Parasitemia in an immunocompetent horse experimentally challenged with Sarcocystis neurona sporocysts

Equine protozoal myeloencephalitis (EPM) is a serious neurological disease of horses in Americans. Most cases are attributed to infection of the central nervous system with Sarcocystis neurona. Parasitemia has not been demonstrated in immunocompetent horses, but has been documented in one immunocompromised foal. The objective of this study was to isolate viable S. neurona from the blood of immunocompetent horses. Horses used in this study received orally administered S. neurona sporocysts (strain SN 37-R) daily for 112 days at the following doses: 100/day for 28 days, followed by 500/day for 28 days, followed by 1000/day for 56 days. On day 98 of the study, six yearling colts were selected for attempted culture of S. neurona from blood, two testing positive, two testing suspect and two testing negative for antibodies against S. neurona on day 84 of the study. Two 10 ml tubes with EDTA were filled from each horse by jugular venipuncture and the plasma fraction rich in mononuclear cells was pipetted onto confluent equine dermal cell cultures. The cultures were monitored weekly for parasite growth for 12 weeks. Merozoites grown from cultures were harvested and tested using S. neurona-specific PCR with RFLP to confirm species identity. PCR products were sequenced and compared to known strains of S. neurona. After 38 days of in vitro incubation, one cell culture from a horse testing positive for antibodies against S. neurona was positive for parasite growth while the five remaining cultures remained negative for parasite growth for all 12 weeks. The Sarcocystis isolate recovered from cell culture was confirmed to be S. neurona by PCR with RFLP. Gene sequence analysis revealed that the isolate was identical to the challenge strain SN-37R and differed from two known strains UCD1 and MIH1. To our knowledge this is the first report of parasitemia with S. neurona in an immunocompetent horse.     

Multi-centre assessment of mycotic rhinosinusitis in dogs: a retrospective study of initial treatment success (1998 to 2008)

Objectives : To retrospectively review the first treatment response of dogs with mycotic rhinosinusitis to commonly utilised treatment techniques. Methods : Medical records of dogs treated for mycotic rhinosinusitis were obtained retrospectively via a manual review of the clinical databases of six veterinary referral centres for the period of January 1998 to June 2008, and first treatment outcome was evaluated. Historical and clinicopathological findings were also reviewed to evaluate their impact on treatment success or failure. Results : There was no significant difference in first treatment outcome between treatment groups (P=0·21). When all topical treatments were considered together (n=85), 39 dogs (45·8%) had a successful first treatment. Initial treatment success was associated with a younger age (56·3 versus 75·8 months; P=0·02) and was 2·7 times more likely in dogs with unilateral disease, although this was not significant (P=0·07). Adjunctive therapy with systemic antifungal agents was associated with treatment failure (PÄ0·01). Fifty-nine dogs (69·4%) responded successfully following multiple treatments. Clinical Significance : Treatment of mycotic rhinosinusitis remains challenging, and multiple treatments are frequently required for adequate treatment. Reasons for first treatment failure are likely multifactorial in origin, making it difficult to predict those dogs that are likely to have a superior prognosis, regardless of the treatment type used.     

Masitinib as a chemosensitizer of canine tumor cell lines: a proof of concept study

Masitinib, a selective tyrosine kinase inhibitor, has previously been shown to enhance the antiproliferative effects of gemcitabine in human pancreatic cancer, demonstrating potential as a chemosensitizer. This exploratory study investigated the ability of masitinib to sensitize various canine cancer cell lines to doxorubicin, vinblastine, and gemcitabine. Masitinib strongly sensitized histiocytic sarcoma cells to vinblastine (>70-fold reduction in IC(50) at 5 μM masitinib), as well as osteosarcoma and mammary carcinoma cells to gemcitabine (>70-fold reduction at 5-10 μM). In addition, several cell lines were sensitized to doxorubicin (2-10-fold reduction at 10 μM). These data establish proof-of-concept that masitinib in combination with chemotherapeutic agents can generate synergistic growth inhibition in various canine cancers, possibly through chemosensitization. The findings justify further investigation into those combinations that may potentially yield therapeutic benefit.     

Treatment of insulinoma in a springer spaniel with streptozotocin

An eight-year-old, female springer spaniel was treated for metastatic insulinoma with a single intravenous dose of 500 mg/m2 streptozotocin (SZN), and pre- and post-treatment diuresis. A tapering dose of corticosteroids was also administered over a 28 day period. SZN and corticosteroid administration resulted in resolution of hypoglycaemia and subsequent development of diabetes mellitus. Further metastases caused cervical spinal pain and the dog was euthanased 118 days after SZN administration. SZN can be safely used for the treatment of canine insulinoma, but, when compared with other published cases, a marked variation in clinical response to this drug exists and further study is warranted.     

Trichuris suis excretory secretory products (ESP) elicit interleukin-6 (IL-6) and IL-10 secretion from intestinal epithelial cells (IPEC-1)

Immune responses to gastrointestinal helminth infections have received increasing attention due to similarities to allergen-induced responses. In fact, the whipworm parasite of swine, Trichuris suis, has been used in beginning clinical trials as an antidote to inflammatory bowel disease. This strategy was based on this similarity and the recognition that other worms have been documented to induce anti-inflammatory responses in the host. In an effort to understand the basis for this response, we hypothesized that the proteins and peptides secreted by T. suis stimulate local intestinal epithelial cells to produce anti-inflammatory cytokines. To test this hypothesis in a correlate system of the natural swine host, T. suis excretory secretory products (ESP) were used to treat both differentiated and undifferentiated intestinal pig epithelial cells (IPEC-1) in vitro as a model for the effect on villus tip and crypt epithelial cells in the vicinity of the worms. IPEC-1 were exposed to low-level doses (0.3mg/ml) of T. suis ESP, and IL-4, IL-6 and IL-10 cytokine responses were measured by an enzyme-linked immunosorbant assay (ELISA). IL-6 was the predominant cytokine produced, accompanied by moderate IL-10 secretion from both differentiated and undifferentiated cells. As expected, IL-4 was not produced by IPEC-1. Additionally, IL-6 and IL-10 cytokines were produced within 24h, suggesting that these two cytokines form part of the primary host response to T. suis infections. These data suggest that T. suis ESP could enhance host immune responses and modulation through the induction of enteric IL-6 and IL-10.     

