There are several disease conditions of adult dairy cows that are more worrisome than respiratory disease in terms of morbidity and mortality, but respiratory disease can still be a problem. However, many dairy producers don’t focus too much effort on diagnosing respiratory disease in the adult cow herd.
“Oftentimes pneumonia is more nebulous in well-managed herds,” notes Greg Goodell, DVM, The Dairy Authority LLC, Greeley, Colo. “In these herds cows are vaccinated appropriately and signs of pneumonia are mild and difficult to tell apart from other diseases. Common presentation would be cows with an increased temperature and mild to moderate lung sounds. The lung sounds often go undetected by lay personnel. I often find pneumonia cows in the fever-of-unknown-origin (FUO) category.”
Goodell doesn’t believe that veterinarians are missing respiratory cases, but that the number of individual cows seen by the veterinarian has decreased in the past five years with more widespread use of protocols. “If cows are not getting presented to the veterinarian for diagnosis then it may be the perception of the veterinarian that pneumonia rates are low assuming that all cows are diagnosed correctly by lay personnel.”
It can be difficult for veterinarians to gain access to cows on these dairies since protocols have worked so well.
“Additionally there are limited antibiotics available and if the FUO responds to penicillin or another of the broad-spectrum antibiotics, then there is no reason for the dairy to present the cow to the herd veterinarian for further diagnosis,” Goodell says.
He used to do a lot more necropsies and sampling in previous years. The economy of the last couple of years combined with the increased prevalence of protocols has led to fewer and fewer necropsies and definitive diagnoses. “In our area we would typically find BRSV and Pastuerella when sampled.”
Lack of treatment for pneumonia is directly related to lack of diagnosis, Goodell suggests. He typically prescribes oxytetracycline and sulfadimethoxine in combination along with fluids and NSAIDS if clinical signs warrant. “If the pneumonia is detected early enough many of the broad-spectrum antibiotics will work well,” he adds.
How much brd is there?
The National Animal Health Monitoring System’s Dairy 2007 study indicates that adult dairy cow morbidity due to respiratory disease has slightly increased from 2.5 percent in 1996 to 3.3 percent in 2007. Mortality from respiratory disease also increased from 9.6 percent in 1996 to 11.3 percent in 2007.
Goodell believes morbidity due to pneumonia is higher than 3 percent in most herds. “I’ve monitored health events and cause of death in herds for 15 years at this point,” he says. When I see mortality rates at 15 percent and morbidity rates at 3 percent I know there is either a detection issue or the dairy is treating with therapies that are hugely unsuccessful. If 10 percent of the herd dies annually and 15 percent of that is due to pneumonia I have a herd level death rate caused by pneumonia of 1.5 percent. If morbidity is 2–3 percent that means 50–75 percent of the cows treated for pneumonia died. Successful treatment outcomes are not difficult to achieve. The bottom line is that pneumonias are not getting diagnosed so the morbidity is underestimated. I saw these rates 10 years ago. Many of these cows are never diagnosed until the necropsy. If the NAHMS data has shown an increase then perhaps it is because producers are beginning to pay more attention to it.”
Fresh cows and heat-stressed cows and heifers are the typical victims of respiratory disease. The most common time to see pneumonias is fall and spring when there are large differentials in daily temperatures. Additionally, long periods of heat stress tend to cause an increase in pneumonias as well.
A springer that has just freshened is likely under the most stress she’ll ever see in her life. She has just calved for the first time, she has been introduced to the milking pens, she has been put on a ration that she has probably not seen much of previously, she is getting pushed through the parlor at least two to three times per day, etc. “If she is not well-vaccinated and managed well nutritionally before freshening, she will most likely present as a pneumonia case or a metritis case and maybe even both,” Goodell says.
A syndrome he has seen over the years is a combination of both metritis and pneumonia. When doing blood work on these heifers he often sees severe left shifts in the white blood cell (WBC) panel. “I’m not sure which came first (pneumonia or metritis) but the metritis likely consumed a large quantity of WBCs and the enduring stress and lack of immune response set the heifer up for a case of pneumonia she has a difficult time recovering from. In herds where I see 10–15 percent morbidity rates for pneumonia, one of the biggest culprits is usually heifer
replacement programs that are not managed correctly.”
Preventing respiratory disease
The NAHMS Dairy 2007 study indicates about 65–70 percent of adult dairy cows are vaccinated against respiratory disease pathogens such as IBR, BRSV and PI3, which hasn’t changed significantly from 1996. Goodell also sees more pneumonia in first lactation heifers that haven’t had at least two to three doses of modified-live vaccine throughout their two years as a growing heifer. The study indicates that fewer than 70 percent of dairy heifers, for example, are vaccinated against respiratory disease pathogens such as IBR, BRSV and PI3.
Goodell likes to get a good vaccine program into a heifer, then by the time she enters the lactating herd he usually sees good pneumonia control by administering one modified-live vaccine (MLV) dose 3–4 weeks after freshening. “If the herd has a problem with pneumonias then I may administer another MLV dose 3–4 weeks prior to dry off,” he adds.
Goodell says when bringing new animals into the herd, the old rules for disease prevention are still effective. “Quarantine the animal for at least two weeks,” he says. “Four weeks is preferred. This also makes it easier for
observing the newly arrived animals for diseases they arrived with or outbreaks of BRD due to shipping.”
Keep to a vaccine plan
Livestock producers have the fortunate circumstance of widely available cattle vaccines at affordable prices, which may tempt many of them to use a variety of combinations. There seems to be a strong movement of switching vaccine brands and even switching back and forth between modified-live (MLV) and killed vaccines, says Greg Goodell, DVM.
“The impact on this may be negligible and some data may even show improved protection on animals that were vaccinated appropriately beforehand; however, I’ve seen problems with vaccinal protection when mixing and matching products on animals that are getting their vaccinations for the first time.”
“I’m not sure if the problems are related to different strains of organ-isms in the vaccine or maybe even a bad combination of a killed and MLV at the wrong time causing an inappropriate immune response,” he explains. “I see this more commonly with youngstock programs. It is my impression that the producer sees this more as a money-saving tool and assumes all vaccines are the same. My recommendation would be to get on the same product for the introduction of vaccinations to the animal, then, if desired, change things up later on.”