If you breed sheep for any length of time, you’re likely to run across a case of mastitis at some point. This is particularly true for dairy animals. The increased udder volume and the larger, lower placed teats that are desirable for milking make the animals more susceptible to mastitis. So today we are going to take a quick look at what mastitis is, and how to reduce the chances of your ewes getting it.
As you probably know, mastitis is an infection of the mammary gland. The inside of the udder is supposed to be sterile. Mastitis occurs when bacteria has made its way up the teat canal into the udder. Milk, being full of nutrients, is the perfect place for bacteria to thrive. Mastitis is painful for your ewe and can cause loss of production and even death.
Most commonly, mastitis will cause damage and scar tissue to the udder resulting in permanent loss of milk production. The lack of milk production often causes the ewe to need to be culled (or her lambs bottle fed) because she will be unable to produce enough milk to feed her lambs. Thus, it is important to treat mastitis as quickly as possible to minimize the damage occurring. Mastitis is one of the primary reasons animals of prime reproductive age get culled.
How do I know if my ewe has mastitis?
There are two types of mastitis. Clinical and sub-clinical. Common symptoms of clinical mastitis include a swollen, hot, painful to touch udder. Ewes often have a fever, may be off food/ inactive/ acting sick. Clinical mastitis is usually pretty obvious, and it’s also obvious that it needs immediate attention.
Sub-clinical mastitis can be much more difficult to detect. In this case your ewes are not showing outward symptoms of being sick. However, if you did a mastitis test like they do on dairy cows you’d see a high somatic cell count (white blood cells fighting an infection). You might also be able to see flakes or chunks in the milk. There might be able to feel heat in the udder. The milk might look watery and, in some cases, might contain blood. Lambs from these ewes will not be growing as fast as they should be. They are often seen milk stealing from other ewes. Undetected sub-clinical mastitis is where most economic mastitis related losses come from.
Many times in sheep and goats, sub-clinical mastitis goes undetected until the next lambing. By then the damage is done and treatment is too late. These ewes present with only half an udder and are unable to feed both of their lambs. The side of the udder that was infected with mastitis is now hard and filled with scar tissue and produces little to no milk.
Treatment for mastitis
Mastitis treatment is typically with intramammary infusions and or systemic antibiotics. This should be done under the guidance of a veterinarian as there are no mastitis treatments labeled for use in sheep or goats. Mastitis will not cure itself, so don’t take a “wait and see” approach to this painful condition.
How do we prevent mastitis in our sheep?
First and foremost, sanitation. You need to keep everything clean. Your bedding should be clean and dry. If you’re milking your sheep, your hands, and their udders should be cleaned and disinfected before and after milking. Encourage them to stay standing after milking rather than going back to lay down.
Don’t overcrowd your sheep. Closely confined flocks have higher rates of mastitis. Additionally, the bacteria responsible for lamb pneumonia and sore mouth can also cause mastitis. So, keeping your animals outdoors on clean pasture in the fresh air can help reduce mastitis rates.
When you do find an ewe that has developed mastitis, it is important to separate them and their lambs from the rest of the flock. You do not want their lambs spreading mastitis by stealing milk from other ewes. For this reason, milk stealing should be discouraged in your flock, and the dams of lambs set on stealing milk should be checked for mastitis.
You should also go through your flock after weaning and pre-breeding and check udders
Ewes with hard masses in their udders should be culled. These ewes will have poor milk production and may be unable to feed their lambs. Additionally, it is thought that there is a genetic component to mastitis susceptibility, so these ewes that have proven themselves susceptible aren’t something you want in your flock.
It is also important to select for ewes with good udders. Compact, well suspended udders with small teats angled diagonally off the sides are ideal for minimizing mastitis in meat sheep. Unfortunately, these traits are in opposition to what we consider ideal for milking, so it’s a balancing act. If you’d like to read more in depth on udder shape and mastitis, this is an excellent article with diagrams.
Lastly, your ewes should be dried off carefully. Most mastitis cases are seen either in the first few days of lactation or post weaning. Earlier weaning can make ewes more susceptible to mastitis at time of weaning. Ewes that are dried off while producing very little milk are less prone to mastitis. Thus, late weaning and or restricting feed and water intake at time of weaning can help to reduce post weaning mastitis cases.
Unfortunately, this isn’t always enough
As we have learned from extensive research in dairy cows, many of your subclinical ewes and your treated and seemingly ‘cured’ ewes actually have chronic, incurable mastitis caused by Staph aureus. They don’t have symptoms, but even with antibiotic treatment this mastitis cannot be cured. These animals are latent carriers capable of infecting your other ewes either via the bedding or milk stealing.
The unfortunate reality, is that if you have high rates of mastitis in your flock (or have had milk cultures come back with Staph aureus), ewes that have had mastitis should be culled even if they seem ‘cured’. In dairy cows they even recommend culling daughters of infected cows. The heifer calves can become infected from drinking infected milk and or colostrum, and often have Staph aureus infections prior to their first lactation. Consider culling mastitis cases and their daughters, because as we mentioned before there is a genetic component to mastitis susceptibility.
Lastly, if you have a high incidence of mastitis, and you cannot seem to get it under control, you may wish to consider a recently released mastitis vaccine.
The VIMCO vaccine is only registered for use in goats in this country, so should only be used under a veterinarian’s supervision. However, it is licensed for use in sheep in other countries and has been shown to significantly reduce the incidence of mastitis.
Of course, some case of mastitis are inevitable in a breeding flock. However, through good management, careful culling and genetic selection it is possible to maintain mastitis cases at less than 1% in your flock. And if you do have a mastitis problem in your flock, we hope this inspires you to make some management changes to improve animal welfare and to reduce your economic losses.
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