Treatment of blastomycosis with itraconazole in 112 dogs

Itraconazole in human medicine and veterinary practice

Diagnosis and management of fungal infections are challenging in both animals and humans, especially in immunologically weakened hosts. Due to its broad spectrum and safety profile when compared to other antifungals, itraconazole (ITZ) has been widely used in the treatment and prophylaxis of fungal infections, both in human and veterinary medicine. The dose and duration of management depend on factors such as the type of fungal pathogen, the site of infection, sensitivity to ITZ, chronic stages of the disease, the health status of the hosts, pharmacological interactions with other medications and the therapeutic protocol used. In veterinary practice, ITZ doses generally vary between 3 mg/kg and 50 mg/kg, once or twice a day. In humans, doses usually vary between 100 and 400 mg/day. As human and veterinary fungal infections are increasingly associated, and ITZ is one of the main medications used, this review addresses relevant aspects related to the use of this drug in both clinics, including case reports and different clinical aspects available in the literature.

Short Review on the Biological Activity of Cyclodextrin-Drug Inclusion Complexes Applicable in Veterinary Therapy

Cyclodextrins (CDs) are a family of carrier molecules used to improve the pharmacokinetic parameters of therapeutic molecules. These cyclic oligosaccharides have medical and pharmaceutical applications by being able to form inclusion complexes with molecules that are poorly soluble in water. The benefits of these complexes are directed towards improving the chemical and biological properties-i.e., solubility, bioavailability, stability, non-toxicity and shelf life of drug molecules. Since the 1960s, the first inclusion complexes used in therapeutics were those with α-, β- and γ-CD, which proved their usefulness, but had certain degrees of particularly renal toxicity. Currently, to correct these deficiencies, β-CD derivatives are most frequently used, such as sulfobutylether-β-CD, hydroxypropyl-β-CD, etc. Therefore, it is of interest to bring to the attention of those interested the diversity of current and potential future clinical applications of inclusion complexes in veterinary medicine and to present the contribution of these inclusion complexes in improving drug efficacy. The most important biological activities of β-CD complexed molecules in the veterinary field are summarized in this short review.

Review of Novel Oral Amphotericin B Formulations for the Treatment of Parasitic Infections

Amphotericin B (AmpB) is a polyene macrolide antibiotic used in the treatment of blood-borne parasitic and fungal infections. However, its use, particularly in the developing world, has been limited by dose-dependent kidney toxicity, other systemic-related toxicity issues following injection, the inconvenience of parenteral administration, and accessibility. Oral formulation approaches have focused on the dual problem of solubility and permeability of AmpB, which is poorly water soluble, amphoteric and has extremely low oral bioavailability. Therefore, to enhance oral absorption, researchers have employed micellar formulations, polymeric nanoparticles, cochleates, pro-drugs, and self-emulsifying drug delivery systems (SEDDS). This paper will highlight current uses of AmpB against parasitic infections such as leishmaniasis, preclinical and clinical formulation strategies, applications in veterinary medicine and the importance of developing a cost-effective and safe oral AmpB formulation.

Mandibular Blastomycosis in a 5-Year-Old Dog

A case of localized oral mandibular blastomycosis is described in a five-year-old dog. Complete resolution of clinical signs and oral radiographic changes were seen following itraconazole therapy at 5 mg/kg/day for four and a half months. The patient remained free of Blastomyces at the one year follow up based on the Mira Vista Blastomyces urine antigen test by EIA (Enzyme Immunoassay)^a. A literature review of localized blastomycosis cases in humans and dogs was performed, available diagnostic tests evaluated, and treatment comparisons made.

Cytochrome P450 reaction phenotyping of itraconazole hydroxylation in the dog

Itraconazole (ITZ) is an important drug in the treatment of superficial and deep mycoses in dogs. Its primary metabolite is hydroxy-itraconazole, which has antifungal activity similar to the parent compound. The purpose of this study was to identify the cytochrome P450 enzyme (CYP) isoform(s) responsible for ITZ hydroxylation in canine liver. Reaction kinetics for ITZ hydroxylation were determined in a panel of canine recombinant CYPs and dog liver microsomes (DLMs). Findings were confirmed using CYP isoform-specific inhibitors in rCYPs and DLMs. In rCYP experiments, CYP2D15 and CYP3A12 had highest activity for ITZ hydroxylation. In inhibitor experiments, quinidine and erythromycin inhibited ITZ hydroxylation in CYP2D15 and CYP3A12, respectively, in an isoform-specific manner. In DLMs, quinidine and erythromycin combined inhibited ITZ hydroxylation more than erythromycin alone but not quinidine alone. However, this may be related to inhibitor potency rather than the contribution of the individual CYP isoforms to the reaction. These findings support a role for CYP2D15 and CYP3A12 in ITZ biotransformation in canine liver.

Antiparasitic treatment with itraconazole and amiodarone in 2 dogs with severe, symptomatic Chagas cardiomyopathy

Chagas cardiomyopathy, caused by the protozoal parasite Trypanosoma cruzi, is characterized by arrhythmias, myocardial damage, heart failure, and sudden death. We describe 2 dogs with severe, symptomatic Chagas cardiomyopathy characterized by myocardial dysfunction and electrocardiographic abnormalities that were managed with a combination of cardiac medications and antiparasitic treatment with itraconazole and amiodarone. Both dogs died suddenly within 6 months of diagnosis. These cases highlight the need for early detection of Chagas disease in dogs and continued research to develop effective antiparasitic treatment protocols.

