Feline aelurostrongylosis and canine angiostrongylosis: a challenging diagnosis for two emerging verminous pneumonia infections

Aelurostrongylus abstrusus and Angiostrongylus vasorum (Nematoda, Metastrongyloidea) are causative agents of verminous feline and canine pneumonia. Both are presently emerging in several geographical areas and are of major clinical importance. Given the range of parasitic and non-parasitic pathogens which may cause cardio-respiratory distress in dogs and cats, the unequivocal specific diagnosis of both diseases is pivotal for unravelling their epidemiology and central to therapy and control. Several conventional clinico-pathologic, diagnostic imaging and parasitological approaches are currently used in practice, but all have major limitations in the specific diagnosis of these diseases. Serological methods have shown promise in the diagnosis of A. abstrusus and A. vasorum infections, but no clinically useful tests are currently available. Additionally, there have been major advances in the development of novel molecular diagnostic tools for feline aelurostrongylosis, but efforts to develop molecular diagnostic tests are still preliminary for angiostrongylosis. This article provides a review of A. abstrusus and A. vasorum infections in cats and dogs, focusing on the advantages and shortcomings of classical diagnostic methodologies and on present diagnostic advances as well as future perspectives instrumental to epidemiological and clinical studies.     

Feline diarrhoea associated with Tritrichomonas cf. foetus and Giardia co-infection in an Australian cattery

A 10-week-old female Ocicat was presented at a primary care feline veterinary practice for failure to thrive and diarrhoea. Numerous trophozoites, atypical for Giardia sp., were detected on a direct faecal examination, in addition to Giardia cysts. Although the failure to thrive and diarrhoea resolved following treatment for giardiasis, further diagnostic tests performed on faecal specimens from the kitten and 15 other Ocicats from the same cattery, including culture of trophozoites in In Pouch medium, PCR testing and molecular sequencing of PCR amplicons, confirmed infection with Tritrichomonas cf. foetus. This is the first report in Australia of feline trichomoniasis, which appears to be an emerging infectious disease of cats. Pertinent information regarding the clinical features, diagnosis, therapy, and potential source of feline trichomoniasis within Australia are discussed.     

Infection by Eucoleus aerophilus in dogs and cats: Is another extra-intestinal parasitic nematode of pets emerging in Italy?

The occurrence of the infection by the lungworm Eucoleus aerophilus (syn. Capillaria aerophila) in dogs and cats from Italy has been evaluated with conventional diagnostic procedures. Individual faecal samples from 569 dogs and 200 cats were undertaken to faecal flotation with sugar and zinc sulphate solution. Sixteen dogs (2.8%) and 11 cats (5.5%) scored positive for eggs of E. aerophilus when samples were processed with either of the two flotation solutions. Overall 14 of 16 dogs and eight of 11 cats infected by E. aerophilus showed respiratory symptoms and the most common were general respiratory distress, dry cough, wheezing and sneezing. These results indicate that E. aerophilus is not uncommon and that canine and feline capillariosis is of clinical importance. Given the impact that E. aerophilus infections may have upon animal health and its zoonotic potential, it is strongly advisable to routinely include this disease in the differential diagnosis of (cardio)-respiratory diseases of dogs and cats.     

Cryptosporidium infection in cats: prevalence of infection in domestic and feral cats in the Glasgow area.

A clinical and post mortem survey of domestic and feral cats in the Glasgow area revealed that 19 of 235 (8.1 per cent) were infected with Cryptosporidium species. More kittens than adults were infected (P less than 0.01), and of 51 of the cats which had diarrhoea, four also had cryptosporidium infection. Of seven domestic cats with cryptosporidium infection, two were also positive for feline immunodeficiency virus. There was no significant difference between the prevalence of cryptosporidium infection in domestic and feral cats. Cryptosporidium oocysts were detected in faecal and mucosal impression smears stained with auramine-phenol and modified Ziehl-Nielsen techniques. Endogenous developmental stages of cryptosporidium were found in the microvillus region of enterocytes of eight of 19 positive cats in sections stained with haematoxylin and eosin. The results suggest that cryptosporidium infection is common among young and newborn kittens, and that the disease is usually asymptomatic.     

