Isolation of calicivirus from the joint of a kitten with arthritis.

Calicivirus was isolated from the joint of a kitten that had pyrexia, upper respiratory tract disease, and severe shifting-limb lameness. Marked mononuclear inflammation was found in the synovial fluid. Calicivirus infection or live-virus vaccination previously had been associated with arthropathy, but virus had not been recovered from affected joints. Calicivirus infection should be considered as a diagnosis in kittens with fever and arthralgia, especially if there is a history of recent vaccination or upper respiratory tract disease. Lameness associated with calicivirus infection may be severe, but appears to be self-limiting and is associated with an excellent prognosis for recovery.     

Lethal outbreak of disease associated with feline calicivirus infection in cats

Recently, in the USA, virulent mutants of feline calicivirus (FCV) have been identified as the cause of a severe and acute virulent systemic disease, characterised by jaundice, oedema and high mortality in groups of cats. This severe manifestation of FCV disease has so far only been reported in the USA. However, in 2003, an outbreak of disease affected a household of four adult cats and an adult cat from a neighbouring household in the UK. Three of the adult cats in the household and the neighbouring cat developed clinical signs including pyrexia (39.5 to 40.5 degrees C), lameness, voice loss, inappetence and jaundice. One cat was euthanased in extremis, two died and one recovered. A postmortem examination of one of the cats revealed focal cellulitis around the right hock and right elbow joints. The principal finding of histopathological examinations of selected organs from two of the cats was disseminated hepatocellular necrosis with mild inflammatory infiltration. Immunohistology identified FCV antigen in parenchymal and Kupffer cells in the liver of both animals and in alveolar macrophages of one of them. In addition, calicivirus-like particles were observed by electron microscopy within the hepatocytes of one cat. FCV was isolated from two of the dead cats and from the two surviving cats. Sequence analysis showed that they were all infected with the same strain of virus, but that it was different from strains of FCV associated with the virulent systemic disease in cats in the USA. The outbreak was successfully controlled by quarantine in the owner's house.     

Feline panleukopenia virus, feline herpesvirus-1, and feline calicivirus antibody responses in seronegative specific pathogen-free cats after a single administration of two different modified live FVRCP vaccines

Two groups of feline panleukopenia virus (FPV), feline calicivirus (FCV), and feline herpesvirus-1 (FHV-1) seronegative cats (five cats per group) were administered one of two modified live feline viral rhinotracheitis, calicivirus, and panleukopenia virus (FVRCP) vaccines and the serological responses to each agent were followed over 28 days. While all cats developed detectable FPV and FCV antibody titers; only two cats developed detectable FHV-1 antibody titers using the criteria described by the testing laboratory. For FPV and FHV-1, there were no differences in seroconversion rates between the cats that were administered the intranasal (IN) FVRCP vaccine and the cats that were administered the parenteral FVRCP vaccine on any day post-inoculation. For FCV, the cats that were administered the IN FVRCP vaccine were more likely to seroconvert on days 10 and 14 when compared to cats that were administered the parenteral FVRCP vaccine.     

Interaction of a combined feline viral rhinotracheitis-feline calicivirus vaccine and the FVR carrier state.

The effect of field feline viral rhinotracheitis (FVR) virus challenge on cats previously vaccinated with a combined FVR/feline calicivirus intramuscular vaccine was studied in relation to the development of an FVR carrier state. There was no virus shedding of either of the two vaccine viruses following vaccination. Treatment with corticosteroid 60 days after vaccination and before challenge with FVR virus did not induce virus re-excretion in vaccinates or controls; neither did similar treatment induce shedding 63 days after challenge of both vaccinates and controls with virulent field virus. After a further 55 days however, FVR virus shedding was elicited in one of four previously vaccinated and challenged cats compared with two of four unvaccinated and challenged controls. Two sentinel cats remained virologically and serologically free of FVR throughout. The vaccine was shown to be effective in controlling the disease; 12 weeks after initial vaccination no clinical signs were seen in three of four cats following intranasal challenge with 10(5)CCID50 of virulent field FVR virus, and a mild transient unilateral ocular and nasal discharge was seen in the remaining cat for one day only. Severe clinical signs of approximately 10 days' duration were seen in all four unvaccinated challenged controls. The virological and serological responses of the cats were also recorded.     