Mefenoxam, Itraconazole, and Terbinafine Combination Therapy for Management of Pythiosis in Dogs (Six Cases)

Pythium insidiosum is an oomycete that encysts in the skin or gastrointestinal tract, leading to pythiosis. Pythiosis is reported in tropical and subtropical climates, affecting dogs and rarely cats. Surgical resection is the treatment of choice; however, cases present late in the disease and lesions are often nonresectable. Medical management is typically unsuccessful, with uncommon exceptions; however, mefenoxam, an agricultural fungicide, has in vitro efficacy against P insidiosum. We describe the use of mefenoxam, itraconazole, and terbinafine (MIT) in five dogs with gastrointestinal pythiosis and one dog with cutaneous pythiosis. Two of the gastrointestinal cases had disease extending to surgical margins and received MIT: resolution of clinical signs and seronegativity occurred after 189-193 days. Another case underwent surgical resection and MIT. The dog improved but subsequently developed a rectal mass, which responded to addition of prednisone and immunotherapy. Two cases were treated with MIT alone, and response varied. Efficacy of MIT in cutaneous pythiosis could not be determined. MIT may result in improved survival and seronegativity in dogs with incompletely resected gastrointestinal pythiosis. Mefenoxam is EPA registered, and extralabel use under the Animal Medicinal Drug Use Clarification Act does not apply. Additional research is recommended before use.

Serum 25-hydroxyvitamin D concentrations and mortality in dogs with blastomycosis

Blastomycosis is a prominent fungal disease in the United States. Vitamin D status has been found to be altered in critical illness and various infectious diseases. The objectives of this study were to compare serum 25-hydroxyvitamin D (25[OH]D) concentrations in dogs with blastomycosis and healthy controls, to assess the change in serum 25(OH)D concentrations in dogs with blastomycosis after 30 days of treatment, and to determine if baseline serum 25(OH)D concentrations in dogs with blastomycosis were associated with in-hospital, 30-day, or end-of-study mortality. In this prospective cohort study, 19 dogs newly diagnosed with blastomycosis had serum 25(OH)D concentrations measured with a commercially available validated radioimmunoassay at the time of diagnosis and 30 days after start of treatment. These values were compared to 24 healthy control dogs. Serum 25(OH)D concentrations at the time of diagnosis were lower in dogs with blastomycosis (median, 203 nmol/L; range, 31-590 nmol/L) than in clinically healthy control dogs (259.5 nmol/L, 97-829 nmol/L; P = 0.01). Despite clinical improvement, there was no significant change in serum 25(OH)D concentrations from baseline to 30-day follow-up. Dogs with baseline serum 25(OH)D concentrations <180.5nmol/L had a greater odds of death during hospitalization (odds ratio [OR], 15.0; 95% confidence interval [CI], 1.4-191.3; P = 0.04) and at 30 days follow-up (OR, 30.0; 95% CI, 2.5-366.7; P = 0.006). These findings highlight the need for further studies evaluating the prognostic value of vitamin D status in dogs with blastomycosis at diagnosis and throughout treatment and remission.

Retrospective analysis of the effects of Blastomyces antigen concentration in urine and radiographic findings on survival in dogs with blastomycosis

Background

The Blastomyces antigen concentration in urine (BACU) test is used to diagnose blastomycosis and monitor treatment in dogs. It is unknown if a higher BACU is associated with shorter survival.

Objectives

To determine if the magnitude of BACU before treatment is associated with survival in dogs with blastomycosis.

Animals

Fifty‐two dogs with blastomycosis.

Methods

Retrospective case review. BACU, radiographic lung severity (RLS) score (0‐4 scale), and survival time up to 1 year after diagnosis were obtained through medical record review of dogs with Blastomyces dermatitidis.

Results

The overall survival was: discharge, 87%; 1 week, 85%; 2 months, 74%; and 6 months, 69%. BACU correlated with RLS score (r_s = 0.33, P = .02). BACU and RLS scores were lower in survivors to 2 months than nonsurvivors (average BACU difference of 2.5 ng/mL, 95% confidence interval [CI]: 0.2‐4.8 ng/mL, P = .04; median RLS difference of 2; range, 0‐4, P = .02). Dogs with BACU <5 ng/mL and dogs with mild (0‐1) RLS scores had a greater proportion surviving than those with BACU >5 ng/mL (P = .03) and dogs with severe (3‐4) RLS scores (P = .04). All dogs with a BACU <5 ng/mL or mild RLS score were alive at last follow‐up (median, 365 days; range, 44‐365 days). In all, 68.1% of other dogs survived to 2 months (95% CI, 54.8%‐84.8%).

Conclusions and Clinical Importance

Dogs with lower BACU and RLS scores have improved survival; however, it is unclear what specific cutoffs should be used for prognosis.

Cytotoxicity of Cultured Canine Primary Hepatocytes Exposed to Itraconazole Is Decreased by Pre-treatment With Glutathione

Objective: To identify the effect of glutathione (GSH) on cell survival in a novel in vitro model of itraconazole (ITZ)-associated hepatotoxicity using canine primary hepatocytes.

Sample: Commercially sourced, cryopreserved male dog (Beagle) primary hepatocytes from a single donor.

