8 reasons why you aren’t getting the mastitis cure rates you expect

8 reasons why you aren’t getting the mastitis cure rates you expect
By Jemma Guyton, Veterinarian, Anexa Vets Matamata

Research has shown that 80-90% of mastitis should cure clinically and be free of bacteria with standard antibiotic treatment and should not need re-treatment within 21 days.

If you aren’t satisfied with the cure rates of mastitis on your farm and aren’t getting clinical cures of 80-90% there could be several factors that could be at play. Farm staff changes and farm protocol changes can have a big effect on mastitis on your farm. It’s important to make sure all farm staff are following the same protocols that have been set in place for mastitis.

1. What does a cure look like for you vs. your farm staff?

Milk visibly back to normal? No longer reactive on RMT?
A cure for you might look different to what someone else calls a cure.

Usually, a standard treatment of a product will mean the bugs should be gone. However, after a course of treatment, the SCC might still be high, and you might still see clinical signs. This doesn’t mean the mastitis-causing bugs aren’t gone – most of the time the cow’s immune system plus the antibiotic treatment have killed the bugs but it’s just taking a bit longer for the immune response in the quarter to settle and the milk to visually cure.

Quarters can be resampled 7 days after the milk withhold period has finished to see if there is bacteriological cure. If bugs grow, the treatment didn’t cure the infection, or a new infection has occurred.

2. How quickly is the mastitis picked up?

Are farm staff checking for mastitis pre- or post-milking?
Do all farm staff know how to identify mastitis? Hot, swollen, hard, abnormal milk etc.
The longer it is before it is detected, the more established and potentially damaging the infection can be - therefore often making it harder to cure.

3. Have you changed mastitis products? What product was used previously? e.g. changed from 24h to 12h product

Changing between 24- and 12-hour products can sometimes appear that mastitis cases aren’t curing. This is often a reflection of both the treatment and withholding periods - remember that using 3 tubes of a 24-hour product provides treatment over 3 days but using 3 tubes of a 12-hour product provides treatment over 1.5 days. Shorter milk withholding times mean cows are checked to go back into the vat sooner than they were with a product with a longer withholding period and it may appear that the cow hasn’t cured, while in reality the quarter just needs a bit more time for the clinical signs to disappear.

4. Is the quarter getting reinfected after treatment or while the cow is still in withholding? This can make it appear like the case hasn’t cured properly, but really, it’s a new infection.

How is the mastitis mob managed? i.e. are they milked last after the herd? Are cups cleaned between the herd and the mastitis mob, or are mastitis cows potentially getting re-infected during milking? Is there teat end damage?
Bacteria found on cows’ teats and skin often infect quarters if there is enough damage on the ends of teats. Test skin bugs often infect quarters if there is enough damage on the end of the teats.

5. Frequency of milking mastitis cows – has this changed?

Milking mastitis cows twice a day can help to increase cure rates by stripping the quarter more frequently. This is particularly important for nasty gram negative mastitis causing bugs such as E.coli. Twice a day milking of the mastitis mob also allows for more frequent checking of these cows.

6. Other cow health factors

Are anti-inflammatories given to cows with mastitis? Anti-inflammatories can help with cure rates as well as helping to reduce SCC.
General health and immunity of these cows before they get mastitis and during infection i.e. is Salmonella prevalent on your farm? Was it a bad year for facial eczema?

7. Antibiotic resistance

A Dairy Antibiogram Test can provide important information about antibiotic resistance profiles for the two main bacteria that cause mastitis in New Zealand (Strep uberis & Staph aureus). There may be a different bug causing the mastitis in your cows. Without milk culture results from individual cases, there is no way of knowing if the antibiotic you are using is the right one.

8. Incorrect usage of mastitis treatment

Is the appropriate treatment protocol being followed?
Check the packaging of the product or your Anexa RVM chart
  • Number of tubes
  • Frequency of treatments (i.e. 12- or 24-hourly)
  • Hygiene – even though you are using antibiotics, it’s still important to be clean.
    • Wearing gloves while treating clinical cases and cleaning your hands between treating different cows can help prevent the spread of bugs between cows.

Extending treatment

There is the option for some mastitis treatments to be extended to 5 or 6 tubes if the mastitis hasn’t cured after 3 tubes. This is a much better option than changing antibiotics altogether as some antibiotics don’t work well together and it can cause resistance issues. Using two different antibiotics without completing the withholding period for the first antibiotic is also off-label use.

Talk to your vet or refer to your Anexa RVM chart for guidance on extending treatment or if you’re thinking about changing treatment for a cow.


What tools can you use to help increase cure rate on your farm?

Pre-treatment sterile milk samples. These samples can be tested at the Anexa lab in Morrinsville. Refrigerate the sample if it is going to the lab to be cultured that day, otherwise, freeze it. Taking samples from every case and freezing them also allows you to test the samples later from those cows who aren’t responding well. The results will help to identify the likely cause and the most appropriate treatment. Milk culture tests are also discounted when you submit 10 or more samples.

If you need more information around taking samples ask your vet or ask for an information sheet from your local clinic.
Dairy Antibiogram test looks at the susceptibility of the two most common mastitis-causing bacteria to a range of antibiotics. This can provide you with invaluable information for choosing the right treatments for your cows and monitoring the resistance status of your herd. Many clients have already had a Dairy Antibiogram performed a season or two ago, but if you aren’t continuing to monitor, the resistance patterns of these bugs in your herd may have changed. Talk to your local Anexa Vet for more information, we’re here to help!


Date Added: Saturday, 3rd October 2020


Back...