2016 Zoetis Clinical Dermatology: Lessons Learned and Prospective Therapies Symposium Proceedings

2016 Zoetis Clinical Dermatology: Lessons Learned and Prospective Therapies Symposium Proceedings

The following are the speaker responses to questions from the audience during the Symposium sponsored by Zoetis held Sunday, January 17, 2016 at NAVC in Orlando, FL.

The opinions expressed in these answers are those of the speakers and do not necessarily reflect the official label recommendations and point of view of the company or companies that manufacture and/or market any of the pharmaceutical agents, products, or services mentioned.

Session 1: Responsible Use of Antimicrobials in the Face of Resistance

Catherine A. Outerbridge, DVM, MSc, DACVIM (SAIM), DACVD
University of California, Davis, CA

George Zhanel, PhD, FCCP
University of Manitoba, Winnipeg, Canada

  1. What do you tell the nervous client whose dog cultured methicillin-resistant bacteria in ears or skin?

    Dr. Outerbridge: I tell them that proper hand washing is always important after handling your dog, not just for staph bacteria. I let owners know that the species of staph that infect dogs’ ears or skin does not readily cause infections in people. Methicillin-resistant staph is no more able to cause disease than non-methicillin resistant staph. Dr. Scott Weese has a nice blog on the Worms & Germs website:

    http://www.wormsandgermsblog.com/2010/03/articles/diseases/mrsamrsp/my-dog-has-mrsp-should-i-be-concerned/

  1. How do you culture the scaly, nasty skin of Sassy, the dog in the case you presented?

    Dr. Outerbridge: We cultured the advancing edge of collarette lesions.

  1. When you mention pets that don’t respond to antibiotic therapy, do you only do one round and if they don’t respond to that round consider them non-responders?

    Dr. Outerbridge: If an appropriate tier 1 antibiotic was empirically chosen and administered correctly (appropriate dose, duration, no issues with administration) and the dog does not improve after 3 weeks I would consider getting a culture. If there was some issue with administration (eg, owners stopped because it caused vomiting) then I would select another 1st tier antibiotic. If I know a dog has received an appropriate antibiotic at the appropriate dose for 3 weeks with no change I would get a culture or rethink diagnosis and consider further diagnostics if not already done, including possible skin biopsy.

  1. In humans, how much topical versus systemic treatment is being done for skin infections?

    Dr. Zhanel: It’s tough to quantitate topical use as the vast majority of topical agents are OTC. We recommend use of gramicidin, bacitracin, polymyxin topical products for minor skin soft tissue infections (SSTI); these are all OTC. We do not recommend typical aminoglycosides such as gentamicin. For more severe SSTI we recommend oral therapy (eg, oral cephalexin). When methicillin-resistant Staphylococcus aureus (MRSA) is of concern we recommend trimethoprim/sulfamethoxazole (TMP/SMX) or doxycycline. 

  1. Is there evidence pets are reservoirs for MRSA?

    Dr. Outerbridge: Yes, in one study by Iverson et al published in Veterinary Microbiology in 2015 titled Anatomical Patterns of Colonization of Pets with Staphylococcal Species in Homes of People with Methicillin-Resistant Staphylococcus aureus (MRSA) Skin or Soft Tissue Infection (SSTI). In this study, swab samples were taken from 196 pets (dogs, cats, reptiles, birds, fish and pocket pets) that lived in households with an MRSA-infected person. S aureus was identified in 27 of 179 (15%) pets sampled at baseline and 19 of 125 (15%) pets sampled at a 3-month follow-up home visit.

  1. Can you speak to BID versus TID cephalexin usage for pyoderma?

    Dr. Outerbridge:  I think this is another area that could have more research. A dose of 22 to 30 mg BID to TID is what is reported and what is done is to some degree clinician preference. For me, frequency of administration depends on depth of pyoderma. I am more likely to use TID administration in cases of deep pyoderma. In all cases of pyoderma I try to dose towards the top end of the dose range. Reduced dosages are recommended for pets with kidney failure so if reduced renal function is known I would use a different antibiotic or only dose twice a day.  

    Dr. Zhanel: In humans we recommend cephalexin 500 mg QID; however, pharmacodynamically it can be used as 1 gram BID with similar T > MIC.

  1. Where can you get a 4% chlorhexidine spray?

    Dr. Outerbridge: Dechra makes 4% chlorhexidene spray called trisCHLOR 4 spray.

