C. Quintavalla

Efficacy of a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine in pigs naturally exposed to a heterologous European (Italian cluster) field strain: Clinical protection and cell-mediated immunity

The purpose of this study was to assess clinical protection in pigs vaccinated with a commercially available attenuated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine (Porcilis) PRRS) and then naturally exposed under field conditions to a heterologous (Italian cluster) strain of virulent PRRSV. A total of 30, 4-week-old pigs seronegative for PRRSV were allocated to 1 of 3 groups (IM, ID, and C groups). At 5 weeks of age, pigs of groups IM (n=10 pigs) and ID (n=10 pigs) were vaccinated intramuscularly and intradermally, respectively, with modified live PRRSV-1 vaccine (Porcilis) PRRS). Pigs of group C (n=10 pigs) were kept as non-vaccinated controls. At post-vaccination (PV) days 0, 7, 14, 28, and 45, blood samples were collected for detection of vaccine virus (PCR) and antibody response (ELISA), identification of changes in lymphocyte subpopulations by cytometry, and IFN-gamma PRRSV-specific secreting cells (SC) by ELISpot. At PV day 45, pigs of A, B, and C groups were moved to a site 3 conventional finishing herd with a history of respiratory disease caused by PRRSV and the most common bacteria to be exposed to a natural challenge. The PRRSV field strain, belonging to the Italian cluster of the PRRSV-1, demonstrated a 84% identity with the vaccine virus (DV strain) at ORF5 sequencing. At 0 (exposure day=45 days PV), 4, 7, 11, 14, 19, 21, 28, and 34 days post-exposure (PE) blood samples were collected for detection and titration of PRRSV and antibody, as well as for lymphocyte and IFN-gamma measurement as described above. Throughout the post-exposure period, all pigs were observed daily for clinical signs. The overall clinical signs were reduced by 68 and 72%, respectively in the intramuscularly and intradermally vaccinated pigs compared to controls. Respiratory signs were reduced by 72 and 80%, respectively in the IM and ID groups. Clinical protection was associated with marked activation of cell-mediated immune response. The highest levels of specific IFN-gamma production at 21-34 days PE were concomitant and associated to changes in natural killer (NK) cells, gamma/delta T, and cytotoxic T lymphocytes in the blood. In our field study, evidences of EU attenuated vaccine-induced clinical protection against natural exposure to a genetically diverse (84% homology) PRRSV-1 isolate (Italian cluster) was demonstrated by the statistically significant reduction in clinical signs in terms of incidence, duration and severity and by a more efficient cell-mediated immune response in the vaccinated pigs as compared to the unvaccinated controls.

A combination of doxycycline and ivermectin is adulticidal in dogs with naturally acquired heartworm disease (Dirofilaria immitis).

Canine heartworm disease is caused by infection with Dirofilaria immitis, a filarial nematode that resides in the pulmonary arteries and occasionally in the right heart chambers of infected dogs. Here the authors evaluated the effect of a combination of doxycycline (10 mg/kg/sid for 30 days) and ivermectin–pyrantel(6μg/kg [DOSAGE ERROR CORRECTED] of ivermectin+5mg/kg of pyrantel every 15 days for 180 days) on microfilariemia, antigenemia and parasite load at echocardiography in naturally infected dogs from an endemic region of Italy. Dogs were examined monthly for 6 months and followed-up 4 months later. One hundred percent of dogs became negative for circulating microfilariae by day 90, while 8/11 (72.7%) of dogs became antigen-negative by day 300. Of the 7 dogs that were positive for visualization of parasites at echocardiography, 6 (85.7%) became negative by day 300. Treatment was well-tolerated by all dogs. These results suggest that a combination of doxycycline and ivermectin is adulticide in dogs with D. immitis.

