Even top farms have a few cases of mastitis each season, so this video is a handy review of treatment best-practice, including how to give intra-mammary antibiotics.

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Clinical mastitis (abnormal milk and/or quarter) and subclinical mastitis (normal milk and quarter, but high somatic cell count (SCC)) are treated differently.


If you have identified mastitis in the milking shed, do not milk the affected cow into the vat. Instead, follow MRS. T:

M – Mark

Follow the convention on your farm so everyone sees that the cow has mastitis.

R – Record

Record the cow’s tag number, quarter with mastitis and today’s date in your permanent animal health records.

S – Separate

Separate the cow with mastitis from the milking mob so she can’t be milked into the vat. Put her into a mob with other cows on treatment (“red mob”).

  • If you want to take a milk sample for bacterial culture from this cow, do this before she is milked
  • Once the cow with mastitis has joined the red mob and the milk line has been diverted, milk the cow

T – Treat

Make a mastitis treatment plan with your vet and update it before calving each year. A decision-making flow chart next to the medicine cupboard is a handy way to make sure everyone treating cows on your farm knows what to use, and when.

  • Intra-mammary antibiotics (put into the quarter) are usually best for mastitis treatment
  • Some cases of mastitis (eg, very sick, heifer with small teats, multiple quarter mastitis) might need an injectable antibiotic
  • Follow product label exactly, unless you have written instructions from your vet telling you otherwise. Not following instructions may effect cure rates
  • If you use an injectable anti-inflammatory drug to help cows feel better faster, make sure you have, in writing from your vet, how to alter the withholding periods for using two separate medicines at the same time


  • Be clean and gentle, so you don’t make the cow’s mastitis worse
  • Clean and dry your gloves
  • Thoroughly clean the teat end with a new teat wipe or cotton ball soaked in 70% methylated spirits
  • Uncap the treatment tube and partially insert it into the teat end no more than a few millimetres
  • Instil the product by pressing the plunger gently
  • If the product label says to strip/massage the product into the quarter, then hold off the end of the teat with the forefinger and thumb of one hand and use your other hand to strip the product up.
  • Spray the cow’s teats with teat spray
  • Give any other treatments the cow requires, such as an anti-inflammatory after the intra-mammary antibiotic
  • Record all treatments in your permanent animal health records, and check that withholding periods are being properly followed
  1. If the cow’s milk/quarter are still abnormal at the end of treatment, continue to check her for a few days rather than switching or extending your treatment. Ring your vet if your treatments aren’t working as you expect.
  2. Once the cow’s milk and quarter is back to normal and clear of the milk withholding period, mark her to signal she can go back into the vat, and draft her into the milkers


Ask your vet for advice. Depending on the case, they may suggest that you:

  • Take a milk sample for bacterial culture to find out what’s going on
  • Monitor the cow in the red mob for some time to see if she self-cures
  • Dry her off early with dry cow antibiotics
  • Stop milking the quarter
  • Cull the cow


  1. McDougall et al. (2018). Antimicrobial usage and risk of retreatment for mild to moderate clinical mastitis cases on dairy farms following on-farm bacterial culture and selective therapy. NZVJ. 66:2 98-107.
  2. Ruegg, P. (2017). A 100 Year Review: mastitis detection, management and prevention. Journal of Dairy Science. 100:10381–10397.
  3. Ruegg, P. (2018). Making antibiotic treatment decisions for clinical mastitis. Veterinary Clinics of North America: Food Animal Practice. 34:3. 413-425.
  4. NZVA. (2018). Antibiotic judicious use guidelines for the New Zealand veterinary profession: Dairy.
  5. DairyNZ SmartSAMM. (2012). Calving Technote 4: Rapidly find, record and treat clinical mastitis in recently calved cows.
  6. DairyNZ SmartSAMM. (2012). Lactation Technote 10: Rapidly find, record and treat clinical cases.


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Top Farmers Know-How provides a reference library of industry best practice in some key animal health management areas including mastitis, dry off, calf health, BVD, salmonella and campylobacter. We know that farmers and vets are busy people, so we’ve created resources in different formats and in bite-sized chunks to make it more flexible and accessible.