., VIRGINIA VE I ERINARY NOTES

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1 Virginia Cooperative Extension Service w I., VIRGINIA VE I ERINARY NOTES ~, 4i VIRGINIA-MARYLAND REGIONAL COLLEGE OF VETERINARY MEDICINE 6" \ \~:S November - December 1993 b~ Fis 8 SUL! y No.66 WHAT'S INSIDE! ANESTHETIC INDUCTION TECHNIQUES IN THE DOG: ALTERNATIVE TO BIOTAL Page 2 ELIZABETHAN COLLARS REQUIRE AWARENESS Page 3 WOULD YOU BELIEVE? Page 4 FALSE POSITIVE LYME DISEASE TITERS ASSOCIATED WITH PERIODONTAL DISEASE IN DOGS :-. Page 4 A SAFER, MORE EFFICIENT DRUG FOR NAVICULAR DISEASE... Page 5 FELINE HEARTWORM DISEASE Page 5 NEW SEROLOGY FOR CAT SCRATCH DISEASE Page 6 FIELD MANAGEMENT OF SIMPLE INTESTINAL OBSTRUCTION IN HORSES Page 6 CONTINUING EDUCATION OPPORTUNITIES Page 7 CONTINUING EDUCATION SERIES Page 7 CENTENNIAL CELEBRATION Page 7 THOUGHT FOR THE MONTH Talk is cheap - until you hire a lawyer. Kent C. Roberts, DVM Extension Veterinarian Virginia JI) Tech INIA POLYTEOINIC INSlTTUTB AND STATE UNIVERSITY Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, religion, sex, age, national origin, handicap, or political affiliation. An equal opportunity/affirmative action 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 STATE UNIVERSITY

2 2 ANESTHETIC INDUCTION TECHNIQUES IN THE DOG: ALTERNATIVE TO BIOTAL Based on the number of phone calls we have received about Bio-TaKID availability over the past two months, we decided to summarize some of the anesthetic induction alternatives that we have used successfully. Hopefully, by late 1993 the supply of thiopental and the availability of Bio-TaKID will increase to again meet the needs of the veterinarian. Until then, here are some alternatives you might find useful (and in some instances preferable): A. Other Barbiturates {Thlopental and Methohexltal) Thiopental (PentothaKID, Sanofi Animal Health Inc.) or methohexital (Brevital ) could be used. Even though thiamylal is slightly more potent than thiopental, the technique is similar to that used for thiamylal. The calculated dose of IV anesthetic induction with thiopental is approximately 5-10 mg/lb, and we suggest using the lower end of this range if the dog is not premedicated. Methohexital has been recommended for use in Sighthound breeds, and the induction dose of methohexital is similar to that of thiopental. As used for induction, either thiopental or methohexital should be given "to effect," and, hence, ranges given above are only guidelines of the calculated dosage. B. Dissociative Anesthetics Telazol (1-2 mg/lb IV) can be used for tracheal intubation. Alternatively, a combination of diazepam ( mg/lb) and ketamine (2-3 mg/lb) can be used for induction in dogs. More typically, the two drugs are mixed in the same syringe (0.5 ml of each drug per 20 lbs) just prior to IV injection. Premedication with a tranquilizer or neuroleptanalgesic combination (Table 1) will often make induction (and recovery) smoother. Tachycardia, tighter jaw tone, and intact palpebral reflex are distinguishing features of this technique from barbiturate induction. C. Propofol Propofol (Diprivan, Stuart Pharmaceuticals, Wilmington, Delaware) is an approved human anesthetic agent in the US, but it is a relatively new (and yet not approved) anesthetic in veterinary medicine. Propofol, which is supplied in 20 ml ampules (1 Orr g/ml), is a hypnotic (like the barbiturates) and may only be given by IV injection. Since propofol contains no preservatives, once opened, the contents of the ampule must be used or discarded within 24 hours. Although propofol is expensive compared to thiamylal, we find it very useful for either short term outpatient procedures or for anesthetic induction in Sighthounds owing to its short metabolic half-life. The usual IV induction dose is 4-6 mg/lb without premedication and 1-3 mg/lb ir. premedical dogs. D. Mask Induction after Premedication Tranquilizers (phenothiazines, a. 2 agonists and benzodiazepines) given alone or (better yet) in combination with opioids, will produce sedation which decreases the anxiety and stress during mask induction. Depending on the specific premedications selected, the use of atropine or glycopyrrolate should be considered. After waiting minutes for the premedication effects, we use either halothane or isoflurane at a 5% vaporizer setting and a 3-4 Umin oxygen flow to induce anesthesia in dogs via mask. Within 3-5 minutes, the dog will be ready for tracheal intubation. Do be aware that prolonged recovery may be associated with heavy premedication and that mask induction techniques can potentially pollute your work environment.

