Virginia Cooperative Extension Service

I W VIRGINIA VE I ERINARY NOTES ~

VIRGINIA-MARYLAND REGIONAL COLLEGE OF VETERINARY MEDICINE

September-October 1993 No.65

WHAT'S INSIDE!

PATHOGENIC ESCHERICHIA COLI: A PATHOGEN OF ANIMALS AS WELL AS HUMANS? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2

PARVOVIRUS VACCINATION .............................................. Page 3

FISH MEDICINE SHORT COURSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 3

FIELD SAFETY AND EFFICACY OF A COMMERCIALLY AVAILABLE LYME DISEASE v ACCINE . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4

ALBENDAZOLE EFFICACY AGAINST CANINE GIARDIASIS . . . . . . . . . . . . . . . . . . . . . . . Page 4

NEW RADIOLOGY SERVICES AVAILABLE .................................... Page 5

PRODUCER/DISTRIBUTOR TO LIMIT ANIMAL SOURCE INSULIN LINE . . . . . . . . . . . . . . . Page 5

CONTINUING EDUCATION OPPORTUNITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6

BOVINE PRACTITIONERS FALL CONFERENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6

SOUTHERN FEDERATION MEETING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6

MAILING LIST UPDATE

K~ oberts, DVM Extension Veterinarian

THOUGHT FOR THE MONTH

Page 7

Trust is the essence of all satisfying interpersonal relationships. Trust can only be earned--without it , there is no unity. In an environment or relationship which lacks trust , there is a lack of unity of purpose.

Virginia II Tech IRGINIA POl.YIBOINIC INSTTlUTE

AND STA"IB UNJVERSITY

Virginia Cooperative Extension programs and employment are open to all, r~ardless ol race, color, religion, sex, age, national origin . handicap, or political affiliation. An equal opportunity/affirmative

ac;tion employer. Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University , and the U.S. Department of Agriculture cooperating.

William A. Allen . Interim Director , Virginia Cooperative Extension , Virginia Tech , Blacksburg; Lorenza W . Lyons. Interim Administrator . 1890 Extension Program. Virginia State , Petersburg . VIRGINIA ST A TE UNIVERSITY

2

PATHOGENIC ESCHERICHIA COLI: A PATHOGEN OF ANIMALS AS WELL AS HUMANS?

Most veterinarians know that enterotoxigenic Escherichia coli may cause serious enteric disease, such as calf scours, in newborn animals. These pathogenic E.coli strains produce heat-stable and heat-labile exotoxins that cause the release of fluid into the intestinal lumen. The heat-labile toxin is detected by Chinese hamster ovary cell assay, and heat-stable toxin is detected by an infant mouse model. In order to be pathogenic, these strains also require pili or adhesion antigens to attach to and colonize the intestine. Most clinical laboratories identify such pathogenic strains by agglutination or other serologic tests with antisera to the pilus antigens (eg. K88 in pigs and K99 in calves), which is suggestive for enterotoxigenic E. coli. These strains have also been long recognized as the cause of "traveler's diarrhea" in humans. In addition, enteropathogenic, enteroinvasive, Shiga-like toxin-producing, and enterohemorrhagic £.coli are also well recognized pathogens of humans, and are identified by production of specific toxins or toxicity in cell culture. Enteropathogenic E. coli are important agents of infant and childhood diarrhea in developing countries, and produce characteristic histopathologic lesions. Many of these strains produce a toxin similar or identical to the Shiga toxin of Shigella dvsenteriae. Enteroinvasive E.coli strains penetrate the intestinal epithelium, producing a Shigella-like dysentery. These strains are relatively rare. Shiga-like toxin (verotoxin) producing E. coli produce one or both of two antigenically distinct toxins, which are identified by toxicity for HeLa or Vero cells in tissue culture. These isolates cause keratoconjunctivitis in the eye of a guinea pig (Sereny test), and are usually identified in reference labs. Each of these pathogenic types belong to specific serotypes and can therefore be distinguished by serotyping. Whether enteropathogenic, enteroinvasive, and Shiga-like producers cause disease in animals is not known, due to the difficulty in identifying these strains, but the occurrence in animals should not be ruled out.

