major hair loss

[sampson farms]

we have cow calf herd of 100. Three weeks ago we worked herd like we do every year before breeding.
All cows got cattle master gold and pink eye vaccine, wormed with ivermec plus injectable and dosed with 4 oz of delice.

Now we have one cow, angus cross with 2 month old calf that has lost all her hair, falling out in clumps, no open sores, but she is loosing weight even with feed.

herd is on rotational grazing moving to new pasture every 4 days, fresh water and minerals available at all times.
no other cow is showing these signs.

I would think mites are not a problem since we wormed with ivermec and she was deliced.

suggestions welcome, thank you

 

[Animal Track Farm]

My first thought might be an allergic reaction to one of the medications. Some of the more experienced people on here may know more. I would at least call the Vet before she gets too run down, especially since she is supporting herself and a calf.