The re-excretion of feline viral rhinotracheitis (FVR) virus (feline herpesvirus I) by FVR-recovered cats is recorded both spontaneously and following a variety of stimuli, namely, corticosteroid administration, change of housing, and parturition and lactation. At least 27 of 33 (82%) FVR-recovered cats studied were shown to be viral carriers. The carrier state was characterised by periods of viral latency interspersed with episodes of viral shedding. Administration of 0-75 mg dexamethasone trimethylacetate and 2-25 mg prednisolone on days 0,2 and 4 resulted in re-excretion after a mean lag period of 7-2 days in 22 of 32 (69%) FVR-recovered cats on a total of 31 of 57 (54%) occasions. Rehousing resulted in virus re-excretion after a mean lag period of 7-2 days in four of 22 (18%) cats tested on a total of six of 40 (15%) occasions. Apparently spontaneous shedding occurred on a total of 10 occasions in nine of 31 (29%) cats during a mean observation period of 8-8 months. Four of six FVR-recovered queens in a total of four of 10 litters (40%) shed virus within two to 10 weeks of parturition. Serum neutralising antibody titres were generally boosted at the time of first re-infection but afterwards remained essentially constant. Although 82% of cats in these studies were shown to be viral carriers, only 45% of cats shed virus spontaneously or as a result of the natural stress situations and it is postulted that these naturally excreting cats are of most significance epidemiologically.

The transmission of feline viral rhinotracheitis (FVR) virus was investigated. Virus could be successfully transmitted between shedding carrier cats and unrelated susceptible kittens, but only if there was intimate contact between them. Studies on the transmission of FVR virus from carrier queens to their kittens showed that although four of 10 queens shed virus in the post partum period, a total of only four kittens from three litters developed a contact infection. All four kittens remained asymptomatic. Two shed for one day only and did not become carriers (as evidenced by corticosteroid treatment) and two shed for 15 days and 25 days and were subsequently shown to have become carriers. None of the remaining kittens tested shed virus. There was no evidence of in utero transmission between FVR-recovered queens and kittens. Passive antibody titres in kittens born to FVR-recovered queens declined to less than 1 in 4 in individual animals by two to 10 weeks of age. Mean titres calculated from a linear regression equation reached less than 1 in 4 and less than 1 in 2 by six and nine weeks of age, respectively. Experiments using a multistage liquid impinger demonstrated that FVR virus was unlikely to be transmitted between cats by aerosol and this was confirmed by the ability of a sentinel cat to withstand virus shedding from carriers over a six month period, although housed in the same air space.

A survey of healthy and respiratory‐diseased cats, post‐mortem kitten specimens and serum samples, showed the widespread occurrence of feline rhinotracheitis virus infection (FVR) and feline picornavirus infection (FPI) in Britain. Both virus groups were on occasions isolated from clinically healthy cats but they were more frequently associated with upper respiratory disease. No colony outbreak of respiratory disease was investigated without either FVR or FPI being incriminated. Clinical differentiation of FVR and FPI was imposible with certainty although FVR infection was typically more severe. Pathologically, FVR could be distinguished particularly in the early stages by the presence of specific intranuclear inclusions in mucosal and submucosal gland cells of the respiratory tract and by a generally more severe mucosal destruction. FPI was typified by a mild disorganization of mucosae and mononuclear cell infiltrations. Serological investigations demonstrated that, in colonies particularly, high titres of antibody against both FVR virus and a spectrum of feline picornaviruses were attained in adult cats, a reflection of the endemic nature of these viruses. Bacteria played a secondary role in both FVR and FPI, and there was no evidence for chlamydial agents being important in the aetiology of feline respiratory disease in Britain. Résumé. Une étude de chats sains et atteints de maladies des voies respiratoires, de spécimens d'autopsie de chatons et d‘échantillons de sérum montre que les rhinotrachéites félines avec infection d'origine virale (RFV) et les infections ftlines de “picornavirus” (IFP) sont très répandues en Grande‐Bretagne. A différentes occasions, les deux groupes de virus, provenant de chats sains du point de vue clinique, ont été isolés mais ces virus étaient le plus souvent lies aux maladies respiratoires d'origine otorhinolaryngologique. Toutes les recherches sur les maladies respiratoires se declarant par colonies indiquaient la présence soit de RFV ou de I'IFP. La dif‐férenciation clinique certaine de RFV et d'IFP fut impossible bien que l'infection RFV fût plus grave come prévu. Pathologiquement, il fut possible de distinguer le RFV, surtout dans les premiers stades, par la présence d'inclusions intranucléaires spécifiques dans les cellules des glandes muqueuses et submuqueuses des voies respiratoires et par une destruction muqueuse généralement plus grave. L'IFP était caracterisée par une légère désorganisation des membranes muqueuses et des infiltrations de cellules mononucléaires. Des recherches sérologiques ont montré, surtout pour les colonies, qu'on rencontre des titres élevés d'anticorps contre le virus RFV ainsi qu'un spectre de “piconavirus” felins chez des chats adultes, ce qui réflète la nature endémique de ces virus. Les bactéries n'ont joué qu'un rôle secondaire, à la fois dans les RFV et les IFP et il n'y eut pas d'indices indiquant l'importance des agents “Chlamydiaux” dans l‘étiologie des maladies respiratoires félines en Grande‐Bretagne. Zusammenfassung. Ein zusamm...

