Platelet-bound antibodies detected by a flow cytometric assay in cats with thrombocytopenia

In cats, primary or secondary immune-mediated thrombocytopenia have rarely been described or characterised. The objective of this study was to determine platelet-bound antibodies (PBA) by a flow cytometric assay in both healthy and thrombocytopenic cats. Direct PBA testing was performed in 42 thrombocytopenic cats (platelet counts 6-179 x 10(9)/l, median 56 x 10(9)/l). Of these 42 cats, 19 had positive PBA test results, 17 of which were considered to have secondary immune-mediated thrombocytopenia (sITP). Underlying diseases included fat necroses (four cases), feline infectious peritonitis (three), feline leukaemia virus (two) or feline immunodeficiency virus (two) infections, lymphoma (two), leukaemia (one), hepatitis (one), pyelonephritis (one), or hyperthyroidism (one). In two cats, no underlying disease was found suggesting a primary immune-mediated thrombocytopenia (pITP). The PBA test was negative in 23 cats diagnosed with varying underlying diseases and in 47 healthy control cats with platelet values within the reference range. Only seven of the 42 cats with thrombocytopenia (platelet count 10-57 x 10(9)/l, median 34 x 10(9)/l) had spontaneous bleeding. This study suggests that immune-mediated destruction of platelets might be an important pathological mechanism for feline thrombocytopenia caused by various underlying diseases. In cats, pITP appears to be rarely diagnosed.     

Clinical and laboratory findings in cats infected with feline immunodeficiency virus

Thirty-two cats referred to the Feline Studies Centre between June 1987 and October 1988, and 14 in-contact cats, were found to be infected with feline immunodeficiency virus. Most of the 46 cats were non-pedigree and free ranging; 27 were male (19 neutered) and 19 were female (18 neutered). Their ages ranged from one to 17 years and the average age was 5.8 years. The most common clinical signs were lethargy, inappetence, weight loss, pyrexia and lymphadenopathy; most cases had multiple abnormalities. Other common signs were gingivitis, diarrhoea, rhinitis and ocular discharge. Eight cats had neoplasia. The commonest haematological abnormalities were anaemia, neutropenia, lymphopenia and monocytosis. Eight cats had lymphocytosis; seven of these were in a single house-hold. Several cats had high serum globulin levels and half of those tested had high IgG levels. Seven cats had no detectable antibody to feline immunodeficiency virus even though the virus was cultured from the peripheral blood lymphocytes. During follow-up for up to 60 weeks one cat died and 23 were destroyed on humane grounds.     

Resolution of renal adenocarcinoma-induced secondary inappropriate polycythaemia after nephrectomy in two cats

Two cases of secondary, inappropriate polycythaemia caused by renal adenocarcinoma in domestic shorthair cats, are described. The cats were 9 and 12 years old and both were presented because of generalised seizures presumably due to hyperviscosity. Both cats had a markedly increased haematocrit (0.770 and 0.632 l/l) and thrombocytosis (744 x 10(9)/l and 926 x 10(9)/l). An abdominal ultrasound revealed a mass in the cranial pole of one kidney in both cats. Serum erythropoietin (EPO) concentration was within the reference interval (RI) in both cats but was inappropriately high considering the markedly increased haematocrit. The cats were initially stabilised and managed by multiple phlebotomies and intravenous fluid therapy and underwent nephrectomy of the affected kidney later on. Both the polycythaemia and thrombocytosis resolved following surgery. Postoperative serum EPO concentration, measured in one cat, decreased markedly. Histopathology of the affected kidneys confirmed a diagnosis of renal adenocarcinoma. Both cats were stable for an 8-month follow-up period; however, one cat had developed a stable chronic kidney disease (CKD), while the other was represented 8 months postoperatively due to dyspnoea, and had radiographic evidence of lung metastasis, presumably because of the spread of the original renal tumour and was euthanased. Initial stabilisation of polycythaemic cats should include multiple phlebotomies. Nephrectomy should be considered in cats with secondary, inappropriate, renal adenocarcinoma-related polycythaemia when only one kidney is affected by the tumour, and provided that the other kidney's function is satisfactory. Nephrectomy should be expected to resolve the polycythaemia and lead to normalisation of serum EPO concentration.     

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.     