Enterohemorrhagic £. coli (particularly serotype 0157:H7) produce a toxin that causes a hemorrhagic colitis, characterized by abdominal. pain, and watery diarrhea followed by bloody diarrhea. In young children, this strain is particularly virulent and may cause mortality and hemolytic-uremic syndrome, characterized by blood in the urine due to kidney infection. Several outbreaks of enteric disease due to enterohemorrhagic E. coli have been reported in this country. The most recent outbreak occurred in the Northwest as a result of improperly cooked hamburger served at Jack-in-the-box restaurants. Since 0157:H7 infections in humans are of animal origin, one would think that infections in animals may also occur. A paper presented at the recent American Association of Veterinary Laboratory Diagnosticians (AAVLD) Meeting in Louisville, KY, reported that 16 of 913 bovine herds tested had positive fecal samples for serotype 0157:H7. It was not clear if disease was present in the positive herds. Serotype 0157:H7 can easily be distinguished from other E. coli serotypes by their ability to ferment sorbitol, and can therefore be screened on MacConkey agar containing sorbitol. Identification can be confirmed by commercially available serologic agglutination tests. Although serotypes other than 0157:H7 can also be enterohemorrhagic, they are not easily identified and are not as common.

A separate paper from the AA VLD meeting reported that two E. coli isolates from calves with fat al diarrhea were identified as adhering and effacing strains, which are identified by attachment to Hep-2 and other tissue cell types. These strains may cause cellular necrosis and detachment. It is not known how common these strains may be, but it was emphasized that the strains would have been missed without the use of proper cell culture techniques.

In summary, it is highly likely that there are many types of .. ~ .. coli strains that can cause disease in animals. Other than enterotoxigenic and enterohemorrhagic strains, identification of these pathogens in most clinical laboratories is difficult or not possible. Although there is not an established correlation between hemolysin-producing E. coli and the pathogenic serotypes, our laboratory screens all fecal samples on a blood agar plate for normal flora. Normal flora is considered predominately nonhemolytic E. coli. Occasionally, pure or predominant cultures of hemolytic E. coli are found and a susceptibility test is done and reported on these isolates. Clinicians should keep in mind the variety of pathogenic£. coli strains that may exist and be significant causes of enteric disease in both young and adult animals. -Thomas J. Inzana, PhD, Director, Clinical Microbiology, VA-MD Regional College of Veterinary Medicine, Blacksburg, VA.

3

PARVOVIRUS VACCINATION

Canine parvovirus was first isolated and identified in this country in 1978. It was the second parvovirus described in dogs and is known as CPV-2. There is speculation that CPV-2 mutated from another virus, possibly the feline parvovirus that causes feline distemper.

In recent months there has been talk of the need for a new canine parvovirus vaccine because vaccinated dogs are being infected with the disease. Here is the most authoritative explanation available. It comes from the highly respected Canine Infectious Diseases Laboratory of the James A. Baker Institute for Animal Health at Cornell University.

The apparent vaccination "breaks" are the result of certain commercially available vaccines having lost their ability to stimulate high enough levels of protective immunity in dogs vaccinated with these vaccines. It is also known that there is normal parvovirus "evolution" over time. This has been documented at the Baker Institute where three distinct antigenic types of the parvovirus CPV-2 have been isolated since the identification of the original canine virus in 1978.

Another important point for owners and breeders t'o remember is the potentially dangerous period from birth to four months of age when maternal antibodies transferred from the bitch to the puppy can interiere with the pup's ability to produce effective immunity against parvovirus. So called vaccination "breaks" may occur at this time even though the puppy has been vaccinated with an antigenically good vaccine. The only sure protection during this period is to protect the pups against virus exposure by means of isolation and strict hygiene. Because of vaccination and the prevalence of adult immunity, clinical cases of parvovirus are limited primarily to the six weeks to six months age group. Subclinical cases apparently occur in adult dogs rather commonly.