The prevalence of feline calicivirus (FGV) and feline viral rhinotracheitis (FVR) virus was assessed in three different groups of clinically healthy domestic cats. The 1500 cats were sampled using single oro‐pharyngeal swabs. The rate of isolation for FCV and FVR virus respectively was 8% and 1% in the household pet sample, 24·02% and 1·75% in the cat‐show sample and 41·5% and 0·4% in colonies A and B. The differences are discussed in relation to the different carrier states of these viruses and the social habits of the cats in each group. A computer analysis of the cat‐show group with regard to age, sex and breed demonstrated a statistically significant, lower infection rate of FCV in (1) neutered animals as compared with entires, (2) older cats compared with 0–1 year old animals and (3) certain age groups in both the Longhaired and Burmese cats as compared with other breeds. Résumé. On a évalué la fréquence de virus calice félin et de virus rhinotrachéite viral félin dans les différents groupes de chats domestiques cliniquement en bonne santé. On a essayé un seul prélèvement oropharyngien dans 1500 chats. Le pourcentage d'isolation pour le virus FCV et le virus FVR était respectivement de 8% te de 1% dans l'échantillon de prélèvement du chat domestique, 24,02% et 1,75% dans l'échantillon du chat d'exposition et de 41,5% et de 0,4% dans les colonies A et B. On discute des différences en relation avec les différents états des porteurs de ces virus et des habitudes sociales des chats dans chaque groupe. Une analyse par machine à calculer électronique du chat d'exposition concernant l'âge, le sexe et la race a démontré un pourcentage statistiquement significatif plus faible d'infection de FCV chez (1) des animaux châtrés comparés â des animaux non‐châtrés, (2) des chats plus âgés comparés à des animaux de 0 à 1 an et (3) des groupes d'une certaine classe chez des chats à poils longs et des chats de Birmanie en comparaison avec d'autres races. Zusammenfassung. Das Vorherrschen von Katzen‐Kalizivirus (FCV) und Katzen‐virusalen Rhinotracheitis (FVR) Virus wurden in den verschiedenen Gruppen von klinisch gesunden Hauskatzen geschächtzt. Die 1500 Katzen wurden geprüft indem man einem einzigen Mundrach‐enabstrich machte. Das Verhàltnis von Isolierung für FCV und FVR Virus war jeweilig 8% und 1% in der Hauskatzenprobe, 24,02% und 1,75% in der Katzenschauprobe und 41,5% und 0,4% in den Kolonien A und B. Die Unterschiede werden diskutiert in bezug auf den verschiedenen Übertragungszustand von diesen Viren und den geselligen Angewohnheiten dieser Katzen in jeder Gruppe. Eine Komputeranalyse der Katzenschaugruppe in bezug auf Alter, Geschlecht und Rasse bewies eine statistisch bedeutsame, niederere Infektionsrate an FCV in (1) kastrierten Tieren als der verglichen mit Nichtkastrierten, (2) ältere Katzen verglichen mit 0–1 jährig alten Tieren und (3) gewisse Altersgruppen bei den langhaarig‐ und Burmesischen Katzen verglichen mit anderen Rassen.

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