Atypical case of subcutaneous filariosis in a cat caused by Dirofilaria immitis.

Subcutaneous dirofilariosis is a well-known disease caused mainly by Dirofilaria repens and described in several mammalian species including humans, dogs, and cats. Additionally, early developing stages of the heartworm Dirofilaria immitis are rarely reported in subcutaneous localization from humans and dogs. To our knowledge, confirmed clinical evidence of this condition has not been described in the cats yet, even if the feline hosts can be affected either by the classic adult-related heartworm form or heartworm-associated respiratory disease (HARD) caused by immature stages. A 2 year old, spayed male cat was presented for three subcutaneous nodules on the head and trunk. The cat lived in Northern Italy and was regularly vaccinated and treated monthly with an antiparasitic spot on formulation containing selamectin. One of the three nodules was surgically excised and examined. Histology showed the presence of a nodular lesion in the subcutis characterized by a severe inflammatory infiltrate composed of macrophages, small lymphocytes, with fewer eosinophils, and mast cells, supported by a proliferation of mature fibroblasts (fibrosis). Inflammatory cells were multifocally surrounding sections of parasites identified as adult nematodes. Microscopic features were compatible with D. immitis, which has been molecularly confirmed (98.2% identity to D. immitis isolate OP107739). The cat tested negative for D. immitis antigenemia and the two remaining nodules disappeared spontaneously in a few months. In region where heartworm is prevalent, aberrant localization of D. immitis should be considered in the differential diagnoses of subcutaneous filarial worms in cats and dogs.

Are analytical performance specifications derived from reference intervals of any use in the veterinary clinical laboratory? A preliminary study on the empirical biological variation model.

BACKGROUND: Analytical performance specifications (APS) are vital for method evaluation and quality control validation. However, the limited availability of biological variation (BV) data, regulatory guidelines, and expert opinion (EO) may present challenges in veterinary medicine. The empirical biological variation (EBV) approach, based on population reference intervals (pRI), has emerged as an alternative method to derive APS in human medicine. OBJECTIVES: This study aimed to assess the practicality and usefulness of the EBV approach in deriving performance limits for various measurands in dogs and cats. METHODS: Eight hematology and 13 biochemistry measurands were analyzed in dogs and cats. Estimates of combined biologic variation based on traditional biological (CVB ) and EBV-derived (CVE *) formulas were calculated and assessed for evidence of correlation. Performance limits for expanded uncertainty/total error and imprecision were compared among EO, BV, and EBV. RESULTS: Strong and significant correlations were found between CVB and CVE * for both dogs (r = .86, p < .00001) and cats (r = 0.95, p < .00001). The EBV-derived APS were generally comparable to EO and BV, with a subjective criterion of 1.5% difference for imprecision and 3% for total error/expanded uncertainty. CONCLUSION: The EBV approach, using pRI, shows promise as a surrogate marker for biological variation and as a practical tool for determining performance limits in dogs and cats. Assuming accurate pRI generated on analyzers with stable analytical performance, this approach could offer benefits when expert recommendations or robust BV studies are lacking or yield conflicting results. Further research is needed to explore the applicability and advantages of the EBV in veterinary medicine.

First autochthonous clinical case of Hepatozoon silvestris in a domestic cat in Italy with unusual presentation.

Hepatozoon spp. is the causative agent of a vector-borne parasitic disease in many animal species. In felids, Hepatozoon felis, Hepatozoon canis and Hepatozoon silvestris have been molecularly isolated. Hepatozoonosis usually causes asymptomatic infections in domestic cats, but clinical cases have recently been reported in Europe. We describe the first Italian case of hepatozoonosis in a cat with an unusual presentation. An 11-year-old neutered European shorthair cat was urgently hospitalized for intestinal intussusception. Hematology, biochemistry, FIV-FeLV tests, blood smears and molecular investigation targeting the 18S rRNA gene of Hepatozoon spp. were performed on blood samples; in addition, histological and molecular investigations were performed to analyze surgical samples to identify Hepatozoon infection. Hepatozoon gamonts were detected in granulocytes in the blood smear, and Hepatozoon spp. DNA was confirmed by PCR on blood. The intussusception was caused by a sessile endoluminal nodule that was surgically removed. Histologically, many elements referring to parasitic tissue forms were identified in the intestinal cells, and then the specimens were molecularly confirmed to harbor H. silvestris. This is the first description of symptomatic hepatozoonosis in a domestic cat in Italy. Hepatozoon silvestris has been described in wild felids, which are usually resilient to the infection, whereas the domestic cat seems to be more susceptible. Indeed, H. silvestris in cats usually presents tropism for skeletal muscle and myocardium with subsequent clinical manifestations. This is the first description of a domestic cat with H. silvestris localized in the intestinal epithelium and associated with intussusception.

Occurrence of canine and feline extra-intestinal nematodes in key endemic regions of Italy.