Canine parvovirus in asymptomatic feline carriers

Canine parvovirus (CPV) and feline panleukopaenia virus (FPLV) are two closely related viruses, which are known to cause severe disease in younger unvaccinated animals. As well as causing disease in their respective hosts, CPV has recently acquired the feline host range, allowing it to infect both cats and dogs. As well as causing disease in dogs, there is evidence that under some circumstances CPV may also cause disease in cats. This study has investigated the prevalence of parvoviruses in the faeces of clinically healthy cats and dogs in two rescue shelters. Canine parvovirus was demonstrated in 32.5% (13/50) of faecal samples in a cross sectional study of 50 cats from a feline only shelter, and 33.9% (61/180) of faecal samples in a longitudinal study of 74 cats at a mixed canine and feline shelter. Virus was isolated in cell cultures of both canine and feline origin from all PCR-positive samples suggesting they contained viable, infectious virus. In contrast to the high CPV prevalence in cats, no FPLV was found, and none of 122 faecal samples from dogs, or 160 samples collected from the kennel environment, tested positive for parvovirus by PCR. Sequence analysis of major capsid VP2 gene from all positive samples, as well as the non-structural gene from 18 randomly selected positive samples, showed that all positive cats were shedding CPV2a or 2b, rather than FPLV. Longitudinally sampling in one shelter showed that all cats appeared to shed the same virus sequence type at each date they were positive (up to six weeks), despite a lack of clinical signs. Fifty percent of the sequences obtained here were shown to be similar to those recently obtained in a study of sick dogs in the UK (Clegg et al., 2011). These results suggest that in some circumstances, clinically normal cats may be able to shed CPV for prolonged periods of time, and raises the possibility that such cats may be important reservoirs for the maintenance of infection in both the cat and the dog population.     

The diagnostic significance of a positive direct antiglobulin test in anemic cats.

The preparation of a feline Coombs serum (rabbit antifeline gamma globulin) is described. The direct antiglobulin test using this serum was performed on 20 anemic and 20 healthy control cats. Red cell membrane antibodies were detected in cats with feline leukemia virus infection and in others with inflammatory and neoplastic diseases. A low titre of cold agglutinating antibody was present in a high proportion of the control cats. Positive direct antiglobulin tests were noted in cats without overt hemolytic disease. It was concluded that the direct antiglobulin test in anemic cats has certain diagnostic limitations. A positive reaction should be interpreted cautiously especially when there is no clinical or laboratory evidence to support a diagnosis of autoimmune hemolytic anemia.     

Feline non-ocular melanoma: a retrospective study of 23 cases (1991-1999).

Non-ocular melanoma is considered to be a rare neoplasm in cats; however, more than 150 cases have been reported in the literature since 1961. The objective of this study was to characterise this tumour better by evaluating case outcome and survival data for cats with melanoma and to compare clinical and histopathological findings with those of previous reports. Twenty-three feline non-ocular melanomas were identified, the most common locations being the nose, digit and pinna. Cats with digital melanomas had survival rates similar to their canine counterparts. Histological assignation of benignity, malignancy or junctional activity was not found to be an accurate predictor of clinical behaviour. Melanoma should be considered as a differential diagnosis for cats presenting with pigmented or non-pigmented masses and histopathology is essential for definitive diagnosis, as other tumours may clinically appear quite similar. Regular follow-up examinations are recommended indefinitely for benign or malignant feline melanomas.     

Frequency of blood type A, B, and AB in 515 domestic shorthair cats from the Lisbon area

Background: The A, B, and AB feline blood types are recognized worldwide and their frequencies vary geographically and among breeds. Frequencies of feline blood types have been reported previously from northern Portugal; however, they are unknown in other parts of the country. Objectives: This 13‐year retrospective study was undertaken to determine the frequency of feline blood types in domestic shorthair (DSH) cats from the Lisbon area of central Portugal. Methods: Blood samples were obtained at the Veterinary Teaching Hospital of the Technical University of Lisbon and its Veterinary Blood Bank and at several veterinary clinics in the Lisbon area. Blood‐typing was performed by the classical agglutination assay or using a cartridge assay. Results: The study population comprised 515 DSH cats of both sexes and various ages. Frequencies of blood types A, B, and AB were 97.5%, 2.1%, and 0.4%, respectively. Conclusion: As in other parts of the world, this study showed a clear predominance of type‐A cats in the Lisbon area of Portugal.     

