Udder health and Mastitis (new)

Udder health and Mastitis (new)

Udder of a goat with contagious agalactia (mastitis)

(c) John B. Bashiruddin

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Mastitis, or inflammation of the udder, is of great importance in dairy cattle. Even in well managed dairy herds, on average 15% of the cattle are infected with mastitis bacteria. Up to 75% of the cattle in poorly managed herds can be infected with mastitis. The infection is very painful for the cows. Mastitis infected quarters produce between 15% and 30% less milk, as compared to healthy quarters. Mastitis in dairy cattle cannot be fully prevented, but its' frequency, severity and the economical losses caused by this disease can be drastically reduced.

Mastitis leads to suffering in the affected cows due to painful infection, losses in milk production, premature culling of dairy cows and reduced incomes of dairy farmers. At the same time mastitis treatment is costly and quite often inefficient. For this reason it is very important to do everything possible in order to prevent mastitis and reduce its occurrence.



Milk sample: (A) normal milk, (B) mastitis - discoloured, yellowish, here also tinged with blood

Milk sample: (A) normal milk, (B) mastitis - discoloured, yellowish, here also tinged with blood



Udder Health

The inside of a healthy udder is free of bacteria. The teat canal closes in between milking times and also when the cow is dry. It acts as a seal that protects the inside of the udder from the outside. Mastitis bacteria invade the udder almost always through the teat canal. In a few cases bacteria can also enter the udder tissue directly from infected wounds and from the blood when the cow has fever. Wrong hand milking (forced stripping) or incorrect machine milking (faulty teat cups, fluctuating vacuum) cause injury to the teats every time an animal is milked. This progressive weakening of the teat tissue reaches a point where the teat canal can no longer close completely. It loses its role as a barrier to protect the udder against outside bacteria in between milking times.

-> In consequence, in most cattle that had more than six calvings the udder is very susceptible to mastitis.


Factors that contribute to poor udder health and more frequent Mastitis in dairy cattle:

*    Dirty stable and bedding - high contamination of the cows environment with mastitis bacteria
*    Dirty milking shed / milking parlour - high contamination of the milking area with mastitis bacteria
*    Milking with dirty hands, teats not cleaned before milking, dirty udder cloth used for washing
*    Faulty machine milking - dirty teat cups, dirty milk pipes, fluctuating  vacuum (machine not serviced)
*    Dirty udder skin harbours more bacteria, more bacteria on the skin of the udder means more mastitis
*    Purulent wounds of the udder skin and teats (such wounds can be caused by injury, insects and ticks)
*    Untreated purulent infections of the feet and hooves - pus bacteria cause mastitis
*    Oversized teats - teat canal does not close properly between milking times, prone to mastitis
*    Low hanging udders and very long teats are more exposed to dirt and very prone to injury
*    Cattle with chronic mastitis that act as permanent source of infection for other animals in the herd
*    Heifers suckling each others teats before  calving
*    Use of under-strength and contaminated teat dip
*    Mouldy feed (contains fungal  toxins)
*    Acute infections with high fever and bacteria or viruses in the blood of the cow
*    A lot of  flies in stables, milking area  and on pasture

-> Avoiding these factors will significantly reduce the occurrence of mastitis.


Bacteria that have succeeded in entering the udder through the teat canal can be cleared by the defensive response of the udder or persist inside the gland. If they persist they start multiplying rapidly inside the milk gland and cause mastitis. The mastitis bacteria can survive inside the udder for weeks, for months or sometimes even for life.


Healthy Teats & healthy udder skin -> less mastitis

The number of bacteria on the teat skin determines how many bacteria can reach and enter the teat canal in between milking times.

  1. If more bacteria are present on the teat skin -> more of them can enter the teat canal.
  2. If more bacteria enter the teat canal -> more of them move through the canal and reach the milk gland tissue inside the udder.
  3. If more bacteria reach the gland tissue -> it is more difficult for the udder defence to eliminate them completely.
  4. If bacteria survive and start multiplying inside the gland -> the cow suffers from mastitis.

Therefore, the cleanliness of the teat skin (or in other words: the number of bacteria on the teat skin) determines whether a cow catches mastitis!


The density of bacteria on the tea surface depends on the health of the teat skin.

