Comments on the Preservation of Antibiotics Act
The AVMA's “nonsupport of passage” of the Preservation of Antibiotics for Medical Treatment Act1 stands in stark contrast to the overwhelming consensus among hundreds of human health, sustainable agriculture, and environmental organizations, including the American Medical Association and American Public Health Association, who support an end to the routine use of medically important antimicrobials as feed additives.
Dr. Vogel's statement that “general overarching bans on classes of use are not appropriate” ignores the reality of extraordinarily slow FDA examination procedures and appeal processes. Witness the 2005 ban on enrofloxacin: according to the Associated Press, the FDA's Center for Veterinary Medicine first proposed to pull the drug from use in chickens and turkeys in 2000, but the manufacturer, Bayer, asked for a hearing,2 delaying crucial action for 5 years. In addition, prior withdrawals took six years for diethylstilbestrol and 20 years for nitrofurans, according to the organization Keep Antibiotics Working.3 Such bureaucratic delays are precisely what the bill intends to avoid, in light of the alarming potential risk to human health.
It is true, to quote a study by Dritz et al4 on use of antimicrobials in pig feed, that “the magnitude of the impact of agricultural antimicrobial use on development of antimicrobial resistance in human pathogens has not been conclusively established.” Such a conclusion was also reached in a two-year, comprehensive review of available medical and scientific evidence by experts spanning a variety of human, veterinary, and biological fields, all brought together by the Alliance for the Prudent Use of Antibiotics (APUA). Despite the finding, the APUA joins with most of the human medical community in concluding that “when data are scarce, regulators should invoke the precautionary principle, and regulatory procedures should be revised when more data becomes available.”5 It is also true that the ban would likely cause health risks to animals, but these could be mitigated through judicious use of antimicrobials, good husbandry practices, and other methods.
In judging the possible effects on the ban, we may turn to previous studies on the subject for hints. One such example is the World Health Organization's 2002 examination6 of the termination of antimicrobials for growth promotion in Denmark, which found that “from a precautionary point of view, Denmark's program of antimicrobial growth promoter termination appears to have achieved its desired public health goal,” which “was done without major consequences.” The practice “in other countries should be broadly similar to Denmark,” the WHO remarks, “but may vary in some respects depending on the health status of animals and prevailing animal husbandry conditions.” The AVMA's wait and see approach would effectively stall a potentially life-saving ban, and with such crucial health issues at stake, perhaps the AVMA should join most of the medical community in adopting the precautionary principle.
Shannon G. Swink, DVM
Knoxville, Tenn
- 1↑
Rezendes A. Europe bans antimicrobials, legislation proposed in U.S. J Am Vet Med Assoc 2006;228:496.
- 2↑
Schmid RE. FDA bans antibiotic from use on poultry. Associated Press 2005; Jul 28. Available at: www.ap.org/. Accessed Mar 29, 2006.
- 3↑
Keep antibiotics working. Frequently asked questions about agricultural use of antibiotics. Available at: www.keepantibioticsworking.org/new/resources_library.cfm?RefID=36471. Accessed Mar 29, 2006.
- 4↑
Dritz SS, Tokach MD, Goodband RD, et al. Effects of administration of antimicrobials in feed on growth rate and feed efficiency of pigs in multisite production systems. J Am Vet Med Assoc 2002;220:1690–1695.
- 6↑
Taylor D, Horzowski A, Mitema E, et al. Impacts of antimicrobial growth promoter termination in Denmark. Geneva: World Health Organization, 2002;8.
Dr. Vogel responds:
I'd like to clarify some misunderstandings regarding the AVMA's position on the Preservation of Antibiotics for Medical Treatment Act, starting with the misbelief that the AVMA has a “wait and see approach.” In fact, that is far from the truth.