Procedures: Using a sandwich culture technique, canine primary hepatocytes were exposed to serial dilutions of ITZ. Calcein AM, 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), and neutral red were investigated as potential cell viability assays. Hepatocytes were then pre-incubated with GSH, exposed to serial dilutions of ITZ, and cell viability determined at 4 and 24 h post-ITZ exposure. Each condition was performed in technical triplicate and the effect of time, GSH concentration, and ITZ concentration on % cytotoxicity assessed using a multivariate linear regression model. Tukey's post-hoc test was used to detect individual differences.

Results: The neutral red cell cytotoxicity assay was chosen based on its superior ability to detect dose-dependent changes in viability. Hepatocyte cytotoxicity significantly increased with ITZ concentration (P < 0.001) and time (P = 0.004) and significantly decreased with GSH treatment (P < 0.001).

Conclusions and Clinical Relevance: This in vitro model demonstrates dose- and time-dependent ITZ-induced cytotoxicity, which is similar to clinical changes observed in canine patients and in in vivo rodent studies. Pre-treating with GSH is protective against in vitro cell death. These results suggest that GSH precursors may have a role in the management or prevention of ITZ-associated hepatotoxicity in dogs. Clinical trials are needed to evaluate their utility for this adverse drug reaction.

Prevalence, distribution, and risk factors for canine blastomycosis in Michigan, USA

Blastomycosis is a systemic fungal infection that most commonly affects dogs and humans. The disease is thought to be endemic in southern regions of Michigan, USA, but epidemiologic investigations have not been reported in detail for this state. The primary aims of this study were to investigate the prevalence and distribution of canine blastomycosis cases in Michigan and to identify risk factors for infection. Over 200 primary care veterinary clinics throughout the state were surveyed regarding blastomycosis prevalence, and demographic information was obtained from medical records of affected dogs that were evaluated at these clinics. A retrospective case control study was conducted for an additional 49 dogs with blastomycosis that were evaluated at specialty referral centers located in the southern mid-Michigan region. Prevalence rates were calculated for each county, and cases were mapped using geocoding software. Univariable and multivariable analyses were used to identify risk factors for infection. Prevalence rates were ≥100 cases per 100,000 dogs in five counties. Most blastomycosis cases originated from the Upper Peninsula or from a high-density area in the northern Lower Peninsula. Multivariable regression analysis identified travel or residence north of the 45^th parallel as a strong risk factor for infection (P < .001). Blastomycosis was uncommon in southern counties. These results refute previous speculations and should be of value to both human and animal health. Given that many heightened risk areas are popular tourist destinations, practitioners across the USA should be mindful of the spatial distribution of blastomycosis in Michigan.

Biliary Dilation: An Unusual Presentation of Histoplasma capsulatum in a Dog

A 4 mo old intact male Labrador retriever was referred to the authors’ institution for a 3 wk history of weight loss and progressive abdominal distension. Thoracic radiographs revealed sternal lymphadenopathy and a diffuse unstructured interstitial and bronchial pulmonary pattern. An abdominal ultrasound revealed multifocal lymphadenopathy, hepatosplenomegaly, and biliary duct dilation. Fine-needle aspirates of the spleen and liver revealed Histoplasma capsulatum organisms. Antifungal therapy was initiated with itraconazole and terbinafine. Repeat ultrasound examinations revealed resolving hepatosplenomegaly and resolving cystic duct dilation. Ultrasonographic findings mirrored a decrease in urine H capsulatum antigen levels. Histoplasmosis should be considered as a differential for unexplained biliary duct dilation or obstruction in dogs. Dogs with disseminated histoplasmosis should be monitored for this potential complication.

Antifungal Resistance Regarding Malassezia pachydermatis: Where Are We Now?

Malassezia pachydermatis is a yeast inhabiting the skin and ear canals in healthy dogs. In the presence of various predisposing conditions it can cause otitis and dermatitis, which are treated with multiple antifungal agents, mainly azole derivatives. This manuscript aims to review the available evidence regarding the occurrence of resistance phenomena in this organism. Various findings support the capacity of M. pachydermatis for developing resistance. These include some reports of treatment failure in dogs, the reduced antifungal activity found against yeast isolates sampled from dogs with exposure to antifungal drugs and strains exposed to antifungal agents in vitro, and the description of resistance mechanisms. At the same time, the data reviewed may suggest that the development of resistance is a rare eventuality in canine practice. For example, only three publications describe confirmed cases of treatment failure due to antifungal resistance, and most claims of resistance made by past studies are based on interpretive breakpoints that lack sound support from the clinical perspective. However, it is possible that resistant cases are underreported in literature, perhaps due to the difficulty of obtaining a laboratory confirmation given that a standard procedure for susceptibility testing of M. pachydermatis is still unavailable. These considerations highlight the need for maintaining surveillance for the possible emergence of clinically relevant resistance, hopefully through a shared strategy put in place by the scientific community.

Selected Clinical Features of Coccidioidomycosis in Dogs

Canine coccidioidomycosis, a systemic fungal infection endemic to arid and semiarid regions of North, Central, and South America, is commonly diagnosed in dogs living in or traveling through lower Sonoran life zones in the states of California and Arizona. Canine and human cases have geographic overlap. Similarities between clinical coccidioidomycosis in dogs and humans include asymptomatic infection, primary respiratory disease and disseminated disease. Differences include a high rate of dissemination in dogs, differences in predilection of dissemination sites, and a granulomatous or diffuse meningoencephalopathic form in the canine central nervous system (CNS) without the obstructive component seen in humans. Dogs presenting with CNS coccidioidomycosis most commonly experience seizures. Prior disease history and serology are unreliable indicators of CNS coccidioidomycosis. Magnetic resonance imaging (MRI) is advantageous for diagnosis of CNS coccidioidomycosis in dogs. Long-term administration of antifungal medication is promoted for treatment of both primary and disseminated coccidioidomycosis in dogs. Supportive treatment addressing pain, fever, inappetance, coughing, and other clinical signs improves patient care. Glucocorticoids and or anticonvulsants are also recommended for canine disseminated CNS disease. Protracted treatment times, lack of owner compliance, failure of the disease to respond to the first antifungal drug selected, and high cost are challenges of successfully treating dogs.