An isolated epizootic of hemorrhagic-like fever in cats caused by a novel and highly virulent strain of feline calicivirus

An isolated epizootic of a highly fatal feline calicivirus (FCV) infection, manifested in its severest form by a systemic hemorrhagic-like fever, occurred over a 1-month period among six cats owned by two different employees and a client of a private veterinary practice. The infection may have started with an unowned shelter kitten that was hospitalized during this same period for a severe atypical upper respiratory infection. The causative agent was isolated from blood and nasal swabs from two cats; the electron microscopic appearance was typical for FCV and capsid gene sequencing showed it to be genetically similar to other less pathogenic field strains. An identical disease syndrome was recreated in laboratory cats through oral inoculation with tissue culture grown virus. During the course of transmission studies in experimental cats, the agent was inadvertently spread by caretakers to an adjoining room containing a group of four normal adult cats. One of the four older cats was found dead and a second was moribund within 48-72h in spite of symptomatic treatment; lesions in these animals were similar to those of the field cats but with the added feature of severe pancreatitis. The mortality in field cats, deliberately infected laboratory cats, and inadvertently infected laboratory cats ranged from 33-50%. This new isolate of calicivirus, named FCV-Ari, was neutralized at negligible to low titer by antiserum against the universal FCV-F9 vaccine strain. Cats orally immunized with FCV-F9, and then challenge-exposed shortly thereafter with FCV-Ari, developed a milder self-limiting form of disease, indicating partial protection. However, all of the field cats, including the three that died, had been previously immunized with parenteral FCV-F9 vaccine. FCV-Ari caused a disease that was reminiscent of Rabbit Hemorrhagic Disease, a highly fatal calicivirus infection of older rabbits.     

Molecular analysis of isolates of feline calicivirus from a population of cats in a rescue shelter.

Two visits, six weeks apart, were made to a cat rescue shelter and single oropharyngeal swabs were taken from all the compliant cats. Feline calicivirus was isolated from 14 of 45 swabs (31 per cent) taken on the first visit and 12 of 46 swabs (26 per cent) taken on the second visit. Nucleotide sequences were obtained for nine isolates from the first visit, six isolates from the second visit, and for the vaccine virus used in the cattery. Distance analysis showed that the majority of the isolates could be assigned to one of two groups. All the isolates obtained from cats sharing the same pen or isolates obtained from the same cat on successive visits, were less than 5 per cent distant, whereas most of the isolates from cats in different pens were more than 20 per cent distant. Phylogenetic analysis showed that at least seven distinct field isolates were present in the cattery. The only good evidence for virus transmission within the cattery was a case in which two viruses isolated from cats in different pens had sequences that were less than 5 per cent distant.     

Evaluation of the immunogenicity of attenuated feline calicivirus vaccines by ELISA.

An ELISA test was developed to measure the levels of IgG antibody in specific-pathogen-free (SPF) cats immunised with two doses of an attenuated feline calicivirus (FCV) vaccine. All eight vaccinates were protected from virus challenge, but four out of five non-vaccinates were not. There was a significant difference in respect of protection from virus challenge between SPF cats with and without three-fold or greater increase in antibody units (P = 0.01). Each serum absorbance was standardised against the reference positive which has an arbitrary value of 100 antibody units. In SPF cats, the 99% confidence level for seropositivity to FCV was determined as greater than or equal to 2.5 antibody units. The results suggest that the sensitive ELISA test can be used to monitor the antibody status of SPF cat colonies prior to FCV vaccine trials, and to measure the immunogenicity of attenuated FCV vaccines. Thus, the ELISA test may replace the need for virus challenge, with consequent reduction in animals used in future FCV vaccine trials.     

Serological responses to the cell associated herpesvirus and the manx calicivirus of SPF male cats with herpesvirus-induced urolithiasis

The feline cell associated herpesvirus (CAHV), but not the Manx calicivirus, was previously reported to induce urolithiasis in specific pathogen free (SPF) cats. Serum neutralization (SN) antibody studies, reported here, revealed that the experimental SPF cats did not have SN antibodies either against the CAHV or the Manx calicivirus in preinoculation serum samples. However, all cats inoculated with the CAHV (either alone or in combination with the Manx virus) developed SN antibodies against the herpesvirus. SN antibodies against the CAHV were detected 21 days post inoculation (PI) in 7 cats, 41 days PI in 4 cats, and 89 days PI in 1 cat. Cats inoculated with the Manx calicivirus alone, or in combination with the CAHV developed SN antibodies against the calicivirus in 7 to 21 days PI with that virus.     