  1. If the teat skin is dry and has small wounds and cracks the bacteria multiply inside these small wounds and cracks and become more. Using milking fat regularly keeps the teat skin elastic and healthy with by far less bacteria on its surface.
  2. If the teat skin is affected by Foot-and-Mouth-Disease (FMD) or other infections with fever that also produce lesions on the teats (e.g. pseudo-Cowpox, Herpes virus) an anti-septic ointment must be applied after each milking until lesions have healed completely. During infections like FMD the risk of a cow suffering from mastitis increases; it's important to observe maximum cleanliness at milking.
  3. In cows with low hanging udders and oversized very long teats the cow can accidentally step on the teats causing injury. This can either damage the teat beyond repair or cause wounds that constantly harbour lots of bacteria. - Providing cows that have low hanging udders and/or oversized teats with an udder support (the "udder bra", made of nylon mesh) reduces risk of teat injury. Breeding for compact udders with normal sized teats reduces mastitis risk.
  4. If the teats are too short it also takes a shorter distance for bacteria to reach the inside of the milk gland -> higher risk of mastitis.
  5. Warts on the teats are harmless and should only be removed if they really interfere with milking.
  6. Udder acne are small pustules with pus appearing on the skin of the udder and teats; keeping the hair in the affected area very short and washing the udder skin thoroughly each day with antiseptic soap will solve the problem.
  7. Ticks must be immediately removed from the teats and udder, tick bites harbour dangerous bacteria.
  8. Udder Sores are moist foul-smelling skin lesions that appear in areas where the udder is pressed tightly against the thigh (= udder skin permanently pressed against inner skin of the legs) - this can also happen when the udder has an oedema (see dry period); the affected skin should be washed daily with an antiseptic solution and thoroughly dried.


What to observe at milking in order to maintain good udder health

The udder, and in particular the teats of the udder, must be clean before milking. Although widely practised, washing the whole udder immediately before milking is not a good method. The water that runs down from a freshly washed wet udder reaches the teat and carries dirt and bacteria towards the teat opening and onto the milkers' hands during milking. If udders are very dirty they must be washed and dried in good time before milking starts. Udders must be dry when milking begins. Udders that are dry and reasonably clean do not need washing at every milking time. It is good practice to only clean the teats immediately before milking. The safest way to clean the teats is to use dry tissue paper, one fresh piece of paper for each teat. (For example one piece of tissue paper can be torn off a fresh roll of toilet paper that is used only for milking; this is not expensive.) Udder cloths are frequently used for cleaning the teats and the udder. Very often these cloths get contaminated and carry bacteria from one cow to the next. If udder cloths are used each cow must have her own cloth; the cloths must be washed in hot water and ironed or dried in between every milking time (this is often not practical -> easier to use tissue paper).

-> In short: Keeping udders generally in clean condition is easier and safer than washing them before every milking. Teats must be dry-cleaned immediately before each milking.


These first streaks of milk should always be milked onto a strip cup (with dark surface) and examined for abnormal colour, watery consistence and presence of flakes or lumps. If any abnormal signs are present in the milk, such a cow is likely to suffer from mastitis and should be milked last. If the cow cannot be milked last the milkers' hands and the milking bucket must be thoroughly washed with antiseptic soap before milking the next cow.


Strip Cup

Strip cup



After milking the teat canal is still open and the mastitis bacteria on the teat skin are trying to move into the teat canal as soon as the milk flow stops. To prevent this it is important to apply disinfectant teat dip (containing iodine). Immediately after milking each teat is briefly dipped into a dip cup containing the teat dip fluid - this kills off all bacteria on the tip of the teat near the teat opening. Teat dip fluid must always be fresh and clean. Only a very small volume is needed to dip a cow at each milking. Discard any leftovers and squeeze the bottle below to fill the cup with fresh dip fluid. Old contaminated teat dip can transmit bacteria from one cow to the next.


Dip Cup



Cattle with diarrhoea shed more dangerous bacteria in their faeces than cattle with normal dung. These dangerous bacteria are then very numerous on the bedding, in the milking parlour and on the teat skin of the cow and can easily enter the teat canal and cause acute mastitis. Feeding cows enough good hay to avoid diarrhoea reduces the risk of dangerous mastitis.