Opportunistic Fungal Infections in Small Animals

Opportunistic fungal infections have long been recognized as rare causes of disease in immunocompetent dogs and cats. Recently, the escalating use of multiagent immunosuppression protocols (especially those that include cyclosporine) has resulted in an increased number of patients with opportunistic fungal infection encountered by small animal practitioners and has altered the typical case phenotype. Based on histologic and cytologic features such as pigmentation, hyphal diameter, and distribution in tissue, these opportunistic mycoses can be placed into categories such as phaeohyphomycosis, hyalohyphomycosis, and eumycotic mycetoma. This review aims to summarize the clinical presentations, methods for diagnosis, treatment recommendations, and prognosis for both immunocompetent and immunosuppressed patients with opportunistic fungal infections. An example case description is included to illustrate the most common current clinical presentation.

Therapy of Non-Dermatophytic Mycoses in Animals

This review focuses on aspects of antimycotic therapy specific to veterinary medicine. In the first part, drug availability, limited mostly by economic consideration but also by clinical applicability and specific adverse effects, is described for polyenes, 5 fluorocytosine, azoles, echinocandins and terbinafine. In the second part, current knowledge and experience in the treatment of selected fungal infections are overviewed. These mycoses include disseminated mold infections in small animals (dogs and cats) and avian species, upper respiratory tract infections of small animals (sino-nasal and sino-orbital aspergillosis) and horses (guttural pouch mycosis), eumycetoma, infections caused by dimorphic fungi, (blastomycosis, histoplasmosis, coccidioidomycosis, paracoccidioidomycosis and sporothrichosis) and by yeasts and yeast-like microorganism (Cryptococcus spp. and Malassezia pachydermatis).

25-Hydroxyvitamin D concentrations in dogs with naturally acquired blastomycosis

Background

Hypovitaminosis D is common in humans with tuberculosis, and adequate serum 25‐hydroxyvitamin D [25(OH)D] concentrations may improve response to therapy. The pathomechanism of Blastomyces dermatitidis is similar to that of Mycobacterium tuberculosis, but the 25(OH)D status of dogs with blastomycosis has not been investigated.

Objectives

To determine if dogs with blastomycosis have lower 25(OH)D concentrations compared with healthy controls and to explore the prognostic value of 25(OH)D concentrations in blastomycosis.

Animals

35 control dogs (16 client‐owned, healthy dogs and 19 healthy, random‐source hound mixes) and 22 dogs with blastomycosis.

Methods

Prospective study. Serum concentrations of 25(OH)D, parathyroid hormone (PTH), ionized calcium were measured, and biochemistry and hematology profiles were performed. The 25‐hydroxyvitamin D concentrations were compared between groups, and factors associated with 25(OH)D variation were investigated in dogs with blastomycosis. Dogs with blastomycosis were followed for up to 5 years after discharge and factors associated with survival were investigated.

Results

Dogs with blastomycosis had significantly lower concentrations of 25(OH)D and PTH and higher concentrations of ionized calcium than did control dogs. In dogs with blastomycosis, 25(OH)D concentrations were independently associated with neutrophil count, pCO₂, and with bone and skin involvement. The 25‐hydroxyvitamin D concentration was not associated with survival in dogs with blastomycosis, whereas lactate concentrations; bone, skin, and lymph node involvement; number of affected sites; and, presence of respiratory signs were associated with survival.

Conclusions and Clinical Importance

Dogs with blastomycosis had lower 25(OH)D concentrations than did healthy controls. Despite no impact on survival, investigating the effect of 25(OH)D supplementation on recovery is warranted.

Comparison of Compounded, Generic, and Innovator-Formulated Itraconazole in Dogs and Cats

The triazole antifungal itraconazole may be cost prohibitive in brand name form; therefore, compounded and generic products are often used as alternatives. Itraconazole blood concentrations have not been studied in clinical patients receiving these formulations. Itraconazole bioassay was performed on serum/plasma from 95 dogs and 20 cats receiving itraconazole (compounded from bulk powder, generic pelletized, or brand name) for systemic mycosis treatment. Mean itraconazole concentration was lower in the compounded group (n = 42) as compared with the generic (n = 40) or brand name (n = 33) groups (0.5 µg/mL versus 8.3 µg/mL and 6.5 µg/mL, respectively; P < .001). No statistical difference was observed between itraconazole concentrations in the generic and brand name groups. Forty animals (95.2%) in the compounded group had subtherapeutic (<1.0 µg/mL) values. All cats in this group (n = 10) had undetectable itraconazole concentrations. Some animals in the generic and brand name groups had subtherapeutic values (12.5 and 12.1%, respectively) or potentially toxic values (>10 µg/mL; 37.5 and 24%, respectively). Compounded itraconazole should be avoided, but generic itraconazole appears to serve as a reasonable alternative to brand name itraconazole. Therapeutic drug monitoring may be beneficial in all cases.

