Upper Respiratory Screening in Cats
"We regularly screen our cats with, and thoroughly recommend, Idexx Lab's"
- Stylisticat
Calicivirus (FCV)
Feline calicivirus (FCV) is a highly contagious virus that is one of the major causes of upper respiratory infections (URIs) or cat flu in cats.
This virus is ubiquitous and causes disease in cats all over the world. Also, upper respiratory infections (URIs, cat flu) in cats are seen. Together, FCV and feline herpesvirus cause most URIs in cats.
What is FCV, and how is it spread? Feline calicivirus (FCV) is a small virus that mainly causes acute upper respiratory infections (URIs) in cats, although it has also been associated with some other diseases (see below). The virus is readily transmitted between cats through:
What are the clinical signs of FCV infection?
Treatment and management of FCV infectionsFCV infections are frequently complicated by secondary bacterial infections, so supportive antibiotic treatment is usually required. Good nursing care is critical, and cats may need to be hospitalised for intravenous fluid therapy and nutritional support in severe cases. Steam inhalation or nebulisation may help in cases of severe nasal congestion, and as the cat will not be able to smell food well, using tinned or sachet foods that are gently warmed will help.
In colonies of cats, any cat showing clinical signs should be isolated if possible. Strict hygiene should be ensured through disinfection, using separate feeding bowls, litter trays, implements, etc., careful hand washing, and using separate (or disposable) aprons etc.
Vaccination against FCVVaccination against FCV is important for all cats. Two or three injections are recommended in kittens, starting at around 8 weeks of age. Cats should receive a booster at a year of age and, after that, should receive further booster vaccines every 1-3 years.
Vaccination does not necessarily prevent infection with FCV but will significantly reduce clinical disease severity. Additionally, as there are many strains of the virus, it is challenging to design a vaccine that will protect against all of them. Some newer vaccines incorporate more than one strain of FCV to provide a broader range of protection.
This virus is ubiquitous and causes disease in cats all over the world. Also, upper respiratory infections (URIs, cat flu) in cats are seen. Together, FCV and feline herpesvirus cause most URIs in cats.
What is FCV, and how is it spread? Feline calicivirus (FCV) is a small virus that mainly causes acute upper respiratory infections (URIs) in cats, although it has also been associated with some other diseases (see below). The virus is readily transmitted between cats through:
- Direct contact – through contact with saliva, ocular or nasal secretions
- Inhalation of sneeze droplets
- Sharing food bowls and litter trays
- A contaminated environment (including bedding and grooming aids) – FCV can survive up to a month in the environment, although it probably often does not survive more than 7-14 days.
What are the clinical signs of FCV infection?
- Acute upper respiratory infection – Acute URI is the most common manifestation of FCV infection. Typical signs include sneezing, nasal discharge, ocular discharge, conjunctivitis, tongue ulceration, lethargy, inappetence and fever. Signs may vary in severity from a few days to a few weeks. In young kittens, the virus may also cause pneumonia.
- Gingivitis and stomatitis – chronic gingivitis is a common disease in cats, although the underlying cause(s) are not fully understood. However, FCV can be isolated from virtually all cats with this condition, and it is thought that the persistence of FCV infection in these cats is part of the cause of the gingivitis. This is not a simple disease, though, as other cats exposed to the virus from a cat with chronic gingivitis will usually only develop upper respiratory signs. Other factors, therefore, seem to predispose individual cats to developing gingivitis in response to persistent FCV infection.
- Limping syndrome – occasionally, in young cats, infection with FCV may also cause joint inflammation (arthritis). This is a transient problem, usually only lasting a few days, but the kitten or cat may be highly uncomfortable with painful joints during this time. Often, but not always, there will be signs of URI at the same time. (See: Limping syndrome and feline calicivirus)
- Virulent systemic FCV infection – vsFCV – on rare occasions, disease outbreaks have been reported with much more pathogenic strains of FCV termed vsFCV. These are associated with mutations of the virus that allow infection to be established within different organs and in the cells that line blood vessels. This can result in severe disease, including pneumonia, hepatitis (liver inflammation), pancreatitis, skin swelling and ulceration, and bleeding from the nose and intestine. Fortunately, these outbreaks are sporadic, but up to 50% or more of affected cats may die
Treatment and management of FCV infectionsFCV infections are frequently complicated by secondary bacterial infections, so supportive antibiotic treatment is usually required. Good nursing care is critical, and cats may need to be hospitalised for intravenous fluid therapy and nutritional support in severe cases. Steam inhalation or nebulisation may help in cases of severe nasal congestion, and as the cat will not be able to smell food well, using tinned or sachet foods that are gently warmed will help.
In colonies of cats, any cat showing clinical signs should be isolated if possible. Strict hygiene should be ensured through disinfection, using separate feeding bowls, litter trays, implements, etc., careful hand washing, and using separate (or disposable) aprons etc.
Vaccination against FCVVaccination against FCV is important for all cats. Two or three injections are recommended in kittens, starting at around 8 weeks of age. Cats should receive a booster at a year of age and, after that, should receive further booster vaccines every 1-3 years.
Vaccination does not necessarily prevent infection with FCV but will significantly reduce clinical disease severity. Additionally, as there are many strains of the virus, it is challenging to design a vaccine that will protect against all of them. Some newer vaccines incorporate more than one strain of FCV to provide a broader range of protection.
