Neonatal Calf Diarrhea - Part 2

(Part 1 can be found in the August edition of the California Dairy Newsletter)

Adapted by Patricia C. Blanchard, DVM, PhD, Associate Director California Animal Health and Food Safety Laboratory

Table 1 represents the frequency of various organisms and the age reported in calves submitted for necropsy at Tulare laboratory over 4 years.  An important aspect of breaking the cycle of disease is to identify key factors where intervention could prevent future cases.  If affected calves are usually born in the evenings this might signal a delay before they receive colostrum or are moved to a clean, dry area which reduces their exposure to organisms.  If affected calves are usually the offspring of first calf heifers that only receive dam’s colostrum, this could indicate the heifers are not receiving the same dry cow vaccines (rotavirus, coronavirus and K99 E. coli) as the older cows.  In general, colostrum of first calf heifers may have less variety or lower amounts of antibodies than older cow colostrum due to lower exposure to organisms.  If transport devices (carts, trucks) used to move newborn calves to hutches are also used to remove dead calves this exposes newborn calf to high levels of organisms that killed other calves.  The source of milk, treatment (pasteurized or not), and type (replacer, whole, etc.) may be factors contributing to diarrhea and were discussed in the previous article.

The optimal calf or fecal sample to submit for testing is from a calf that has had diarrhea for 1-3 days and has not been treated with antibiotics as antibiotics can suppress the ability to grow Salmonella in culture.  A response in diarrhea calves to antibiotic treatment would support the presence of a bacterial agent.  However, bacterial overgrowth due to undigested feed in the intestine may show some response to antibiotics even though the primary cause of diarrhea is damage from a virus (coronavirus, rotavirus) or cryptosporidia which do not respond to antibiotics.  Antibiotic treatment failure does not rule out bacterial causes as the organism may be resistant to the antibiotic or the antibiotic may not be in high enough levels to kill bacteria in the intestine.  Use of antibiotics on non-bacterial diarrheas (rotavirus, coronavirus or cryptosporidia) may worsen the diarrhea by suppressing the normal bacterial flora which allows yeast, Salmonella and attaching and effacing E. coli to overgrow.

Diagnosing the cause(s) of diarrhea in calves can assist in implementing an effective prevention and treatment program by providing information on what organisms are present so optimal vaccination, management and therapeutic strategies can be implemented.  Examination of management factors on the farm can identify weaknesses in calf management particularly when an outbreak of diarrhea occurs. 

Table 1: CAHFS –Tulare (2008-2011) data from 2,311necropsied calves less than 35-days old with diarrhea.

Link to PDF Version: Neonatal Calf Diarrhea