The Use of Ultrasound for Pregnancy Diagnosis & Fertility Examinations

Pregnancy diagnosis in alpacas traditionally relies on “spitting off” – in other words checking whether a female is receptive to the male. It is usually done a week or more after mating. However, there are some limitations to this technique. Firstly, not all huembras give clear signals as to whether they are “sitting” or “spitting”. This tends to be more common in younger females and can be quite confusing if you are trying work out what she is trying to tell you.

The other common reason that a female will spit when not pregnant is a high level of circulating progesterone in her bloodstream, caused by a persistent corpus luteum. When an alpaca is mated and ovulation occurs, the follicle in her ovary which releases the egg forms a “corpus luteum”. This is a structure which produces the hormone progesterone. Progesterone has many functions but is primarily concerned with preparing the body for pregnancy. One of its actions is to suppress the normal cyclical maturation of follicles in the ovary and hence to stop the female from being receptive. It is progesterone which is responsible for changing the animal’s behaviour from sitting to spitting. If she does not fall pregnant after mating, normally the corpus luteum regresses after a few days and the female becomes receptive again. However, sometimes this does not occur and the corpus luteum persists and keeps pumping out progesterone. This stops any more follicles from developing in the ovaries and the animal keeps spitting, just as if she were pregnant. The corpus luteum can persist for many months and the animal keeps “spitting off”. Eventually the corpus luteum regresses and all of a sudden you have a female that you thought was pregnant but is now sitting again. This occurs often enough to be a problem for most breeders and is a significant cause of reproductive loss and wasted time for the alpaca industry.

The beauty of ultrasound is that you can see the developing cria, so there is no doubt about the state of pregnancy. From about 6 weeks of pregnancy, the foetal heartbeat is visible and then later on other structures are visible, so you can see that you have a live and normally developing cria. Any time after 6 weeks, the ultrasound examination is performed through the abdominal wall, by placing the probe against the skin in the flank area, just in front of the udder. In later pregnancy, the weight of the expanding uterus means it is further forward in the abdomen, so you have to scan over a larger area. There is no adverse effect on the cria of this examination and there is no risk to the mother, apart from the fact that she has to be held still for a few minutes while the examination is performed.

For very early pregnancy diagnosis (i.e. before 5 to 6 weeks) and for infertility investigations, a different technique is employed, using a rectal probe. This enables more detailed examination of the uterus and ovaries. If performed carefully by an experienced operator on a well-restrained patient, it is a safe procedure although, since it is an internal examination, there is always the slight risk of injury to the female, especially if she moves suddenly. Once again, this procedure is quite safe for the cria.
Ultrasound examination is a routine part of reproductive examination and pregnancy diagnosis in many species, including alpacas. It gives us much more information about what is happening within the reproductive tract and with a developing pregnancy than any other form of investigation.

The beauty of ultrasound is that you can see the developing cria, so there is no doubt about the state of pregnancy. From about 6 weeks of pregnancy, the foetal heartbeat is visible and then later on other structures are visible, so you can see that you have a live and normally developing cria. Any time after 6 weeks, the ultrasound examination is performed through the abdominal wall, by placing the probe against the skin in the flank area, just in front of the udder. In later pregnancy, the weight of the expanding uterus means it is further forward in the abdomen, so you have to scan over a larger area. There is no adverse effect on the cria of this examination and there is no risk to the mother, apart from the fact that she has to be held still for a few minutes while the examination is performed.

A normal alpaca pregnancy at 3 months

For very early pregnancy diagnosis (i.e. before 5 to 6 weeks) and for infertility investigations, a different technique is employed, using a rectal probe. This enables more detailed examination of the uterus and ovaries. If performed carefully by an experienced operator on a well-restrained patient, it is a safe procedure although, since it is an internal examination, there is always the slight risk of injury to the female, especially if she moves suddenly. Once again, this procedure is quite safe for the cria.

Ultrasound examination is a routine part of reproductive examination and pregnancy diagnosis in many species, including alpacas. It gives us much more information about what is happening within the reproductive tract and with a developing pregnancy than any other form of investigation.