RADIOGRAPHIC AND 2-D ECHOCARDIOGRAPHIC FINDINGS IN EIGHTEEN CATS EXPERIMENTALLY EXPOSED TO D. ZMMZTZS VIA MOSQUITO BITES

Eighteen cats were exposed to Dirofikria immitis infected mosquitoes. Thoracic radiography was performed prior to exposure and at 5, 7, and 9 month intervals following exposure. Immunologic testing for adult heartworm antigen was performed on days 168,195,210,224,237,254 and 271 post infection. Necropsies were performed on all cats. Adult heartworms were found in 61% of the exposed cats. Radiographic findings in heartworm positive cats included bronchointerstitial lung disease, lobar pulmonary arterial enlargement and pulmonary hyperinflation. In most heartworm positive cats, lobar arterial enlargement resolved as the disease progressed while pulmonary hyperinflation progressively became more common. Pulmonary patterns in heartworm positive cats remained abnormal throughoutthe study while abnormal pulmonary patterns resolved in over 50% of the heartworm negative cats. Cardiomegaly was seen in less than 50% of the cats with adult heartworms at necropsy. This study suggests that the radiographic appearance of heartworm disease is variable and radiographic changes are dependent on the time post infection at which cats are evaluated. Echocardiographic examinations were randomly performed on 16 of 18 cats. Heartworms were identified in 7 cats. No false positive identifications were made. Persistent pulmonary disease accompanied by resolving vascular disease in heartworm cats with pulmonary hyperinflation may be difficult to distinguish from cats with feline allergic lung disease. Echocardiograms may be helpful in identifying adult heartworms in cats in which the radiographic signs or immunodiagnostic data are insufficient to provide a diagnosis.     

Clinical evolution and radiographic findings of feline heartworm infection in asymptomatic cats

Clinical manifestations of heartworm disease in cats are variable; most cats seem to tolerate the infection well for extended periods. Heartworm-infected cats may undergo spontaneous self-cure due to the natural death of parasites without any symptomatology, or they may suddenly show dramatic and acute symptoms. Sudden death in apparently healthy cats is not a rare event. Thoracic radiographs are important tool for the diagnosis of cardiopulmonary disease. However, thoracic abnormalities are often absent or transient and highly variable in heartworm-infected cats. Findings, such as enlargement of the peripheral branches of the pulmonary arteries, with a varying degree of pulmonary parenchymal disease and hyperinflation, are the most typical features consistent with infection. A field study was performed for cats referred to the Veterinary Hospital Città di Pavia from January 1998 to December 2001 for routine health examinations and procedures to evaluate the clinical evolution and radiographic findings of feline heartworm infection. Thirty-four asymptomatic cats diagnosed with feline heartworm infection by antibody and antigen tests together with an echocardiogram that allowed worm visualization were included in the follow-up study. Cats were routinely examined every 3 months from the time of heartworm diagnosis until the outcome (self-cure or death). Self-cure was defined as no positive serology for heartworm antigens and no visualization of worms by echocardiography. A final examination for antibodies was carried after 12 months as a final confirmation of self-cure. Twenty-eight cats (82.4%) self-cured; including 21 that showed no clinical signs of infection throughout the study. Six cats died. The most common clinical features observed were acute respiratory symptoms and sudden death. Infection lasted over 3 years in the majority of the cats enrolled in the study. Thoracic radiograph appearance was variable, and the most commonly observed findings were focal and diffuse pulmonary parenchymal abnormalities.     

Histopathologic study of uveitis in cats: 139 cases (1978-1988)

Histopathologic findings in 158 globes obtained from 139 cats by enucleation or at necropsy, with histopathologic diagnosis of uveitis, were compared, and morphology was correlated with clinical and/or histopathologic diagnosis. The most common morphologic feature was a lymphocytic-plasmacytic anterior uveal infiltrate that was either diffuse or nodular; specific cause could not be associated with this nongranulomatous anterior uveitis. In decreasing order of frequency, other common causes of uveitis in cats included feline infectious peritonitis; FeLV-associated lymphosarcoma; trauma; and lens-induced uveitis.     

Diagnosis of pancreatitis.

