NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare.

Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

Identifying The Cause Of Mastitis

As shown by the NADIS data the number of mastitis cases increase as autumn progresses. However, there are currently too many outbreaks where no cause of the mastitis is diagnosed. It is important to know what bacteria are causing the majority of infections along with detailed records of overall incidence, pattern of incidence, recurrence of infection, symptoms, treatment and cure rate. If a herd has no mastitis problem, records will take little time to keep or review and if a problem does appear, accurate historic records are of great use to herd manager and veterinarian in the choice of appropriate action. As standard, record all clinical cases (cow, quarter, date, treatment, bacteria if known). One case of mastitis should be defined as one quarter infected once, a cow with two quarters infected at the same time counts as two cases and the same quarter recurring seven or more days after the disappearance of a previous case is a new case. Records should be reviewed monthly, to identify problem cows and changes in herd incidence.

Early identification of the problem

Identifying infected cows and quarters early allows for prompt treatment and reduces further spread. Foremilk should be examined (it is a legal and contractual requirement) before other udder preparation at each milking and if in-line filters are used they need checking after every cow milked. Abnormalities or changes in the udder should be investigated..

Milk sampling

All mastitis cases should be sampled before any treatment is given. If the incidence remains low, the samples can be frozen after collection and can be discarded later, if not required. However if there is cause for concern or if information is required for monitoring purposes, the samples can be sent for analysis. Sending batches of samples, rather than individual samples, may also have the advantage of reducing analysis cost per sample. At current prices, a total cost for the year would be around £150 per 100 cows assuming an incidence of 40 cases/100 cows. In addition to identifying the pathogens responsible for causing the infection, antibiotic sensitivity can also be determined from the same samples if needed.

Milk sampling technique

High standards of milk sampling techniques are required to avoid the wasted costs of ‘dirty’ samples. Everyone milking cows should know how to take ‘clean’ milk samples:

· Clean hands (wear clean disposable/disinfected gloves)

· Wash and thoroughly dry visibly dirty teats

· Clean the teat end with a cotton wool swab soaked in spirit or antiseptic wipes

· Strip out 4 to 6 (more is better than less) squirts of milk to flush out the teat canal

· Remove the lid from a sterile sample bottle (get bottles from the vet’, lab’ or dairy consultant)

· Hold the bottle at an angle of approximately 45⁰ to the teat to prevent dust/debris falling from the udder into the bottle (keep the lid held with the underside facing down to avoid contamination)

· Draw one or two squirts of milk into the bottle, the bottle must not be filled to the top if it is to be frozen.

· Replace the bottle lid immediately, label the bottle with farm, cow and quarter identity and date and place immediately in the fridge at 4⁰C.

· The sample should be at the lab’ within 72 hours (max.) of collection

· If longer storage is essential, freeze the samples immediately after collection

· Freezing tends to reduce bacterial numbers especially coliforms and must not be used for SCC samples, although results are still useful.

Richard Laven PhD BVetMed MRCVS