The effectiveness of paramunization for the control of feline coryza]

20 cats in a cat home were treated prophylactically and therapeutically with Baypamun HK. The animals were allocated into three groups as described. 7 freshly admitted clinically healthy cats were treated prophylactically on day 1, 2 and 9 with 1 ml Baypamun HK (group I). 7 cats, who already were allocated for one year in the home and were sick of the feline respiratory disease complex were treated as described for group I (group II). 6 further cats, who also showed symptoms of the feline respiratory disease complex and had stayed for one year in the home were treated with physiol.saline solution according to group I (group III). From all cats blood samples were taken at day 1, 3, 10 and 17. The blood samples were checked for antibodies against feline calicivirus (FCV), feline herpesvirus (FHV), panleukopenia virus (PLV), feline peritonitis virus (FIPV) and feline immunodeficiency virus (FIV). Also the occurrence of the feline leukemia virus (FeLV) was evaluated. The cellular immunity was evaluated by means of the lymphocyte transformations test (LTT), nitroblue-tetrazolium reduction test (NBT) and cytochrome C-reduction test (CRT). Mean value and standard deviation was calculated from the results. The significance was determined by the t-test. The animals were examined clinically daily for 20 days for the feline respiratory disease complex. When necessary, the animals were treated by homeopathic and antibiotic products. At the time of admission to the home all cats were or had been treated with an attenuated panleukopenia vaccine. The serologic parameters were not influenced in the cats of group I.(ABSTRACT TRUNCATED AT 250 WORDS)     

Orthopaedics

Practice records from November 1994 to April 2000 were searched for cats with a diagnosis of osteoarthritis (OA). Signalment, historical features and findings, treatment and response to treatment were recorded with the aim of planning prospective studies. Thirty-one cases were found. The average age at presentation was 13·8 years (range, nine to 17 years); 67 per cent were female and 33 per cent male. Clinical signs noted included chronic changes of stiff/abnormal gait (12), difficulty/reluctance in jumping (20) and reluctance to move (five). Eleven cases had acute or chronic lameness. Seven of the records indicated that the cat had been overweight. Physical findings included thickened joints (23), pain on joint manipulation (seven) and crepitus (four).Twenty cases had been radiographed. Findings included osteophytes (14), sclerosis (10), periosteal new bone (four) and remodelling (three). Routine blood tests were performed in 15 cats and showed single abnormalities in five cases. Concurrent diseases diagnosed included hyperthyroidism, dental diseases and chronic renal failure. The final diagnosis had been based on the history, examination, diagnostic tests and response to treatment. The joints thought to have been affected by OA were as follows: bilateral elbows (12), bilateral stifles (four), bilateral elbows and stifles (four), unilateral elbow (three), bilateral hips (two), other combinations of joints (six). Seventeen cats had both meloxicam treatment and a follow-up examination (they may have had concurrent treatments). The clinical notes recorded whether the owners considered there to have been an improvement: three showed marked improvement, 11 showed moderate improvement, one showed no improvement, one had an inconclusive response, and side effects stopped treatment in one. One cat showed a marked improvement after treatment with courses of pentosan polysulphate.     

Neutralisation patterns among recent British and North American feline calicivirus isolates from different clinical origins

The neutralisation patterns of 103 recent isolates of feline calicivirus from cats with chronic stomatitis or acute feline calicivirus disease, and from cats with neither oral nor respiratory disease were compared. There were no statistically significant differences between the proportions of isolates from each clinical source neutralised by individual feline calicivirus cat antisera. Different antisera showed widely differing degrees of cross reactivity; antisera to the most widely used vaccine strain F9 being the most cross reactive, neutralising 54 per cent of all the field isolates, and antisera to a field isolate LS015 the next most cross reactive, neutralising 29 per cent of the field isolates. However, the cross reactivity of antisera to early British isolates (A4, 68/40 and 69/1112) was much reduced (overall less than 10 per cent) whereas in the early 1970s 65 per cent of 117 field isolates from clinically normal cats were neutralised by A4 antiserum, and 40 per cent by each of 68/40 and 69/1112 antisera. This suggests a change in the spectrum of antigenicity among feline calicivirus isolates over the past 15 years. However, the cross reactivity of F9 antisera appeared to be similar to that in earlier studies. The relevance of these findings to vaccination is discussed.     

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.     

Immunologic responses in healthy random-source cats fed N,N-dimethylglycine-supplemented diets.