In 1998, the AVMA began development of general and species-specific judicious use guidelines and an educational program to support implementation. Those materials and guidelines are continually reviewed, updated, and posted on the AVMA's Web site. In addition, the AVMA has consistently advocated for improved national surveillance of antimicrobial resistance in humans, animals, and foods. In fact, the AVMA funded a project to measure resistance in animal pathogens and provided funding to develop a Veterinary Antimicrobial Decision Support System.
The AVMA continues to advocate for improved risk analysis of antimicrobial resistance and has participated in an examination of potential means of collecting antimicrobial use data. Those efforts, combined with food safety initiatives, may have had some beneficial effects. For example, there has been a 51% decrease in the case rate of multidrug-resistant Salmonella human illness and a 65% decrease in the case rate of pentaresistant Salmonella ser Typhimurium human illness between the FoodNet base period of 1996 to 1998 and 2004.1,2
Dr. Swink mentions “the alarming potential risk to human health.” But what is the real risk? The JAVMA article mentions the FDA risk assessment on the use of virginiamycin in feed.3 The risk assessment addressed the risk of humans failing treatment with quinupristin and dalfopristin for Enterococcus faecium infections attributed to acquisition of resistance as a result of the ingestion of resistant strains in food. It is estimated that the average risk for the general US population ranges from 0.7 to 14 chances in 100 million in one year if 10% of the human infections are acquired through food. Another assessment evaluated the risks from all labeled uses of tylosin and tilmicosin in poultry, swine, and beef cattle.4 That assessment demonstrated that use in animals presents a very low risk for human treatment failure, with an approximate annual probability of less than 1 in 10 million Campylobacter-derived and approximately 1 in 3 billion E faecium–derived risks for treatment failure attributed to a food source. Phillips5 concluded that there are no reasons to consider that the use of zinc bacitracin for growth promotion poses any current or foreseeable risk to human health.
Because of space limitations, I am unable to discuss critical reviews of Denmark's termination of antimicrobial growth promoters, except to say that many have criticized the conclusions of the World Health Organization Review Panel's evaluation that it “achieved its desired public health goal” and “was done without major consequences.” If the goal was to decrease the level of resistance in humans, however, the achievement of the goal is not clear. There are mixed results.6
The food safety and the antimicrobial resistance information currently available and pertinent to the United States does not indicate that precipitous action is needed, especially when considering the potential unintended consequences on animal and human health.
Lyle P. Vogel, DVM, MPH, DACVPM
Director, Scientific Activities Division
American Veterinary Medical Association Schaumburg, Ill
- 1
CDC. Preliminary FoodNet data on the incidence of infection with pathogens transmitted commonly through food—10 Sites, United States, 2004. MMWR Morb Mortal Wkly Rep 2005;54:352–356.
- 2
CDC. Human isolates final report, 2002. National antimicrobial resistance monitoring system: enteric bacteria. 2005. Available at: www.cdc.gov/narms/reports.htm. Accessed Mar 23, 2006.
- 3↑
FDA Center for Veterinary Medicine. Risk assessment of streptogramin resistance in Enterococcus faecium attributable to the use of streptogramins in animals—virginiamycin risk assessment, draft for comment. 2004. Available at: www.fda.gov/cvm/Documents/SREF_RA_FinalDraft.pdf. Accessed Mar 23, 2006.
- 4↑
Hurd HS, Doores S, Hayes D, et al. Public health consequences of macrolide use in food animals: a deterministic risk assessment. J Food Prot 2004;67:980–982.
- 5↑
Phillips I. The use of bacitricin as a growth promoter in animals produces no risk to human health. J Antimicrob Chemother 1999;44:725–728.
- 6↑
Statens Serum Institut, Danish Veterinary and Food Administration, Danish Medicines Agency, Danish Institute for Food and Veterinary Research. DANMAP 2004—use of antimicrobial agents and occurrence of antimicrobial resistance in bacteria from food animals, foods and humans in Denmark. 2005. Available at: www.dfvf.dk/Files/Filer/Zoonosecentret/Publikationer/danmap/Danmap_2004.pdf. Accessed Mar 23, 2006.
