With antibiotic use on dairy farms under closer scrutiny, consideration for alternative mastitis therapies is on the rise. Diagnostic testing and knowing what the predominant mastitis bugs are on the farm is crucial before looking to reduce or eliminate antibiotic use for mastitis. This is because recommended treatment protocols will vary depending on the pathogen and whether mastitis is mild, moderate or severe.
It is well known that mild or moderate cases of mastitis caused by gram negative bacteria (Escherichia coli, Klebsiella and Enterobactor sp) have a high spontaneous cure rate without the need for antibiotics. However, Streptococcal and Staphylococcal infections (gram positive bacteria) normally require prompt antibiotic treatment for an effective cure.
Alternative treatments to antibiotics for treating gram negative cases include fluid therapy, NSAIDS (non-steroidal anti-inflammatory drugs) and oxytocin. Treatment strategies may also include more frequent milking of the infected quarter, udder massage, liniment creams and isolation of the animal for optimal comfort and feeding, if facilities allow.
Depending on the severity of mastitis, cows can develop disruption to normal fluid and electrolyte balance, leading to dehydration. As cows lose a large volume of water each day through milk production, they are prone to becoming dehydrated very quickly. Dehydration can be assessed by examining the appearance of the eye or doing the skin pinch test. Pinch the skin on the neck, turn it almost 90 degrees and then let go. It should spring back immediately. The longer the skin takes to return to normal, the more dehydrated the cow. The severity of dehydration will impact on survival and future milk production and can be assessed as follows:
|Level of Dehydration||Skin Response to Pinch Test||Eye Appearance|
|Mild||Springs back within 2-4 seconds||Slight eyeball recession|
|Moderate||Springs back within 4-8 seconds||Obviously sunken|
|Severe||Little response||Severely sunken into orbit|
Source: Adapted from Hoards Dairyman
Be aware that treatments for rehydrating calves are not suitable for cows. When calves have scours, their blood tends to become more acidic and they require alkalising agents such as bicarbonate to increase blood pH. However when cows become sick their blood pH either remains the same or starts to rise and so treatment with electrolytes should not contain alkalising agents but rather sodium, chloride and potassium.
Fluid administration is most commonly carried out intravenously with hypertonic saline solution (extremely concentrated salt water). The recommended dosage rate is around 4ml/kg to 5ml/kg of bodyweight over 4 to 5 minutes which is around 3 litres for a 650kg cow. However always check with your vet for correct dosage instructions. Provide animals with fresh water immediately post-infusion. They should drink between 20-40 litres within 10 minutes, if not the rumen should be pumped with water to help return circulatory volume to normal and your vet may be needed if this is required. Supplementing with calcium fluids is sensible as many cows with clinical mastitis often have low blood calcium levels.
NSAID’s are routinely used in the treatment of severe cases of mastitis but their importance in supporting recovery in mild and moderate cases should also be considered, especially if antibiotics are not administered. They help to reduce inflammation and body temperature and provide pain relief which is essential from a cow welfare point of view.
Oxytocin administration may help with milk let down and help remove mastitis associated constituents from the udder. However, in severe cases with swollen quarters, the use of oxytocin may not always be helpful as some of the milk ducts may be blocked with cell debris and pus.
There is the chance that not using antibiotics in mild or moderate mastitis cases may lead to recurrent infections and accurate records should be kept of cases detailing the quarter infected to monitor recurrence rates in the herd. On-going laboratory diagnostic results from untreated milk samples should be used to re-evaluate both mastitis control programmes and therapeutic treatments under veterinary consultation.
Lorna MacPherson for the Farm Advisory Service
Sign up to the FAS newsletter
Receive updates on news, events and publications from Scotland’s Farm Advisory Service