Blastomycosis in Mammals

Blastomycosis is a serious fungal disease of dogs, humans, and occasionally other mammals caused by geographically restricted, thermally dimorphic Blastomyces species. Blastomycosis is primarily a canine disease, with approximately ten dogs diagnosed for every human case. Dogs also develop disease more rapidly, thus becoming sentinels for possible human disease. Human and canine blastomycosis may differ according to epidemiology/epizoology, clinical features, performance and use of diagnostics, and management.

Diagnosis and treatment of dermatophytosis in dogs and cats.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Dermatophytosis is a superficial fungal skin disease of cats and dogs. The most common pathogens of small animals belong to the genera Microsporum and Trichophyton. It is an important skin disease because it is contagious, infectious and can be transmitted to people.

OBJECTIVES

The objective of this document is to review the existing literature and provide consensus recommendations for veterinary clinicians and lay people on the diagnosis and treatment of dermatophytosis in cats and dogs.

METHODS

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document.

CONCLUSIONS

No one diagnostic test was identified as the gold standard. Successful treatment requires concurrent use of systemic oral antifungals and topical disinfection of the hair coat. Wood's lamp and direct examinations have good positive and negative predictability, systemic antifungal drugs have a wide margin of safety and physical cleaning is most important for decontamination of the exposed environments. Finally, serious complications of animal-human transmission are exceedingly rare.

Pharmacokinetics and Relative Bioavailability of Orally Administered Innovator-Formulated Itraconazole Capsules and Solution in Healthy Dogs

Background

Itraconazole is commonly used for treatment of systemic and cutaneous mycoses in veterinary medicine. Two formulations, capsule and solution, are used interchangeably in dogs. However, marked differences in bioavailability have been reported in other species. Similar investigations have not been performed in dogs.

Objective

To determine and compare pharmacokinetics of itraconazole in dogs after oral administration of commercially available capsule and solution formulations intended for use in humans.

Animals

Eight healthy, adult, purpose‐bred dogs.

Methods

Dogs received approximately 10 mg/kg of innovator‐formulated itraconazole solution and capsule PO in randomized, crossover design with a 10‐day washout period. To ensure maximal absorption, solution was administered to fasted dogs, whereas capsules were co‐administered with food. Blood samples were collected at predetermined time points, and plasma drug concentrations were measured using high‐pressure liquid chromatography. Pharmacokinetic parameters were determined with compartmental analysis.

Results

The mean relative bioavailability of the capsule was 85% that of the solution, but drug absorption was variable, and overall drug concentrations were similar between formulations. Mean elimination half‐lives of both formulations were nearly identical at approximately 33 hours. Regardless of formulation, simulations suggest that a loading dose of 20 mg/kg, followed by 10 mg/kg once every 24 hours, will result in plasma concentrations considered to be adequate in most dogs.

Conclusions and Clinical Importance

Contrary to findings reported in other species, overall drug exposures after capsule and solution administration are not substantially different in dogs. Despite some pharmacokinetic differences between itraconazole capsule and solution, formulation‐specific dosages do not appear to be necessary.

Comparison of two systemic antifungal agents, itraconazole and terbinafine, for the treatment of dermatophytosis in European hedgehogs (Erinaceus europaeus)

BACKGROUND

Dermatophytosis caused by Trichophyton erinacei is a common scaling and crusting skin disease affecting European hedgehogs (Erinaceus europaeus) admitted to wildlife rescue centres. The application of topical therapy can be challenging because wild hedgehogs are subject to stress and often roll into a ball when handled. Systemic antifungal therapy is more convenient but has not been evaluated in this species.

HYPOTHESIS/OBJECTIVES

To compare the efficacy of oral itraconazole versus oral terbinafine for the treatment of dermatophytosis affecting hedgehogs.

ANIMALS

A treatment trial was undertaken in a wildlife hospital involving 165 hedgehogs with naturally occurring dermatophytosis.

METHODS

Animals were randomly divided into two groups and treated with either itraconazole or terbinafine orally for 28 days. The therapeutic efficacy was evaluated after 14 and 28 days by mycological culture and clinical dermatological lesion scores.

RESULTS

Both drugs were well tolerated and clinically effective. After 14 and 28 days of treatment, the respective mycological cure rate was 36.6% and 65.9% for the itraconazole-treated group and 92.8% and 98.8% for the terbinafine-treated group.

CONCLUSION AND CLINICAL IMPORTANCE

Itraconazole and terbinafine were both effective for the treatment of dermatophytosis affecting hedgehogs; however, terbinafine was more effective.

Imaging characteristics of disseminated Geosmithia argillacea causing severe diskospondylitis and meningoencephalomyelitis in a dog

A 4-year-old male castrated Labrador Retriever presented for severe spinal pain. Radiographs and magnetic resonance imaging showed evidence of diskospondylitis and meningoencephalomyelitis. Blood culture revealed a Geosmithia argillacea fungal infection after DNA sequencing, initially misdiagnosed as Penicillium species. Geosmithia argillacea should be considered as a differential for disseminated fungal diskospondylitis.