Extra-intestinal nematodes of companion animals are of growing concern in veterinary medicine for their pathogenic potential and the current expansion throughout Europe. The present study has evaluated the occurrence of major canine and feline extra-intestinal nematodes in regions of Italy having epidemiological relevance. Associations of various recorded parameters related to the examined animals have been statistically evaluated, along with a comparative analysis with the most recent epidemiological data. Overall, 1055 dogs and 1000 cats were tested. Among extra-intestinal nematodes Angiostrongylus vasorum was the most common in dogs followed by Capillaria aerophila and Dirofilaria spp.; Aelurostrongylus abstrusus was the most recorded parasite in cats, followed by C. aerophila and Troglostrongylus brevior. The statistical analysis revealed that outdoor access is associated with A. vasorum, A. abstrusus and T. brevior infections, that were also more prevalent in animals with cardio-respiratory signs. Moreover, cats aged less than 12 months had more chances to be infected by lungworms. The data herein presented confirm the occurrence and the possible risk of expansion of different extra-intestinal parasitoses of dogs and cats in Italy, underlining the importance of a constant epidemiologic vigilance and of appropriate control methods.

Heat treatment and false-positive heartworm antigen testing in ex vivo parasites and dogs naturally infected by Dirofilaria repens and Angiostrongylus vasorum.

BACKGROUND: Heartworm antigen testing is considered sensitive and specific. Currently available tests are reported as detecting a glycoprotein found predominantly in the reproductive tract of the female worm and can reach specificity close to 100%. Main concerns regard sensitivity in the case of light infections, the presence of immature females or cases of all-male infections. Research and development have been aimed at increasing sensitivity. Recently, heat treatment of serum prior to antigen testing has been shown to result in an increase in positive antigen test results, presumably due to disruption of natural antigen-antibody complexes. Cross-reactions in dogs with both natural and experimental infections with Angiostrongylus vasorum and Spirocerca lupi have been reported, but cross-reactions with other helminths have not been extensively studied. In order to evaluate potential cross-reactivity with other canine and feline parasites, two studies were performed. Study 1: Live adults of Dirofilaria immitis, Dirofilaria repens, Toxocara canis, Toxocara cati, Dipylidium caninum, Taenia taeniaeformis and Mesocestoides spp. larvae were washed and incubated in tubes with saline solution. All worms were alive at the time of removal from the saline. Saline solutions containing excretory/secretory antigens were then tested for heartworm with six different, commercially available antigen tests. All results were evaluated blind by three of the authors. Study 2: Sera from dogs with natural infections by A. vasorum or D. repens, living in areas free of heartworm disease, were tested with the same tests before and after heat treatment (103 °C for 10 min). RESULTS: Results suggest that antigens detected by currently available tests are not specific for D. immitis. They may give positive results through detection of different parasites' antigens that are normally not released into the bloodstream or released in a low amount and/or bound to antibodies. Tests may even detect antigens released by male D. immitis adult worms. D. repens appears to release more detectable antigens than the other worms studied. CONCLUSIONS: Cross-reaction with A. vasorum and D. repens does occur in the field and could potentially occur with other helminths. Heat treatment decreases specificity by enhancing cross-reactivity.

Comparison of 3 options for choosing control limits in biochemistry testing.

BACKGROUND: The purpose of statistical quality control (QC) is to provide peace of mind with regard to the production of results that are suitable for analytically sound clinical interpretation and making reliable decisions about patient diagnosis, monitoring, and prognosis. OBJECTIVES: In this study, we compared 3 options for choosing control limits for biochemistry testing. They focus on the probability of error detection (Ped) and probability of false rejection (Pfr) achievable for a veterinary biochemical analyzer using the following 3 combinations: the quality control material (QCM) manufacturer's acceptable ranges; a standard 12s rule customized for the instrument's observed performance; and candidate rules selected for the instrument's observed performance using a computerized program (EZrules). METHODS: For assessing customized QC, we used mean, SD, CV, bias, total error, and sigma metrics calculated from 3 months of control measurements on a laboratory biochemical analyzer, for 24 commonly used analytes, on 2 QCM levels. RESULTS: Given the desirable combination of high Ped (> 90%) and low Pfr (≤ 5%), the candidate rules selected by the computerized program-related EZrules provided the best performance combinations. CONCLUSIONS: The present work shows acceptable QC performance basing the QC on customization of the acceptable ranges of results from the achievable performance of an individual instrument. The QC performance is maximized by the application of candidate rules based on customized ranges obtained from a computerized QC tool, providing the ability to achieve the highest Ped and acceptably low Pfr values.

Computed tomography, radiology and echocardiography in cats naturally infected with Aelurostrongylus abstrusus.

