Joaquin presented for an 8-month history of progressive papillomatosis in the oral cavity, as well as tremendous halitosis. No response was noted to a month long course of azithromycin.
Christie Yamazaki DVM, DACVD
Dermatology For Animals, Oakland, CA
SUBJECTIVE
Joaquin is a 2 year 4 month old MC Husky Mix with an 8-month history of multifocal white nodules in the oral cavity and halitosis. The owner’s friend hosted play dates with Joaquin and noted that her own dog presented similar lesions that self-resolved. A 6 week course of azithromycin was ineffective at resolving the growths nor malodor. The patient was adopted from a shelter about 1 year prior with no known medical conditions and had not received any other therapies aside from monthly parasiticides (Nexgard®, Heartgard®).
OBJECTIVE
Weight: 30.4 kg (67 lb)
Temp: 100.7 F (rectal)
Pulse: 90 bpm
Resp: 32 bpm
Dermatologic physical examination: BARH, BCS 4/9. Joaquin was sweet and easily examined though sensitive to oral cavity evaluation. Multifocal light pink to white hyperkeratotic papules and nodules with fronding on the surface, ranging from 4 mm to 35 mm, and some forming coalescing plaques were present on the lip margins, buccal mucosa, tongue and rostral chin. There was moderate malodorous purulent exudate amongst the nodules on the rostral chin. There were no other dermatologic abnormalities. All lymph nodes palpated symmetric with no obvious lymphadenomegaly.
DIAGNOSTICS
Skin cytology of the exudate on the rostral chin revealed full fields of rods and cocci with nuclear chromatin streaming and polymorphonuclear cells. A biopsy was not performed, though would have provided definitive diagnosis. Complete blood count, chemistry, urinalysis and thyroid screening was performed and all results were within normal limits.
ASSESSMENT
The clinical presentation in this young dog was strongly suggestive of canine oral papillomatosis with secondary bacterial infection. Differential diagnoses included infundibular keratinizing acanthoma, cutaneous horns and melanocytic neoplasia.
Given the extent of affected tissue, recommendations were made to proceed with carbon dioxide surgical laser removal and cryotherapy. As the patient was unable to be scheduled for a few weeks, the recommendation was also made to begin an experimental papillomavirus vaccine (Georgetown University) reported to have a 40% success as treatment for oral and paw pad warts. The patient was also prescribed Thuja 30C, a homeopathic remedy, at a dose of 2 drops/5 kg body weight.
A culture was collected and submitted of the purulent exudate associated between the growths and revealed a Staphylococcus pseudintermedius susceptible to cefpodoxime.
FOLLOW-UP
Joaquin was presented for CO2 laser ablation and cryotherapy which was performed under general anesthesia. At the time of intubation, marked involvement of the hard palate, soft palate and epiglottis was noted. Large plaques were excised and debulked, though the majority of tissue was treated with CO2 laser ablation and cryotherapy (liquid nitrogen).
Nine days later, the patient presented to start the canine papillomavirus vaccine and a marked reduction of lesions was evident. The patient continued therapy with thuja and the vaccine over the next 10 weeks and was advised to schedule follow up cryotherapy and CO2 laser ablation of remaining warts as client finances and schedule would allow. The owner reported satisfaction with the degree of reduction of both numbers and severity of growths and halitosis/malodor since completing the 4 week course of cefpodoxime. At time of this report, follow up cryotherapy had not yet been scheduled.
COMMENTS
Canine papillomas are secondary to canine papillomavirus infection and can affect the skin and oral cavity of young dogs. Papillomaviruses are species-specific small non-enveloped double-stranded DNA viruses that infect mucous membranes and skin of humans and animals that are highly transmissible. Affected patients are usually immunocompromised – young, geriatric, and/or receiving immunosuppressive therapies.
Diagnosis generally requires histopathology though the clinical presentation often is sufficient to begin therapy. Though cutaneous viral papillomas are usually benign, transformation into squamous cell carcinoma has been documented.
For the lesions that do not self-resolve, treatment to consider includes surgical excision, laser therapy, cryotherapy, azithromycin, imiquimod, interferon-alpha2a, autologous or recombinant papillomavirus vaccine and systemic retinoids. CO2 laser ablation can stimulate cell-mediated immunity as well as debulk and remove affected tissue. Cryotherapy is understood to induce tissue necrosis and immune system response to target tissue antigens.
Azithromycin is a macrolide antibiotic that was been reported as an effective, well-tolerated therapeutic option for the treatment of papillomatosis in humans. It is unknown if azithromycin modulates the host inflammatory response or whether it eliminates latent pathogens that can trigger chronic inflammation.
Homeopathic treatment using Sulfur 30C, Thuja 30C, Graphites 30C, and Psornium 30C has been evaluated with promising results – the treatment group showed early recovery with significant reduction in oral lesions compared with placebo.
As these lesions can be transmissible, it is important to isolate affected patients until lesion resolution.
REFERENCES
- Miller WH, Griffin CE, Campbell KL. Viral, Rickettsial, and Protozoal Skin Diseases: Canine Papillomavirus Infection. Muller and Kirk’s Small Animal Dermatology. 7th Philadelphia, PA: Saunders, 2013; 349-350.
- Raj PA, Pavulraj S, Kumar MA et al. Therapeutic evaluation of homeopathic treatment for canine oral papillomatosis. Vet World: 2020 Jan; 13 (1): 206-213.
- Richman, A.W., Kirby, A.L., Rosenkrantz, W. and Muse, R. (2017), Persistent papilloma treated with cryotherapy in three dogs. Vet Dermatol, 28: 625-e154.