Also, if cows are treated rough before and during milking they will pass faeces more frequently at milking time because they are afraid. More defecation means more bacteria near and on the teat and again a higher risk of mastitis.  Handling cows gently before and during milking reduces the risk of mastitis. Feeding dairy meal during milking also makes the cow relax and defecate less often.

The milking parlour or location where milking takes place and the milking equipment, must be kept as clean as possible. Milking buckets must be washed with hot water and antiseptic detergent after every milking time and kept in inverted position to dry before the next milking. Faeces contain bacteria that can cause mastitis. Bacteria also survive and multiply in standing water (puddles on the floor) or inside not well cleaned milking buckets. Flies move around, including on the ground and on dung. When they land on the teats to sip some drops of milk they leave behind dangerous bacteria on the teat skin. These bacteria then enter the udder and cause mastitis.

Some bacteria that can also cause mastitis are shared between humans and cattle. The person(s) carrying out the milking  must wear clean clothes and gum boots, be in good health (no fever, not coughing or sneezing, no infected skin wounds), wash their hands thoroughly before milking and refrain from eating, drinking or smoking during milking.

In between milking times some bacteria will always manage to enter the teat canal. They are flushed out with the first streaks of milk when the milking begins (these are the very same streaks of milk that are normally being checked in the Strip Cup). It is important to discard these first  streaks of milk and NOT include them in the milking bucket -> this leads to cleaner milk with less bacteria and which keeps fresh for longer and fetches a better price. Milk with mastitis bacteria in it spoils much more rapidly, fetches lower prices or cannot be sold at all. Mixing mastitis milk with clean milk in the same container leads to contamination and spoilage of all the milk. (Rather than milking the first streaks onto the floor collect them into the Strip Cup.)


The Dry Cow Period

The first two weeks after a cow has been dried off can be a critical period for the health of the udder, especially if it has already been infected by bacteria during the lactation. After these two weeks the dry udder is generally resistant to new bacterial infections until the next lactation. The dry period should not be too long or too short, 6-8 weeks is recommended.  When the cow gives birth, for about two weeks starting just before calving, the udder defence is low and the risk of mastitis is again very high (see Coli mastitis).

Before the cow gives birth she develops an oedema on the lower side of her body that also affects the udder. The oedema swelling can be differentiated from the swelling caused by acute mastitis by the following signs:

  • The swelling does not feel hot
  • The swelling is not painful
  • The swelling is soft and has a dough-like consistence, when pressing it with a finger the created depression persists for a while

This swelling is normal and disappears soon after birth, although it may sometimes persist for a while. It may interfere with milking when it is very strong. There is no treatment to reduce it faster.



Local names: Luo: Tuo thuno / Embu: yele / Borana & Gabbra:hiha goru, butha / Kamba: Uwau wa nondo, mukamo / Kipsigis: miatapkinai / Maragoli:lifuuti / Somali: candho-barar, canda-barar, carar, galleh, goof / Turkana: loebeta / Kikuyu: Murimu wa nyondo, kuruara mukamo / Maasai: Enkeeya Ollki / Kiswahili: matiti

Common names: mammitis, mammite (French), inflammation de la ubres (Spanish)

Description: Management disease

Mastitis, or inflammation of the udder, is a result of the udders' response to bacteria invading the milk gland and rapidly multiplying inside it.

  • Clinical (visible) mastitis: The udder swells up, the skin looks reddish and feels hot and the swollen quarter/teat is painful. The milk looks abnormal (watery consistence, discoloured, small lumps in the milk); the milk flow is reduced or stops. In some mastitis cases there can be difficulties in extracting the milk because teat canals are blocked and secretion of milk by the gland is reduced. Clinical mastitis can be mild, severe or very severe.
  • Acute mastitis is very severe mastitis. The cow has high fever, stops feeding and can even die. It is caused by bacteria that normally live in the guts of the cow.
  • Subclinical mastitis: In the majority of cases the beginning of the mastitis after bacteria have entered the milk gland is more gradual. Signs can be so mild as to go almost unnoticed. There may be a very mild transient swelling that disappears quickly; slight changes in the milk can be seen but don't last; milk flow is not affected; the cow shows no pain and feeds normally. This very common almost invisible form of mastitis is called subclinical mastitis.