Sees dry diet as culprit in lower urinary tract disease
The article1 that dealt with risk factors in lower urinary tract disease in indoor-housed cats was interesting in that it was typical of all such studies in virtually every veterinary publication I have read. While a great deal of the article was devoted to examining cats' lifestyles, they gave just one brief mention to the major cause of signs of lower urinary tract disease. As a practitioner with over 40 years of experience in pet practice, I can say with certainty, and no further research, that dry diet is the major culprit. Cats are obligate carnivores; thus, a diet heavy in grains is certain to rock their biological boats. One clinical sign that the authors neglected to study, and which I have used for years, was sensitivity of the cats to having their kidneys palpated. Cats on largely dry diets are moderately to severely sensitive to palpation of their kidneys, whereas cats fed canned or fresh diets are not. The former have referred lower back pain all the time, which may account for many of the other signs noticed by owners. I have even had owners tell me that their cat fed a dry diet did not like to be petted anymore, and it turned out to be because of their dry diet.
Let's not take a very manageable problem and turn it into something mysterious. Just feed our cats what nature intended, and the problem goes away.
Bud Stuart, DVM
Santa Barbara, Calif
Buffington CAT, Westropp JL, Chew DJ, et al. Risk factors associated with clinical signs of lower urinary tract disease in indoor-housed cats. J Am Vet Med Assoc 2006;228:722–725.
The author responds:
My coauthors and I thank Dr. Stuart for his interest in our work. We gave only brief mention to diet because we were unable to find a difference in this parameter between cases and controls. This result surprised us as well, as we discussed in the manuscript. We urge Dr. Stuart to publish his findings, since they may illuminate the source of the differences in our experiences. And while we agree that cats are metabolic carnivores, there are far less data to suggest that this somehow prevents them from thriving on diets containing grains, as tens of millions of healthy cats in the United States do every day.1 The role of the diet may take on additional importance in cats with idiopathic cystitis, however, because the apparently sensitized emotional motor system in (at least some of) these cat may result in unusual responsiveness to their surroundings.2,3
When considering the role of diet in indoor-housed cats with idiopathic cystitis, many factors other than the ingredients may be relevant. For example, the taste, mouth feel, and owner-related interactions surrounding feeding also may be pertinent. If the diet is changed to one with a taste or mouth feel that the cat prefers, the number of potentially stressful stimuli in the cat's environment may be reduced, leading to a reduction in lower urinary tract signs. Provision of a canned food could do either or both of these. It also could increase interactions with the owner related to the increased time required to open and serve canned food. Since indoor-housed cats are utterly dependent on their owners for a food source, such changes might change the cat's perception of its environment in a beneficial way. This is not to say that ingredients in dry foods cannot influence the course of the syndrome. Idiopathic cystitis appears to be a chronic neuropathic visceral pain syndrome.2 Since soy contains phytoestrogens, which can be analgesic at some concentrations,4 dry foods might affect signs of the disorder by this or other as yet unrecognized mechanisms. The relevance of the multitude of dietary factors can only be determined by carefully controlled studies that build on practice experiences.
We try to consider all these issues as part of multimodal environmental modification (MEMO) treatment for cats with idiopathic cystitis.5,6 Additionally, we only change the diet when the owner and the cat seem positively disposed to the change. We can determine the owner's willingness by asking them; we “ask” the cat by providing the new diet in a separate container next to the usual diet, rather than removing the familiar diet, or mixing it with the novel (to the cat) food. If both do not support the change, it may serve as an additional environmental stressor.
We also were intrigued by Dr. Stuart's assertion that cats fed dry foods are more sensitive to palpation of the kidneys than are cats fed canned or fresh diets. To our knowledge, this has not heretofore been reported in the veterinary literature, and we encourage him to publish his findings and any proposed mechanism through which such a difference might occur. Idiopathic cystitis is so named because the etiopathogenesis is not yet resolved, so novel ideas and mechanisms are surely welcome.
