Dermatology advancements: An overview of the latest treatment options
During his lecture at the Atlantic Coast Veterinary Conference (ACVC), Paul Bloom DVM, DACVD, DABVP, highlighted a few new medications to consider implementing into your treatment plan for patients with pyoderma, pruritus, and otitis.
Treatment options for veterinary dermatology patients have advanced significantly in the past several years. Paul Bloom, DVM, DACVD, DABVP, summarized the latest treatments available for treating pyoderma, pruritus, and otitis. If you were not already aware, these are important additions to your treatment arsenal.
Bloom separated these new medications into the broad categories of antibiotics and antipruritics. The mainstay of antibiotics for pyoderma has previously been cephalexin, a first-generation cephalosporin. While this arguably remains the first-line treatment for bacterial folliculitis, the newer antibiotics used to treat pyoderma include cefpodoxime (an oral antibiotic) and cefovecin (trade name Convenia, a long duration injectable antibiotic), which are both broad-spectrum third-generation cephalosporins. Bloom discussed the potential concerns with using third-generation cephalosporins as a first-line treatment.
The oral medication cefpodoxime is promoted by the company as a first-line antibiotic for pyoderma; however, the broad-spectrum nature enhances the development of extended spectrum beta lactamase producing gram negative bacteria. These very resistant bacteria are important causes of serious infections in humans. Whether targeted by the treatment or not, and whether pathogenic or not, resistant bacterial organisms can transfer their resistant genes to other organisms in the environment or other species (animal to humans). The advantage of administering cefpodoxime over cephalexin appears to be primarily logistical, as cefpodoxime is administered once daily, versus cephalexin which is administered twice daily. However, Bloom stated, the risks to developing resistant organisms outweigh the logistical benefits
Similar concerns exist for cefovecin. This parenteral antibiotic has been approved in other countries for treatment of numerous organisms (including Staphylococcus intermedius, beta-hemolytic Streptococci, Escherichia coli, Pasteurella multocida, Proteus spp, Staphylococcus intermedius, and Streptococcus canis. Due to similar risks of selecting for resistant bacteria, Bloom cautions that cefovecin should be reserved for patients who cannot be medicated orally. Therapeutic concentrations are maintained for approximately 7-14 days post-injection, with specific therapeutic timing dependent on the specific bacteria and MIC. Although subtherapeutic, tissue levels persist for up to 65 days. There is question as to whether or not this persistent subtherapeutic tissue concentration will select for the resistant bacterial. Specific concerns exist about selecting for extended spectrum beta-lactamases (Enterobacteriaceae such as E. coli and Klebsiella pneumoniae) that are multidrug-resistant. Bloom also reminded us that, with any new therapeutic, long-term adverse effects are not yet fully known.
Available antipruritic medications include oclacitinib (Apoquel), modified cyclosporine (Atopica and Cyclavance), and lokivetmab (Cytopoint). These 3 medications have different mechanisms of action.
Oclacitinib is a janus kinase (JAK 1) pathway inhibitor. Janus kinase 1 is an intracellular pathway that is activated when cytokines bind to specific cell membrane receptors. Activation results in production of various cytokines that trigger and perpetuate pruritus. Oclacitinib inhibits activation of the JAK 1 pathway, limiting the amount of pro-inflammatory and pruritogenic cytokines produced. It may also be helpful off-label for other immune-mediated diseases, including vasculitis, ischemic dermatopathy, pemphigus foliaceus, and discoid lupus erythematous. Adverse effects appear to be rare, but may include neutropenia or leukopenia, and may reduce seizure threshold.
Bloom does remind us of one important factor to be aware of when using oclacitinib; it will mask pruritus regardless of etiology. For example, a patient with sarcoptic mange, flea allergy dermatitis, or bacterial or yeast pyoderma, possibly masking the untreated underlying disease. For this reason, identifying the underlying cause of pruritus is an important component of diagnostic and treatment planning.
Although not new, modified cyclosporines remain highly utilized in dermatology. Bloom does caution that it is essential to use the modified cyclosporines, such as Atopica or Cyclavance, to achieve consistent absorption. Bloom recommended using modified cyclosporine in uncomplicated atopic dermatitis, where oclacitinib and lokivetmab have failed. Full therapeutic effect is typically reached within 4-6 weeks of administration. Adverse effects appear to be minimal and consist of gastrointestinal signs, cutaneous papillomatosis, and gingival hyperplasia. Maropitant or ondansetron may help offset vomiting.
Another new medication used in veterinary dermatology is lokivetmab, a canine monoclonal antibody that binds to and neutralizes IL-31. Blooms noted that, although low amounts of IL-31 are beneficial, higher amounts are detrimental and contribute to the pathogenesis of atopic dermatitis. Lokivetmab is administered via subcutaneous injection, once every 30 to 60 days. As it is a specific canine monoclonal antibody, it can only be used in dogs. Bloom recommended using it in cases of pruritus from allergic skin disease, with or without concurrent demodex or bacterial pyoderma or cystitis, or patients with a history of (or current) cancer. Bloom does find that cases that failed to respond to either oclacitinib or lokivetmab, may respond to the other treatment, due to the different mechanisms of action. As such, if a therapeutic trial with one of these medications is not effective, it is worth trying the other.
Bloom’s final update in “new drugs in veterinary dermatology” relates to treatment of otitis. Administering topical ear medications can be tricky for owners, and often treatment is prescribed for 7 to 14 days. Easotic is a new product containing hydrocortisone aceponate, miconazole, and gentamicin. What is particularly unique about this treatment is the delivery system. Easotic is in a pump bottle, with a flexible tip that allows easy application of the medication deep (but safely) into the ear canal. The pump is metered to allow 1cc dispensed with each pump, and treatment duration is only 5 days. Bloom’s experience with this has been positive, due to both compliance and efficacy.
Dermatological conditions are one of the more common diagnoses requiring veterinary care, and several new treatments have become available over the past few years. Bloom’s overview of novel treatments should help all practitioners better understand the options available to care for their patients.
Dr Rebecca A Packer is board certified in neurology by the American College of Veterinary Internal Medicine and is an associate veterinarian at BluePearl Specialty and Emergency Pet Hospital in Lafayette, Colorado. She is also the founder and owner of the Pre-Veterinary Mentoring Group, LLC, through which she provides mentorship for pre-veterinary students during their path to veterinary school, and is the founder and owner of The Pocket Neurologist, LLC, a vet-to-vet teleconsulting service.