This second article in the series on alpacas deals with some common diseases:
- Ryegrass staggers
- Facial eczema
- Clostridial diseases
There isn’t space to discuss all the potential problems of alpacas of course, but these are conditions to which they seem particularly susceptible.
- Alpacas are very susceptible to ryegrass staggers, which are caused by toxins in an endophyte that grows inside ryegrass plants.
- The toxin is concentrated in the seedheads and the base of the stems and levels are highest in summer and autumn.
- Alpacas selectively graze seedheads and this may increase their risk.
- The first sign to develop is usually a slight tremor of the head and neck.
- With continued exposure the shaking gets worse, leading to an unstable gait, and the risk of death caused by misadventure.
- At the first signs, the affected animals must be removed from the infected pasture and provided with fresh water and good-quality hay (with no ryegrass).
- Eventually, most affected animals recover but some are left permanently shaky.
- Most perennial ryegrass in New Zealand has been deliberately infected with an endophyte to provide protection from the drought and from attack by the Argentine stem weevil.
- Long-term prevention means replacing high endophyte ryegrasses with low or safe endophyte ryegrass cultivars or other species of grass.
- Rickets is a condition in which bone development is abnormal because of a deficiency of vitamin D in growing animals.
- It usually shows up in alpacas 18 to 24 months old and especially autumn-born animals.
- It can result in bowing of the forelegs, or the animals may be reluctant to move or they may stand in a hunched posture. There are ill-thrift, lameness, swollen joints, and swollen rib ends.
- Treatment involves vitamin D injections from your vet.
- This is only effective if begun at about 8 weeks of age with further injections over the winter and spring until the animal is 2 years old. It can also be wise to inject pregnant females with vitamin D a month before they are due to ‘unpack’.
Vitamin D is closely involved with calcium and phosphorus metabolism in the body and it is necessary for the development of strong healthy bones. Sunlight on the skin is required to help convert precursor metabolites in the blood into vitamin D.
Even though there is plenty of UV light in New Zealand, it sometimes isn’t enough for alpacas, especially in winter, in dark-colored animals and animals with dense fleece.
- Alpacas are susceptible to facial eczema, probably even more susceptible than sheep and cattle.
- The disease occurs in late summer and autumn mainly in the North Island.
- Fungal spores in the dead litter are ingested, they cause damage to the liver and this, in turn, means a breakdown product from chlorophyll in pasture circulates in the blood.
- This substance is photodynamic, and it reacts with sunlight causing skin damage like severe sunburn.
- There is no treatment except to try to reduce the ingestion of spores until the liver has a chance to recover.
- High roughage, low protein feed can be provided and plenty of shade, e.g. keeping them indoors during the day and putting them out at night).
In at-risk areas in late summer and autumn, it is wise to try to prevent the disease:
- Avoid high-risk pastures.
- Feed zinc oxide by mouth.
- Alpacas need to consume around 2 gm per 100kg body weight daily.
- Beware of over-dosing and don’t use zinc sulphate.
- Like sheep and cattle, alpacas are susceptible to clostridial diseases such as pulpy kidney and tetanus.
- Pulpy kidney causes sudden death and rapid decomposition of the carcass.
- Tetanus causes muscle rigidity (rocking horse-like) then death.
- Most alpaca owners vaccinate against clostridial diseases and this is generally effective.
- A 5-in-1 clostridial vaccine at the sheep dose rate is usually sufficient.
- This protects against pulpy kidney, tetanus, and three forms of gangrene.
Maximum protection involves:
- Vaccination of the cria at 6 to 8 weeks followed by a booster 4 to 6 weeks later, then a booster every 6 months.
- A booster shot for pregnant females 4 to 6 weeks before ‘criating’ to ensure maximum protection for the cria.