Feline leucocyte antigen class II polymorphism and susceptibility to feline infectious peritonitis

There are four outcomes to feline coronavirus (FCoV) infection: the development of feline infectious peritonitis (FIP, which is immune-mediated), subclinical infection, development of healthy lifelong carriers and a small minority of cats who resist infection (Addie and Jarrett, Veterinary Record 148 (2001) 649). Examination of the FCoV genome has shown that the same strain of virus can produce different clinical manifestations, suggesting that host genetic factors may also play a role in the outcome of infection. FIP is most prevalent amongst pedigree cats, although how much of this is due to them living in large groups (leading to higher virus challenge and stress which predisposes to FIP) and how much is due to genetic susceptibility is not known. If host genetics could be shown to play a role in disease, it may allow the detection of cats with a susceptibility to FIP and the development of increased population resistance through selective breeding. The feline leucocyte antigen (FLA) complex contains many genes that are central to the control of the immune response. In this preliminary study, we used clonal sequence analysis or reference strand conformational analysis (RSCA) to analyse the class II FLA-DRB of 25 cats for which the outcome of FCoV exposure was known. Individual cats were shown to have between two and six FLA-DRB alleles. There was no statistically significant association between the number of alleles and the outcome of FCoV infection. No particular allele appeared to be associated with either the development of FIP, resistance to FCoV, or the carrier status. However, the analysis was complicated by apparent breed variation in FLA-DRB and the small number of individuals in this study.     

Comparisons between cats with normal and increased fPLI concentrations in cats diagnosed with inflammatory bowel disease

Objectives : The aim of this study was to compare age, serum albumin and cobalamin concentrations, serum alanine amino transferase and alkaline phosphatase activities, feline inflammatory bowel disease clinical disease activity index, pancreatic ultrasound findings, intestinal histopathology scores, outcome, treatment and clinical response between cats diagnosed with inflammatory bowel disease with normal or increased serum feline pancreatic lipase immunoreactivity concentrations. Methods : Medical records for 23 cats diagnosed with inflammatory bowel disease and with serum feline pancreatic lipase immunoreactivity concentrations available were reviewed. Three groups were compared; cats with serum feline pancreatic lipase immunoreactivity concentrations 2·0 to 6·8 µg/l (group A), 6·9 to 11·9 µg/l (group B) and ≥12·0 µg/l (group C). Results : Sixteen of the 23 cats had increased serum feline pancreatic lipase immunoreactivity concentrations; 9 cats in group B and 7 cats in group C. The remaining seven cats were in group A. Cats with serum feline pancreatic lipase immunoreactivity concentrations ≥12·0 µg/l had significantly lower median serum albumin and cobalamin concentrations. No significant differences were identified between the three groups for age, serum alanine amino transferase and alkaline phosphatase activities, feline inflammatory bowel disease clinical disease activity index, pancreatic ultrasound findings, intestinal histopathology scores, clinical outcome, treatment or clinical response. Clinical Significance : Hypoalbuminaemia and hypocobalaminaemia were more frequently observed in cats with serum feline pancreatic lipase immunoreactivity concentrations ≥12·0 µg/l.     

Hematologic abnormalities and outcome of 16 cats with myelodysplastic syndromes

We investigated the hematologic abnormalities and prognoses in 16 cats with myelodysplastic syndromes (MDS). Nonregenerative anemia, thrombocytopenia, and neutropenia were observed in 15, 13, and 4, respectively, of the 16 cats with MDS. Morphologic abnormalities characteristic of MDS included megaloblastoid rubricytes (9 cats), hyposegmentation of neutrophils (7 cats), nuclear abnormality of rubricytes (10 cats) and neutrophils (13 cats), and micromegakaryocytes (10 cats). Disease in these 16 cats was subclassified into refractory anemia (RA; 8 cats), RA with excess of blasts (RAEB; 5 cats), RAEB in transformation (RAEB in T; 1 cat), and chronic myelomonocytic leukemia (CMMoL; 2 cats), according to the human French-American-British (FAB) classification. In the cats in which the clinical outcome was known, 3 of 6 cats with high blast cell count MDS, including RAEB, RAEB in T, and CMMoL, developed acute myeloid leukemia, but only 1 of 8 cats with low blast cell count MDS (RA) developed acute myeloid leukemia. Based on the Dusseldorf scoring system for the prognosis of human MDS, the survival times of the cats showing high scores (> or =3 points) were significantly shorter than those of the cats with low scores (<3 points). The FAB classification and Dusseldorf scoring system were considered to be useful for predicting the prognosis of feline MDS. Furthermore, 15 of the 16 cats with MDS in this study were infected with feline leukemia virus, indicating its possible etiologic role in the pathogenesis of feline MDS.     