In summary, pancreatitis is common in dogs and cats, but it seems that most cases remain undiagnosed. Serum amylase and lipase activities are useful as a quick screening test for pancreatitis in the dog only. Serum amylase or lipase activity must be at least three to five times the upper limit of the reference range to suggest a diagnosis of pancreatitis. Furthermore, the diagnosis must be confirmed by other diagnostic modalities, and normal test results do not eliminate the possibility of pancreatitis. Abdominal ultrasound is highly specific for pancreatitis in dogs and cats but is not particularly sensitive, especially in cats. Serum cPLI concentration is highly specific for exocrine pancreatic function and is also highly sensitive for pancreatitis. Similarly, initial data would suggest that serum fPLI is the most sensitive and specific diagnostic test for feline pancreatitis. Until further data are available, however, serum fPLI should be used in conjunction with other diagnostic tests to arrive at a diagnosis of feline pancreatitis. Histopathologic evidence of pancreatitis is conclusive for a diagnosis of pancreatitis. In most cases, however, lesions are localized, and the lack of histopathologic evidence of pancreatitis does not eliminate a diagnosis of pancreatitis.     

Lower respiratory tract infections in cats: reaching beyond empirical therapy

PRACTICAL RELEVANCE: Lower respiratory tract infections (LRTIs) in cats can be due to bacteria, parasites, fungi and viruses. This review details the practical investigation of these infections and highlights specific therapy where possible. The aim is to avoid the all-too-frequent temptation in practice to treat cats with lower respiratory tract signs empirically for feline bronchial disease (FBD)/asthma. This is potentially hazardous as immunosuppressive therapy for FBD/asthma could exacerbate disease due to a LRTI. Empirical treatment of suspected LRTI is also difficult to recommend given the wide range of potential pathogens. CLINICAL CHALLENGES: Making a clinical ante-mortem diagnosis of LRTI in a cat can be challenging. Consistent historical, clinical, haematological and radiographic abnormalities are often lacking and findings may be non-specific. Astute clinical acumen, thorough investigation and high quality laboratory analysis are usually required for a diagnosis. Bronchoalveolar lavage, if feasible, and tests for lungworm should be routine in cats with lower respiratory tract signs. Lung fine needle aspiration may be useful in cases of diffuse or nodular pulmonary disease. Histopathology is rarely employed in ante-mortem investigations. EVIDENCE BASE: The authors have reviewed a substantial body of literature to provide information on many of the reported bacterial, parasitic, fungal and viral pathogens, including some that occur in Asia. Attention has been given to specific therapy for each pathogen, with evidence-based comments when there is a deviation from routine recommendations.     

Characterisation of lymphosarcomas in Australian cats using polymerase chain reaction and immunohistochemical examination

Objective To examine tumour tissue of cats with lymphosarcoma for the presence of feline leukaemia virus and feline immunodeficiency virus and analyse the immunophenotype of the tumours.
Design A retrospective study of feline lymphosarcoma cases.
Methods Formalin-fixed, paraffin-embedded tumour tissue of 14 feline lymphosarcomas was examined for the presence of feline leukaemia virus and feline immunodeficiency virus by polymerase chain reaction and immunohistochemistry. Using polyclonal and monoclonal antibodies against T and B lymphocytes, the phenotypic expression of the tumours was characterised.
Results No feline leukaemia virus antigen or proviral sequences were detected. Feline immunodeficiency virus proviral sequences were detected in two cases by polymerase chain reaction. Immunophenotyping of all 14 cases resulted in seven cases being classified as B-cell phenotype, four as T-cell phenotype, and the remaining three undetermined.
Conclusions In contrast to previous reports overseas, our results suggest that feline leukaemia virus infection appears to be an infrequent cause of lymphosarcoma in the cats that were necropsied. Feline immunodeficiency virus may have a role in lymphomagenesis. The potential role of feline immunodeficiency virus needs to be explored in more depth. Compared with most previous reports, B-cell tumours were more common than T-cell tumours in this series of cats.     