The immunomodulatory capacities of N,N-dimethylglycine (DMG) were examined in random-source cats. Blood mononuclear leukocytes of healthy adult cats that had negative results to tests for FeLV and feline immunodeficiency virus were exposed in vitro to various concentrations of DMG (10 to 1,000 micrograms/ml) and were evaluated for proliferative responses to T- or B-cell phytomitogens. Although increased, mean lymphocyte blastogenic responses to phytolectins in DMG-treated cultures did not differ significantly from responses of untreated cultures. For in vivo studies, cats were given a solution containing either 100 mg of DMG or a control solution without DMG orally at 8 AM and 6 PM for 40 consecutive days. On post-treatment day 24 and 25, mean blastogenic responses to phytolectins in DMG-treated and control cats inoculated 10 days earlier with an inactivated feline virus vaccine were similar. Cats given DMG and inoculated twice in a 3-week interval with a commercial vaccine containing inactivated feline herpesvirus-1 and feline calicivirus had significantly (P = 0.045) lower virus neutralizing serum antibody titers against feline herpesvirus-1, compared with titers of control cats, whereas feline calicivirus titers were similar in both groups. On day 25, mean serum interferon activity, induced after IV inoculation of Newcastle disease virus, was significantly (P = 0.021) lower in the DMG-treated cats. Results of this study of DMG in healthy cats failed to demonstrate enhancement of either specific or nonspecific immunity.     

Herpesvirus induced feline urolithiasis--a review.

Three viruses were isolated during early studies of feline urolithiasis. These viruses were: feline calicivirus, feline syncytium forming virus (FeSFV), and a previously undescribed cell associated herpesvirus (CAHV).Urolithiasis in all its manifestations (hematuria, urethral obstruction, and cystitis) has been reproduced in specific pathogen free (SPF) male cats following inoculation with the herpesvirus alone. The disease has not been induced in SPF cats with the calicivirus alone. However, when SPF cats were inoculated with both the CAHV and calicivirus, clinical signs of disease developed earlier and more urinary tract disease complications were produced. From these results, it is postulated that the calicivirus may act as an enhancing or complicating factor in the development of the disease. Because urolithiasis was produced in SPF cats without the FeSFV, it is further postulated that this virus either may have no role in pathogenesis of the disease, or it too may produce secondary complications.     

Protection against bovine respiratory syncytial virus challenge following a single dose of vaccine in young calves with maternal antibody

Twenty-one young calves with maternally derived antibody to bovine respiratory syncytial virus (BRSV) were divided into three groups of seven, each group balanced for BRSV antibody titre. The calves had no evidence of previous exposure to BRSV. The calves in one group were given a single dose of a monovalent modified live BRSV vaccine; the calves in the second group were given a single dose of an inactivated combined BRSV, parainfluenza virus type 3, Mannheimia haemolytica vaccine and the calves in the third group were left as unvaccinated controls. Three weeks after the single doses of vaccine, all the calves were challenged with BRSV. The clinical signs of disease were mild, and virus excretion was limited to two calves in the group given the inactivated vaccine, compared with six in the negative controls (P = 0.05) and five in the group given the live vaccine. The mean virus excretion titres after the challenge were not significantly different between the groups. There was little seroconversion before the challenge, but six of the seven calves in the group given the inactivated vaccine showed significant seroconversion within two weeks after the challenge, compared with only one calf in each of the other two groups (P = 0.015).     

Mycoplasma gateae arthritis and tenosynovitis in cats: case report and experimental reproduction of the disease

Polyarthritis and tenosynovitis were diagnosed in a cat. Clinical signs of 2 months' duration included swollen limbs, painful joints (sensitive to touch), lameness, and pyrexia. Laboratory test data revealed hypogammaglobulinemia, hypoalbuminemia, leukocytosis, and mild anemia. The cat was euthanatized and necropsied; there were chronic necrotizing fibrinopurulent tenosynovitis and arthritis with bone and cartilage erosions. Cultural examinations of synovia were positive for Mycoplasma gateae, but bacterial and viral cultural examinations were negative. Organisms propagated from the M gateae isolate were inoculated IV into 6 specific-pathogen-free cats--3 of these being subjected to immunosuppression induced with azathioprine. The 6 inoculated cats became lame 5 to 9 days later, and 5 became febrile. Cultural examinations of the pharynx in 4 cats were positive for M gateae and in 3 cats, the organism was isolated from various joints. Microscopically, arthritis and tenosynovitis were identified in all cats. Two specific-pathogen-free cats were used as controls (noninoculated); these did not become lame, had negative M gateae cultures, and were free of histopathologic abnormalities. Reproduction of disease with recovery of the causative agent indicates the pathogenicity of this particular isolate of M gateae in the cat when inoculated IV.     