Prevalence of Congenital Heart Disease in Boxers in Italy

OBJECTIVE To evaluate the prevalence of congenital heart disease in boxers in Italy by auscultation and echocardiography. METHODS This randomized study involved 500 boxers. The inclusion criteria were that the animals should be asymptomatic, older than 1 year and with a pedigree. Dogs with a heart murmur underwent a complete echo-Doppler examination. The criteria for the diagnosis of aortic or pulmonic stenosis were: heart murmur on cardiac auscultation; direct imaging of the obstructive lesions; turbulent aortic or pulmonic flow with peak velocity of >2 m/sec and > 1.5 m/sec, respectively. RESULTS 265 out of 500 dogs exhibited a heart murmur on cardiac auscultation. According to echo-Doppler examination, 89 (17.8%) dogs were affected with congenital heart disease. Subaortic stenosis and/or pulmonic stenosis accounted for all cases identified, although subaortic stenosis was more prevalent. Type I (63.75%) and Type II (21.25%) subaortic stenosis were the most common forms of the disease. Type A was the most prevalent type of pulmonic stenosis (74.2%). None of the dogs with a heart murmur of grade 1/6 or 2/6 complied with all the pre-selected criteria, and they were not considered to be affected with congenital heart disease. CONCLUSIONS The prevalence of congenital heart disease in boxers in Italy appears to be very high (17.8%). In this study, subaortic stenosis and pulmonic stenosis accounted for all identified heart diseases. These findings support a the suspicion of these diseases when a heart murmur is found in a boxer, but only Doppler echocardiography can differentiate between subaortic stenosis and pulmonic stenosis.

Disseminated histoplasmosis in a cat in Europe

A cat was presented with a history of vomiting, decreased appetite and weight loss. Abnormal findings were poor body condition, pale mucous membranes, dehydration and a palpable abdominal mass. Abdominal ultrasound showed lymph node enlargement, a mass of uncertain origin, thickening of the muscularis layer of the small bowel, focal thickening of the ileum with loss of layering and free peritoneal fluid. Cytology revealed a piogranulomatous infiltrate and numerous macrophages containing oval or round yeast‐like cells 2 to 5 µm diameter with a central, spherical, lightly basophilic body surrounded by a clear halo, compatible with Histoplasma capsulatum, within the cytoplasm. Post‐mortem examination revealed cavity effusions, granulomatous nodules in lungs, intestine and omentum, thickened intestinal walls and intestinal perforation. Staining with Grocott and immunohistochemistry (IHC) revealed numerous organisms within the granulomatous reaction. H. capsulatum has a worldwide distribution in temperate and subtropical climates. To the author’s knowledge, this is the first report of feline histoplasmosis in Europe.

Congenital heart disease in boxer dogs: results of 6 years of breed screening.

The aim of this study was to analyse the results of 6years (1999-2004) of mandatory breed screening for congenital heart disease in Boxer dogs using physical examination and echocardiography. Records of 1283 Boxers were reviewed and 165 dogs (12.86%) were found to be affected by heart disease, with aortic and pulmonic stenosis being the most frequent cardiac lesions. Comparison of these results with those of a previous survey showed a lower overall prevalence of both outflow obstructions, particularly of the more severe forms. A male predisposition for both aortic and pulmonic stenosis was evident from the study. Consistent with reports from other countries, soft left basilar heart murmurs were detected in both healthy dogs and dogs affected with congenital heart disease.

Aorto-septal angle in Boxer dogs with subaortic stenosis: an echocardiographic study.

The present study was designed to determine the aorto-septal angle (AoSA) in Boxer dogs with or without subaortic stenosis (SAS) by using two-dimensional echocardiography. Forty-five Boxer dogs were prospectively included in the study. The AoSA was steeper in the group with SAS than in healthy Boxers with a mean difference of 10 degrees . According to the proposed regression model, the AoSA is associated with SAS in Boxers, particularly because it becomes steeper as SAS severity increases. Several studies in humans demonstrate that small changes in the AoSA produce important changes in septal shear stress, which in turn causes proliferation of the endocardial cells resulting in subaortic obstruction. A definite conclusion about the role of the AoSA on the formation and/or progression of subvalvular lesions in Boxers cannot be drawn from the data analysed due to the transversal nature of the observations.

