2017 Merck Advanced Medicine Symposium - Audience Q&A from WVC

2017 Merck Advanced Medicine Symposium - Audience Q&A from WVC

The following are the speaker responses to questions from the audience during the Advanced Medicine Symposium, sponsored by Merck Animal Health, held March 6, 2017.

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.

Lyme Disease Update

Steve Callister, PhD and Scott Stevenson, DVM, MSc (Note: Dr. Callister reviewed these answers)

  1. What is your recommended protocol when you have a dog that is Lyme positive on a routine 4Dx test but is not clinical?

    Dr. Stevenson: In my practice, we follow the ACVIM Consensus Statement and immediately check for proteinuria and educate the owner about canine Lyme disease, tick control, and public health. We then implement a program to prevent future tick exposure: daily tick checks, the use of a preventive, and vaccination (if asymptomatic and non-proteinuric). Once this is complete, we explain that most dogs that test positive for Borrelia burgdorferi may not develop clinical signs of Lyme disease, and the recommendation of the ACVIM Consensus Statement is to not treat asymptomatic dogs. Researchers have also demonstrated, however, that some Lyme-positive dogs may have spirochetes in the tendon sheaths that may eventually cause enough inflammation to cause clinical abnormalities such as lameness. Therefore, if the owner still desires treatment, we comply, but with the condition that the owner must also comply with our prevention protocol to prevent future exposure.

  2. Do oral tick preventatives prevent the spread of Lyme?

    Dr. Stevenson: We have been very pleased with the efficacy of the oral flea and tick preventives. For maximum protection, we recommend also combining the oral preventive with tick checks and a Lyme vaccine.

  3. Is it still the mindset that we should vaccinate all asymptomatic pets recovering from Lyme disease to aid in the recovery process?

    Dr. Stevenson: We vaccinate 4Dx Lyme–positive dogs as long as they are asymptomatic and non-proteinuric. The goal of vaccination is to prevent subsequent exposures, not to aid in treatment of a current infection. Antibiotic therapy is the only way to treat the existing infection.

  4. How do you know if there is a direct correlation between a 4Dx Lyme–positive state and kidney disease/glomerulonephritis? Are there any special treatment considerations?

    Dr. Stevenson: Unless a renal biopsy is available, a diagnosis of Lyme nephritis must be arrived at primarily by ruling out other possibilities. If Lyme nephritis remains a possibility, we continue antibiotic therapy until the urine protein:creatinine ratio normalizes.

  5. When is the best time of year to vaccinate and how often should the vaccine be administered?

    Dr. Stevenson: Optimally, dogs should be vaccinated immediately prior to the start of tick season, but this is not always possible. We therefore prefer Nobivac Lyme (Merck Animal Health) because researchers have shown the vaccine provides a high level of protection for at least one year.

  6. How do you feel about using Convenia for one month based on studies showing its efficacy? Is Convenia better if the disease is in tissues (e.g., joint membrane) versus other drugs like doxycycline?

    Dr. Stevenson: We have had great success with doxycycline, so we continue to prefer this antibiotic. A recent study, however, showed the efficacy of Convenia (Zoetis; cefovecin) was comparable to both doxycycline and amoxicillin for eliminating spirochetes, which makes it another viable option for treating Lyme disease (https://www.ncbi.nlm.nih.gov/pubmed/26205247).

  7. A recent lecture showed dogs with chronic Lyme disease that were positive and never treated developed more significant degenerative joint disease signs than those that were positive and treated or were never positive at all. Have you found this with your practice?

    Dr. Stevenson: We have not seen this, but the majority of our positive dogs get an initial treatment with antibiotics coincident with implementation of our tick prevention program.

  8. What is the dose of doxycycline?

    Dr. Stevenson: The recommended dosage of doxycycline according to the ACVIM Consensus Statement is 10 mg/kg PO q24h for a minimum of one month. Plumb’s Veterinary Drug Handbook recommends 10 mg/kg PO q12–24 hours for 30 days.

Canine Flu: When Disaster Strikes

Brenda Dines, DVM, and Michael Mayer (Note: Natalie Marks, DVM, also presented during this session.)

  1. What types of disinfectants do you use?

    Mr. Mayer: We use Top Performance 256 disinfectant and diluted bleach.

    Dr. Dines: We use Accel (now known as Rescue; Virox Animal Health), which is an accelerated hydrogen peroxide.

  2. We are doing some post-mortem PCR canine infectious respiratory disease (CIRD) testing with results that are H3N2 negative but Mycoplasma and parainfluenza positive. Could we have missed the H3N2 shedding?

    Dr. Dines: It is possible, but some information about the rest of your population would be helpful if this is a shelter setting. H3N2 can intermittently shed. It would be helpful to know if all the dogs became sick and if all newly introduced animals became sick. Keep in mind I have also dealt with a parainfluenza outbreak in my shelter in which many of the dogs became quite ill as well. It is very possible for parainfluenza to be a culprit, too.

Extended Flea & Tick Control for Dogs & Cats: Benefits for Your Business & Your Patients

Dr. Dan Markwalder and Dr. Rob Armstrong

  1. Bravecto is a wonderful drug to treat Demodex in dogs. Do you know if the cat version is effective in the treatment of scabies?

    Dr. Markwalder: As you may know, Bravecto (fluralaner) has been shown to be effective against sarcoptic mange in dogs*. Although I'm not aware of any current research showing the efficacy of feline Bravecto against scabies, I'm confident this product could be highly effective. In fact, I plan on using the product clinically when I have my next case of feline sarcoptic mange.

    *The FDA has not approved the use of Bravecto for Sarcoptes scabiei or Demodex spp. in dogs and cats.

