The Transition Period Part II: Infectious Diseases

Previously, we talked about metabolic diseases of fresh cows.  Cows are also at risk for infectious diseases surrounding calving due to contamination of the reproductive tract and the start of lactation.  The two most significant of these are metritis and mastitis.

Metritis

Metritis is an infection of the uterus.  During calving the uterus is contaminated with bacteria, which is normally removed quickly by the immune system as the uterus returns to its normal size.

Several risk factors can allow the bacteria to overwhelm the immune system and cause an active infection.  Dystocia (difficulty calving) and retained afterbirth disrupt the normal involution (uterus contracting to non-pregnant size) process; afterbirth can also act as a tract into the uterus for bacteria.  A dirty maternity pen can lead to overwhelming contamination that the cow cannot fight off on her own.  Low calcium levels weaken uterine muscle contractions that expel fluid.  This can be a factor whether obvious signs of milk fever are present or not.  All of these factors put cows at risk for metritis.

Clinical Signs:  Signs of metritis may be localized to the uterus or throughout the cow’s body.  Most commonly, cows will have a foul-smelling vaginal discharge.  This may only be found with rectal palpation, so it is a good idea to have fresh cows palpated to screen for metritis.  Cows may also have a decreased appetite, drop in milk production, fever, and act painful with their backs arched.

Treatment:  Treating metritis can be tricky and varies based on how severely the cow is affected.  Mild cases will often resolve with a lutalyse injection, activating the cow’s natural defenses when going through heat.  More moderate cases require antibiotics.  While there has been some debate among veterinarians about the infusing antibiotics into the uterus, we have found that intra-uterine infusion of oxytetracycline (or iodine) can be very helpful in conjunction with injectable antibiotics (such as excede or penicillin) or alone.  Cows that are severely affected may need additional supportive care also (such as anti-inflammatories or fluid therapy.)  The goals of treatment for metritis are resolving signs in the uterus and rest of the body and returning the cow to breeding as soon as possible.

Prevention:  Prevention focuses on the risk factors mentioned above.  It is important to keep the maternity pen CLEAN, both for the calf and the cow.  Cows with difficult births should be monitored closely and treated promptly if they show signs of metritis.  Following our recommendations from The Transition Period Part I on preventing milk fever can also decrease the risk of metritis.

Mastitis

Mastitis is an infection of the mammary gland (udder).  There are several bacteria that can cause mastitis; these can spread from cow to cow during milking or come from the environment.

Mild-Moderate Mastitis: Cows with mastitis can be divided into mild-moderate or severe cases based on their disease signs and this will determine how best to treat them.  Cows with mild-moderate mastitis will have abnormal milk (flakes or clumps) and may have some swelling of the udder.  These cows are not affected in other body systems. Mild cases generally can be treated with intramammary antibiotics, but it should be taken into account how far into lactation she is and whether the cow has other problems before treating her.  It may be more economical to dry the cow (or affected quarter) early in preparation for her next lactation.

Severe Mastitis:  Severely affected cows are often depressed and not eating; they may be down and unable to rise.  These cows require more intensive treatment that should be done by or in consultation with a veterinarian.  They will often need antibiotics and possibly fluids in the vein as well as anti-inflammatory drugs (e.g. banamine and/or dexasone).

Mastitis at the Herd Level: All dairy farms will have the occasional mastitis case.  However, if your farm starts to have an increased number of cases or cows that are not responding to your typical therapy, we recommend that you take milk samples from affected animals.  It is important when taking these samples to avoid environmental contamination.

  1. Wear gloves when taking samples.
  2. The teat should be cleaned of any dirt or manure and then wiped with an alcohol swab.
  3. Strip a little milk out of the teat first.
  4. Hold your collection tube slightly to the side of the udder so that material on the udder cannot drop into it.  Squirt milk into your tube at this angle.
  5. Cap your tube and label it with the cow number, which quarter it came from, and the date.
  6. Refrigerate sample until it can be submitted, within 24 hours of collection.  (Samples can be frozen if there is no way to submit them in this time period, but this is not ideal.)

Milk can be submitted to MSU’s diagnostic lab, where it is cultured and the specific bacteria affecting your farm identified.  Then your veterinarian can help you design a unique prevention plan for that bacteria.

Prevention: Maintaining adequate clean bedding for cows and not overcrowding pens can help prevent environmental causes of mastitis; optimizing your milking procedure (e.g. pre- and post-dipping teats in iodine) and cleaning milking equipment prevents bacteria from passing from cow to cow.  All cows should be treated with an appropriate intramammary antibiotic at dry-off also.

The transition from late pregnancy to early lactation puts the cow at risk for infectious diseases as well as metabolic.  Maintain a CLEAN maternity pen and keep a close eye on your fresh cows (particularly those that had difficult calvings), so you can catch problems early.  As always, if you think you are having a problem, consult your veterinarian.