Case Study #2: Older Cow with History of Chronic Mastitis

December 22, 2016

Farm Description: 60 lactating cows. Cows are milked 2x in an older tie stall barn that has rubber mats and is bedded with sawdust. The owner and an employee milk the cows twice daily. The ambient temperature is 50F (10C). All cows are treated with antibiotics at dry off. The bulk tank SCC of the farm is 395,000 cells/ml.

Cow Description: 6 year old Holstein/Jersey cross. Calved 8 months ago and is 150 days pregnant. She is producing 53 lb (24 kg) and has a BCS of 3.50. Her SCC at dry off at the end of the last lactation was 880,000 cells/ml and she was treated for clinical mastitis 2 times. At the end of that lactation, she was treated with an intramammary dry off antibiotic that contains a 1st generation Cephalosporin (Tomorrow®)

Her milk appeared normal after calving for this lactation and her SCC so far this lactation are:

Month 1 – 260,000 cells/ml
Month 2 – 330,000 cells/ml
Month 3- 1,560,000 cells/ml
Month 4 – no test day data is available
Month 5 – 560,000 cells/ml
Month 6 – 465,000 cells/ml
Month 7 – 306,000cells/ml
Month 8 – 275,000 cells/ml

In the current lactation she has been treated for clinical mastitis twice (once in month 2 and once in month 5). This morning, one of the owners is milking and notices that she has clots and flakes in the foremilk but her udder appears normal. Her body temperature is 101.5 F (38.6C) and she is eating normally and appears to have good rumen contractions.

Each month the farm submits a bulk tank culture and results of the last bulk tank culture are as follows:

200 cfu coagulase-negative Staphylcococci (CNS)
<50 cfu coliform
0 cfu strep ag
150 cfu Streptococci spp
400 cfu Staph aureus

DISCLAIMER: These cases are teaching examples and do not represent all outcomes of individual cases. The treatments assume that the cow is in the United States and that the FDA rules for use of drugs are applicable. Individual cases in real cows should receive treatment protocols that has been discussed and developed with the local veterinarian.

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