Following subclinical mild mastitis the quarter may return to normal, eliminate all mastitis bacteria from inside the gland and make a full recovery. But in a number of cases quarters that look normal remain infected with bacteria for weeks and months. With some mastitis bacteria the affected quarters can remain infected forever! This is called chronic mastitis. Over one to three successive lactations quarters with chronic mastitis undergo changes from the normal "spongy" consistence of healthy gland tissue to the hard consistence of dead tissue. The final outcome of a chronic mastitis is a 'dead quarter' that no longer produces any milk. It is estimated that chronic mastitis leads to between 20% and 40% loss of milk available for consumption and for sale. Older cows whose udders are more likely to be affected by chronic mastitis are a common source of mastitis for young cows with healthy clean udders.

  • Pigs sometimes get mastitis immediately after giving birth when the piglets are very young.
  • Trauma and injury during milking or during fighting between cattle can damage the teat !!!
  • Mycoplasma are special bacteria, which may spread from cow to cow through the air. They infect the body of the animal and then invade the udder via the blood. This is a very specific infection which infects all cattle, causes mastitis, respiratory disease, abortions and makes the whole herd unproductive.
  • Sheep and goats can also get a very severe form of  mastitis called Contagious Agalactia, caused by another type of mycoplasma, which has similar devastating effect on the goat herd (mastitis, arthritis, abortion, septicemia) as the  mycoplasma in cattle.


Sahiwal cow with dead quarter 1

Sahiwal cow with dead quarter 1


Udder of a goat with contagious agalactia (mastitis)

Udder of a goat with contagious agalactia (mastitis)






Detecting Mastitis


The California Mastitis Test (CMT)

When an udder is infected by mastitis bacteria and is inflamed it produces inflammation cells. A high number of these cells is a clear sign of mastitis. The high number of cells can be detected by examining a milk sample from each quarter. The most common mastitis detection test, used at milking is the 'California Mastitis Test' (CMT), sometimes also called 'Schalm Test'. The California Mastitis Test fluid is mixed 1:1 with the milk (slightly more test fluid than milk does not affect the test outcome). The test fluid contains a purple dye and picks up slight invisible changes in the milk that are caused by the mastitis.  If the quarter is affected by mastitis the mix of test fluid and milk becomes thick and can also change in colour. If the quarter is free of mastitis the test fluid-milk-mix does not change colour and retains the normal milk fluid consistence (see illustrations below).


How to perform the California Mastitis Test (CMT):

  1. Milk one streak of milk into each cup of the test paddle


  1. The four cups of the test paddle should be maximum half full



  1. Add an equal amount of test fluid to each cup (milk and test fluid = one to one)


  1. Mix test fluid and milk by rotating the CMT paddle gently


  1. Where the fluid becomes thick and changes in color the quarter has mastitis


  1. Always remember from which quarter you took the mastitis milk




CMT Results - what do they mean

After mixing milk and test fluid and rotating the paddle...

  • The mixture remains watery and does not thicken -> Negative Reaction - this is the best result, it means there is no infection with mastitis bacteria in the tested quarter.
  • There is slight thickening of the mixture, which disappears when paddle is rotated -> Trace Reaction - possible infection (if all 4 quarters* show a trace reaction there is no infection, but if only one quarter shows trace reaction presence of infection in this quarter is possible)
  • Mixture clearly thickens but remains liquid (no gel formation) after  long rotation of the test paddle (more than 20 seconds) thickening may disappear -> Weak Positive Reaction (1+) - mastitis infection
  • Mixture thickens immediately and forms a slight permanent gel, which sits at the center of the test cup when paddle is rotated  -> Clear Positive Reaction (2+) - mastitis infection
  • Gel is formed and surface of the mixture remains raised like a fried egg when rotating the paddle -> Strong Positive (3+) - severe mastitis infection

* In old cattle and in very late lactation all 4 quarters can show a Trace Reaction without being infected by mastitis bacteria.


The Different Types of Mastitis

Many different bacteria can infect the udder and cause damage to the milk gland. A few mastitis bacteria are specialized and live mostly inside the udder. But the majority of mastitis bacteria are found everywhere in the outside environment, including in pus, in faeces and in dirty water and bedding. So the bacteria that can cause mastitis come basically from two sources:

  1. The environment - this includes floor, bedding, housing, pasture, dirty water, but also faeces and purulent wounds on the cows' skin and feet. Coli mastitis comes from the environment.
  2. Infected quarters - Bacteria are transferred from 'mastitis cows' to 'clean cows' via the milkers hands, the udder cloth, contaminated teat dip, contaminated milking equipment and also through flies; cows that have one or more quarters affected by chronic mastitis are the most important source of infection for other cows with healthy clean udders. The mastitis infected quarter is a reservoir of bacteria from where other cattle in the herd become infected over and over again. Examples are Streptococcus & Staphylococcus mastitis.