Clinical assessment of post-adulticide complications in Dirofilaria immitis-naturally infected dogs treated with doxycycline and ivermectin.

This study shows that a combination of doxycycline (10mg/kg/sid for 30 days) and ivermectin (6 μg/kg/every 15 days for 6 months) is well tolerated for the treatment of canine heartworm disease (HWD). Monthly echocardiography showed that 84% of treated dogs either progressively improved parameters indicative of pulmonary hypertension or, following slight worsening, resolved all signs. Thoracic radiography showed the persistence of interstitial inflammation, even though also in this case, approximately 70% of the dogs steadily improved or worsened but then improved by the end of the study.

Tumour Thrombus: Direct Endoluminal 'Caudal Caval Vein - Right Atrium' Extension in a Dog Affected by Adrenal Neoplasia

D. Pradelli1*, C. Quintavalla1, O. Domenech2 and C. Bussadori2 1Department of Animal Health, Section of Veterinary Internal Medicine, Faculty of Veterinary Medicine, University of Parma, V ia del Taglio 8, 43100 Parma; 2Practitioner, Milan, Italy *Correspondence: Dipartimento di Salute Animale, Sezione di Clinica Medica Veterinaria, Facoltà di Medicina Veterinaria, V ia del Taglio 8, 43100 Parma, Italy E-mail: danitza.pradelli@libero.it

Cytokine expression in peripheral blood mononuclear cells of dogs with mitral valve disease.

Inflammation plays an important role in the pathogenesis of congestive heart failure (CHF). In humans with CHF, increased production and high plasma concentrations of tumour necrosis factor-α (TNF-α), interleukin (IL)-6, IL-1, IL-8 and transforming growth factor-β (TGF-β) have been associated with disease progression and a negative prognosis. The aim of this study was to investigate whether differences in cytokine blood mRNA expression exist between clinically healthy dogs and dogs with myxomatous mitral valve disease (MMVD); to determine if the expression was related to the severity of MMVD, and to detect any correlations with echocardiographic parameters of cardiac remodelling. Twenty-three dogs with MMVD of varying severity and six clinically healthy dogs were included in the study. Whole blood samples were obtained for measurement of mRNA expression of IL-1α, IL-1β, IL-6, IL-8, TGF-β1, TNF-α by reverse transcriptase-PCR (RT-PCR). There were statistically significant differences between clinically healthy dogs and dogs with MMVD for IL-8 and TGF-β1 gene expression. IL-8 expression increased with increasing MMVD severity and TGF-β1 expression was higher in asymptomatic dogs with echocardiographic signs of cardiac remodelling (American College Veterinary Internal Medicine class B2) than in all other groups. These results could suggest the involvement of these cytokines at different stages of the disease.

Wolbachia, doxycycline and macrocyclic lactones: New prospects in the treatment of canine heartworm disease

Melarsomine dihydrochloride (Immiticide®, Merial) is the only approved adulticidal drug for the treatment of canine heartworm disease (HWD). However, in cases where arsenical therapy is not possible or is contraindicated, a monthly heartworm preventive along with doxycycline for a 4-week period, which targets the bacterial endosymbiont Wolbachia, might be considered. There are published reports on the efficacy of ivermectin and doxycycline in both experimentally and naturally infected dogs, but no data on the use of other macrocyclic lactones (MLs) with a similar treatment regime. Preliminary results of studies in dogs show that a topical formulation of moxidectin, the only ML currently registered as a microfilaricide, is also adulticidal when combined with doxycycline. It is not yet known if the efficacy of these combination therapies is due to pharmacokinetic synergism. A recent study showed that serum levels of doxycycline in dogs treated with the combination protocol were not statistically different compared to dogs treated with doxycycline alone. However, lungs from dogs treated with the combination therapy showed a marked reduction in T regulatory cells, indicating that treatment efficacy may be due to a heightened immune response against the parasite. Further studies are necessary to evaluate the long-term clinical outcome of combination protocols and to establish the most efficient treatment for HWD in dogs.