johnes Disease is widespread in sheep, cattle, goats and deer in NZ, and usually presents as a syndrome of a non-responsive chronic diarrhoea and weight loss, usually in older animals. It has been reported in Australia in alpacas, and it is probably only a matter of time until it is reported in this country.
Mange in Alpacas
Skin disease in alpacas can be due to a variety of different causes; bacteria, fungi, allergies and nutritional problems but by far the most commonly reported skin disease are those caused by ectoparasites – mites and lice. Alpaca are susceptible to 3 common mange mites; Sarcoptes, Chorioptes and Psoroptes and all can be present on the one animal simultaneously. The treatment plan will vary depending on which mites are involved in the problem. Mange in NZ alpacas is more commonly associated with infection by Chorioptes. This condition often presents as a somewhat “itchy” animal with spotty hair loss and if left untreated results in the development of scale, crusts and thickening of the skin. Injectable ivermectin works extremely well against Sarcoptes and Psoroptes (blood sucking mites), which it can reach through the blood vessels in the skin. Injections are generally given fortnightly for 3 treatments. Ivermectin however is much less effective against Chorioptes because this mites stays on the surface of the epidermis feeding on dead skin and dander. In addition, the alpaca has almost no lipid layer/lanolin in its fleece so the traditional topical treatment options are also less effective. For these reasons treatment of Chorioptic mange can be a real therapeutic challenge. Frontline spray is currently being used in alpacas for the treatment of Chorioptic mange and works by altering the function of the mites nervous system. It will kill the mites it contacts within two hours and will continue to work for up to one month as it slowly wicks out of the sebaceous glands. The affected alpacas will need 4 treatments at 3 weekly intervals. So how do I know which treatment to give my alpaca? If you suspect your alpaca has mange, skin scrapings with examination with a microscope will allow your vet to differentiate between the 3 mite species & develop an effective treatment plan.
ALPACAS – Don’t forget the “D”!
Because alpacas evolved in the upper Andes, they often get short of vitamin D in our NZ winter due to relatively low UV exposure. This affects calcium and phosphorous balance and can lead to rickets. This can present as swollen bones / joints and lame or lethargic animals. A simple preventative is an injection of Vitamin D, especially to growing crias and animals with dark fibre who are more prone to this problem.
Worm Control in Alpacas
The effective and sustainable control of internal parasites in alpacas involves a combination of planned stock and farm management, monitoring of worm burdens using faecal egg counts and strategic timing of drenching. Alpacas are susceptible to the same internal parasites that are prevalent in cattle, sheep, goats and deer in this country. The basic life cycle of gut worms follow a similar pattern. Adult worms in the gut lay eggs which are passed out in the faeces. Once on the pasture the eggs hatch into larvae in about 1 or 2 days. Over the next few days if conditions are ideal, either not too hot or cold, the larvae go through a few stages of development and it is the 3rd stage larvae that if ingested are the ones that are infective and go on to cause clinical parasitism in the host animal. Once inside the host, the infective larvae develop to the adult stage over a period of about three weeks and begin to produce eggs and so the cycle continues. Therefore if an uninfected animal is introduced to infected pasture it will be about three weeks before the eggs can be detected in the faeces. Egg production varies with the worm species, for example, a single haemonchus contortus [Barber’s Pole worm], can produce over 10,000 eggs per day, whereas a black stomach worm [Trichostrongylus spp] or a small brown stomach worm [Ostertagia sp] may produce only 500 eggs per day. An animal infected with a moderate worm burden of about 3000 worms can produce about 1.5 million worms per day, but may produce 10 to 20 times this amount if infected with Barber’s pole worm. Therefore a birthing paddock can rapidly become highly infected and a big risk for cria when they start to graze. Barber’s pole is particularly dangerous as large worm burdens can develop very rapidly causing significant anaemia, protein loss and death without warning. The large numbers of developing worms can suck enough blood to kill an animal before eggs can be detected in the faeces and before the development of typical worm symptoms such as diarrhoea and ill thrift. Fortunately under extensive pasture grazing the incidence of gut worm infections should remain low due to the habit of alpacas to use a communal dung pile reducing widespread pasture contamination. However the practice of having heavier stocking rates in smaller paddocks will increase grazing pressure and force animals to graze closer to the dung heaps and so heavier worm burdens may occur. Adult animals tend to develop a resistance to worm infections, which does not mean that they are worm free, but that their immune system helps them maintain worm burdens at a manageable sub-clinical level and also has some control over the production of eggs from this population.. However the rise of the hormone Prolactin in late pregnancy appears to interfere with this mechanism so incoming larvae will develop without any constraints from the host immune system and constraints on the egg production of existing female worms will be removed which leads to an increase in the output of worm eggs during late pregnancy and lactation. The normal immune response to worms is restored when the cria is weaned. Faecal egg counts are a useful and simple method to monitor a drenching program both to identify times when drenching is required and also the effectiveness of any particular drench. Drench resistance is becoming an increasing problem in all classes of stock. Benzimidazoles [White drenches] and Levamisoles [Clear drenches], are not now used extensively because of resistance problems, however combinations of these drenches can still be effective. Macrocyclic lactones are the most modern types of drench and include, ivermectin, abermectin, doramectin and moxidectin. Recent Australian experience with preparation of alpacas for export has shown the injectible form of moxidectin [sold here as Vetdectin or Cydectin] to be the product of choice. Ivermectin was found to be less effective especially against Nematodirus. Doramectin [Dectomax] was also very effective. Dosage for these is at about twice the level of standard sheep doses, ie 1 ml per 25 kg bodyweight. Note that none of the available drenches are actually registered for use in alpacas so any use is therefore considered to be ‘off-label.’
- The most effective worm control strategies in any species involves the use of safe pastures onto which animals may be moved following drenching.
- To ensure a paddock is safe the pasture may have to be spelled for up to six months to allow the killing of infective larvae
- Avoid paddocks grazed in the past by pregnant or lactating animals or last years young stock.
- Avoid grazing crias with large numbers of older animals
- Monitor faecal egg counts
- Pay particular attention to those animals that appear to lag behind when being moved or who are not growing as expected or losing body condition [often difficult to detect until too late because of the length of the fleece]
- Drench all animals moving on or off the property.
- Consider disposing of faecal piles from the paddocks.
So we diagnosed Chorioptes in this alpaca, which is a surface chewing mite, and it makes sense to treat it with a course of fipronil spray (and a shot of anti-inflammatories).
The crucial point here is that most mites found have been Sarcoptes, which burrows into tunnels deep within the skin. Obviously, spray wont penetrate deep enough here, so we would treat with an injectable abamectin, and the prognosis can be guarded if the mange has become extensive and chronic. The point from this lovely (and so far successful) little story, then, is to underline the importance of a definitive diagnosis to initiate the best treatment.