    Duoxo Chlorhexidine PS is a line of topical products with 3% chlorhexidine and climazole. Bayer has Malaseb, which is 2% chlorhexidine with 2% miconazole and they are synergistic towards each other.

Session 2: Innovative Therapies for Skin Disease: What’s on the Horizon?

Douglas J. DeBoer, DVM, DACVD
University of Wisconsin, Madison, WI

Peter H. Eeg, BSc, DVM
Poolesville Veterinary Clinic, Poolesville, MD

  1. If monoclonal antibodies are shutting down important cytokines would it make sense to take occasional breaks during chronic monoclonal antibody therapy to allow cytokines to at least occasionally do their job?

    Dr. DeBoer: This would depend mostly on the specific functions of the cytokine, how important these functions are, and whether there is another pathway that can accomplish any functions that are critical. So far, it appears that IL-31 isn’t critically important for normal immune functioning, so eliminating it has little consequence that we can see. Perhaps its important (yet non-itch) functions can be taken over by another pathway. So we need to consider this concept in theory, but time will tell if we need to take a “cytokine break” or not. This is a great example of the important questions that we will have to answer after more experience with biological therapies.

  1. Would this new monoclonal antibody therapy for atopic dermatitis be a lifelong therapy or would the treatment allow the animal to begin making antibodies?

    Dr. DeBoer: In theory, it will be lifelong. IL-31 is a protein produced normally during inflammation, and the immune system should not ever make antibodies against normal proteins! With monoclonal antibody therapies, we assume that the cytokine is being produced in excessive quantities or with excessive effect, so eliminating it in part with a therapeutic will require constant treatment. This is why dermatologists view this therapy as best used in combination with treatments that may produce more permanent effect, such as allergen-specific immunotherapy.

Session 3: Food Allergy: Skin Disease or GI Disease?

Stanley Marks, BVSc, PhD, DACVIM (SAIM, Oncology), DACVN
University of California, Davis, CA

  1. What can we do to help a dog with a leaky gut and/or barrier dysfunction? Would it help to avoid cutaneous adverse food reaction (CAFR)?

    Dr. Marks: Intestinal barrier function can be enhanced with the advent of enterally administered functional nutrients (including amino acids arginine and glutamine, essential micronutrients vitamin A and zinc, and food additives such as probiotics). Most complete and balanced diets are replete in these amino acids and micronutrients, and the million dollar question is whether augmentation of complete diets with one or more of these amino acids or micronutrients will provide further benefit. Probiotics exert many beneficial functions, including promotion of intestinal barrier function. There are many different mechanisms by which probiotics exert this effect, including promotion of mucus secretion, augmentation of sIgA levels, production of antimicrobial peptides, increased tight junction integrity of epithelial cells, and competitive adherence for pathogens. Further research is needed to determine which probiotic strains exert these functions most effectively so that development of a complementary mix of probiotics can be initiated. Of equal importance, avoidance of drugs (steroids, NSAIDs, long-term antibiotics, prolonged use of acid-suppressants) that can alter the intestinal microbiota or increase intestinal permeability is pivotal. There is evidence in rodent models that enhancement of intestinal barrier function can help reduce the incidence of CAFR.

  1. I recently had a client tell me she knew a person who became allergic to beef after being bitten by a tick and gave me some Web MD printouts. Is this possible? Could ticks play a role in hypersensitivity to protein antigens?

    Dr. Marks: This is an intriguing question and there is now compelling evidence in humans documenting the association between bites from the Lone Star tick (Amblyomma americanum), which transfers the carbohydrate allergen, galactose-alpha-1,3-galactose (alpha-gal) to the person, and the subsequent development of a delayed allergic response triggered by the consumption of mammalian meat products that also contain alpha-gal. Ingestion of poultry and fish do not trigger the reaction. A typical reaction to alpha-gal has a delayed onset, occurring 2 to 10 hours after consumption of mammalian meat products. After the delayed onset, the allergic response is typical of most food allergies, and in particular an IgE-mediated allergy, and symptoms include generalized pruritus, urticaria, angioedema, diarrhea, vomiting, and possible anaphylaxis. Management of mammalian meat allergy involves avoidance of mammalian meat and mammalian-derived products as well as prevention of tick bites. Interestingly, the cancer chemotherapeutic drug, cetuximab, also contains alpha-gal and has been associated with immediate-onset anaphylaxis in sensitized humans following intravenous administration. The link between exposure to bites from the Lone Star tick and development of meat allergy in dogs has not been studied to date.

 

 

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