CAUSES OF DIARRHEA , PNEUMONIA , AND ABORTION IN 1991 CATTLE SUBMISSIONS TO THE KSU VETERINARY DIAGNOSTIC LABORATORY

Causes of diarrhea, pneumonia, and abortion in Kansas cattle submissions to the Kansas State University Veterinary Diagnostic Laboratory during 1991 were summarized. Antimicrobial susceptibility results for Pasteurella haemolytica, Pasteurella multocida, Hemophilus somnus, and Salmonella spp., the common causes of pneumonia and/or diarrhea in cattle with increasing antibiotic resistance patterns, were also summarized. The most commonly diagnosed causes of diarrhea in young calves (under 1 month of age) were coronavirus, Escherichia coli, and Salmonella. The three most common causes of diarrhea in 1 to 18 month-old cattle were BVD virus, coccidia, and Salmonella. Most respiratory submissions were 7to 18-month-old cattle. P. haemolytica and P. multocida were the most commonly identified pathogens from these cattle. In 20% of the cases, more than one pathogen was identified. The most commonly diagnosed cause of abortion was bacterial infection (20%), but a cause was not identified in nearly 70% of abortion submissions.


Introduction
Enteric and respiratory diseases account for large economic losses to the cattle industry each year.Fetal wastage, including abortion, also significantly impacts cow herds.An accurate diagnosis of the cause of pneumonia, diarrhea, and abortion is essential for effective prevention and control of the various causes of these diseases.
Bovine respiratory disease or "shipping fever" is considered to result from a combination of viral and bacterial infections and stress.Pasteurella haemolytica is the most important pathogen in fatal cases and may cause respiratory disease in the absence of a predisposing virus.Other bacteria frequently contribute to pneumonia caused by P. haemolytica, once damage has begun.
Causes of fetal abortion may be classified as maternal or fetal.Maternal causes include physiologic changes caused by metabolic disease, hormonal imbalances, nutritional deficiencies or imbalances, environmental stresses or trauma, toxins, and infectious agents.Fetal and placental changes are usually due to infectious agents including bacteria, viruses, fungi, or protozoa.
The present summary was performed to demonstrate the relative importance of various causes of enteric, respiratory, and fetal wastage in Kansas cattle determined at the diagnostic laboratory level.

Experimental Procedures
Cattle diagnoses and age were summarized for cases of diarrhea, pneumonia, and abortion in cattle from computer records of submissions to the KSU Veterinary Diagnostic Laboratory for calendar year 1991.Specimens included carcasses or tissues submitted by practicing veterinarians throughout Kansas.Tissues submitted for bacterial culture or viral examination alone were not included in the present study.A diagnosis was made following light microscopic, bacteriologic, and virologic examination of tissues, and information was summarized in a computer database.Antimicrobial susceptibility studies were conducted using an automated Sensititre® system.Pathogenic bacterial isolates were classified as percentage susceptible, moderately susceptible, or resistant to the various antimicrobial agents.

Results and Discussion
Causes and numbers of submissions for diarrhea in cattle are summarized in Table 1 according to age.Most submissions for diarrhea were for calves less than 1 month old (117 cases).In 8.5% of these submissions, more than one pathogen was identified.The most common pathogens identified were coronavirus, E. coli, and Salmonella (22.2%, 13.7%, and 12.8% of submissions, respectively).Few of the E. coli isolates were K99 positive.Antibiotic susceptibility results for Salmonella isolates are summarized in Table 2. None of the antibiotics cleared by the Food and Drug Administration for use in cattle were effective against more than 39% of the Salmonella isolates.The three most common causes of diarrhea in 1-to 18-month-old cattle were BVD virus, coccidia, and Salmonella.
Causes and numbers of submissions for respiratory disease in cattle are summarized in Table 3 according to age.Most submissions for cases of pneumonia were from feedlot cattle 7 to 18 months of age.The two most commonly identified types of pneumonia in calves less than 1 month old were that caused by P. multocida and interstitial pneumonia (11.1% of submissions each).The latter was usually associated with septicemia (generalized bacterial infection from Salmonella, E. coli, etc.).In 1-to 6month-old calves, P. multocida and P. haemolytica (24.4% and 20.0% of submissions, respectively) were the most commonly isolated pathogens.P. haemolytica and P. multocida also were the most commonly isolated pathogens in yearlings with pneumonia (29.2% and 17.7% of submissions, respectively).In 20% of the yearling cases, more than one pathogen was identified, including various combinations of bacteria and/or viruses.Antimicrobial susceptibility results for P. multocida, Haemophilus somnus, and P. haemolytica isolates from all 1991 bovine respiratory submissions are summarized in Table 2.
The three most commonly identified causes of bovine abortion were bacteria (approximately 20% of submissions), BVD virus, and IBR virus (Table 4).
Cases of diarrhea, pneumonia, or abortion with an idiopathic diagnosis were those for which no cause could be determined by routine laboratory testing.The primary reasons for no diagnosis were 1) submitting tissues from animals extensively treated with antibiotics or late in the disease process, 2) advanced postmortem change in submitted tissues, and 3) improper tissue collection and/or submission by the referring veterinarian.Even with extensive laboratory workup in abortion cases, the cause was not determined in nearly 70% of the cases, a finding similar to those of most other U. S. diagnostic laboratories.
Radiometer America, Westlake, OH 44145.Exact cause of the diarrhea could not be determined from submitted specimens.
a N = number of occurrences; % = percentage of cases with this diagnosis.Note that number b of occurrences is not the same as number of cases because more than one pathogen was identified in some cases.

S
= % of isolates susceptible; I = % of isolates moderately susceptible; R = % of isolates resistant; N = Total number of isolates tested.a Antibiotics not cleared by the FDA for systemic use in cattle.b Ceftiofur (Naxcel®) was used at the 0.5 and 1.0 microgram levels.Thirty of the 90 P. haemolytica isolates were tested at the 1.0 and 2.0 microgram c levels; 29 isolates were susceptible and 1 was resistant.
of cases; % = percentage of total cases.Cause of abortion could not be determined from a b the submitted tissues or fetuses.BVD = bovine virus diarrhea; IBR = infectious bovine rhinotracheitis.c

Table 3 . Causes of Respiratory Disease in Three Age Groups of Cattle for 1991 Diagnostic Laboratory Submissions
N = number of occurrences; % = percentage of cases with this diagnosis.Note that number of a occurrences is not the same as number of cases because more than one pathogen was identified in several cases.BVD = bovine virus diarrhea; BRSV = bovine respiratory syncytial virus; IBR = infectious b bovine rhinotracheitis.Exact cause of the pneumonia couldn't be determined from c submitted specimens.Other than P. haemolytica and P. multocida.d