Mastitis is one of the most common diseases affecting dairy cattle and results in significant economic losses for the global dairy industry every year. Our Leatherstocking Veterinary Services team knows the serious toll mastitis can take on a herd, so we offer information about this disease and explain prevention techniques.
Mastitis causes severe inflammation of the mammary gland and udder tissue and is considered the most common disease that results in dairy industry economic losses, because of reduced yield and poor quality milk. Relevant information includes:
- Cause — Mastitis occurs when pathogens enter the teat canal and infect the teat. Any pathogen can invade the teat canal, but most mastitic infections are caused by Streptococci sp, Staphylococci, and gram-negative rods.
- Transmission — Transmission most commonly occurs during milking from the milker’s hands or contaminated equipment. Mycoplasma sp can also spread through aerosol transmission and infect the udder tissue through the blood.
- Clinical mastitis — Clinical mastitis is an inflammatory response to infection that causes signs that include visibly abnormal milk and udder swelling, heat, pain, and redness, and fever and inappetence in severe cases. Typically, only one quarter of the herd display clinical mastitis.
- Subclinical mastitis — In subclinical mastitis cases, no abnormalities are visible in the udder or milk, but milk production decreases and somatic cell counts increase. Subclinical mastitis accounts more for financial losses than clinical infection.
Mastitis predisposing factors
Certain factors tend to increase a cow’s mastitis risk:
- Genetics — High-yielding cattle breeds, such as Holstein-Friesian cattle, are more vulnerable to mastitis.
- Udder structure — Cows with large, funnel-shaped teats or pendular-shaped udders are at greater risk.
- Age — Older cows are at higher risk, likely because the teat opening is wider from frequent milking.
- Transition period — Cows are most vulnerable to mastitis three weeks before and after parturition.
- Nutrition — A cow whose nutritional needs are not met during lactation are at higher risk.
- Environment — High stocking density, contaminated floors, wet bedding, poor ventilation, and hot, humid weather can promote the growth of mastitis pathogens, resulting in a higher infection rate.
Mastitis consequences are significant and include:
- Loss of contaminated milk
- Reduced milk yields from illness and permanent udder damage
- Predisposal of affected cows to other diseases
- Decreased fertility rates
- Additional labor and veterinary costs to treat affected cows
- Reduced longevity
- Premature culling
Clinical mastitis detection
Stripping and examining milk prior to milking is the best method for early clinical mastitis detection, because changes in the milk are often the first sign. Visually examining and palpating the udder prior to milking is also important. Clinical mastitis is graded:
- Mild — The milk exhibits abnormalities, such as color change and fibrin clots, but no other signs are present.
- Moderate — Milk abnormalities and udder changes, including heat, swelling, and pain, are present.
- Severe — Marked milk and udder abnormalities are present, as well as systemic effects, such as fever, inappetence, lethargy, dehydration, and collapse.
Subclinical mastitis detection
Routine milk sample testing is the best way to detect subclinical mastitis. Options include:
- California Mastitis Test (CMT) — This test, also called the Rapid Mastitis Test (RMT), provides results in seconds and can be performed cow-side. Results are graded negative, +, ++, or +++.
- Somatic Cell Count (SCC) — Somatic cells are leukocytes (i.e., a white blood cell type) and epithelial cells. During mastitis, leukocytes arrive at the infected quarter in massive numbers, leading to an SCC increase in the milk.
- Electrical conductivity — This method is based on salt concentration differences in infected and non-infected quarters, and is integrated in most automatic milking systems.
Mastitis treatment involves antibiotic therapy administered by intramammary infusion or intramuscular injection. Internal teat sealants are also useful as a physical barrier to help reduce new infections. The dry cow period when no milk production occurs is the best time to address mastitis, since the risk of incorporating antibiotics into the food chain is minimized.
Mastitis prevention involves instigating and maintaining strict hygiene at all stages in the cow’s care to keep teats clean and healthy. Specific recommendations include:
- Keep milking cubicles and housing facilities as clean as possible, and apply fresh bedding regularly to reduce cross contamination between cows.
- Handle cattle carefully and calmly to reduce stress and avoid rushing them through muck that could cause excessive udder soiling.
- Clean milking equipment regularly, and check for broken equipment to help prevent physical teat damage.
- Avoid over milking to promote teat and udder health.
- Keep cows out of muddy areas.
- Reduce udder swelling in periparturient cows by providing proper nutritional management.
- Prevent frostbite and fly exposure.
- Dip teats post-milking with an effective germicide.
- Vaccinate the herd to protect against certain mastitis pathogens.
Mastitis causes significant economic losses for dairy farmers, but practicing proper milking hygiene, keeping your herd healthy, and vaccinating your cows can help decrease mastitis incidence. If your herd has a mastitis issue, contact our Leatherstocking Veterinary Services team, so we can assess the situation and develop an appropriate management strategy.
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