Environmental mastitis treatment: NSAIDs and other approaches

I think now is a good time to consider a complete redesign of the dairy cow, given many farmers don’t allow calves to suckle cows to reduce the risk of Johne’s disease. So why not relocate the udder on to the back of the cow?

Think of the benefits – clinical mastitis levels would plummet, the udder would no longer come into contact with faecal contamination and, as the teat ends are constantly clean, fewer bacteria would have the opportunity to enter the udder.

The pain associated with mastitis is immense. Lots of work has been done to prove this, but ask any mother who has had mastitis and see the reaction on her face – the grimace and reminder of the discomfort and pain she had to endure.

Mothers have some additional advantages – they can rest and take time out, be nursed in comfortable conditions and, most importantly, lie on their backs. The dairy cow, however, does not have any of these luxuries. It has to lie down on a painful and swollen mammary gland (Figure 1) and as for nursing, comfortable beds and additional care – well, some are better than others.

Seriously, though, people are responsible for mastitis in the dairy cow. Mastitis is a rarity in the suckler cow because there is one calf to one cow, which is constantly removing milk and flushing out any bacteria that might have entered the udder. We only milk the dairy cow twice or sometimes three times a day – maybe more if you use robots. The risk of cross contamination is remote, unlike our dairy cows where the risk is much higher. Sucklers generally live in more extensive conditions compared to our dairy cows, which can be packed like sardines in the older dairy units.

Aetiology

The vast majority of clinical mastitis in the UK is due to environmental bacteria, such as Escherichia coli and Streptococcus uberis. More and more herds now have cell counts below 150 and levels of S uberis are falling in these herds. People realise you have to minimise the risks of S uberis to avoid having problems with high cell count cows, clinical mastitis and, in particular, repeat cases that can occur. In an ideal world, it would be nice if the only bacteria we had to manage were E coli.

E coli numbers double every 20 minutes. About 300 different strains of E coli exist and the problem with these infections is not the bacteria, but the toxin they produce. The toxins are responsible for the clinical signs. Up to 80% of these infections are eliminated by the cow.

Antibiotic therapy is not indicated if you have an E coli or other Gram-negative infection, provided the cow is healthy and does not have a temperature. Cure rates with Gram-negative infections are good, even without antibiotics.

When you look at Staphylococcus aureus and S uberis clinical mastitis, where antibiotic treatment is indicated, the cure rates are quite depressing and can be as low as 25%. If you were paid on success, you would never become a rich man. The average cure rate for S aureus and S uberis clinical mastitis is around 35% and 70%, respectively.

Desired therapy

The problems with mastitis treatment are quite simple. We want a convenient treatment that requires minimal labour and we want a short treatment so milk can go back into the tank quickly. To achieve this we need low levels of antibiotics in the milking cow tubes, but we are trying to treat an udder with a vast surface area, containing a large amount of milk that has clots and other debris present. It’s no wonder treatments are not that successful.

Treatment approaches

So, it’s time to review how we manage clinical mastitis to the benefit of the cow. Let’s move to Africa for some help with this. I have been working with dairy farmers in Africa for the past five years, ranging from a herd size of one cow to large commercial dairies.

If you are a small dairy farmer and have one cow that gets mastitis and you use antibiotics, your daily income immediately stops as you cannot sell your milk. This is totally different to our situation, where we have large herds and there will always be milk sold off the farm. Just imagine the consequences of losing your daily income and not being able to feed your family.

Stripping

Clinical mastitis is dealt with in very different ways in Africa. Antibiotics are rarely used and one of the most common reasons for this is they are difficult to obtain. So, what they do is strip out the infected quarter up to six times a day for five days. The bacteria are being constantly flushed out of the udder and so don’t build up to such high numbers (Figure 2). Frequent stripping works with the cows’ immune system to fight infection. A spin off means the milk from the other three quarters can still be sold as no antibiotics have been used.

Most African farmers also will apply Japanese peppermint ointment to the infected quarter and massage this for a couple of minutes before they start stripping out the infected quarter. This helps with milk letdown to try to get as much mastitis milk out of the udder at every stripping. This also makes the cow feel more comfortable. Some farmers will also hose the affected quarter with cold water after milking to sooth the pain.

This approach is now taken by most dairy farmers in the developing world, irrespective of herd size, and there is plenty of labour who are willing and able to strip out cows every four hours throughout the day.

The interesting thing is the treatment success, which can be measured by the number of repeat cases of mastitis and also cell count. We find very few quarters repeat and the cell counts of these animals are low for the rest of lactation. We have carried out bacteriology and know we are dealing with a mix of E coli, S aureus and S uberis mastitis, but more than half of the cases that have been sampled are Gram-negative.

Pain has a very negative effect on how we feel, what we do and our overall well-being. This will be greater for ill animals, as they have fewer options for taking life easier, slowing down what they have to do and so on.

Just imagine a woman has mastitis and she is told by her husband to walk half a mile and back to the shops to get his paper and a pint of milk. The husband would probably not be reading this article, or if he was, it would be from a bed in an intensive care unit with a divorce lawyer outside his room. Yet, we expect cows with clinical mastitis to walk out with the rest of the herd and back as if they were healthy. The same for lame cows. How sympathetic are we to animals that are sick?

A few years ago I was on a farm in New Zealand and asked why there were four cows in a small paddock by the parlour. The answer was three were lame and one was sick. You can’t expect these animals to walk out with the rest of the herd and get better quickly. In fact, the lame cows were only milked once a day until they got better. How many of our farmers take a similar approach? What would you prefer if you were a dairy cow? Which choice would help you get better sooner?

NSAIDs

One way we can really make a difference is in the use of NSAIDs as supportive therapy. One of our farmers’ wives had mastitis and insisted every animal with clinical mastitis was treated with flunixin. They reported cows recovered more quickly, treatment duration was reduced and the cows appeared happier. More of our clients are using NSAIDs on all types of clinical mastitis and seeing the benefit. We must also remember we have an obligation to reduce pain in farm animals.

There is a lot of work to show these are real, and not just perceived, benefits. NSAIDs will reduce inflammation, pain, pain sensitivity and overall body temperature. In experimental mastitis challenge studies, NSAIDs were shown to help maintain rumen motility and decrease heart rate. The decrease in heart rate will be either due to less distress of the animal or the impact of pain relief.

In one large New Zealand field study1, cows that were given meloxicam in addition to antibiotics had lower cell counts after treatment (Figure 3) and were less likely to be culled from the herd (17% for meloxicam compared to 29% for the control cows). No difference was seen in milk production between the two groups.

Some farmers might be reluctant to use NSAIDs from an economic point of view. However, when you look at the total costs of mastitis, it is clear by far the biggest cost is the impact on future milk production. There is an average 5% reduction in total milk yield following a case of clinical mastitis, so a cow giving 8,000 litres would lose 400 litres of production.

Figure 4 shows the breakdown of costs from an average case of mastitis. The costs of medicines are small, on average 10% of the total cost including an NSAID treatment, and there is likely to be a significant return on investment. More importantly, the cow with mastitis will be very grateful for the pain relief.

A herdsman once commented if a cow looks sick and sad then it will benefit from a non-steroidal treatment. It’s great most farmers are now thinking along these lines and are very receptive to using supportive treatments and minimising pain in animals.