Objectives The aims of the study were to describe the radiographic and computed tomographic features in cats naturally infected with Aelurostrongylus abstrusus, and to identify signs of pulmonary hypertension with echocardiography. Methods Fourteen cats positive on Baermann test for A abstrusus were included in the study. All cats underwent thoracic radiography, CT and echocardiography. Results The most common clinical signs were coughing (10/14) and dyspnoea (5/14). Radiographic findings included a generalised unstructured interstitial pulmonary pattern (8/14), mixed bronchointerstitioalveolar pattern (3/14) and bronchointerstitial pattern with bronchial wall thickening (3/14). Sternal lymphadenopathy was detected on thoracic radiographs in six cats. On CT, features were mixed bronchointerstitioalveolar pattern with ground-glass appearance in six cats, interstitioalveolar with multiple pulmonary nodules in five, interstitial ground-glass infiltrates in three, regional lymph node enlargement in 11 (10 sternal, three cranial mediastinal and three tracheobronchial lymph nodes) and subpleural thickening in four. None of the thoracic radiographs revealed subpleural thickening. In all cases, pulmonary vessels were normal in terms of size, shape and attenuation on both radiography and CT. Pulmonary hypertension and cardiac abnormalities were not observed in any cat during echocardiography. Conclusions and relevance CT provided a more thorough characterisation of pulmonary and mediastinal lesions compared with thoracic radiographs in cats naturally infected with A abstrusus. Although feline aelurostrongylosis has been previously associated with histopathological lesions in lung arteries, in this cohort clinical evidence of pulmonary hypertension was not documented.

Nodular presentation of Dirofilaria repens infection in a cat mimicking a fibrosarcoma.

A cat with multiple subcutaneous nodules suggesting a soft tissue sarcoma by physical and computed tomographic examination was diagnosed as being affected by subcutaneous filariosis based on cytologic and ultrasonographic assessments. Nodules were surgically removed and extracted nematodes were identified by PCR as Dirofilaria repens. Furthermore, DNA of Dipetalonema dracunculoides (syn. Acantocheilonema dracunculoides) was detected by PCR, with no evidence of circulating microfilariae. To the best of the authors' knowledge, this represents the first report describing adults of D repens in multiple subcutaneous nodules in a cat. Cytopathologic examination allowed characterization of the parasitic nature of the nodules. Veterinary practitioners should be aware of the possible nodular presentation of D repens in cats and should include D repens in the differential diagnosis of subcutaneous neoformations in the cat.

Respiratory nematodes in cat populations of Italy.

The occurrence of common respiratory parasites of domestic cats (the metastrongyloid "cat lungworm" Aelurostrongylus abstrusus and the trichuroid Capillaria aerophila) and of neglected respiratory nematodes of felids (Troglostrongylus brevior, Angiostrongylus chabaudi and Oslerus rostratus) was here evaluated in two and three geographical sites of Northern and Central Italy, respectively. In 2014-2015, individual fecal samples of 868 domestic cats were examined microscopically and genetically, and epidemiological data related to parasitic infections were evaluated as possible risk factors by binary logistic regression models. The most common parasite was A. abstrusus in both mono- and poli-specific infections, followed by T. brevior and C. aerophila, while cats scored negative for other parasites. Cats positive for A. abstrusus (1.9-17 % infection rate) and C. aerophila (0.9-4.8 % infection rate) were found in all examined sites, while cats scored positive for T. brevior (1-14.3 % infection rate) in four sites. Also, T. brevior was here found for the first time in a domestic cat from a mountainous area of Northern Italy. The occurrence of lungworms was statistically related to the presence of respiratory signs and more significant in cats with mixed infection by other lungworms and/or intestinal parasites. Cats living in site C of Central Italy resulted statistically more at risk of infection for lungworms than cats living in the other study sites, while animals ageing less than 1 year were at more risk for troglostrongylosis. Finally, the presence of lungworms was more significant in cats with mixed infection by other lungworms and/or intestinal parasites. These results are discussed under epidemiological and clinical points of views.

Elusive Angiostrongylus vasorum infections.

BACKGROUND: The parasitic nematode Angiostrongylus vasorum causes severe clinical signs in dogs. The disease is often challenging because infected animals are often presented with clinical signs overlapping those of other diseases. METHODS: The present article describes six angiostrongylosis cases (Cases 1-6) that represent key examples of how canine angiostrongylosis may be extremely confounding. The six animals presented clinical signs compatible with canine angiostrongylosis but they were subjected to clinical examinations for other diseases (e.g. dirofilariosis or immune-mediated disorders) before achieving a correct diagnosis. RESULTS: In Case 1 clinical, radiographic and ultrasound examinations' results resembled a lung neoplasia. Case 2 was a dog with a mixed infection caused by A. vasorum and Dirofilaria immitis. Case 3 was a critically ill dog presented in emergency for an acute onset of dyspnoea caused by lungworm infection. The dog died a few hours after presentation despite support and etiologic therapy. Case 4 was a dog presented for chronic hemorrhages and ecchymoses caused by thrombocytopenia of unknown origin, thought to have an inherited, immune-mediated or infective cause. Case 5 was referred for neurological signs due to a suspected discospondylitis. Case 6 was erroneously diagnosed infected only with D. immitis although the dog was infected only with A. vasorum. A timely administration of an anthelmintic (mostly moxidectin) showed to be effective in treating the infection in those dogs (i.e. Cases 1,2, 4 and 5) that did not suffer with severe lung haemorrhages yet. CONCLUSIONS: Dogs 1-5 were referred in two regions of Italy that are considered non-endemic for A. vasorum. These findings indicate that veterinarians should include angiostrongylosis in the differential diagnosis of cardio-respiratory distress also in non-endemic regions and should perform appropriate diagnostics in the presence of compatible signs even if the clinical picture is atypical.