Studies at the Baker Institute indicate that almost all available vaccines produce effective immunity in healthy dogs when properly handled. Some vaccines have had periods of inadequate potency (and the resulting inability to effectively immunize dogs) because of mutations in the cell lines used to produce these vaccines.

The Baker Institute at Cornell is testing new strains of parvovirus to see if they can develop a vaccine with an improved ability to produce immunity in dogs against the disease.

It would seem that subtle problems in vaccine production may account for occasional breaks in a dog's immunity against parvovirus. Evolutionary virus mutations are difficult to detect, predict and make adjustments for in producing effective vaccines. New parvovirus vaccines may be available in the future and it is comforting to know that the problem is receiving careful attention. --Kent Roberts, DVM, Extension Veterinarian, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA.

FISH MEDICINE SHORT COURSE

A College-sponsored short course for veterinarians on clinical fish medicine is scheduled for November 5-6 in Blacksburg. Featured speakers are Dr. Brent Whitaker, Director of Animal Health at the National Aquarium in Baltimore and Dr. Stephen Smith, Aquatic Medicine, VMRCVM, Blacksburg.

Program topics include common aquarium diseases, environmental problems affecting fish, preventative medicine programs, and case discussions. Course participants will have the opportunity for hands-on experience in water quality testing, anesthesia, biopsy, and necropsy techniques. This interesting and practical course will provide ten hours of CE credit.

4

FIELD SAFETY AND EFFICACY OF A COMMERCIALLY AVAILABLE LYME DISEASE VACCINE

A recently published study reports that vaccination of dogs with Borrelia burgdorferi bacterin (Ft. Dodge Laboratories) is both safe and effective. Minor reactions were observed in 38 of 1,969 vaccinated dogs (1 .9 percent). Thirty-two dogs had delayed reactions such as fever, lethargy, soreness, signs of depression or anorexia within 1 to 3 days of vaccination. One of these dogs experienced reactions after the first and second vaccinations. Another dog had one seizure. Six dogs had immediate reactions associated with pain at the injection site. All 38 dogs having reactions recovered within 72 hours. No immune-mediated disease was observed in any dog after vaccination.

Protective effects of immunization were suggested by a 1.0 percent incidence (20 of 1,969) of clinical borreliosis in vaccinated dogs compared to a 4.7 percent incidence (211 of 4,498) in nonvaccinated dogs. Vaccination seemed to prevent disease better in unexposed dogs than in previously exposed animals. The authors concluded that vaccination against borreliosis is more efficacious when dogs are young and have not been exposed to infected ticks. ··Abstracted from S.A. Levy, B.A. Lissman, and C.M. Ficke. "Performance of a Borrelia burgdorferi Bacterin in Borreliosis-endemic Areas." Journal of the American Veterinary Medical Association, Vol. 202, No. 11, June 1, 1993, pp. 1834-1838, as reported in Veterinary Quarterly Review, Vol. 9, No. 2, April-June 1993, Texas A&M University, College Station, TX.

ALBENDAZOLE EFFICACY AGAINST CANINE GIARDIASIS

A recently published study has demonstrated that four consecutive doses of 25 mg/kg albendazole administered orally every 12 hours was highly effective in eliminative Giardia cysts from experimentally infected dogs. This treatment regimen removed Giardia cysts from 5 of 5 and 18 of 20 infected dogs, while only 1 of 5 and O of 20 infected, nontreated dogs (controls) became clear of Giardia cysts..

Results were tested with the zinc sulfate concentration technique (ZSCT) for detecting Giardia cysts in feces . Three fecal samples were examined within 5 days of the last albendazole treatment (at least 24 hours elapsed between the three samples). If one or more of the three tests demonstrated Giardia cysts, the dog was scored positive. With the use of the ZSCT, there is a possibility that not all positives were detected because cysts are intermittently shed in feces. Also, conducting two tests on the same dog makes the results only 93 percent accurate in detecting infected dogs. Another unknown was the length of time treated dogs remained clear of cysts. Treatment by albendazole may have only temporarily stopped cyst production through the observation period; cysts may have been shed again later. Because dogs also may become reinfected after treatment, it could not be determined whether or not albendazole only interrupted cyst production or killed Giardia.

