Dairy cows: Preventing mastitis in heifers 

Find out how to prevent mastitis infections in heifers through environment management and optimised husbandry.  

Your strategy for controlling udder infections in your heifers should focus on preventing environmental infection and optimising management and husbandry. The calving environment is particularly important, with fly control and adequate nutrition and mineral supplementation among the key ways of preventing mastitis.  

Early detection and prompt treatment of heifer mastitis will improve herd health, production and milk quality. Most infections are subclinical pre-calving, but may result in clinical mastitis in early lactation and/or an increased somatic cell count (SCC) at first recording.  

To ensure early detection, check your heifers for mastitis when handling them for other reasons, such as AI or pregnancy checks. It’s important to train heifers in the milking area pre-calving, and this can be a good opportunity to check for mastitis.  

If mastitis levels in your heifers are high, consider doing a CMT on all freshly calved heifers to identify infected quarters. You should also:  

• Ensure each cow has milk let-down at each milking, particularly heifers  
• Avoid both over- and under-milking  
• Remember that reducing the interval between calving and first milking will help reduce udder oedema (see below) and clinical and subclinical mastitis at calving  

Don’t feed waste milk from infected cows to replacement heifers. Heifers reared in herds with a high bulk milk SCC are more likely to be infected with major pathogens in early lactation. There may be a risk that mastitis pathogens are transferred to the developing udders of young calves via suckling, especially if feeding milk from infected cows. For this reason:  

• Try to prevent cross-suckling in groups of calves  
• Feed milk replacer or pasteurised milk  

Other reasons not to feed waste milk include the risks of antibiotic residues and infection with Mycobacterium avium paratuberculosis (Johne’s disease).  

Pooled colostrum should not be fed to calves, and nor should colostrum from infected cows or cows of unknown status.  

Udder swelling is the result of excessive accumulation of fluid, although the actual milk-producing tissue is not involved. Udder oedema can be caused by disease, but it’s more common to see it before calving.  

This can be the result of a number of factors, including genetic predisposition, energy density of the ration, overconditioning and high milk yield. Other potential causes are excessive salt in the diet, or circulatory problems.  

Udder oedema causes a number of problems for heifers, including:  

• Pain, causing reduced lying times and poor mobility  
• Poor circulation of blood around the udder and teats, causing increased risk of mastitis and of damage to teat skin  
• Altered udder pressure, causing poor milk let-down  
• Shortened teats, resulting in poor milking cluster alignment  

To prevent udder oedema in heifers:  

• Reduce the cation content (sodium and potassium) of the ration  
• Provide an adequate loafing and exercise area (see mastitis management)  
• Monitor BCS and don’t let heifers get overfat – check the ration and its mineral content with your nutritionist or vet to ensure diet is not a factor in severe oedema  

The most important point is to reduce the risk of udder oedema and risk of assistance at calving due to high BCS.  

The aim of treatment of udder oedema is to prevent, control and relieve the side effects until the swelling eases. Anti-inflammatory treatment should be used and ask your veterinary surgeon for advice if cows are very uncomfortable. 

The spread of summer mastitis is linked to flying insects, specifically the sheep headfly. To reduce the risk of summer mastitis:  

• Implement measures to control and minimise exposure to flies, and start fly control before the fly season starts  
• Isolate heifers and cows with summer mastitis to prevent the spread of the illness  
• Check cattle for mastitis on a regular basis  
• Avoid grazing areas known to be associated with summer mastitis  
• Avoid areas where teats may be damaged or where flies are a particular problem, such as damp, sheltered areas near rivers and woods  
• In cows, maintain good teat condition pre-drying off, and ensure good dry cow nutrition  
• Discuss with your vet the use of internal teat sealants and antibiotic dry cow therapy in high-risk situations

Effective fly control is key to minimising the risk of summer mastitis. Use it to minimise fly exposure in heifers at pasture and reapply it regularly, particularly in periods of intense fly activity.  

Flying insects should be controlled early on, before the fly season, using pour-on or spot-on antiparasitic treatments. Remember, the chemicals take time to distribute themselves around the coat, so don’t wait until there are a lot of flies before starting treatment.  

Using fly ear tags and applying fly repellents to teats (such as traditional Stockholm tar and brown salves) can also be helpful.

If your heifers are at a high risk of environmental infections, consider using internal teat sealants (ITS). These form a physical barrier in the teat canal, stopping bacteria from entering. They may also reduce milk leakage pre-calving, which is a risk factor for mastitis.  

A protocol to administer teat sealant and dry cow therapy can be found in our Dry cow management guide. Good hygiene is critical, as any bacteria introduced when administering the teat sealant will be trapped in the quarter and can cause a severe acute and often fatal mastitis.  

It’s also important to consider both your safety and that of your heifers when administering internal teat sealants. Milking parlours are not ideal environments to be infusing tubes in small heifers. In New Zealand, many farms use vet technicians and special equipment, such as a trailer designed for operator safety.  

A New Zealand study looked at the use of an internal teat sealant one month before the expected calving date in 255 heifers from five herds. The risk of an infection with Strep. uberis after calving was significantly decreased in those quarters that received a teat sealant (13 infections in 471 quarters) compared with quarters that did not (29 infections from 483 quarters). Overall, the use of a teat sealant in heifers before calving tended to reduce the overall risk of clinical mastitis after calving. In New Zealand, it is regarded as cost-effective in herds where 15% or more heifers have clinical mastitis at calving.  

Parker, K. I., Compton, C., Anniss, F. M., Weir, A., Heuer, C., McDougall, S. (2007). 'Subclinical and clinical mastitis in heifers following the use of a teat sealant precalving', Journal of Dairy Science, 90 (1), pp. 207–18.  

External teat sealants are non-irritant latex, acrylic or polymer-based films applied like a teat dip to create a layer over the teat end that stops bacteria from entering the teat canal. You can use them on heifers from around 10 days before calving and again as required to reduce the risk of infection.  

You can use teat dip or teat spray on heifers being trained through the milking parlour. An iodine teat spray three times a week for at least three weeks before calving may help reduce the prevalence of Strep. uberis on the teat end 24 to 48 hours before calving and the prevalence of subclinical mastitis at the first milking after calving.  

In herds with a high incidence of severe E. coli mastitis, you could consider vaccination, which has been shown to reduce the severity of E. coli mastitis (though not the number of cases). Discuss this with your vet. 

If you would like to order a hard copy of the Control of contagious mastitis guide, please contact: Email: publications@ahdb.org.uk or Telephone: 0247 799 0069