Retrospective study on the occurrence of the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus spp. in endemic areas of Italy

Aelurostrongylus abstrusus is a metastrongyloid nematode infesting the respiratory system of domestic cats worldwide. Troglostrongylus brevior and Troglostrongylus subcrenatus, two lungworms thought to infest wild felids, have been found recently in domestic cats from Spain and Italy. These unexpected findings have raised doubts about the assumed past and present occurrence of Troglostrongylus spp., especially T. brevior, in domestic hosts and suggest that there may have been missed detection or misdiagnosis. The present retrospective study evaluated the presence of lungworms in cats from Italy with a diagnosis of respiratory parasitism or with compatible lung lesions from 2002 to 2013. Sixty-eight samples of DNA and larvae from cats with a diagnosis of aelurostrongylosis, and 53 formalin-fixed paraffin-embedded lung samples from cats confirmed as lungworm infested or with compatible lesions, were investigated using two DNA-based assays specific for A. abstrusus or T. brevior. All DNA and larval samples were positive for A. abstrusus and one was additionally positive for T. brevior. Most paraffin-embedded lung tissues were positive only for A. abstrusus, but two samples tested positive for both lungworms and one for T. brevior only. This study supports the major role of A. abstrusus in causing feline respiratory parasitism in endemic areas of Italy.     

Virological Survey in free-ranging wildcats (Felis silvestris) and feral domestic cats in Portugal

To determine the presence of viral pathogens in natural areas a survey was conducted on an opportunistic sample of fifty eight wild (Felis silvestris silvestris) and feral cats (F. s. catus). The biological materials included serum, lung tissue extract and stool. Feline leukemia virus p27 antigen was detected in 13/50 serum/lung tissue extract samples (26%), canine distemper virus antibodies were detected in 2/26 serum/lung tissue extract samples (7.7%), feline coronavirus RNA was present in 6/29 stool samples (20.7%) and feline parvovirus DNA in 2/29 stool samples (6.9%). Canine distemper virus RNA was not detected. Feline immunodeficiency virus and feline coronavirus antibodies were not detected. Evidence of exposure to feline leukemia virus, canine distemper virus, feline coronavirus and feline parvovirus was found in wild and feral cats raising the importance of performing a comprehensive survey to correctly evaluate the potential threat of infectious diseases to endangered species, namely to the wildcat and to the Iberian lynx, which is meant to be reintroduced after 2012 in Portugal.     

Feline adrenal disorders

Although only recently discovered, feline adrenal disorders are becoming increasingly more recognized. Feline adrenal disorders include diseases such as hyperadrenocorticism (Cushing's syndrome) and hyperaldosteronism (Conn's syndrome). The clinical signs of feline hyperadrenocorticism, which include unregulated diabetes mellitus and severe skin atrophy, are unique to the cat. Other signs of feline hyperadrenocorticism, such as potbellied appearance, polydipsia, polyuria, and susceptibility to infections are also seen in dogs with hyperadrenocorticism. Conn's syndrome has only recently been described in the cat and is in fact more common in cats than in dogs. Characterized by severe hypokalemia, hypertension, and muscle weakness, Conn's syndrome may be misdiagnosed as renal failure. The clinician should become familiar with the clinical signs of adrenal disorders in cats and the common diagnostic tests used to diagnose these syndromes in cats as they differ from those in the dog. Treatment of feline adrenal disorders may be challenging; the clinician should become familiar with common drugs used to treat adrenal disorders in cats.     

Understanding feline heartworm infection: disease, diagnosis, and treatment

Feline heartworm disease is a very different clinical entity from canine heartworm disease. In cats, the arrival and death of immature heartworms in the pulmonary arteries can cause coughing and dyspnea as early as 3 months postinfection. Adult heartworms suppress the function of pulmonary intravascular macrophages and thus reduce clinical disease in chronic feline heartworm infection. Approximately 80% of asymptomatic cats self-cure. Median survival time for symptomatic cats is 1.5 years, or 4 years if only cats living beyond the day of presentation are considered. Aberrant worm migration is more frequent than it is in dogs, and sudden death can occur with no prior clinical signs. The bacterial endosymbiont Wolbachia likely contributes to the inflammatory pathology of heartworm disease, but its role is not yet fully clear. Unfortunately, the diagnosis, treatment, and management of feline heartworm disease are far from simple. Antemortem diagnosis is hampered by low worm burdens, the frequency of all-male infections, and nonspecific radiographic lesions. It is up to the veterinarian to determine the correct index of suspicion and choose the right combination of diagnostic tests to achieve an answer. Treatment is symptomatic because adulticide therapy is risky and does not increase survival time. Despite the dangers of feline heartworm disease, less than 5% of cats in the United States are on chemoprophylaxis. It is important for veterinarians to take a proactive preventive stance because heartworm infection in cats is a multisystemic disease that has no easy cure.