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Pregnancy Testing in Alpacas

How do I know if my alpaca is pregnant?

Until she actually comes to light with a live cria, it can sometimes be very difficult to tell! No form of pregnancy test is 100% proof that a live cria will be born. Even tests that cannot return a false positive, will tell you only that the alpaca was pregnant at the time of testing – a foetus can be resorbed or aborted subsequently, and you may not be aware that this has happened. However, most alpaca who test positive for a pregnancy will have a cria in due course, and you will want to have some idea whether or not you need to remate your alpaca. The following are the most common forms of pregnancy testing currently in use:

Spit-off:  a mated female is re-introduced to the stud male. A female that has ovulated or is pregnant will reject the males advances by running away, kicking, and spitting. This is termed a “spit-off”.  A receptive (non-pregnant) female may initially run away, but will normally go into the cush position fairly readily, and accept a mating. Spit-off’s are generally only viable with pen-mating procedures.

A spit-off is the common first indicator of whether a pregnancy has occurred, and it is generally understood that if a female is still spitting off at 28 days after mating, she is pregnant. It is generally smart to repeat spit-offs every 3 months or so to ensure the pregnancy is progressing normally – however this may be difficult if you are not the stud owner. Be aware, also, that there are some hormonal conditions that will cause a female to reject the males advances, while some females react to the presence of a male with aggression regardless of whether they are pregnant or not. A spit-off can return a false positive.

Blood test: A blood test taken 45 days after mating will indicate the raised hormone levels associated with pregnancy. Once popular, this form of pregnancy testing is falling in disfavour as raised hormone levels can be associated with other hormonal conditions, not just pregnancy. A blood test can return a false positive.

Visual Ultrasound Scans: A scan that returns a “picture” of the internal organs and any foetus that may be present. Some skill is needed to accurately identify the presence of a foetus, and this procedure is generally done by a veterinary surgeon for this reason. Small hand held scanners are available from USA, but these are extremely pricey (in excess of NZ$3000) so not viable for small herds.

Scans are performed no earlier than 60 days after mating. It can be very difficult even for the experienced to get an reliable scan result. There are two kinds of scan procedures in common use, an external scan which is less accurate, and an internal scan which is more likely to give an correct result, but is extremely invasive. We have always refused to subject our alpaca to internal scanning. A positive result relies on correctly identifying an ultrasound picture of the cria. A visual ultrasound can return a false negative.

Audible Ultrasound Scans: A scan that returns a audible sound when it encounters the fluid surrounding the unborn cria. As with a visual scan, this is best done 60 days after mating. Effectiveness deteriorates in late pregnancy as there is little fluid left to detect. Easy to use even by the inexperienced, they are available in NZ for around $1000, so are a viable investment for those with moderate sized herds. They are non-invasive, but may return a false negative if used incorrectly.