C. A. Tony Buffington, DVM, PhD, DACVN
Columbus, Ohio
- 1↑
Morris JG. Idiosyncratic nutrient requirements of cats appear to be dietinduced evolutionary adaptations. Nutr Res Rev 2002;15:153–168.
- 2↑
Buffington CAT. Comorbidity of interstitial cystitis with other unexplained clinical conditions. J Urol 2004;172:1242–1248.
- 3
Westropp JL, Kass PH, Buffington CAT. Evaluation of the effects of stress in cats with idiopathic cystitis. Am J Vet Res 2006;67:731–736.
- 4↑
Shir Y, Campbell JN, Raja SN, et al. The correlation between dietary soy phytoestrogens and neuropathic pain behavior in rats after partial denervation. Anesth Analg 2002;94:421–426.
- 5
Westropp JL, Buffington CAT. Feline idiopathic cystitis: current understanding of pathophysiology and management. Vet Clin North Am Small Anim Pract 2004;34:1043–1055.
- 6
Buffington CAT, Westropp JL, Chew DJ, et al. Clinical evaluation of multimodal environmental modification in the management of cats with lower urinary tract signs. J Feline Med Surg 2006;in press.
Requests information on outcome in feline case
In response to Drs. Wegner and Pablo's article1 on altered respiratory function during anesthesia of a cat for removal of a lung lobe abscess, which was a meticulous and well-documented article, I have a question. How did the patient do?
Rick Wulff, DVM
Archer, Fla
The authors respond:
We appreciate your interest in the well-being of the cat of our report that had a challenging intraoperative airway compromise and subsequent resolution.1 Once extubated and stable within the oxygen cage in the intensive care unit, we turned care of the cat over to the Small Animal Internal Medicine Service at the University of Florida Veterinary Medical Center. Careful postoperative monitoring by the senior student involved with the case proved critical as the cat suffered slow but insidious postoperative intrathoracic hemorrhage. The cat's condition stabilized following the transfusion. With continued antimicrobial, analgesic, and fluid therapy, along with careful nursing care, it had dramatic daily improvement thereafter. The cat was moved out of the oxygen cage three days after surgery and was able to maintain an SpO2 greater than 95% on room air. Five days after surgery, the thoracic tube was removed. The cat was discharged the following day with antimicrobial treatment continued at home an additional 4 to 6 weeks. On two subsequent recheck examinations, the first 14 days after surgery and the second 30 days after surgery, the cat continued to show dramatic improvement clinically and in radiographic resolution of the thoracic abnormalities. As anesthetists, we often do not know the long-term disposition of patients briefly in our care, so it is pleasure to report this positive outcome.
Kirsten Wegner, DVM La Jolla, Calif
Luisito Pablo, DVM, MS, DACVA, Gainesville, Fla
Offers suggestions for embolization of patent ductus arteriosis
The emerging use of medical devices within our profession is a testament to the advancements we are making on many fronts. I commend the authors of the article1 on coil placement for emobilization of patent ductus arteriosis (PDA) for writing their report in a straightforward manner that allows the typical veterinary practitioner to follow along and understand this unusual case. I would, however, like to touch on a few things presented in this paper for clarification and informational purposes.
The authors did not mention use of heparin as an anticoagulant. Heparin is a common anticoagulant used for these types of cases (with intra-arterial manipulations) to ensure the activated clotting time is prolonged enough to inhibit clot formation. At therapeutic doses, heparin is well tolerated in most dogs.
As far as the potential disadvantages or complications of this type of procedure, the authors are correct in stating that the time to perform this intervention can vary. In experienced hands, this procedure (once vascular access is gained) should cut the time to occlusion considerably (potentially by 70%) over surgery. As more veterinarians gain experience with these highly specialized procedures, the time it takes to perform this type of intervention should become minimal. As a result, anesthesia and radiation exposure time (which is minimal) will be reduced.
