You already may have had a calf or two with some kind of intestinal (enteric) disease this year. Reviewing possible causes and presentations may help in discussing preventive programs with your veterinarian.
Escherichia coli (E. coli) is a bacterial disease primarily occurring in calves one week old or younger. Certain types of E. coli attach themselves to the intestinal wall, then secrete an enterotoxin that interferes with the gut's normal function.
This disease occurs so early that the best prevention is to vaccinate cows (particularly heifers) to bolster their colostrum with antibodies to the disease. Oral calf vaccines are also available, but the results are much more variable.
Rotavirus and coronavirus cause disease by a different mechanism than E. coli. While E. coli interferes with intestinal function through a toxin, rotavirus and coronavirus infect the cells of the intestinal villi (small projections that increase the intestinal surface area). Under the microscope, the result is intestinal villi that appear “mowed off.” This loss of surface area needed for nutrient absorption causes diarrhea due to malabsorption.
Rotavirus typically occurs in calves 5-15 days old. Coronavirus may occur in calves from 5 to 30 days old. The most important preventive factor is to calve in a clean, dry environment where cattle are spread over a large area. Vaccines can be effective if the strains in the vaccine and those in your calves are the same. Because these are viruses, antibiotic therapy won't help.
Salmonella is a bacterial enteric disease resulting from overgrowth of the pathogen in calves from one week to 30 days old, although salmonella infections may occur any time in cattle's life. Like E. coli, these pathogens can release enterotoxins, and also invade the intestinal lining to invade the bloodstream.
Some salmonella species (e.g., salmonella typhimurium and salmonella newport) have become resistant to many antibiotics. Salmonella is a zoonotic pathogen (moves from animals to humans), so care should be taken when handling diarrhetic calves of this age. This devastating disease generally enters a herd when a calf is purchased to put on a cow that lost her own calf — always a bad idea.
Clostridium perfringens types C and D are common inhabitants of the calf intestinal tract. Type C is the most common cause of hemorrhagic enterotoxemia (bloody diarrhea resulting from an intestinal infection).
Clostridium perfringens causes disease by secreting toxins that increase permeability of blood vessels, rupture red blood cells and destroy the intestinal lining. The disease occurs in calves from birth to two weeks old and may cause death so quickly that bloody diarrhea is never observed.
The organism overgrows when the intestine is flooded with protein and readily available energy such as starch or milk. The calves most at risk are those aggressively nursing on high-milking cows.
There are numerous vaccines against type C and D toxins, and these should be used on the cows and heifers (twice on the heifers for a booster effect) to engender good colostral immunity. Calves may be vaccinated at birth, but many believe vaccination with this product under four months of age is blocked by maternal immunity sufficiently such that an additional vaccination is necessary after four months of age.
Cryptosporidium parvum is a zoonotic pathogen and, therefore, highly contagious to people. Cryptosporidia cause disease in calves by infecting cells on the tip of the villi and causing malabsorptive diarrhea. The disease is generally apparent in calves between one and three weeks of age. Cryptosporidia can become infective in the gut without being excreted, so the organism can grow very quickly in the host.
Discuss any recommended treatments very clearly with your veterinarian as some treatments are of questionable efficacy. One extra-label treatment used in the field may be fatal to calves if used in a high dose. It's also possible to have relapses that are more severe than the original case.
Other Zoonotic Diseases
Giardia, known among campers as “beaver fever,” is another zoonotic disease that merits careful handling of affected calves. This water-borne parasite is typically seen in calves from two to four weeks of age.
Coccidiosis is largely thought of as a feedlot disease, but it can affect neonatal calves. The single-celled parasite infects intestinal lining cells in the lower large intestine, which causes cell swelling and death. Affected calves develop bloody diarrhea after 21 days of age (more common at 30-45 days of age), can experience severe straining and are markedly depressed.
No vaccine is available and treatment must be early and vigorous. Anticoccidial treatment, along with aggressive fluid therapy, are needed for a successful outcome.
Treatment of the different infectious agents varies. Some of the pathogens won't respond to drugs used for other causes.
Work with your veterinarian to achieve a diagnosis that will target therapy so calves have a full chance at recovery. Oral electrolyte solutions are used in nearly all neonatal calf diarrhea cases, but once a calf can't get up, oral fluids and/or antibiotics are unlikely to save it. In this case, an intravenous catheter is needed to maintain kidney function and body hydration.
Prevention revolves around environmental control and biosecurity. Biosecurity means taking steps to isolate the diseased, or potentially diseased, animals to prevent disease spread.
One of the best preventive measures is to calve cows and heifers separate from each other on open grass traps. Too often, disease problems in calves are caused by their birth in a mud/manure lot where their mothers' teats become coated with pathogens for which the calf isn't yet prepared.
If you had neonatal calf disease this calving season, make an appointment with your herd health veterinarian to formulate next season's plan of prevention. We see many herds that consistently have zero incidence of neonatal calf disease.
The key is to identify the herd's risk factors. While immunization of the dam with an appropriate vaccine is a factor in prevention, the neonatal disease will surely continue if environmental and biosecurity issues are not addressed. Other tips include:
Calve at a time of year of minimal weather stress.
Separate cows from heifers 50-60 days precalving until breeding or pasture turn-out.
If you have a neonatal calf disease outbreak, leave cows with calves on the contaminated ground and move the cows yet to calve to a new, clean and dry calving area.
Be sure calves suckle adequate colostrum within a few hours of birth. If unsure if calves have nursed, give the cow 1cc of Oxytocin intramuscularly in the neck, milk the cow out and tube the calf.
These tips are a good start to prevention of neonatal disease, specifically diarrhea, but each operation has unique challenges. Producers need to routinely work with their veterinarians to diagnose infectious diarrhea problems. If manure or tissue samples are needed for exact diagnosis, be sure to collect samples at the initial phases of the disease outbreak. It's also essential to invest in post-mortem examinations to get a clear picture of any disease challenges in your cow herd.
Mike Apley, DVM, PhD, is an associate professor of beef production medicine at Iowa State University in Ames. W. Mark Hilton, DVM, is a clinical assistant professor of beef production medicine at Purdue University in West Lafayette, IN.