Myocoplasma bovis primer
Friday, June 11th, 2010
by Dave Horn DVM,
Cargill Business Development Manager
I have been involved in 2 cases over the past few weeks dealing with Mycoplasma. Both farms had multiple clinical expressions. One farm had mastitis and pneumonia in milk cows and the other had ear infections and joint infections in calves and also had mastitis in the milk herd.
Both herds had recently purchased animals over the previous few months. They had purchased bred heifers and fresh animals.
Mycoplasma bovis is the most common strain but there are a few other strains that can cause disease including M. bovirhinis and M. alkalescens
I thought it would be good to go over some Myco information:
1- Mycoplasma organism are the smallest organisms capable of self-replication. They do not have a cell wall and are very resistant to antimicrobials. There are some antibiotics that show effectiveness against infections in animals under 20 months but not all contain label claims against Myco. There are no label claims against for Myco in animals over 20 months of age. Antibiotics shown to have some effectiveness include Draxxin, Nuflor Gold, Micotil, and Tetracycline but treatment is generally less rewarding than with many other respiratory infections in heifers. Consult local veterinarian recommendations for treatment protocols.
2- Most new herd outbreaks follow the addition of purchased animals. Once on a farm testing, culling and good milking protocols and hygiene are essential to control. Treating calves early before joint infections or inner ear infections can be successful but treatment of milk cows is not successful and is not recommended.
3- The prevalence is increasing and it there is a higher prevalence in larger farms over 500 probably due to increased purchasing of animals with expansions.
4- Infected animals shed from multiple orifices including nose, mouth and udder. Animals are intermittent shedders so one negative culture does not mean the animal is not infected. Repeated negative cultures are a must to ensure an animal is clean. Once an animal comes up positive on milk culture, she should be considered positive for life. Even calves that respond to treatment may end up having mastitis later as first calf heifer.
5- Routine milk cultures on farms will not isolate Myco. You have to specifically ask the lab to culture for this as well.
6- Ingestion of contaminated milk or Colostrum is the most common cause of outbreaks in calves but there have been apparent spontaneous Infections in calves or heifers without mastitis outbreaks in the herd.
7- Experiments with as few as 3 feeding of infected milk have been shown to infect calves.
8- Infections generally occur due to direct contact with infected animals and shedders but it may be spread by people and things that spread contaminated secretions or milk from animal to animal. Hygiene is critical to controlling the spread including people’s hands and clothing, pails, nipples, tubes and common tools like whisks and scoops.
9- There is a commercial vaccine with M. bovis and autogenous can be made for any strain but vaccination has mixed result when used to stop or control an outbreak. Vaccines may have some application in young stock as a way to prevent or limit outbreaks prior to the addition of ne animals. Vaccination in adults to prevent mastitis has not been proven to be effective.
10- Routine bulk tank screening and culturing of all clinical mastitis for several months is part of the follow up after an outbreak occurs. Work with QMPS in NY as well as local vets to manage this serious problem.