3 3 We hope that the alteratives offered here provide some options to veterinary practitioners during the interim period until thiobarbiturates again become more readily available. The selection of any of these options must be based on the physical status of the patient and expertise of the clinician as well as availability of drugs and equipment. You are welcome to telephone any of us ( ) for further discussion or explanation of these combinations. -Chuck McGrath, DVM, DACVA; Jeff Ko, DVM, MS; John Jacobson, DVM, MS; Jim Kenny, BS; Veterinary Teaching Hospital, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA. TABLE 1 IM DOSAGES OF TRANQUILIZERS AND OPIOIDS Tranquilizers Acepromazine: Morphine: O mg/lb mg/lb (maximum 3 mg tota~ Diazepam: Butorphanol: mg/lb mg/lb Opioids Midazolam: Oxymorphone: mg/lb O O mg/lb (maximum 4 mg tota~ Xylazine: 0.25 mg/lb lnnovar-vet : 1 ml per 15 to 20 lbs ELIZABETHAN COLLARS REQUIRE AWARENESS Elizabethan collars render dogs helpless in certain situations when they need to use their front feet and legs. Two examples highlight the need to be aware of dangers when sending animals home from surgery with Elizabethan style collars: 1. A six-year-old collie cross was sent home fitted with an Elizabethan collar to prevent him interfering with a corneal ulcer. After four uneventful days he was left on his own for a few hours in the owner's house. The owner returned to find the dog dead with a plastic bag over his head -- the dog had tried to take something out of a wastepaper bin that was lined with a plastic bag, the bag had covered his head, and the collar prevented its removal. 2. The second case concerned a small border collie fitted with an Elizabethan collar which was left alone in the owner's house for no more than an hour. Upon the owner's return they found the dog dead with the inner plastic liner from a box of cornflakes over its nose -- again the dog had been unable to remove it because of the collar. The lesson is to remind pet owners that their animals are like young children -- inquisitive and mischievous -- and advise them when collecting their animals fitted with such collars of the dangers described above. --Abstracted from S. Wilson, Vet. Record 132 (1993) p. 664, as reported In Veterinary Medical Extension Communications Newsletter #396-V7444, August 1993, Iowa State University, Ames, IA.

4 4 WOULD YOU BELIEVE? are: Recent figures on agricultural production read more like something from Robert Ripley. Here they Only 2.5% of the US population is involved in food production compared to 75% of the populations of Senegal and Mali. A farmer in developing countries produces an average 4,400 pounds of food, one in Russia or the European countries produces 33,000 pounds and an average American farmer produces 375,000 lbs. One US farmer could feed 17 people in 1950, 48 people in 1970, 79 people in 1980, and 129 people in Planning a trip to Japan? Recent city meal prices include a breakfast of bacon, eggs, and coffee for $28 and a glass of milk for $ From an address by Dr. Milton B. Wise, Vice President, Clemson University, 7/15/93. FALSE POSITIVE LYME DISEASE TITERS ASSOCIATED WITH PERIODONTAL DISEASE IN DOGS As demonstrated in Lyme disease testing from human patients, the reliance on antibody detection in the diagnosis of Lyme borreliosis is questionable. False positive reactions have been found in patients with autoimmune disorders, rheumatoid arthritis and certain viral, rickettsial and other bacterial diseases; the latter includes periodontal disease. Animals with clinically detectable periodontal disease were selected from a group of dogs presented for dental prophylaxis. Sera from these dogs were collected and tested for the presence of antibodies against B burgdorferi using an indirect fluorescent antibody (IFA) test and a commercial ELISA. The test results of the dogs with dental disease were compared with a selected group (similar age and breed) of, orally and otherwise, healthy dogs from which sera were submitted during routine spring testing for heartworm disease. Only one of the 20 healthy dogs, which also had no detectable heartworm infection, showed any evidence of B burgdorferi antibodies. Half of the 20 dogs with detectable periodontal disease had detectable serum antibodies in the IFA test; four in the ELISA. The titer of six dog sera dropped at least one dilution in the IFA test after cross adsorption. Sera of the ELISA-positive dogs became negative after adsorption with T phagedensis sorbent. In this preliminary trial no effort was made to isolate Treponema species from the periodontal tissue of these dogs. Neither was any effort made to test these dogs (except the two positive-controls) for Borrelia species infection by PCR or culture. However, all negative control dogs came from an urban setting in a region where ticks and Lyme disease are rare. It is of interest to note that at least half of the dogs with periodontal disease showed a detectable anti-8 burgdorferi titer. A number of Treponema species have been implicated in periodontal disease in humans and in dogs; the fact that not all sera demonstrated a drop in titer after cross adsorption may have been because the oral infection was caused by species which were antigenically not closely related to T phagedensis. It seems justified, however, to conclude that periodontal disease may cause false positive results in the antibody tests for Lyme disease. --Abstracted from T. W. Schlllhorn et al., Vet. Rec. 132 (1993), p. 512, as reponed In Veterinary Medical Extension Communications Newsletter #396-V7444, August 1993, Iowa State University, Ames, IA.