Frequency and significance of feline leukemia virus infection in necropsied cats

Feline leukemia virus (FeLV) infection was diagnosed immunohistologically on paraffin-embedded tissues obtained from 1,095 necropsied cats. Significant association of FeLV infection was demonstrated by chi 2 and Fisher's tests with various conditions and diseases (ie, anemia, tumors of the leukemia/lymphoma complex, feline infectious peritonitis, bacterial infections, emaciation, FeLV-associated enteritis, lymphatic hyperplasia, and hemorrhage). Unexpected findings associated with FeLV infection were icterus, several types of hepatitis, and liver degeneration. A negative association with FeLV infection was found for most parasitic and viral infections, including feline panleukopenia. Neither positive nor negative associations were established for FeLV infection and most forms of nephritis, including severe glomerulonephritis. Feline leukemia virus-infected cats were significantly (Kruskal-Wallis test) older than were FeLV-negative cats with the same nonneoplastic FeLV-associated diseases.     

Prevalence of and risk factors for feline hyperthyroidism in Hong Kong

A study was conducted to determine the prevalence of and potential risk factors for feline hyperthyroidism in Hong Kong. Serum total thyroxine (T(4)) was measured in 305 cats aged 10 years and older that presented at various veterinary clinics in Hong Kong. The prevalence of hyperthyroidism (T(4)>50 nmol/l) within this population was 3.93% and there was no significant difference in prevalence between healthy (3.16%) and sick (4.37%) cats. Older cats (>15 years) were more likely to be affected and domestic shorthair cats were less likely to be diagnosed with hyperthyroidism than the other breeds combined. No specific association between the development of feline hyperthyroidism and food type was observed. The prevalence of feline hyperthyroidism in Hong Kong was less than that reported for most other parts of the world, despite the presence of previously identified risk factors.     

A study of naturally occurring feline coronavirus infections in kittens.

Feline coronavirus is a common infection in cats, as indicated by the high prevalence of antibodies against the virus, especially in multicat households. Approximately 5 to 12 per cent of seropositive cats develop classical feline infectious peritonitis. A survey of kittens born into households of seropositive cats demonstrated the existence of healthy coronavirus carriers. Seronegative animals did not appear to excrete virus. No specific antibody titre could be linked to carrier status and some carrier cats subsequently became seronegative. The management of the kittens strongly influenced whether they became infected, and some degree of protection appeared to be conferred by maternally derived antibody. At present, feline infectious peritonitis virus and feline enteric coronavirus can only be differentiated by their different clinical histories in infected catteries. In this survey, cases of feline infectious peritonitis occurred in kittens from households where the initial presentation had been enteritis and vice versa. Therefore no difference in epidemiology could be found.     

Retrospective study of snake envenomation in 155 dogs from the Onderstepoort area of South Africa

A retrospective study was undertaken to evaluate the incidence, signalment, haematological and biochemical changes, therapy, and outcome of dogs presented to the Outpatients section of the Onderstepoort Veterinary Academic Hospital for confirmed snake envenomation. Three hundred and seventy-six records of dogs presented for snake envenomation from 1998 to 2002 were reviewed and 155 were selected on the basis of there being a positively identified snake. The 2 most commonly encountered snake envenomations in dogs were puff-adders (Bitis arietans) and snouted cobras (Naja annulifera annulifera). The majority of cases (56%) occurred in the autumn (March to May), with most being bitten by puff-adders. Dogs were 3 to 168 months old with a median of 36 months. No sex predilection was identified. Ten per cent of cases died because of the snake envenomation. Fifty-seven per cent and 43% of snakebites were puff-adders and cobras, respectively. There was no difference in mortality between the 2 groups of snakes. Of the cobras 60% were the snouted cobra, 14% Mozambique spitting cobra, and 24% rhinkals. Swelling in the area of the bite, usually the face and forequarters, was the primary clinical abnormality. Significant haematological findings were leukocytosis (median 17.3 x 10(9)/l; range 0.4-44), neutrophilia (median 13.6 x 10(9)/l; range 0.3-39.9), band neutrophilia (median 0.4 x 10(9)/l; range 0-5.32), and thrombocytopaenia (median 124 x 10(9)/l; range 3-555). Dogs envenomated by a puff-adder and Mozambique spitting cobra had a greater degree of thrombocytopaenia: median of 68 and 66, respectively, versus 243 for the cobra group. The most commonly used treatments were intravenous fluids, antibiotics and glucocorticoids. Thirty-eight dogs were treated with polyvalent antiserum: 9 for puff-adder envenomation and 29 for cobra envenomation. Only 2 of the dogs that received antisera died, both of them of cobra envenomation. The study concluded that snake envenomation in dogs is associated with high morbidity but moderate mortality rate and that the most significant haematological abnormality is thrombocytopaenia.     

