£5.00, $9.00, €7.50 Melchizedek publications www.catvirus.com If you print this book out – please do so on recycled paper! Cover photos – feline calicivirus ulcer on tongue unilateral conjunctivitis typical of early Chlamydophila felis infection feline chronic lymphocytic plasmacytic gingivostomatitis © Diane D. Addie PhD BVMS MRCVS Sep 2006 2 Contents Page Introduction ………………………………………………………………………. 4 Feline calicivirus………………………………………………………………….. 4 Feline chronic gingivostomatitis ………………………………………….. .….. 7 Feline herpesvirus (viral rhinotracheitis)……………………………………….. 10 Chlamydophila felis……………………………………………………………….. 13 Bordetella bronchiseptica ……………………………………………………….. 16 Avian influenza virus H5N1 …………………………………………………….. 17 Poxvirus …………………………………………………………………………… 19 Feline coronavirus ……………………………………………………………….. 19 Haemophilus felis ………………………………………………………………… 19 Aelurostrongylus abstrusus …………………………………………………….. 19 Mycoplasma felis ………………………………………………………………… 20 Corynebacterium spp ……………………………………………………………. 20 Cryptococcus spp ……………………………..…………………………………. 20 Capillaria aerophila ………………………………………………………………. 21 Cuterebra larval migrans ………………………………………………………… 21 Differential diagnoses …………………………………………………………… 22 acute oral ulceration …………………………………… 22 chronic gingivostomatitis……………………………….. 22 chronic rhinitis ………………………………………….. 22 conjunctivitis ……………………………………………. 23 coughing ………………………………………………… 23 fading kittens ……………………………………………. 23 bronchopneumonia of kittens …………………………. 24 Preventing respiratory infection 25 hygiene ………………………………………. 25 barrier nursing ………… …………………… 25 good building design ……………………….. 25 cat breeders ………………………………… 27 cat rescuer/shelter ………………………… 27 boarding cattery ……………………………. 27 Recommended laboratories …………………………………………………….. 28 Useful contact details and websites 30 Index ………………………………………………………………………………. 31 3 Introduction The major feline upper respiratory tract (URT) infections are: Feline calicivirus Feline herpesvirus Chlamydophila felis Bordetella bronchiseptica Mycoplasma felis Less common infectious causes of URT signs in the cat: Poxvirus (cat pox) Haemophilus felis Aelurostrongylus abstrusus Corynebacterium spp (conjunctivitis) Cryptococcus spp Capillaria aerophila Avian bird flu (H5N1) I am pleased to present the first edition of Feline Infectious Upper Respiratory Disease for veterinary surgeons. The purpose of this book is to present you with everything you might require to know about feline infectious upper respiratory disease in an easily accessible format. Infectious diseases of the lower respiratory tract are outwith the scope of this book at this stage, as are non-infectious causes, though they will be briefly mentioned in the section on differential diagnoses. These may be added later or be the subject of another book, if there is any demand for it. There will soon be a sister book written for non-veterinarians, which you may find useful for your clients and veterinary nurses (technicians) and a book is planned specifically for cat breeders. I am keen for feedback and any suggestions on how the book can be made better will be welcomed. My email address is [email protected] Feline calicivirus (FCV) Feline calicivirus (FCV) is a small, unenveloped, positive strand RNA virus belonging to the Vesivirus genus. RNA viruses are more prone to mutations than DNA viruses and FCV exists in each cat as a quasispecies (a cloud of viruses with slightly differing genomes and therefore antigenicity). Quasispecies variation is greatest where there are many cats, for example, in boarding and rescue catteries, and in these environments mutants with unusual clinical manifestations are most likely to appear first. Virus shedding: in oropharyngeal secretions, shedding is continuous. Half life of 75 days. Transmission: mainly direct, but FCV is slightly more robust than FHV and can survive up to 7 days in the environment so fomite transmission is possible. It is susceptible to bleach. Clinical signs of FCV infection The majority of cats who shed FCV are asymptomatic. 4 Cat flu: FCV is less severe than feline herpesvirus (FHV) infection, but nevertheless causes cat flu in kittens over 2-3 weeks old and adult cats. FCV commonly causes lingual ulceration, sneezing, anorexia, depression and oculonasal discharge. Fading kittens: if kittens are infected soon after birth they may die, post mortem shows thymic atrophy, congested lungs, the body will probably be underweight for the kitten’s age. FCV is found in almost 100% of cases of feline chronic gingivostomatitis, though its role in the aetiology of the condition is controversial (see below). Other signs associated with FCV: shifting lameness (especially some vaccines implicated). Acute haemorrhagic diarrhoea, outbreaks in the USA and UK presented with jaundice