Complications such as severe hemorrhage can be overcome by performing a vascular cutdown and ligating the vessel or closing the arteriotomy. The Seldinger2 technique often leads to hematoma formation (especially with introducer sheaths larger than 5F) because of the lack of substantive tissue superficial to the femoral artery in dogs. Lastly, in most cases, hemolysis can be overcome with proper selection and placement of the occlusive device, which should improve with newly available devices and operator experience. Hemolysis described by Van Israel et al3 was caused by residual shunting past the four coils that were placed, indicating the PDA was still minimally patent. A single, correctly sized, well-positioned occluder should mitigate this risk substantially.
One way to ensure a proper fit is use of a sizing pigtail catheter. There is inherent error with the methods of measurement described in the paper by Szatmári and Stokhof1 because the reference catheter lies below the dog, effectively out of the plane of the PDA. For this reason, proper fit is difficult to achieve because of inaccurate sizing. Use of biplane fluoroscopy might improve outcomes but is still inferior to use of intravascular sizing modalities. Transesophageal echocardiography (TEE) is a useful adjunct for proper placement but also lacks the ability to provide precise measurements. An even better choice would be intracardiac echocardiography (ICE). With this modality, the operator can position the catheter within the aorta or inferior vena cava for superior views of the PDA. Unfortunately, TEE and ICE have limited use in our profession because of their cost. In addition, use of ICE requires added expertise not typically encountered in most specialty practices or university settings. It would be interesting to know whether use of ICE in the animals described would have improved placement of the coils.
Jeff S. White, DVM
Shawnee, Kan
- 1↑
Szatmári V, Stokhof AA. Use of simultaneous fluoroscopic and echocardiographic guidance during transarterial coil placement for embolization of patent ductus arteriosus in dogs. J Am Vet Med Assoc 2006;228:881–884.
- 2↑
Seldinger SI. Catheter replacement of the needle in percutaneous arteriography: a new technique. Acta Radiol 1953;39:368–376.
- 3↑
Van Israel N, French AT, Wotton PR, et al. Hemolysis associated with patent ductus arteriosus coil embolization in a dog. J Vet Intern Med 2001;15:153–156.
The author responds:
Thank you for taking your time and, after having thoroughly read our paper, sharing your thoughts with the profession. I am glad to see that most of your comments support our opinion. Below, I am going to address only the points where we disagree with you.
We did not mention the use of heparin in our paper because we do not give heparin to our patients. We have never experienced any complications related to a possible thrombus or embolus formation, and I am not aware of any publication that documents such an event during or after a minimally invasive closure of a canine ductus. Recently published papers1,2 describing the technique of transarterial coil placement in dogs do not mention the use of anticoagulants. Moreover, I know two respected veterinary cardiology centers (one European and one American) that do not heparinize their patients.a In human medicine, “heparin is recommended for patients in whom a prolonged (> 20 minutes arterial time) catheterization procedure is anticipated or in whom prior clinical indications for use of heparin exist (eg, thrombotic tendency, known severe peripheral vascular disease, embolic phenomenon on previous study). In most medical centers, additional heparin (beyond that included in heparinized flush solutions) is omitted from routine left-sided heart catheterization when the procedure is performed in a timely manner.”3
There are several possible methods to measure the ductal diameter. We use a combination of preoperative transthoracic echocardiography and angiocardiography. So do our human counterparts: “Whereas the measurement of many structures such as atrial septal defects (ASDs), valve annulus and stenosis, ventricular dimensions, aortic and patent arterial duct (PDA) dimensions are increasingly the domain of echocardiography, measurements from angiocardiography remains important.”4 You are right that a ruler placed under the patient can cause inaccuracies in determining the ductal diameter since it is out of the plane of the ductus. For adjustments, a correction factor is used. However, even if we did not use a correction factor, the inaccuracy we made would be clinically irrelevant. When the distance between the fluoroscopic screen and the Xray tube is 114 cm and the ruler is placed on the radiographic table (14 cm above the fluoroscopic screen), a 5.0-mm ductus located 10 cm above the ruler would be measured to have a diameter of 4.5 mm. Using a sizing pigtail catheter is an excellent idea; however, the injected contrast material may obscure its markings. Recently, we have been introduced to the use of 2.5and 5.0-mm diameter metal spheres secured in an esophageal tube placed into the cranial mediastinal segment of the esophagus.5 In human medicine, the following is recommended: “If one wants a true dimension, rather than just a comparative size between two objects on the same cine frame, then the measurement requires correction for magnification by comparison of the measured dimension with a known reference. Thus, various techniques have been developed to estimate a correction factor for magnification using either the injection catheter, grids, spheres of known size, or isocentric techniques.”4
Viktor Szatmári, DVM, PhD
Utrecht, The Netherlands
- 1
Gordon SG, Miller MW. Transarterial coil embolization for canine patent ductus arteriosus occlusion. Clin Tech Small Anim Pract 2005;20:164–172.
