Tackling the deadly challenge of Mannheimia haemolytica
Prevention is the best approach with this ever-evolving bacteria
From 2011 to 2015, bovine respiratory disease (BRD) in nursing calves cost the beef industry approximately $165 million each year.1 Of the bacterial causes of BRD, M. haemolytica is the most predominant and concerning of the group.2 Animals with an M. haemolytica infection can go from seemingly healthy to deceased in a day’s time.
Prevention starts with understanding how pathogens act
M. haemolytica is found naturally in the respiratory tract of cattle. Dust, stress or viral infections make it easier for the bacteria to travel from the respiratory tract to the lungs. Because of multiple virulence factors, M. haemolytica is an expert at avoiding the animal’s immune defenses and remains tough to clear once an infection occurs.
“M. haemolytica typically causes more sudden or acute pneumonia and other BRD bacterial pathogens are commonly secondary invaders causing more chronic pneumonia,” said Jeffrey Sarchet, DVM, Beef Technical Services veterinarian with Zoetis.
produces leukotoxin, which kills white blood cells and leads to severe lung
damage. Enzymatic proteins from the affected white blood cells destroy lung
cells, causing lung lesions that produce irreversible, and potentially fatal,
damage to cattle. Cattle have an extremely low ratio of lung volume to body
size, so any lung damage is detrimental to an animal’s overall health and
bacterial pathogens, like Pasteurella multocida, don’t produce leukotoxin,
so they don’t cause the severe acute lung damage that M. haemolytica
does,” Dr. Sarchet said.
Protecting against M. haemolytica
M. haemolytica is opportunistic and often strikes when a viral infection has weakened the animal’s immune defenses. Effective control requires vaccines providing viral protection, along with anti-leukotoxin antibodies that help block the effect of leukotoxins and capsular antibodies to increase the ability of white blood cells to engulf and destroy the bacteria.
Shot® has proven efficacy for stimulating protection against M.
haemolytica and reducing lung lesions,” Dr. Sarchet said. “Unfortunately,
vaccines available for other BRD bacterial pathogens, like Pasteurella
multocida and Histophilus somnus, have not demonstrated the same
efficacy of One Shot based on research from University of Minnesota. Because Pasteurella
multocida and Histophilus somnus are also Gram-negative bacteria,
adding vaccines to protect against these pathogens can add stress and increase
the risk of adverse reactions, so the cost/benefit should be carefully
Sarchet explains that Gram-negative bacteria have endotoxins in the cell wall,
which are very potent toxins that cause a stress response in cattle resulting
in increased heart and respiratory rate, decreased rumen and intestinal action,
fever, vascular shock and possibly death.
general rule is to not give an animal more than two or three Gram-negative
vaccines at the same time,” Dr. Sarchet said. “Even though blackleg (seven- or
eight-way clostridial) vaccines are Gram-positive, we count them as one-half a
Gram-negative vaccine. So, for example, if we give One Shot with a seven- or
eight-way clostridial vaccine at the same time, it would count as 1½
Gram-negative vaccines. If we add a vaccine to protect against Pasteurella
multocida or Histophilus somnus at the same time, it would push the
protocol to 2½ to 3½ Gram-negative vaccines, which is a higher risk for the
has shown vaccines with leukotoxoid, like what is found in the One Shot®
line of vaccines, can help stimulate effective anti-leukotoxin antibodies
against M. haemolytica.4 Surface antigens in One Shot
have been proven to stimulate production of antibodies which increase the
ability of white blood cells to engulf and destroy M. haemolytica
bacteria before it can cause lung damage.4
Shot has also been shown to decrease the amount and severity of lung lesions in
cattle infected with M. haemolytica in organized studies because the
adjuvanted leukotoxoid from One Shot helps ensure production of predictably
higher antibody levels and more effective M. haemolytica protection.3,4
A comparative study of Zoetis products showed that after 21 days of M.
haemolytica exposure, One Shot mitigated 74.5%-79.6% of lesions and
prevented 89.4% of mortality within the treatment group.4
the right vaccine for the right pathogen is key in helping reduce respiratory
disease,” Dr. Sarchet said. “Your herd veterinarian is a great resource to
develop a protocol that will prevent problems from Mannheimia haemolytica.”
For more information on respiratory vaccination programs, talk to your local veterinarian or visit CompleteCalfProtection.com or UncompromisedProtection.com to learn more about solutions offered by Zoetis for combating BRD pathogens.