None of the 25 treated dogs experience side effects. The authors stated that these results were important for several reasons: Giardiasis is a highly prevalent and serious canine disease; it is a zoonotic disease and drugs currently used for giardiasis treatment have poor efficacy or severe side effects. •• Abstracted from S.C. Barr, D.D. Bowman, R.L. Heller and H.N. Erb. "Efficacy of albendazole against giardiasis in dogs," American Journal of Veterinary Research, Vol. 54, No. 6, June 1993, pp. 926-928, as reported in Veterinary Quarterly Review, Vol. 9, No. 2, April-June 1993, Texas A&M University, College Station, TX.

ANOTHER THOUGHT

You are remembered and respected for the good you do for others.

5

NEW RADIOLOGY SERVICES AVAILABLE

Computed tomography (CT) has recently been added to the diagnostic services offered by the VMRCVM. While CT does not replace conventional X-ray equipment, it does offer several advantages. Computed tomography is the process of production of cross-sectional images using X-rays and computers. The CT scan consists of a number of continuous "slices" or images (usually 2-1 Omm in width) through a selected body part or area of interest. The slices are made as the patient is slowly passed through the CT gantry (where the X-rays are emitted) by a moving table. In the gantry, the X-ray tube circles the patient and collects data from all angles for each particular slice. A computer then collates all the information from all the different angles and puts it together to form a visual image of each cross-sectional slice. The biggest advantage of CT over conventional X-ray images is that CT can image one thin slice at a time ; there is no superimposition of overlying or adjacent structures as there is in regular X-ray images. In addition, CT offers enhanced radiographic contrast and object clarity. On regular X-ray images, all organs, blood vessels, and muscles are the same soft tissue density, and cannot be differentiated. On CT scans, however, the different soft tissues are easily differentiated. This is especially helpful in imaging the brain for tumors . On conventional X-ray images, the brain is not clearly visualized due to the overlying bony skull , and if a mass were present, it could not be separated from other brain density. With CT, the brain is seen clearly , without the overlying skull. Mass lesions within the brain can often be seen, especially with the administration of intravenous contrast. These same advantages are present in CT scans of the spine, thorax , and abdomen. While the skull is most commonly imaged with CT for the detection of brain tumors, CT can also detect tumors of the spine, as well as herniated disks. Abdominal and thoracic CT scans can also detect tumors which are not visible on regular X-ray images. Despite the economic considerations CT scans are more expensive than conventional X-ray images, the diagnostic advantages of CT for certain patients makes it an invaluable imaging modality.

The radiology section at the VMRCVM has also added new digital fluoroscopic equipment. This equipment allows acquisition of rapid serial images of motion studies such as esophagrams, angiocardiograms, and portograms. Each individual image can be enhanced or manipulated to increase diagnostic information. Using the new laser camera, these enhanced images can then be printed onto X-ray film for permanent storage. Digital fluoroscopy offers several advantages over conventional fluoroscopy, including enhanced imag9 quality and the ability to manipulate the image after the study is complete . --Martha Moon, DVM, MS, Diplomate ACVR, VA-MD Regional College of Veterinary Medicine, Blacksburg, VA.

PRODUCER/DISTRIBUTOR TO LIMIT ANIMAL SOURCE INSULIN LINE

Effective September 1, 1993, Eli Lilly and Company will discontinue production and distribution of its Ultralente lletin I (Extended Insulin Zinc Suspension, USP, beef-pork) insulin.

The absence of this insulin will affect the procedure used by the practicing veterinarian when treating diabetes mellitus in dogs and cats . Reported experiences by practicing and research veterinarians indicate that Humulin U (ultralente Human Insulin [rDNA origin] Extension Zinc Suspension) supplied by Eli Lilly and Company, Indianapolis, Indiana, and Ultralente (beef) supplied by Novo Nordisk Pharmaceutical, Inc., Princeton, NJ, are acceptable, available long-acting alternative insulins for the dog and cat. Contact your pharmacist for the appropriate insulin diluting fluid , if required . --As reported in Veterinary Medicine Extension Communications, Newsletter #395-V743, July 1993, Iowa State University, Ames, Iowa.

