Treatment of renal aspergillosis in a dog using nephrostomy tubes

Repeated rhinoscopic and serologic assessment of the effectiveness of intranasally administered clotrimazole for the treatment of nasal aspergillosis in dogs

OBJECTIVE

To determine the role of rhinoscopic evaluation and repeated serologic testing in assessing the success rate of intranasally administered clotrimazole for treatment of dogs with nasal aspergillosis.

DESIGN

Prospective case series.

ANIMALS

23 dogs with nasal aspergillosis.

PROCEDURES

Dogs with nasal aspergillosis were treated with an intranasal infusion of 1% clotrimazole solution. Response to treatment was assessed with repeated rhinoscopic evaluation, with histologic examination and fungal culture when available. Results of repeated serologic testing for aspergillosis were monitored throughout the treatment course.

RESULTS

11 of the 23 (48%) dogs had no rhinoscopic evidence of disease after the first treatment. Three of 7 dogs were free of disease after the second treatment, and 1 of 3 dogs was free after the third treatment. Presence or absence of nasal discharge and results of repeated serologic testing were not consistent with disease status. Overall, the efficacy of intranasally administered clotrimazole for treatment of nasal aspergillosis could be confirmed in 15 of 17 dogs. Delayed recurrence or reinfection was confirmed in 3 of 15 dogs. When recurrences were taken into account, the success rate was 67% (12/15 dogs).

CONCLUSIONS AND CLINICAL RELEVANCE

Clinical signs were not predictive of disease state, and follow-up rhinoscopy is recommended to assess response to treatment. The success rate of intranasally administered clotrimazole was similar to rates in previous reports; however, the number of dogs with recurrent disease was relatively high. Monitoring of the results of serologic testing is not recommended for use in determining response to treatment.

Immune response to fungal infections

The immune mechanisms of defence against fungal infections are numerous, and range from protective mechanisms that were present early in evolution (innate immunity) to sophisticated adaptive mechanisms that are induced specifically during infection and disease (adaptive immunity). The first-line innate mechanism is the presence of physical barriers in the form of skin and mucous membranes, which is complemented by cell membranes, cellular receptors and humoral factors. There has been a debate about the relative contribution of humoral and cellular immunity to host defence against fungal infections. For a long time it was considered that cell-mediated immunity (CMI) was important, but humoral immunity had little or no role. However, it is accepted now that CMI is the main mechanism of defence, but that certain types of antibody response are protective. In general, Th1-type CMI is required for clearance of a fungal infection, while Th2 immunity usually results in susceptibility to infection. Aspergillosis, which is a disease caused by the fungus Aspergillus, has been the subject of many studies, including details of the immune response. Attempts to relate aspergillosis to some form of immunosuppression in animals, as is the case with humans, have not been successful to date. The defence against Aspergillus is based on recognition of the pathogen, a rapidly deployed and highly effective innate effector phase, and a delayed but robust adaptive effector phase. Candida albicans, part of the normal microbial flora associated with mucous surfaces, can be present as congenital candidiasis or as acquired defects of cell-mediated immunity. Resistance to this yeast is associated with Th1 CMI, whereas Th2 immunity is associated with susceptibility to systemic infection. Dermatophytes produce skin alterations in humans and other animals, and the essential role of the CMI response is to destroy the fungi and produce an immunoprotective status against re-infection. The resolution of the disease is associated with a delayed hypersensitive response. There are many effective veterinary vaccines against dermatophytoses. Malassezia pachydermatis is an opportunistic yeast that needs predisposing factors to cause disease, often related to an atopic status in the animal. Two species can be differentiated within the genus Cryptococcus with immunologic consequences: C. neoformans infects predominantly immunocompromised hosts, and C. gattii infects non-immunocompromised hosts. Pneumocystis is a fungus that infects only immunosupressed individuals, inducing a host defence mechanism similar to that induced by other fungal pathogens, such as Aspergillus.