5 5 A SAFER, MORE EFFICIENT DRUG FOR NAVICULAR DISEASE Researchers believe that one contributing cause for the chronic deterioration seen in equine navicular disease is a breakdown in the blood supply to the navicular bone. Several drugs have been used to promote blood supply to the navicular bone, navicular bursa, and adjacent flexortendon, but results have not been consistently good. Equine specialists at Tufts University recently studied a new drug, propentofylline (Karsivan, Hoechst-Roussel Agri-Vet Company), because its chemical properties combine to increase circulatory flow. According to Dr. C. A. Kirker-Head, studies in other species showed that propentofylline could inhibit the formation of thrombi (clots); cause blood vessels to dilate; and perhaps most important, inhibit platelet aggregation, which can lead to blood clot formation in horses. When platelet aggregation after administration of the drug to 1 O horses was measured, it was found that the level of aggregation had in fact dropped. The horses' physical response to the drug was then tested by a technique called force plate analysis, which measures all four legs to determine changes in weight-bearing ability. This objective test showed a significant improvement in soundness. The Tufts researchers found that the drug did not completely cure the lameness caused by navicular disease. However, within the limited time frame of their investigation (three consecutive 30-day periods) all horses benefited from the drug and no horse showed any adverse effects. An incidental finding of the study and one that may help in future investigations is that the platelet measurements may themselves be of value in identifying horses that may be predisposed to navicular disease. The simple tests for platelets may then be used to give warrant for a preventive program and perhaps even for a more accurate diagnosis. As the researchers noted, diagnosing the disease is not easy because early stages of the disease may not be seen in X-ray studies and, equally frustrating, X-rays may show signs of the disease even though the horse itself does not show signs of lameness. --Reprinted with permission, Cornell Animal Health Newsletter. Vol.11, No. 6, August 1993, 52 Park Place, New York, NY FELINE HEARTWORM DISEASE Cats are susceptible hosts for Dirofilaria immitis but differ from dogs in the way they are affected by heartworm disease. the incidence of HWD is much lower in cats than dogs most feline infections are occult most affected cats are asymptomatic intermittent chronic vomiting and cough may occur aberrancy, such as seizures, and sudden death are seen affected cats tend to have fewer adult worms than dogs adult worms don't usually live as long in cats The best diagnostic information in affected cats is most often supplied via thoracic radiographs. Enlarged caudal lobar arteries and typical interstitial alveolar patterns can point to a diagnosis. Microfilaria tests are almost always negative. Treatment should probably not include the intravenous injection of an adulticide as there is the potential for an acute toxic reaction and death in approximately 30% of treated cats. Thromboembolism may also occur. Cage rest and corticosteroid therapy seem to give the best results. Aspirin is not useful or indicated. --Dr. Thomas Hribernik, Clinical Medicine, LSU, Baton Rouge, LA, presented at DC Academy of Veterinary Medicine, March 1993, as reported by Kent Roberts, DVM.