Managing Diabetes in Cats

Dr. Patty Lathan

  1. I have a patient that is a 9-year-old male neutered DSH cat, 8 pounds, FIV positive, with an unknown lung mass present for 6 months. He became diabetic 4 months ago and is currently on 4 units of glargine BID. His glucose was 650 and decreased to 231 at 6 hours. Fructosamine was "uncontrolled." His weight is stable, urine culture is negative, and his clinical symptoms are acceptable. Should we change anything?

    Dr. Lathan: That’s a tough one. Of course I’m going to recommend working up the lung mass, as that can certainly cause insulin resistance, but I assume you’ve already had that discussion with the owners. Given how high that glucose is going, I’d wonder if the cat ever becomes hypoglycemic (meaning, maybe it goes too low at some point, and then swings back up due to a Somogyi-like effect). Or it could be stress hyperglycemia. Did you check blood glucoses every two hours? Was this in the clinic, or at home? If he’s not clinical at all, you could leave the dose where it is. Alternatively, have the client do a blood glucose curve at home and see what it looks like.

  2. What are your thoughts on giving insulin in half units (e.g., 1.5 U glargine BID)?

    Dr. Lathan: We often recommend doing it, but I can’t tell you how well it works! It’s definitely easier to do with a U-40 insulin. Insulin pens also make it easier—if you were using Vetsulin, you could dial up to the 1⁄2 unit on the 8 U pen. There’s not a glargine pen that does half units that’s available in the US, unfortunately.

  3. Is it that you should NOT roll glargine or is it just not necessary?

    Dr. Lathan: Good question. It’s not necessary, but it shouldn’t be a problem if you do it.

  4. What is the cost of the pen versus vials?

    Dr. Lathan: When you take syringes and needles into consideration, I think the pens end up costing about 30% more than using syringes (this is regarding Vetsulin vs VetPen).

  5. How do you compare measuring fructosamine versus using a glucose curve?

    Dr. Lathan: This is similar to looking at the average monthly high temperature versus the daily high temperature and deciding whether to turn on your air conditioner for the whole month.

Treating Immune-Mediated Diseases

Andrew Mackin, BSc, BVMS, MVS, DVSc, DSAM, FACVSc, DACV

  1. To differentiate mild anemia due to azathioprine from a relapse of the immune- mediated hemolytic anemia (IMHA), would you repeat a simple slide agglutination test?

    Dr. Mackin: I’m afraid it wouldn’t help in most cases, for a number of reasons. Many IMHAs are slide agglutination negative, even before therapy. Even if therapy converts a positive slide agglutination to a negative, there STILL can be ongoing red blood cell (RBC) destruction, because even agglutination-negative dogs can have active ongoing hemolysis. On the other hand, dogs often go into remission LONG before their agglutination clears up. Agglutination will persist for as long as antibodies circulate and, even with effective therapy, existing antibodies can linger for the lifespan of the antibody, and antibody can last on a RBC for the lifespan of the RBC. If therapy has turned off RBC destruction (for example, knocked out macrophages), then the dog can be in remission and still agglutinating. Bottom line, agglutination doesn’t correlate well with either remission or relapse.

  2. While waiting for MDR1 genotyping in white-footed breeds, would the patient benefit from going ahead with a dose of vincristine at 50% reduction?

    Dr. Mackin: Yes, sometimes. If the dog is not MDR1, the dose may be too low to help, but it won’t hurt. If the dog is MDR1 heterozygous or homozygous, the vincristine could very well help, and probably won’t hurt. This refers to treatment of immune-mediated thrombocytopenia (IMT). For cancer chemotherapy, I would wait until the MDR1 gene test comes back, and treat with other drugs in the meantime.

  3. Is Fanconi syndrome in cats an immune-mediated disease and how does the treatment work?

    Dr. Mackin: I think it is very unlikely Fanconi is immune mediated. It is either hereditary or, if it is drug-, toxin- or infection-induced, I think it is a direct effect of the agent on the renal tubules. For acquired Fanconi, the best treatment is to remove the cause (drug, toxin, organism). For inherited Fanconi, or for acquired that doesn’t resolve when the cause is removed, cats can be treated in the same way as dogs. Therapy is complex; the most widely available and detailed version of therapy that is widely available is the “Gonto protocol.” Search online for the 2016 version; it was developed by a PhD Basenji owner and has since been evaluated in clinical trials.

  4. Is immunoglobulin still the treatment of choice for autoimmune hemolytic anemia?

    Dr. Mackin: Immunoglobulin is in our armamentarium but I don’t think it is treatment of choice. Why? First, because it is expensive. Second, in the handful of clinical trials out  there, it did not seem to help long-term survival in several of the bigger studies. There was also, in several studies, a fairly high incidence of pulmonary thromboembolism (PTE). This is worrisome because in people, the same therapy is associated with a higher incidence of thrombotic complications. Because PTE is the biggest killer of dogs with IMHA, I tend to wait on using immunoglobulins until I am getting desperate.

Otitis Externa: Real World Case Management

Dr. Wayne Rosenkrantz

  1. Can Osurnia or Claro be used with tympanum compromise when BNT is contraindicated?

    Dr. Rosenkrantz: Any ear product is contraindicated with a ruptured tympanic membrane but I would use, and have used, Osurnia (Elanco; florfenicol/ternbinafine/betamethasone acetate) or Claro (Bayer DVM; florfenicol, terbinafine/mometasone furoate) in ruptured TM and it would be an obvious choice over the BNT (BCP Veterinary Pharmacy; enrofloxacin/ketoconazole/triamcinolone) for sure!


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