Interaction of an intranasal combined feline viral rhinotracheitis, feline calicivirus vaccine and the FVR carrier state

Eight cats were vaccinated intranasally with a combined feline calicivirus/feline viral rhinotracheitis (FVR) virus commercial vaccine. Following intranasal challenge with a field strain of FVR virus and subsequent treatment with corticosteroid, no virus was recovered from any of the eight cats, while FVR virus was recovered following corticosteroid treatment from two of four unvaccinated and challenged controls. No evidence was found for the development of an FVR virus carrier state with the intranasal vaccine virus.     

Effect of chronic FIV infection, and efficacy of marbofloxacin treatment, on Mycoplasma haemofelis infection

The purpose of this study was to investigate the effect of chronic feline immunodeficiency virus (FIV) infection, and efficacy of marbofloxacin treatment, on Mycoplasma haemofelis infection. Six cats chronically infected with FIV-Glasgow8 (Group X) and six FIV-free cats (Group Y) were infected with M. haemofelis on Day 0 by intravenous blood inoculation. From Day 0 until Day 86 post-infection (pi), blood samples were collected for M. haemofelis and FIV provirus quantitative real-time PCR and haematology. Three of the six cats in each of Groups X and Y were randomly selected to receive marbofloxacin treatment (2 mg/kg PO q24 h) from Day 16 to 43 pi, with the remaining cats being untreated controls with no antibiotic treatment. The M. haemofelis copy numbers and haematological data were compared between Groups X and Y, and between marbofloxacin-treated and control cats using a Mann-Whitney U-test. M. haemofelis infection was associated with development of macrocytic hypochromic anaemia. In some cats, marked variation in M. haemofelis copy number over time (>100,000-fold difference within 48 h in some cats) and/or cycling of copy number was seen. No correlation was found between FIV provirus copy number and M. haemofelis copy number or haematological variables. No significant effect of chronic FIV infection on M. haemofelis copy number kinetics or haematological changes due to M. haemofelis infection was found, other than MCHC (P=0.03). Marbofloxacin treatment was associated with a significant decrease in M. haemofelis copy number (P=0.002), although consistent clearance of infection was not demonstrated. This study reveals the presence of marked fluctuations in M. haemofelis copy number kinetics in vivo and a significant response to marbofloxacin antibiotic treatment.     

Feline leukemia virus-associated enteritis--a condition with features of feline panleukopenia

Infection with feline leukemia virus (FeLV) was demonstrated immunohistologically in 218 necropsied cats suffering from enteritis. The animals were divided into three groups according to histopathological criteria. The first group exhibited the signs of feline panleukopenia in intestine, lymphoid tissues, and bone marrow. Only 1.6% of these animals were FeLV-infected. The animals of the second group had histopathological alterations as seen in cats suffering from feline panleukopenia, but these were found only in the intestine and not in lymphoid tissues or bone marrow. Of these 71.9% were infected with FeLV. The third group consisted of all other cats suffering from enteritis of which 6.3% were FeLV-positive. The association between FeLV infection and the lesions seen in the animals of group 1 (feline panleukopenia) and group 3 (other types of enteritis) is statistically not significant whereas the alterations exhibited by the cats of group 2 are significantly FeLV-associated. Cats with FeLV-associated enteritis (group 2) are of a mean age of about 2.5 years and are significantly older than animals with feline panleukopenia which are of a mean age of about half a year. Thus a FeLV-associated enteritis exists as a histopathologically recognizable condition which sometimes might be mistaken for feline panleukopenia in routine post-mortem investigations.     

Feline immunodeficiency virus infection in a population of pet cats from southeastern Florida

Blood samples from 95 randomly selected pet cats that were brought to veterinarians in southeastern Florida were tested for antibodies to feline immunodeficiency virus (FIV). Virus-specific antibodies (indicative of virus infection) were found in 8 of the 95 (8.4%) cats tested. All of the virus-infected cats were males (statistically significant, P less than or equal to 0.016) and were at least 1 year of age. The 3 most severely ill cats infected with FIV were also infected with feline leukemia virus.     

