Immunoglobulins, Plasma and Cria

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The following article was a presentation to Central Region Alpaca owners by Geoff Neal formerly of Manawatu Veterinary Services, Feilding, and is reproduced with his permission.

 

The Facts

In the world of immunology (the study of how an animal’s immune system works) the terms antibody, immunoglobulin, IgG, plasma, Colostrum, etc are used without much concern for whether or not people actually know what these things are; so before we go into too much details let us clarify these terms:

Antibody: A protein molecule that is produced by the body’s immune system in response to a disease process.

Immunoglobulin: Another way of saying antibodies

IgG: Also know as Immunoglobulin G. The main immunoglobulin involved in the maternal protection of newborn animals.

Plasma: The end product when whole, unclotted blood is spun down and the red cells are removed. Contains immunoglobulins, clotting factors and other assorted proteins.

Colostrum: The first milk produced by mammals (except primates). Very rich in immunoglobulins, fat, energy and protein.

 

Why do cria need colostrum?

For the first three weeks of a cria’s life it has no functional immune system of its own. All the antibodies that it needs to fight the masses of bacteria, viruses etc that a newborn cria comes in contact with have to be derived from somewhere other than itself. This is where colostrum plays its role.

The colostrum that a cria drinks in the first 24 hours of its life contains all the antibodies that it will have to support itself on for those first three fragile weeks of its life. If a cria does not get sufficient colostrum, or the cria cannot absorb the antibodies properly, or the colostrum quality is poor, then the chances of that cria dying are greatly increased. The average death rate of alpaca cria in the USA is 10% in the first three weeks of life. Of these deaths, 90% are septicaemia and the crias inability to fight infections.

 

Why is it so important for cria to get colostrum in the first few hours of life?

In a normal healthy cria, the absorption rate of antibodies from colostrum is about 26% from 0-6 hours post delivery. This figure decreases to around 18% from 6-18 hours post birth, and by 24 hours post-delivery, the absorption rate is well below 10%. After 24 hours, the gut of the cria does not allow the antibodies in the colostrum to pass into the blood as whole units, instead the gut begins to digest them up into amino-acids for energy, just as if they were other types of dietary protein.

 

What cria are likely to have problems with inadequate colostrum absorption?

Cria that are likely to have problems with either obtaining adequate colostrum intake or having inadequate colostrum antibody absorption are called the “at-risk” group. The “at-risk” group would contain the following cria:

  • Premature cria
  • Cria that fail to stand and suckle within three hours of hours of birth
  • Weak, cold, slow cria
  • Any cria that requires delivery by caesarean section
  • Any cria that required assistance for delivery where the procedure lasted for more than 15 minutes
  • Cria born to known problem females. Problem females would be those who have had cria die in previous years in the first few weeks of life
  • Cria born to old, weak or sick females, especially if their body condition is less than average.
  • Cria born to females with mastitis
  • Cria born to stroppy females who will not let the cria suckle. Maidens often fall into this category.

The reason for all of these situations to be classed “at-risk” is because they all in some way alter the ability of the cria to get sufficient, good quality colostrum in the first few hours of life. 10% of all alpaca cria born have insufficient colostrum absorption in the first 24 hours of life. It seems ironic that this is the same as the expected mortality rate in alpaca cria???

Cold, stressed or premature cria have a gut absorption rate for antibodies of about 2% (cf 26% in healthy cria).

 

How do I ensure that my “at-risk” cria gets the antibodies it needs?

There are two schools of thought on this; either leave them and hop they’ve had enough, or ensure the cria has enough antibodies by giving them directly to it. This where plasma infusions come into the picture.

By giving an “at-risk” cria a unit of plasma into the abdomen it can raise its IgG levels from less than 200mg/dl to more than 800mg/dl within one hour of the infusion. The minimum required for a healthy alpaca cria is 500mg/dl.

A plasma transfusion involve obtaining plasma from an older, healthy alpaca and injection it into the abdominal cavity of the cria within the first 6 hours of life. The antibodies in the plasma are absorbed into the blood stream through contact with the inside of the abdomen and the abdominal organs. This is called the intra-peritoneal (IP) route of admission and it is used as the preferred route for giving plasma to cria for several reasons. Firstly, cria have very small veins, making intravenous (IV) administration difficult. Another disadvantage of the IV route is that the plasma has to be given very slowly (about 2-3 hours per unit), compare to the IP route, where a single unit can be administered in 10-15 minutes. The final reason for using the IP route is that the absorption rates of IP are almost identical to IV, and is significantly greater than giving the plasma orally.

Giving plasma orally is ineffective as the digestive processes destroy the plasma before it can be of any benefit to the crias.

 

Where do I get plasma and how do I give it to my cria?

Plasma is obtained in the first instance by bleeding adult alpaca into human transfusion bags and then having that blood spun down and the plasma extracted. Extracted plasma is then frozen and has a shelf life of 12 months. This procedure is something your vet may be able to do, but in the majority of cases they will have extreme difficulty in being able to spin it down because of the machinery required to do the spinning and plasma extraction.

Your options are therefore:

1. Obtain frozen plasma directly from Manawatu Veterinary Services, Fielding. The cost is at least $150 per unit of frozen plasma including p&p.

2. Organise with your local vet to have whole blood collected (from your own adult alpaca) and couriered to MVS where we can spin it down and extract the plasma for $20 per unit inc p&p, with a 2 unit minimum. (Plasma must be couriered in a polystyrene box to prevent heat damage).  Costs may alter with time elapsing.