- 2
Campbell FE, Thomas WP, Miller SJ, et al. Immediate and late outcomes of transarterial coil occlusion of patent ductus arteriosus in dogs. J Vet Intern Med 2006;20:83–96.
- 3↑
Bitar S, Kern MJ, Bleyer F. Arterial and venous access. In: Kern MJ, ed. The cardiac catheterization handbook. 4th ed. Philadelphia: Mosby, 2003; 52–125.
- 4↑
Freedom RM, Mawson JB, Yoo S-J, et al. Physical principles of image formation and projections in angiocardiography. In: Freedom RM, Mawson JB, Yoo S-J, et al. eds. Congenital heart disease. Textbook of angiocardiography. Armonk, NY: Futura Publishing Co, 1997; 39–94.
- 5↑
Martin M. PDA occlusion: practical experiences with coils, occluders etc, in Proceedings. 14th Eur Coll Vet Intern Med Comp Anim Cong 2004; 33–34.
Schneider M, Medical and Forensic Veterinary Clinic, Department of Small Animal Internal Medicine, Justus-Liebig University of Giessen, Giessen, Germany and Campbell FE, Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, Calif: Personal communication, 2006.
Reports positive results from sterilization of cats in Connecticut
During the four years that the debate about feral and free-roaming cats has raged on your pages, Connecticut's TEAM Mobile Feline Unit spayed or neutered and vaccinated more than 50,000 cats.
The TEAM Mobile Feline Unit takes a comprehensive approach to solving this human-made problem by making spay and neuter services accessible to every Connecticut resident and every cat. We have the support of thousands of individuals, organizations, and municipalities that believe, as we do, that the goal of ending feline overpopulation is being met.
Since 1997, over 90,000 domestic, feral, and free-roaming cats have been safely sterilized and vaccinated by TEAM. These cats are brought to us by people from all walks of life who have embraced the concept of responsible pet ownership as well as trap, neuter, and return.
This debate will go on in perpetuity unless the spillover from the domestic population is addressed. To do this, we must look at the forest instead of the trees and make spay and neuter services accessible and affordable to the mainstream, encouraging compliance before their pets reproduce.
An increasing number of Connecticut veterinarians are adopting this philosophy, making them part of the solution. As a result, more people are introduced to, and participate in, veterinary medicine. This is not only good for the animals but for the profession too.
In Connecticut, the incidence of rabies is down, free kitten signs are a rarity, and what started out as a cat project has turned into an environmental success story.
John A. Caltabiano, DVM
President Tait's Every Animal Matters Westbrook, Conn
Appreciates new abbreviation key in JAVMA
One of my favorite phrases in scientific discussion is the “elegant solution.” The new policy of providing an abbreviation key on the first page of scientific articles in JAMVA is elegant indeed. A simple answer to a vexing problem.
Kenneth M. Kornheiser, DVM
Plainwell, Mich