Alternate-day dosing of itraconazole in healthy adult cats

The current available formulations of itraconazole are not ideal for dosing in cats. The capsular preparation often does not allow for accurate dosing, the oral solution is difficult to administer and poorly tolerated, and the bioavailability of compounded formulations has been shown to be poor in other species. The aim of this study was to evaluate every other day dosing of 100 mg itraconazole capsule in healthy adult cats. Ten healthy adult cats received a 100 mg capsule of itraconazole orally every 48 h for 8 weeks. Peak and trough serum concentrations of itraconazole were measured weekly using high-performance liquid chromatography (HPLC). Physical examination, complete blood count (CBC), and chemistry profiles were performed weekly. The dosage regimen achieved average therapeutic trough concentrations (>0.5 μg/mL) within 3 weeks. The protocol yielded no adverse effects in 8 of the 10 study cats, with affected cats recovering fully with discontinuation of the drug and supportive care. At 8 weeks, an average peak concentration of 1.79 ± 0.952 μg/mL (95% CI: 0.996-2.588) and an average trough concentration of 0.761 ± 0.540 μg/mL (95% CI: 0.314-1.216) were achieved. Overall, a 100 mg every other day oral dosage regimen for itraconazole in cats yielded serum concentrations with minimal fluctuation and with careful monitoring may be considered for treatment of cats with systemic fungal disease.

Blastomycosis in a postpartum dog

Transplacental infection with Blastomyces dermatitidis is rare in humans and unknown in the dog. A Doberman pinscher bitch was diagnosed with blastomycosis 25 days after whelping. Clinical signs were noted after whelping and were progressive. All 9 pups were free of clinical signs and had negative urine Blastomyces antigen tests at 6 weeks of age and remained free of signs of illness through 11 months of age. The bitch responded to treatment with itraconazole.

Serum and urine Blastomyces antigen concentrations as markers of clinical remission in dogs treated for systemic blastomycosis

Background

Serum and urine Blastomyces antigen concentrations can be used to diagnose blastomycosis in dogs.

Objectives

Blastomyces antigen concentrations correlate with clinical remission in dogs during antifungal treatment, and detect disease relapse after treatment discontinuation.

Animals

21 dogs with newly diagnosed blastomycosis monitored until clinical remission (Treatment Phase), and 27 dogs monitored over 1 year from the time of antifungal discontinuation or until clinical relapse (After Treatment Phase).

Methods

Prospective study. Dogs were monitored monthly during treatment and every 3 months after treatment discontinuation, with a complete history, physical exam, chest radiographs, and ocular exam. Urine and serum Blastomyces antigen concentrations were measured at each visit using a quantitative enzyme immunoassay.

Results

At enrollment in the Treatment Phase, Blastomyces antigen was positive in all 21 urine samples (100% sensitivity; 95% CI 85–100%), and in 18 of 20 serum samples (90% sensitivity; 95% CI 70–97%). At 2–4 months of treatment, urine antigen was more sensitive for clinically detectable disease (82%; CI 60–94%) than serum antigen (18%; CI 6–41%). The sensitivity of the urine test for clinical relapse was 71% (CI 36–92%), with close to 100% specificity (CI 84–100%) during after treatment surveillance in this population.

Conclusions

Urine Blastomyces antigen testing has high sensitivity for active disease at the time of diagnosis and during treatment, and moderate sensitivity but high specificity for clinical relapse. Urine testing should be useful at the time of diagnosis, when treatment discontinuation is being considered, and anytime there is poor clinical response or suspicion of relapse.

Bioequivalence of orally administered generic, compounded, and innovator-formulated itraconazole in healthy dogs

Background

Itraconazole is commonly used to treat systemic fungal infections in dogs, but problems exist with absorption and cost.

Objective

To determine oral bioequivalence of generic and compounded itraconazole compared to original innovator (brand name) itraconazole in healthy dogs.

Animals

Nine healthy, adult research Beagle dogs.

Methods

A randomized, 3‐way, 3‐period, crossover design with an 8‐day washout period. After a 12‐hour fast, each dog received 100 mg (average: 10.5 mg/kg) of either innovator itraconazole, an approved human generic capsule, or compounded itraconazole (compounded using a commercially available compounding vehicle) with a small meal. Plasma was collected at predetermined intervals for high pressure liquid chromatography analysis. Concentration data were analyzed using noncompartmental pharmacokinetics to determine area under the curve (AUC), peak concentration (C_MAX), and terminal half‐life. Bioequivalence tests compared generic and compounded itraconazole to the reference formulation.

Results

Average ratios of compounded and generic formulations to the reference formulation of itraconazole for AUC were 5.52% and 104.2%, respectively, and for C_MAX were 4.14% and 86.34%, respectively. A test of bioequivalence using 2 one‐sided tests and 90% confidence intervals did not meet bioequivalence criteria for either formulation.

Conclusion and Clinical Importance

Neither generic nor compounded itraconazole is bioequivalent to the reference formulation in dogs. However, pharmacokinetic data for generic formulation were similar enough that therapeutic concentrations could be achieved. Compounded itraconazole produced such low plasma concentrations, it is unlikely to be effective; therefore, compounded itraconazole should not be used in dogs.

Cryptococcosis as an emerging systemic mycosis in dogs

OBJECTIVE

To review the etiology, pathogenesis, and clinical presentations of canine cryptococcosis that are of relevance to veterinary emergency and critical care veterinarians. Diagnosis, treatment, and public health considerations of the disease will also be discussed.

ETIOLOGY

Cryptococcosis is a multisystemic disease of dogs, with a predilection for the CNS, caused by encapsulated yeast species of the genus Cryptococcus. The 2 main pathogenic species are Cryptococcus neoformans and Cryptococcus gattii (previously known as C. neoformans var. gattii). Cryptococcosis is an emerging disease in North America, with C. gattii gaining prominence as a cause of serious veterinary and human disease.