Only the analysis of a milk sample at a fully equipped bacteriological laboratory can confirm:

  • If any mastitis bacteria have infected the sampled quarter
  • Which type of mastitis bacteria are present
  • Which drugs are the best choice for possible treatment of the mastitis


One can differentiate between three major types of mastitis, which are named after the bacteria commonly involved.


1. Streptococcus Mastitis

Streptococci are transmitted from infected to clean quarters, mostly during milking. Between the infection and the first signs of mastitis several days can pass. In most cases this mastitis does not produce strong visible signs. It is subclinical and can often only be detected through minor changes in the milk and by using the CMT. Once established Streptococcus mastitis tends to persist and become chronic. It leads to hardening of the gland, progressive loss of milk producing tissue and ultimately dead quarters. This process can take two to three lactations.


2. Staphylococcus Mastitis

The Staphylococcus mastitis is mostly transmitted from infected quarters to clean quarters, but the source of infection can also be infected skin wounds, any lesions that produce pus and even a person that is suffering from a severe cold and is sneezing and coughing while milking. Like Streptococcus mastitis, Staphylococcus also persists and becomes chronic, leading to destruction of the milk gland tissue. In most cases a fresh Staphylococcus mastitis is only recognised from minor changes in the milk and through the CMT.


3. Coli Mastitis

Coli live inside the intestine of the cow and thrive in dung and in dirty wet environments. The quarter is infected at or very soon after milking, before the teat canal has closed. Coli bacteria invade the milk gland through the teat coming directly from the dirty teat skin or from the dirty environment. High yielding and freshly calved cattle are at a very high risk from this type of mastitis. Within a very short time after infection of the quarter with Coli bacteria the cow develops high fever and stops eating, the udder swells up and is very hot and painful. Either there is no more milk coming from the affected quarter or the milk looks completely abnormal (brownish-yellow, very thin and watery). The fever can be very high (41 Celsius), the cow may no longer stand up and is at risk of dying if not treated early. - Outcome of Coli mastitis can vary from spontaneous self-cure to death of the cow.


4. There are other by far less common forms of mastitis.

One very dangerous type of mastitis is caused by Fungi, which are present in wet environments. Fungi cannot invade the teat canal but are introduced into the canal by humans who:

  • Treat cows with Mastitis Tubes (see treatment) without disinfecting the teat
  • Use Mastitis Tubes for more than one treatment (if an opened mastitis tubes is not emptied at once the fungi will live and multiply in the Penicillin that is inside the mastitis treatment tubes!)
  • Try to widen a narrow teat canal or unblock a teat by force using unclean instruments (blocked teat canals should only be opened by a veterinarian)

Mastitis due to Fungi is incurable. Fungi multiply in Penicllin - so using mastitis tubes even makes things worse!


Treating Mastitis

Before we had antibiotics for treatment of infections, mastitis was treated by:

  • Isolating the cow and giving it good hay, feed and access to clean water
  • Talk to the cow and make it feel cared for. It does make a difference.
  • Frequently washing the udder with clean cold soapy water to cool it down and most importantly
  • Very frequent (every 1hour) milking out of the affected quarters until the udder feels normal again. This can take one to three days and nights depending on severity of infection, so is a very labour intensive solution.  If no medicine is available this solution can still be employed with success, but remember the every hour milking is also needed during the night, so a shift of duties of caretakers may be necessary.

This treatment is still the only  one giving a possibility of cure for fungal mastitis.


Modern Treatment

If the mastitis is not acute (with fever) it is normally better to first have a milk sample examined by a laboratory.  This will provide clear information on the chances for curing the infection and on the best choice of drugs to be used. It is often cheaper to pay the lab than treating randomly with whatever drug is available. One easily ends up trying out several mastitis drugs that cost a lot of money - but in the end all of them may not work and the quarter may suffer irreparable damage from successive treatment failures (or even become infected with fungi!).