AND FURTHERMORE --

When negotiating, think of creative solutions for mutual gain.

Date

September 30

*October 1-2

*October 8-9

*November 5-6

November 11

*November 19-20

*December 10-11

*December 17-18

6

VIRGINIA-MARYLAND REGIONAL COLLEGE OF VETERINARY MEDICINE BLACKSBURG, VIRGINIA

CONTINUING EDUCATION OPPORTUNITIES FALL 1993

Sublect Location

Small Animal Medicine Update Charlottesville

Gastrointestinal Endoscopy Intermediate Course Blacksburg

Orthopedic Surgery Canine Hindlimb Blacksburg

Clinical Fish Medicine Blacksburg

Small Animal Behavior Problems Charlottesville

Practical Eye Surgery Blacksburg

Wound Management & Reconstructive Surgery Blacksburg

Small Animal Dentistry Blacksburg

*Limited enrollment course which features hands-on experience.

Contact Hours

4

10

10

10

6

10

10

10

Note: The Clinical Hematology short course scheduled for December 3-4 has been postponed until March 1994.

Note: Program brochures are mailed out six-eight weeks prior to the course date. No registrations accepted until course brochures go out. For further information, please contact: Kent Roberts, DVM, VMRCVM - Virginia Tech, Blacksburg, VA 24061-0442, (703) 231-7181.

BOVINE PRACTITIONERS FALL CONFERENCE

The annual conference for bovine practitioners is scheduled for October 28-29, 1993, at the Holiday Inn, Fracis Scott Key Mall, Route 85, Frederick, MD. Starting at noon on Thursday, October 28, with sessions on practice tips and dairy farm case studies, the conference continues on Friday with sessions on production management, cow comfort, environmental management, and trouble shooting silage based rations.

Registration is $100 for both days and $60 for one day (including meals) with half price for veterinary students and animal health technicians. For more information, please contact: Dr. Douglas Carmel, VMRCVM University of Maryland, College Park, MD 20742, (301) 935-6083.

SOUTHERN FEDERATION MEETING

The 76th annual convention of the Southern Veterinary Medical Federation, Inc. will be held at the Perdido Beach Resort, Orange Beach, Alabama, October 17-20, 1993. The program will include sessions on clinical pathology, radiology, oncology, behavior, marketing, and OSHA requirements. Also, speakers on dentistry, cardiology, endocrinology, and urology are part of the varied program. There is a separate program for technicians and support staff. For convention information, write SVMF, P.O. Box 1695, Cashiers, NC 28717.

7

MAILING LIST UPDATE

Dear Colleagues:

In our continuing efforts at maintaining a current and accurate mailing list for this newsletter, I request that you take a minute to update us on any changes in address, name, practice, etc.

If you no longer wish to receive the newsletter or know of a colleague who would like to be added to our mailing list, please fill out and return the form below at your earliest convenience.

We appreciate your interest in the College and the newsletter, and welcome your constructive comments.

Sincerely,

J/hrf-IVM ~be~M, Ed~or

New Address Old Address

Please discontinue mailings ___ _

It is a great help to us if you include Virginia Veterinary Notes when notifying people of an address change.

Please mail to: Dr. Kent Roberts

College of Veterinary Medicine Virginia Tech

Blacksburg, VA 24061 -0442

Virginia-Maryland Regional College of Veterinary Medicine Extension Staff:

Dr. J.M. Bowen- Extension Specialist - Equine Dr. C.T. Larsen - Extension Specialist - Avians Dr. K.C. Roberts - Extension Specialist - Companion Animals Dr. W. Dee Whittier - Extension Specialist - Cattle

K.C. Roberts, Editor Maura M. Wood, Production Manager of VIRGINIA VETERINARY NOTES

VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY

VIRGINIA COOPERATIVE EXTENSION BLACKSBURG, VIRGINIA 24061-0512

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