Presumptive Nocardia spp. infection in a dog treated with cyclosporin and ketoconazole

Abstract

CASE HISTORY: A dog that had received 8 months of cyclosporin and ketoconazole therapy for treatment of atopic dermatitis subsequently developed severe neurological disease, that failed to respond to treatment with trimethoprim-sulphadiazine and clindamycin.

HISTOPATHOLOGICAL FINDINGS: Histopathological examination of the pulmonary parenchyma and spinal cord revealed loose aggregates of Gram-positive, partially acid-fast, fine, beaded, filamentous bacteria, most consistent with Nocardia spp.

DIAGNOSIS: A presumptive diagnosis was made of disseminated nocardiosis of the spinal cord and lungs.

CLINICAL RELEVANCE: Nocardia spp. is an opportunistic actinomycete that may cause disseminated disease, particularly in immunocompromised animals. Cyclosporin is used in veterinary medicine to control immune-mediated and allergic disorders, with few reported adverse side effects. This case gives further evidence that involvement of the spinal cord in nocardiosis of the central nervous system (CNS) carries a poor prognosis, and opportunistic infection by Nocardia spp. may be a potential complication of immunosuppressive cyclosporin therapy in the dog.     

Remission of Histiocytic Ulcerative Colitis in Boxer Dogs Correlates with Eradication of Invasive Intramucosal Escherichia coli

Background: Historically, histiocytic ulcerative (HUC) (or granulomatous) colitis of Boxer dogs was considered an idiopathic immune-mediated disease with a poor prognosis. Recent reports of dramatic responses to enrofloxacin and the discovery of invasive Escherichia coli within the colonic mucosa of affected Boxer dogs support an infectious etiology.
Hypothesis: Invasive E. coli is associated with colonic inflammation in Boxer dogs with HUC, and eradication of intramucosal E. coli correlates with clinical and histologic remission.
Animals: Seven Boxer dogs with HUC.
Methods: Prospective case series. Colonic biopsies were obtained at initial evaluation in 7 dogs, and in 5 dogs after treatment with enrofloxacin. Biopsies were evaluated by standardized histopathology, and fluorescence in situ hybridization (FISH) with probes to eubacteria and E. coli .
Results: Intramucosal E. coli was present in colonic biopsies of 7/7 Boxers with HUC. Clinical response was noted in all dogs within 2 weeks of enrofloxacin (7±3.06 mg/kg q24 h, for 9.5±3.98 weeks) and was sustained in 6 dogs (median disease-free interval to date of 47 months, range 17–62). FISH was negative for E. coli in 4/5 dogs after enrofloxacin. E. coli resistant to enrofloxacin were present in the FISH-positive dog that relapsed.
Conclusions and Clinical Relevance: The correlation between clinical remission and the eradication of mucosally invasive E. coli during treatment with enrofloxacin supports the causal involvement of E. coli in the development of HUC in susceptible Boxer dogs. A poor response to enrofloxacin treatment might be due to colonization with enrofloxacin-resistant E. coli .     

Concentrations of interleukin-6, -8, -10 and tumour necrosis factor-α in the faeces of dogs with acute diarrhoea

Aim: To compare the concentration of faecal cytokines interleukin (IL)-6, -8, -10, and tumour necrosis factor (TNF)-α in dogs with acute diarrhoea with clinically normal (non-diarrhoeic) dogs.

Methods: A total of 14 dogs presenting with acute diarrhoea, and 25 dogs with no history of gastrointestinal signs in the 2 months prior to enrolment, were recruited from two veterinary hospitals in Melbourne, Australia. Concentrations of IL-6, -8, -10, and TNF-α were measured in faecal samples using canine-specific ELISA.

Results: The diarrhoeic dogs were diagnosed with or managed for acute gastroenteritis (n?=?6), extra-intestinal neoplasia (n?=?2), parvoviral enteritis (n?=?1), hepatopathy (n?=?1), acute pancreatitis (n?=?1), hypoadrenocorticism (n?=?1), gastric dilatation volvulus (n?=?1) and myelopathy (n?=?1). IL-6 was detectable in the faeces of 10/14 (71%) diarrhoeic and 7/25 (28%) non-diarrhoeic dogs, and median concentrations were 10.8 (min 0.0, max?54.0) and 2.0 (min 0.0, max15.0) pg/mL, respectively (p?=?0.01). IL-8 was detectable in the faeces of all diarrhoeic and 11 non-diarrhoeic dogs, and median concentrations were 149.7 (min 3.72, max?730.1) and 3.4 (min 0.0, max?22.5)?pg/mL, respectively (p?<?0.001). TNF-α was detected in the faeces of two of the diarrhoeic dogs (3.4 and 15.6?pg/mL) and none of the non-diarrhoeic dogs. IL-10 was not detected in the faeces of any dog.

Conclusions: Faecal concentrations of IL-6 and -8 were higher in diarrhoeic compared to non-diarrhoeic dogs, and are therefore potential candidates for non-invasive biomarkers to assess the severity and resolution of acute intestinal disease in dogs. However their correlation with disease progression and severity needs to be further investigated before their full clinical application can be determined.