6 6 NEW SEROLOGY FOR CAT SCRATCH DISEASE The Centers for Disease Control and Prevention (CDC) has recently developed a serologic test to aid in the diagnosis of cat scratch disease (CSD) and bacillary angiomatosis (BA). This test is available free of charge to physicians and state health departments. The indirect fluorescent antibody method is used to detect antibodies to various species of the genus Rochalimaea. Several lines of evidence suggest that members of the genus Rochalimaea are associated with CSD. In an initial series of patients with clinical CSD, 88% had elevated antibody titers to Rochalimaea, compared to 3% of health controls. Antibody response to Afipia felis, a distinctly different agent previously proposed as a possible etiology agent for CSD, did not correlate with clinical disease diagnosis. Rochalimaea ribosomal RNA gene sequences have been amplified and sequenced from CSD skin test antigen. R. henselae has been isolated from lymph node biopsies of two patients with clinical CSD, and from the blood of several cats. Cats associated with human CSD cases had a higher prevalence of Rocha/imaea-specific antibodies (81%) than did control cats (46%). BA is also associated with cat ownership. Polymerase chain reaction results and serologic data suggest that patients with BA may be infected with Rochalimaea. In addition, R. henselae has been isolated from an HIV-positive patient with an undiagnosed febrile illness. A complete understanding of the spectrum and role of Rochalimaea in causing human disease is still in the process of evolution. This is why CDC is interested in helping diagnose Rocha/imaea-associated disease. Although only the serologic test is available for diagnostic purposes, CDC is also interested in collecting aspirates and biopsy specimens from lymph nodes, skin lesions, solid organ or bone marrow tissues to develop other detection and identification methods. Interested physicians should contact the Ohio Department of Health Laboratory at for copies of a CDC specimen submission form and information on shipping. Additional questions regarding diagnosis and/or agent isolation can be directed to Viral and Rickettsial Zoonoses Branch, National Centers for Infectious Diseases. CDC, Veterinary News, Pennsylvania State University Cooperative Extension, July 1993, as reported In Animal Health Beat, Nevada Cooperative Extension, University of Nevada, Reno, Vol. 9, No. 8, September FIELD MANAGEMENT OF SIMPLE INTESTINAL OBSTRUCTION IN HORSES Probably the most significant advancement made in field management of equine colic is the past decade has been the willingness of practitioners to administer a large volume of intravenous fluids. Fluid therapy not only provides a cure for most cases of simple intestinal obstruction in horses, it also benefits horses requiring surgery. Fourteen-gauge, three- to five-inch over-the-needle catheters are readily available and can be rapidly inserted into the jugular vein after aseptic preparation of the overlying skin. For convenience, 30-inch extension tubing can then be attached to the catheter hub and the catheter is secured in place with tape, sutures, or cyanoacrylate glue (which is the quickest and easiest method). Five-liter bags of balanced polyionic fluids are also commercially available and, when hooked to large-bore administration sets, can be hung with tack hooks or rope in a stable or wash stall. --Veterinary Notes II, Extension Service, North Dakota State University, Vol. 2, No. 8, August 1993, as reported In Animal Health Beat, Nevada Cooperative Extension, University of Nevada, Reno, Vol. 9, No. 8, September 1993.

7 7 CONTINUING EDUCATION OPPORTUNITIES Date Sublect Location Contact Hours *November 5-6 Clinical Fish Medicine Blacksburg 10 November 11 Small Animal Behavior Problems Charlottesville 6 *November Practical Eye Surgery - COURSE FULL Blacksburg 10 *December Wound Management & Reconstructive Surgery Blacksburg 10 *December Small Animal Dentistry Blacksburg 10 *Limited enrollment course which features hands-on experience. 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 (703) CONTINUING EDUCATION SERIES The College of Veterinary Medicine offers advanced veterinary CE for practitioners who have a special commitment to competence and patient care. The Series programs meet in Blacksburg once each month for hands-on instruction in small groups with faculty specialists. The Clin Path Series with Bernie Feldman, DVM, PhD February - June 1994 The Head & Neck Surgery/Dentistry Series with Mark Smith, VMD March - September 1994 The Soft Tissue Surgery Series with Ors. Martin, Johnston, Waldron August - December 1994 Interested veterinarians should contact Kent Roberts, DVM, VMRCVM - Virginia Tech CENTENNIAL CELEBRATION The Virginia Veterinary Medical Association will celebrate 100 years of state association history and growth at its annual meeting in Williamsburg, February 24-27, For more information, please contact the VVMA, (800)

8 8 Virginia-Maryland Regional College of Veterinary Medicine Extension Staff: Dr. J.M. Bowen Dr. C.T. Larsen Dr. K.C. Roberts Dr. W. Dee Whittier - Extension Specialist - Equine - Extension Specialist - Avians - Extension Specialist - Companion Animals - 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 Nonprofit Org. U. S. Postage PAID Blacksburg. VA 2406( Permit #28