CCTs and the kitten that followed me home...

            After getting a firm grasp on Caudal Fold testing, I took a trip out to Freemont to see Comparative Cervical Tests.  For animals that are “suspects” on the caudal fold, producers have the choice of either doing a gamma interferon (blood test) or a Comparative Cervical Test (CCT).  Some producers elect to do CCTs because they tend to have less positive reactions than the gamma tests.  This particular producer wanted to move his entire 1200-head dairy to Indiana one week from today, so testing needed to be completed ASAP.  With Caudal Fold tests having anyway from 3-10% reaction rate, we were prepared to possible be doing CCTs on 120 animals so two teams of state field vets showed up for the job- I got to be on Dr. Susi Baer’s team.
            CCT tests are pretty simple.  Two area along a cow’s neck are shaved and then the skin thickness of each area is measured.  The first shaved area closest to the head is injected intradermally with Avian tuberculin, the second with bovine tuberculin.  After 72 hours the skin is measured again and we plot the difference in skin thickness along a USDA scattergram.  Basically, a cow can sometimes react on the Caudal Fold test because they have been exposed to Mycobacterium avium NOT Mycobacterium bovis.  The CCT shows what antigen the animal has been exposed to in its lifetime.  If the M. avium patch reacts more, the animal is in the clear; however, if the M. bovis reacts more than the animal is a suspect. 

Measuring skin thickness on a cow's neck (head is haltered and being pulled toward the right-side of the screen).

On this particular farm that suspect would be immediately shipped to the lab at MSU, slaughtered, and examined for lesions.  The State of Indiana doesn’t want to take any chances on getting a TB-infected animal and this producer doesn’t have the patience to wait out re-testing in Michigan (I guess a bad divorce will do that to you, so I heard from this producer).

We ended up with only 30 caudal fold suspects, but finding those 30 animals in a 1200-head dairy is not a quick process.  We brought along chutes and gates, but found it easier to work with the equipment in the dairy barn.  Some animals were tested in their stanchions, some in a chute meant for feet-trimming, and others just along the management rail.  Being flexible and not getting your fingers pinched against any rails are important aspects for being a vet—so I learned from Dr. Baer.

Dr. Schwarck was testing in the other team.  I learned from him that regardless of how long you are a vet and how many animals you’ve seen—you will still have a heart for a crying wet kitten.  I think you just get smarter and instead of taking it home yourself, you convince a vet student to take it home (that student being me). 

Stray kitten that I took home (so happy she found a new home with fellow FSF student Hannah!).