Comparison of serologic evaluation via agar gel immunodiffusion and fungal culture of tissue for diagnosis of nasal aspergillosis in dogs

OBJECTIVE

To compare the sensitivity and specificity of serologic evaluation and fungal culture of tissue for diagnosis of nasal aspergillosis in dogs.

DESIGN

Prospective study.

ANIMALS

58 dogs with nasal discharge and 26 healthy dogs.

PROCEDURES

Dogs with nasal discharge were anesthetized and underwent computed tomography and rhinoscopy; nasal tissues were collected for histologic examination and fungal culture. Sera were assessed for antibodies against Aspergillus spp (healthy dog sera were used as negative control specimens). Nasal aspergillosis was diagnosed in dogs that had at least 2 of the following findings: computed tomographic characteristics consistent with aspergillosis, fungal plaques detected during rhinoscopy, and histologically detectable fungal hyphae in nasal tissue. Histologic characteristics of malignancy were diagnostic for neoplasia. Without evidence of neoplasia or fungal disease, nonfungal rhinitis was diagnosed.

RESULTS

Among the 58 dogs, 21 had nasal aspergillosis, 25 had nonfungal rhinitis, and 12 had nasal neoplasia. Fourteen aspergillosis-affected dogs and 1 dog with nonfungal rhinitis had serum antibodies against Aspergillus spp. Fungal culture results were positive for Aspergillus spp only for 17 dogs with aspergillosis. With regard to aspergillosis diagnosis, sensitivity, specificity, and positive and negative predictive values were 67%, 98%, 93%, and 84%, respectively, for serum anti-Aspergillus antibody determination and 81%, 100%, 100%, and 90%, respectively, for fungal culture.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that seropositivity for Aspergillus spp and identification of Aspergillus spp in cultures of nasal tissue are highly suggestive of nasal aspergillosis in dogs; however, negative test results do not rule out nasal aspergillosis.

Intracranial fusariosis: a novel cause of fungal meningoencephalitis in a dog

The Fusarium species are a group of saprophytic fungal organisms that are occasionally the cause of opportunistic infections in humans and animals. Central nervous system disease associated with a Fusarium species is most commonly described in horse, resulting in equine leukoencephalomalacia. This report describes a 2-year-old, spayed, female German Shepherd Dog with meningoencephalitis secondary to infection with Fusarium spp. Meningoencephalitis in dogs secondary to a species of Fusarium has not been previously reported. The diagnosis was made based on the histopathologic examination of brain tissues postmortem and special immunohistochemical stains specific for Fusarium solani. The clinical signs in this dog were indicative of multifocal brain disease and included seizures and a paradoxical vestibular syndrome. The clinical findings, diagnostic and histopathologic test results, and the comparative characterizations of other disseminated fungal diseases, especially aspergillosis, are described.

The value of the determination of anti-Aspergillus IgG in the serodiagnosis of canine aspergillosis: comparison with galactomannan detection

Diagnosis of canine aspergillosis is difficult using currently available methods. It often passes unnoticed or is diagnosed in the later phases of the disease. We developed an ELISA technique to detect anti-Aspergillus antibodies in canine serum using an Aspergillus antigenic mycelial extract, which could then be used for the diagnosis of canine aspergillosis. We used a cut-off of X + 3SD obtained from 20 control sera. The test was performed on 46 dogs with lesions indicating possible aspergillosis and gave nine positive results: one systemic mycosis, two discospondylitis, one uveitis, two bronchopulmonary processes and three rhinitis. We compared this methodology with the PLATELIA technique in the follow-up of the affected dogs, obtaining the same limitations as in the diagnosis of human aspergillosis. We consider our ELISA technique using sera samples a speedy, safe and reliable method which enables us to follow up the evolution of the disease and the efficacy of the therapy chosen. A definitive diagnosis must still take into account the results of other tests such as clinical examination, radiographic studies, endoscopy and biopsy.