The standard treatment for a mastitis infected quarter is by inserting the tip of a mastitis tube into the teat canal and instilling an antibiotic cream through the teat canal into the udder.  Mastitis tubes are expensive. Some bacteria are resistant against the antibiotics in the mastitis tube. Before buying the tube for treatment it is good to have information from laboratory analysis of a milk sample as to which antibiotic (which brand of mastitis tube) will be efficient for a specific mastitis case.

If used in the wrong way mastitis tubes can easily do more harm than good. When applying an antibiotic by way of the teat canal the utmost care has to be taken NOT TO INTRODUCE MORE BACTERIA or even Fungi into the gland! Otherwise the treatment may start off an additional mastitis which may be worse than the one that is being treated.

When using mastitis tubes for mastitis treatment the following steps must be followed:

  1. Clean the teat
  2. Completely milk out the quarter to be treated
  3. Clean the teat again such that it is perfectly clean and dry
  4. Disinfect the teat, especially the tip (use cotton soaked in 70% alcohol as disinfectant)
  5. Open the mastitis tube by taking of the cap - the tip of the mastitis tube must not touch anything before being inserted into the teat canal! (the person applying the mastitis tube must wash and disinfect their hands before doing this)
  6. Insert the mastitis tube tip into the teat canal, but don't insert it fully
  7. Press the antibiotic cream that is inside the mastitis tube into the teat with continuous gentle pressure
  8.  Pull out the tip of the tube, firmly hold the tip of the teat between thumb and finger and with the other hand massage the teat upward moving the antibiotic cream through the teat into the quarter
  9. Repeat this treatment every 12 hours (or at every milking time) such that the antibiotic is applied for at least three successive milking times
  10. Starting from the last treatment, observe the milk withdrawal period provided on the package of the mastitis tube
  11. The success of the treatment can be checked by sending a milk sample to the laboratory two to three weeks after the last treatment

Bacteria surviving inside the teat canal in between milking times are a potential reservoir for new mastitis infections. Pushing these bacteria up into the udder with the tip of the mastitis tube can easily start a new mastitis.


Special aspects when treating Streptococcus Mastitis: 

If treated early and with the correct choice of drug this form of mastitis normally responds well to treatment. Resistance of Streptococcus to vet drugs is less common than with Staphylococcus. Most Streptococci respond well to Penicillin.


Special aspects when treating Staphylococcus mastitis:

Staphylococcus mastitis is very difficult to treat. Even with correct choice of drug only one out of four mastitis cases are cured. In old cows the cure rate can even be lower. Treating this form of mastitis during lactation almost never succeeds. The best time for treatment is at drying off (see Dry-cow-therapy). Resistance of Staphylococcus to vet drugs is very common and many drugs don't work. - If the cow is old it is better not to attempt any Staphylococcus mastitis treatment.


Dry-cow-therapy is the use of specific dry-cow-mastitis-tubes after the last and final milking (4 tubes are used - one for each quarter). At drying off is the most effective time to treat mastitis. Dry cow therapy has the following advantages over treatments carried out during the lactation period:

  • The cure rate is higher especially for Staphylococcus
  • A much higher dose of antibiotic can be applied
  • The antibiotic is active inside the udder for much longer
  • The antibiotic also protects the dry udder against new mastitis infections
  • Only one single treatment time is needed

When applying the dry-cow-mastitis-tubes follow the same steps as for normal mastitis tubes.


Special aspects when treating Coli mastitis

Treatment must begin as early as possible after the first signs appear! Coli mastitis treatment requires emptying as much milk as feasible from the affected quarter, even if this is difficult. Reducing the swelling by cooling the udder and stripping out a bit of milk again and again can save the cows life. In addition the cow requires injections of an anti-inflammatory drug and an antibiotic. If the cow is in a critical condition she also requires intravenous fluids.



Treatment of mastitis is costly, difficult and can easily cause more harm than good. Especially where no information from laboratory milk analysis is available the success rate of mastitis treatments is very low. Therefore doing everything possible to prevent mastitis is by far more important than trying to treat mastitis infections.


Review process

May 2013: contributed by by Dr Mario Younan (DVM, PhD), Regional Technical Advisor for VSF-Germany, working in East Africa since 1995