DIAGNOSIS

Definitive diagnosis is made by serologic (antigen) testing, culture, and identification of the organism using light microscopy. False negatives and false positives, while uncommon, can occur in dogs using commercially available antigen tests. Cytological examination demonstrates the organism in a majority of cases, although culture is more sensitive. Specific media are required to differentiate between C. neoformans and C. gattii.

THERAPY

The most commonly used antifungal drugs to treat canine cryptococcosis are azole antifungals and amphotericin B. Some strains of Cryptococcus are resistant to antifungal drugs, especially fluconazole. Cautious use of glucocorticoids in critically affected dogs with CNS presentations can improve outcome.

PROGNOSIS

Prognosis is variable and depends on the severity of disease, underlying host immunocompetence, and financial constraints of the owner. Altered mental status in dogs with CNS cryptococcosis is a negative prognostic indicator.

Successful Treatment of Intracardiac and Intraocular Blastomycosis in a Dog with Combination Azole Therapy

A 4 yr old spayed female Labrador retriever with clinical signs of blindness, cutaneous lesions, coughing, inappetence, and lethargy was diagnosed with disseminated blastomycosis based on cytologic (skin and lymph node aspirates) and histopathologic (skin biopsy) examinations of tissue samples. The dog deteriorated clinically during hospitalization and developed sustained ventricular tachycardia. Echocardiography revealed pericardial effusion, a nodule associated with the left ventricular papillary muscle, and a right atrial mural lesion. Therapy for myocardial performance and glaucoma was initiated. A combination of itraconazole and fluconazole successfully treated the dog. The dog regained vision in the left eye (oculus sinister [OS]) and had no residual cardiac disease detectable by either electrocardiography or echocardiography. This report is unique in documenting survival from intracardiac blastomycosis and in the use of combination azole therapy for treating disseminated disease with intraocular involvement.

Cutaneous vasculitis in small animals

Cutaneous vasculitis is an inflammatory process targeting blood vessels. Underlying factors include drugs, infectious diseases, adverse reactions to food, malignancies, and immune-mediated diseases. Vasculitis is a reaction pattern warranting a workup to identify triggers. Presenting symptoms include purpura, pitting edema, and skin ulcerations. Constitutional signs include fever, depression, and anorexia and seem to be present in the majority of patients. Once a diagnosis is confirmed, treatment and follow-up must be tailored to the individual. High-dose immunosuppressive medications are only recommended once infectious diseases capable of producing a similar constellation of clinical signs have been ruled out.

Sinonasal aspergillosis in dogs: a review

Sinonasal aspergillosis is an uncommon, yet debilitating and often frustrating condition to treat in dogs despite years of research evaluating pathogenesis, diagnosis and treatment. The disease is most commonly caused by non-invasive fungal infection, thought to be secondary to altered innate and/or adaptive immune responses. Attempts to confirm this have however failed. A variety of conflicting opinions regarding the diagnosis and treatment of sinonasal aspergillosis exist. Often the use of a particular treatment protocol is based upon personal or regional preference. Evaluation of the veterinary literature demonstrates that the evidence base in support of individual treatment recommendations is weak. A number of recent publications have helped to expand the current knowledge base and therefore our understanding of important practicalities for both diagnostic options and treatment protocols. The following review examines the current evidence for the pathogenesis of sinonasal aspergillosis in dogs, as well as the various diagnostic options. The available evidence for frequently utilised -therapeutic options and their likely outcomes is also explored.

A review of the pathology and treatment of canine respiratory infections

Numerous infectious agents are responsible for causing primary or secondary respiratory disease in dogs. These agents can cause upper or lower respiratory infections commonly observed in veterinary practices. Clinical signs might vary from mild dyspnea, sneezing, and coughing to severe pneumonia with systemic manifestations. Depending on the etiologic agent, the gross and microscopic changes observed during these infections can be rather unspecific or have highly characteristic patterns. While histopathology and cytology are not always required for diagnosis of respiratory infections, they are often useful for establishing a definitive diagnosis and identifying specific etiologic agents. Research regarding epidemiology, pathogenesis, diagnostics, and clinical manifestations related to these infectious pathogens provides valuable information that has improved treatments and management of the diseases they cause. This review discusses the epidemiology, general clinical characteristics, and pathologic lesions for some of the important viral, bacterial, fungal, and parasitic etiologies of canine respiratory disease.

Successful management of an intracranial phaeohyphomycotic fungal granuloma in a dog

CASE DESCRIPTION

A 12-month-old castrated male Boxer was examined because of signs of acute, progressive intracranial disease.

CLINICAL FINDINGS

Cytologic and histologic findings were consistent with an intracranial fungal granuloma in the right cerebral hemisphere. Fungal culture yielded a Cladophialophora sp.

TREATMENT AND OUTCOME

The granuloma was surgically debulked to remove infected brain tissue and the avascular purulent core. Postoperatively, the patient was treated with fluconazole (2.3 mg/kg [1 mg/lb], PO, q 12 h) for 4 months, followed by voriconazole (3.4 mg/kg [1.5 mg/lb], PO, q 12 h) for a further 10 months. The outcome was considered excellent on the basis of resolution of neurologic signs and a lack of evidence of recurrence of the granuloma during magnetic resonance imaging and CSF analysis 8 months after surgery. Magnetic resonance imaging and CSF analysis 9 weeks after administration of antifungal medications was discontinued (16 months after surgery) confirmed resolution.

