Many of you may have heard of Toxoplasmosis
and it’s relationship to pregnant women. I know as a small animal
practitioner, I get many calls from pregnant women who are
wondering if they need to get rid of their cat. Here is the scoop… Toxoplasma is protozoan parasite
that is carried by rodents and birds. Cats are infected when they eat
the mouse or bird and then the Toxo organism will live part of its
life cycle in the cat.
The organism is passed in the cat feces and then must sit in the
environment for a couple of days before it becomes infective to
people or to our goats. (In other words, you could eat
fresh cat poop and NOT get sick, the stool must be OLD to be
infectious! This is a
key point.) Once cats
become infected with Toxo they will always have it, but they will
only pass it in the stool for a brief time just after they are
first infected. Most cats only pass the organism in the stool ONCE
in their lives and usually when they are kittens. The exception to
this would be if an older cat got another disease that suppressed
their immune system (such as feline leukemia or feline
aids).
When kittens that are shedding the organism
defecate in the hay, feed bins, or bedding, the goats can
potentially become infected. People get infected when cats
bury their stool in the garden and people work in the garden
without gloves or face masks…yes you can actually get this by
breathing the dust that is carrying the parasites. Goats can also get it this way.
Another way you can get the organisms is by eating meat that
contains the parasites. When goats, cows, pigs or other
animals are infected by the parasite, they (the organisms) don’t
really know what to do so they swim around in the animal’s body and
form little “cysts” in the muscle tissues. When you eat the cysts
in the muscle, you can get Toxo. What most folks are concerned
with is cleaning the litter box, but if this is done daily the poop
will be fresh and the organisms will not be infective yet.
So what is the big deal? Well….Toxo is one little bug that
can cause big, big problems. People that are not pregnant and
that have good immune systems generally just get slight flu like
symptoms and don’t even know it was the bug. It doesn’t really go away, it
goes to your brain tissue and some in your muscle tissue and just
sits there for years.
If you get AIDS or Cancer and are immunosuppressed for some reason,
the little critters can come out of their “cysts” and cause severe
problems or even death. The biggest problem is in
pregnant women or young children with immature immune systems. The organism will infect
unborn babies and cause severe birth defects or miscarriages. It can get into the retina
of the eyes and cause blindness or it can get into the brain and
cause neurologic disease in children.
So why are we concerned with it in goats? It does many of the same
things as it does to people! If the doe gets infected while
she is pregnant, the organism can multiply in the placenta and
infect the fetus. This
can cause miscarriages and stillbirths, weak kids and kids with
neurologic disease.
Occasionally, but not often, the infected doe will run a fever, but
most show no clinical signs other than abortion. If the doe has a bad immune
system she may develop a neurological form of the disease. Is there
another reason we worry about this in goats? Yes—infectious
organisms can be passed in the milk and will also be in the muscle
of the goat. As I said
earlier, adults that have a good immune system could get infected
by drinking the milk but they will show no or only very mild signs
of a problem. However,
infants or immune compromised people that drink infected goat milk
could come down with very severe disease. Pasteurization or boiling of the
milk will kill the organism. Goat meat that is infected could
also infect a human and that is one reason to cook your meat until
the juices run clear.
Meat does not have to be well done but the juices must not be pink
or red, they must be clear.
How can we diagnosis this? Because most adult does do not
show symptoms it is hard to diagnose it in the adult animal. Diagnosis is most reliable
if the aborted fetus and the placenta are sent to the lab. If your doe aborts, do NOT
let her eat the placenta and do NOT throw it away. The placenta is the key to
diagnosing many causes of abortion (not just toxoplasma.) Wrap everything up,
including the aborted fetus, and put it in a plastic bag in a
refrigerator.
Most of the time it can actually be frozen but not always. Until
your vet examines the tissues and determines which tests need to be
run, it is best to refrigerate. Remember, you cannot refrigerate
it forever without the tissue breaking down. Examination and laboratory
analysis need to be done within 2-3 days maximum. Blood tests can be run on a weak
kid but the blood must be drawn BEFORE the kid gets colostrum. Antibodies may be passed
from the doe to the kid in the colostrum that would make the test
positive. These
antibodies would be present in the doe if she had ever in her life
been infected. If she was infected BEFORE the pregnancy the Toxo
will not cause a problem. The problem is only if she is
infected during the pregnancy. Therefore, antibodies passed to
the kid will show in blood tests but do NOT mean that Toxo was the
problem.
How do we prevent this? That is a tough problem. Many folks recommend
getting rid of your barn cats. The problem is that stray cats
passing through your barn or pasture can also shed the
organism. Other people
have advocated having a few, neutered barn cats. These cats are not going to be
having kittens (the age most likely to shed the parasite) and they
are going to hopefully chase off any stray cats that come
around. The most
successful method of preventing this is to keep the feed and the
hay in areas where cats cannot get to it. Cover your hay feeders and keep
the hay off the ground. Keep feed in closed
containers. Clean any
hay or feed that could potentially have cat feces in it daily.
(Remember-fresh feces is not a problem, the organism cannot infect
you or your goats unless it has sat in the environment for a couple
of days.) Even this method is difficult and we all need to be on
the lookout for signs of a problem.