and oedema, 40% mortality. Dr Kate Hurley, University of California, is an expert in this. Diagnostic testing: the relative fragility of RNA and the variability of the RNA genome of FCV strains renders polymerase chain reaction (PCR) testing more complex than with other organisms: the RNA may get degraded by ubiquitous RNA-ases before the test can be performed (resulting in false negative results) and there is the possibility that the primers used will miss some isolates which are genetically different from the strain the primers were based upon (again resulting in false negative results). In qPCR this is even more of a problem as both the primers and probe must match the target cDNA (DNA copy of the RNA genome) very closely. Therefore virus isolation is probably still the gold standard test. However, there exist cats who shed very low levels of FCV and these cats can be difficult to detect by virus isolation, so 3 tests at intervals of a week to a month are required to be confident that an infected cat has ceased to shed virus. Treatment of FCV infection Treatment is essentially symptomatic and supportive. Supportive treatment of cats with flu is vital: the cat should be tempted to eat with small but frequent portions of aromatic foods such as sardines, roast chicken or liver. In order to clear the nasal passages it is beneficial to the cat if he can be confined to a steamy bathroom for an hour each day. Vick Vaporub can be applied to the chin or a few drops of eucalyptus oil put on the cat's bedding. The cat should be cleaned gently with a cloth and warm water (especially if he can no longer groom himself) and kept warm until dry. Cats with ocular discharge should have their eyes bathed three or four times a day with a warm solution of salt and water, using one teaspoonful of ordinary table salt (sodium chloride) in one pint (half a litre) of water. Feline interferon omega – 1 MU/kg s/c for up to 5 days - can be life saving for cats with acute cat flu. Broad spectrum antibiotics should also be given (doxycycline preferably, unless tooth colour is important) to cover secondary bacterial disease. Treatment of feline chronic gingivostomatitis is given below. Prevention of FCV infection FCV vaccination may ameliorate clinical signs, but does not prevent asymptomatic carrier states. Vaccines are given at 8 or 9 and 12 weeks of age, with a booster at 1 year and thereafter every 3 years if you are following AAFP recommendations. 5 Virus neutralising antibodies to the F9 strain included in many vaccines do not protect against the majority of field strains. Although Fort Dodge claim that their FCV strain (strain 255) covers over 90% of field strains, a published paper placed the figure nearer 55%. A bivalent vaccine was introduced by Merial in 2005 containing two new strains, G1 and 431. It is possible that this vaccine will offer more cross-protection than other vaccines (Poulet et al, 2005). Table 1 FCV strains in vaccines Vaccine Manufacturer FCV Route Comments strain(s) admin Nobivac Intervet F9 s/c live Tricat Katavac CHP Fort Dodge 2113 s/c live (strain info from VMD) Katavac Fort Dodge 2113 s/c live (strain info from VMD) Eclipse Fevaxyn Fort Dodge 255 s/c inactivated Pentofel Felocell CVR Pfizer F9 s/c live Quantum cat Schering F9 s/c live CVRP Plough Purevax RC Merial G1, 431 s/c antigens new FCV strains Eurifel RC Merial 255 s/c inactivated Feline Heska ? i/n live only available in USA Ultranasal (The only way I’ve found of accessing the Veterinary Medicine’s Directorate files on these products is to do a Google search, put in the product name, and the words “Summary Product Characteristics” – this will often give you information you can’t find in the NOAH compendium.) FCV control for cat breeders: test breeding queens by virus isolation or RT-qPCR from an oropharyngeal swab. FCV is shed continuously, so if the test is sensitive enough, a negative result is truly negative. Shedding half-life is 75 days. Separate positive and negative cats and retest after 2-3 months, when half of the cats which were positive should now be negative. Repeat until the whole colony is negative, possibly rehoming any persistent shedders. Preferably breed using only negative queens. If not possible, maternally derived antibody (MDA) lasts up to 2-3 weeks, so kittens can be early weaned and kept in isolation from infected individuals. An intra-nasal vaccine has been introduced by Heska in the USA and may come to the UK – if so, it could be used on young kittens to try to prevent infection when MDA wanes. Quarantine: serious cat breeders should try to prevent this virus from entering their household by testing all new cats and prospective mates of their cats before admitting them into their premises. Disinfection: use bleach diluted