FCV-VBS isolated from cats with typical symptoms caused VSD in experimental cats

Commercially available vaccines have been used widely to prevent feline calicivirus infection (FCI). However, with their widespread use, field strains, which are weakly cross-reactive with the live-virus vaccine strain F9, have posed the problem of vaccine breakdown. Recently the existence of FCV—associated virulent systemic disease (VSD) has been published. But their molecular diversity, antigenic mutations and physicochemical property have not been sufficiently clarified. Thus, we experimentally gave the vaccine breakdown strain (VBS) H10 to cats that had been inoculated with an F9 live vaccine. After the administration of strain H10, vaccinated cats (1 through 4) had no respiratory symptoms, whereas the non-vaccinated cat 5 showed clinical symptoms such as a fever of over 40°C, loss of vitality, decreased appetite, diarrhea, and nasal discharge after receiving strain H10, and died. Lethal FCV is rare, and may be a virulent systemic disease (VSD)—inducing strain. This is the initial report on VSD in Japan. It has been reported that symptoms of VSD were similar in vaccinated and nonvaccinated cats on experimental infection. However, no VSD-like symptoms developed, and the incidence of the disease varied depending on the presence or absence of vaccination, suggesting that there are two mechanisms of vaccine breakdown: one is associated with the vaccine immunity level, and the other is not. The characteristics of the VBS revealed were: (1) the duration of virus excretion was short when the originally carried antibody titer before virus challenge was high, (2) the excreted viral molecular species varied daily, not being limited to a specific species with time, and (3) the acquired physicochemical properties did not persist, and altered daily. FCV-VBS alters the molecular species and physicochemical properties daily due to the reduction of host immunity, which may lead to VSD.     

Clinical signs and results of treatment in cats with patellar luxation: 42 cases (1992-2002)

OBJECTIVE: To describe clinical signs and results of treatment in cats with patellar luxation. DESIGN: Retrospective case series. ANIMALS: 42 cats in which patellar luxation had been diagnosed on the basis of results of palpation of the stifle joints. PROCEDURES: Degree of luxation was graded on a scale from 1 to 4, and severity of lameness was graded on a scale from 0 to 5. Radiographs of stifle joints were evaluated for signs of osteoarthritis. Long-term function was classified as poor, fair, good, or excellent. RESULTS: 34 cats had bilateral luxation and 8 had unilateral luxation. Only 7 (17%) cats had a history of trauma. Mean age of the cats was 3.3 years, and mean weight was 4.26 kg (9.4 lb); 26 (62%) were domestic shorthairs. Seventy-three of the 76 (95%) affected joints had medial patellar luxation. Luxation grades could be assigned to 65 joints, with grade 2 (30 joints) and 3 (22 joints) luxation being most common. Lameness grades could be assigned to 73 joints, with grade 1 lameness (27 joints) most common. Outcome was excellent for 8 of 17 joints treated without surgery and for 23 of 35 joints treated surgically. Complications attributable to surgery were reported in 8 cats. CONCLUSIONS AND CLINICAL RELEVANCE: Patellar luxation should be considered as a cause of hind limb lameness in cats. Low-grade luxation can be associated with lameness of the same severity as high-grade luxation. Surgical correction of patellar luxation in cats with grade 2 or 3 lameness can result in a favorable outcome.     

Histoplasma capsulatum Osteomyelitis in the Cat

Seven cats with osseous lesions as the primary manifestation of disseminated Histoplasma capsulatum infection were evaluated. The major clinical signs in these cats were related to the bony lesions and included lameness, bone pain, and soft tissue swelling of limbs and joints. Other clinical and pathologic findings were similar to previously reported forms of disseminated histoplasmosis in the cat. The radiographic appearance of the lesions was predominantly osteolytic; periosteal and endosteal new bone production was present in some cases. Infection occurred primarily in bones of the appendicular skeleton with a predilection for sites below the elbow and stifle joints.     

Results of molecular diagnostic assays targeting feline herpesvirus-1 and feline calicivirus in adult cats administered modified live vaccines

In this pilot study, 12 adult, gang-housed cats that were known to be previously exposed (n=12) to feline herpesvirus-1 (FHV-1) and/or vaccinated against (n=2) feline calicivirus (FCV) and FHV-1 were randomly assigned to one of two groups of six cats each. Nasal and pharyngeal samples were collected from each cat on days -7, -3, and 0 prior to vaccination and on days 3, 7, 10, 14, 17, 21, and 28 after vaccination with an FHV-1, FCV, and panleukopenia (FVRCP) vaccine developed for intranasal (six cats) or parenteral (six cats) use. FHV-1 DNA was amplified from 1/12 cats (1/69 samples; 1.4%) prior to vaccination and 2/12 cats after vaccination (2/154 samples; 1.3%). FCV RNA was amplified from 2/12 cats (2/69 samples; 2.9%) prior to vaccination and 7/12 cats (12/154 samples; 7.8%) after vaccination. Positive molecular diagnostic assay results for FHV-1 and FCV were uncommon prior to or after vaccination in these cats.