Diseases associated with spontaneous feline leukemia virus (FeLV) infection in cats

More than 2000 cats sent for necropsy in order to provide a diagnosis were investigated immunohistologically using paraffin sections for the presence of a persistent infection with feline leukemia virus (FeLV). The spectrum of neoplastic and non-neoplastic diseases associated significantly with FeLV infection was determined statistically. Three-quarters of the cats with persistent FeLV infections died of non-neoplastic diseases and about 23% died of tumors, nearly exclusively those of the leukemia/lymphoma disease complex. A strong association with liver degeneration, icterus and a FeLV-associated enteritis was found in addition to the known association with non-neoplastic diseases and conditions such as anemia, bacterial secondary infections and respiratory tract inflammations due to the immunosuppressive effect of FeLV, hemorrhages and feline infectious peritonitis. Surprisingly, diseases and conditions like feline infectious panleukopenia, enteritis (of other types than FeLV-associated enteritis and feline infectious panleukopenia), glomerulonephritis, uremia and hemorrhagic cystitis were not associated with persistent FeLV infection. Another unexpected finding was that most pathogenic infectious agents demonstrated in the cats were not FeLV-associated either. Thus, immunosuppression due to FeLV infection seems to make the animals susceptible to certain pathogenic infectious agents, but not to the majority.     

Prevalence of feline immunodeficiency virus and other retroviral infections in sick cats in Italy.

Two hundred and seventy-seven sick pet cats living in Italy were tested for antibodies to feline immunodeficiency virus (FIV) and for feline leukemia virus (FeLV) antigen. Overall, 24% of the cats resulted positive for anti-FIV antibody and 18% for FeLV antigen. FIV was isolated from the peripheral mononuclear blood cells of ten out of 15 seropositive cats examined and from one out of eight saliva samples. No FIV isolations were obtained from six serum samples cultured. Feline syncytium forming virus (FeSFV) could be isolated from blood and/or saliva in ten out of 11 FIV seropositive cats examined, in six out of nine FeLV antigen positive cats, in two cats found positive for both infection markers, and in three out of 11 cats negative for both markers. Thus, the probability of isolating FeSFV was enhanced by infection with other exogenous retroviruses.     

Feline viral rhinotracheitis virus: explant and cocultivation studies on tissues collected from persistently infected cats

Tissues from 16 feline viral rhinotracheitis (FVR) carrier cats and 15 controls were examined by the techniques of homogenisation, cocultivation and explant cultivation. The tissues examined included trigeminal ganglion and maxillary nerve, olfactory lobe and nerve endings, tonsils, submandibular lymph node, spleen and parotid salivary gland. Most of the cats were shedding FVR virus in the oropharynx at the time the tissues were collected. No evidence of a persistent FVR virus infection was found in any of the tissues. Trigeminal ganglion explant cultures from six FVR virus carrier cats were shown to be latently infected with feline syncytia forming virus by treatment with 5-iododeoxyuridine. Five control cats had trigeminal ganglion explant cultures similarly treated but produced no evidence of infection. The possible significance of this is discussed.     

Pneumothorax in cats with a clinical diagnosis of feline asthma: 5 cases (1990–2000)

Objective: This paper characterizes the clinical findings in 5 cats with feline asthma complicated by concurrent pneumothorax. Design: Retrospective study. Medical records of cats with concurrent diagnoses of asthma and pneumothorax that were presented to the Veterinary Hospital of the University of Pennsylvania from 1990 to 2000 were reviewed. Results: Of 421 cases of feline asthma, 5 cats fulfilled the inclusion criteria (1.2%). All 5 had respiratory distress at presentation. One cat was panting, and the other 4 cats had respiratory rates of 28, 52, 58 and 120 breaths per minute (bpm), respectively (mean RR 65±39 bpm). Historical findings included untreated chronic cough (n=3), previously treated asthma (n=1), and no previous illness (n=1). Thoracocentesis was performed in 4/5 cats, and 3 of those cats required thoracostomy tubes. Four cats required immediate oxygen supplementation, and 1 of those cats required ventilation. All 5 cats had evidence of pneumothorax on initial radiographs. Follow‐up radiographs revealed partial or complete resolution of pneumothorax in 4 cats which were discharged alive with total hospitalization of 2–7 days, but were then lost to follow‐up. One cat was euthanized because it could not be weaned off mechanical ventilation, and necropsy confirmed end‐stage feline asthma and emphysema. Conclusion: Small airway obstruction can predispose asthma patients to increased alveolar pressure, emphysema, and spontaneous pneumothorax, which can lead to dyspnea in affected cats. The short‐term outcome in these cats was good despite the severity of dyspnea at presentation.