CLINICAL RELEVANCE

Intracranial phaeohyphomycosis in small animals is rare and is most commonly associated with Cladophialophora infection. Phaeohyphomycosis frequently causes a focal granuloma, whereas other fungal infections typically cause diffuse meningoencephalitis. In all previous reports of phaeohyphomycosis of the CNS in dogs, treatment has been limited to medical management with conventional antifungal drugs and had failed to prevent death. The present report suggested that combined management of granulomas with surgery and newer triazole medications such as voriconazole may represent a novel strategy that improves the prognosis for this disease.

Clinical and Imaging Findings in Five Dogs with Intracranial Blastomycosis (Blastomyces dermatiditis)

Fungal infections affecting the central nervous system are rare. The purpose of this study was to describe clinical and imaging findings in dogs with intracranial blastomycosis (Blastomyces dermatiditis). The radiology database was searched retrospectively for patients with a diagnosis of intracranial blastomycosis which had computed tomography performed as part of their diagnostic work-up. Medical records and imaging studies were reviewed. Five dogs met the inclusion criteria. Major presenting complaints were stertor/nasal discharge (n=2), exophthalmos (n=1), and seizures (n=2). Clinical and laboratory findings were variable. Computed tomographic examination revealed a single contrast-enhancing intra-axial mass (n=1), a nasal mass disrupting the cribriform plate (n=3), and an intracranial mass extending into the orbit and nasal cavity (n=1). Findings in intracranial blastomycosis in dogs are variable, and the disease may mimic other inflammatory disorders or neoplasia.

Antifungal treatment of small animal veterinary patients

Antifungal therapy has progressed significantly with the development of new drugs directed at various processes in fungal cell metabolism. Within veterinary medicine, treatment options for systemic mycoses remain limited to amphotericin B, ketoconazole, fluconazole, and itraconazole. However, newer triazoles, echinocandins, and lipid-based formulations of amphotericin B are now approved for use in humans. This article provides a comprehensive review of the antifungal medications available for veterinary patients, and includes a brief discussion of the newer, presently cost-prohibitive, antifungal therapies used for systemic mycoses in humans.

Patellar blastomycosis in a dog

A 4-year-old, spayed female, mixed-breed dog was presented for evaluation of chronic left hind-limb lameness. Lytic lesions were observed in the left patella on radiographs of the stifle. A biopsy of the patella led to a histopathological diagnosis of blastomycosis. Surgical debridement followed by a 90-day course of itraconazole and physical rehabilitation resolved the clinical signs and stopped the progression of radiographic lesions. Blastomycosis should be considered as a differential diagnosis for stifle joint lameness with lytic lesions in the patella.

Coccidioidomycosis in dogs and cats: a review

The dimorphic fungi Coccidioides immitis and Coccidioides posadasii are the causative agents of coccidioidomycosis. Dogs and cats residing in and visiting endemic areas are at risk of exposure to infectious arthrospores. The primary infection is pulmonary and frequently results in chronic cough. Disseminated disease is common and causes cutaneous, osseous, cardiac, ocular, nervous system, or other organ disease. Radiographic changes include a variable degree of interstitial pulmonary infiltration, hilar lymphadenopathy, and osseous lesions. Serological titers support the diagnosis, but definitive diagnosis relies on identification of Coccidioides in cytological or tissue samples. Coccidioidomycosis should be considered in any dog or cat that has been potentially exposed during the previous 3 years and is presented with chronic illness, respiratory signs, lameness, lymphadenopathy, nonhealing cutaneous lesions, or neurological, ocular, or cardiac abnormalities.

Diagnosis and treatment of blastomycosis affecting the nose and nasopharynx of a dog

CASE DESCRIPTION

A 2-year-old 38.9-kg (85.58-lb) sexually intact male German Shepherd Dog was examined because of a 4-month history of severe nasal swelling and nasal mucosa congestion. The signs were slowly progressive.

CLINICAL FINDINGS

Physical examination revealed that the dorsal aspect of the dog's nose was swollen and hard. Mucous membranes in both nostrils were hyperemic and edematous. Diagnostic investigation revealed severe nasal osteolysis and pyogranulomatous rhinitis and nasopharyngitis attributable to blastomycosis.

TREATMENT AND OUTCOME

Oral administration of itraconazole was initiated (5 mg/kg [2.27 mg/lb], q 12 h for 5 days and then q 24 h). After a treatment period of 3 months, the nose had regained its normal appearance. After 5 months of treatment, the Blastomyces infection was eliminated as confirmed by results of rhinoscopy and biopsy specimen examination. No relapse was evident within 1 year after discontinuation of treatment.

CLINICAL RELEVANCE

In dogs, nasal and nasopharyngeal blastomycosis can result in severe osteolysis of the nasal bone. Resolution of disease can be achieved with oral administration of itraconazole for a period of at least 5 months.

Canine and feline uveitis

The clinical signs of uveitis occur as a result of inflammation within the vascular coat of the eye, which causes breakdown of the blood-aqueous barrier and blood-retinal barrier. Many infectious and noninfectious causes can incite episodes of uveitis. Although a complete diagnostic evaluation is highly recommended to identify any underlying etiologic agent, many cases remain idiopathic in nature. The goals of therapy are preserving vision, minimizing pain, and halting inflammation.