Feline Herpesvirus (FHV)
Feline herpesvirus (FHV) infection
Feline herpesvirus (FHV, FHV-1) is a highly contagious virus that is one of the major causes of upper respiratory infections (URIs) or cat flu in cats.
This virus is ubiquitous and causes disease in cats all over the world. See alsoUpper respiratory infections (URIs, Cat flu) in cats. Together, FHV and feline calicivirus cause the vast majority of URIs in cats.
What is FHV and how is it spread?Feline herpesvirus (FHV) is a virus that mainly causes acute upper respiratory infections (URIs) in cats, although it has been associated with some other diseases also (see below). The virus is readily transmitted between cats through:
What are the clinical signs of FHV infection
Treatment and management of FHV infectionsFHV infections are frequently complicated by secondary bacterial infections, so supportive treatment with antibiotics is usually required. Good nursing care is critical and cats may need to be hospitalised for intravenous fluid therapy and nutritional support in severe cases. Steam inhalation or nebulisation may help in cases of severe nasal congestion and as the cat will not be able to smell food well, using tinned or sachet foods that are gently warmed will help.
Unlike FCV, with FHV infection certain anti-viral drugs are available and can be very helpful in managing the clinical manifestations of disease.
Vaccination against FHVVaccination for FHV is important for all cats. Two or three injections are recommended in kittens, starting at around 8 weeks of age. Cats should receive a booster at a year of age, and after that should receive further booster vaccines every 1-3 years.
Vaccination does not necessarily prevent infection with FHV but will greatly reduce the severity of clinical disease. Unlike FCV, there is effectively only one strain of FHV, so vaccination is not complicated by the existence of different strains.
Feline herpesvirus (FHV, FHV-1) is a highly contagious virus that is one of the major causes of upper respiratory infections (URIs) or cat flu in cats.
This virus is ubiquitous and causes disease in cats all over the world. See alsoUpper respiratory infections (URIs, Cat flu) in cats. Together, FHV and feline calicivirus cause the vast majority of URIs in cats.
What is FHV and how is it spread?Feline herpesvirus (FHV) is a virus that mainly causes acute upper respiratory infections (URIs) in cats, although it has been associated with some other diseases also (see below). The virus is readily transmitted between cats through:
- Direct contact – through contact with saliva, ocular or nasal secretions
- Inhalation of sneeze droplets
- Sharing or food bowls and litter trays
- A contaminated environment (including bedding and grooming aids) – this is less important with FHV than FCV as the virus is fragile can probably only survive for 1-2 days in the environment
What are the clinical signs of FHV infection
- Acute upper respiratory infection – acute URI is the most common manifestation of FHV infection. Typical signs include conjunctivitis, ocular discharge, sneezing, nasal discharge, salivation, pharyngitis, lethargy, inappetence, fever and sometimes coughing. Signs may last from a few days to a few weeks and shedding of virus typically continues for around 3 weeks. Clinical disease with FHV is generally more severe than that seen with FCV.
- Keratitis – although relatively uncommon, one manifestation of chronic (long-term) FHV infection that is seen in a number of cats is conjunctivitis and keratitis (infection and inflammation of the cornea – the clear part at the front of the eye). Although keratitis can have a number of different causes, FHV infection causes the development of multiple small branching corneal ulcers (called ‘dendritic keratitis’) and this is considered diagnostic of FHV infection. .
- FHV-associated dermatitis – a rare manifestation of chronic (long-term) FHV infection is the development of skin inflammation and ulceration. This is most commonly seen around the nose and mouth, but can affect other areas such as the front legs. This is only seen rarely.
Treatment and management of FHV infectionsFHV infections are frequently complicated by secondary bacterial infections, so supportive treatment with antibiotics is usually required. Good nursing care is critical and cats may need to be hospitalised for intravenous fluid therapy and nutritional support in severe cases. Steam inhalation or nebulisation may help in cases of severe nasal congestion and as the cat will not be able to smell food well, using tinned or sachet foods that are gently warmed will help.
Unlike FCV, with FHV infection certain anti-viral drugs are available and can be very helpful in managing the clinical manifestations of disease.
- Systemic antiviral therapy: Famciclovir is a human anti-herpes virus drug that has been shown to be safe and effective in cats. It can be given by mouth and can be valuable in managing severe acute infections in particular.
- Topical ocular antiviral therapy: idoxuridine, trifluridine and cidofovir are all human anti-herpes virus drugs that can be successfully used as topical ocular (eye drops) therapy for FHV-associated conjunctivitis and keratitis. Some of these drugs have to be given very frequently (several times daily) and they may be combined with topical interferon to enhance efficacy.
Vaccination against FHVVaccination for FHV is important for all cats. Two or three injections are recommended in kittens, starting at around 8 weeks of age. Cats should receive a booster at a year of age, and after that should receive further booster vaccines every 1-3 years.
Vaccination does not necessarily prevent infection with FHV but will greatly reduce the severity of clinical disease. Unlike FCV, there is effectively only one strain of FHV, so vaccination is not complicated by the existence of different strains.
Mycoplasma Felis (M.Felis)
Mycoplasma species are part of the normal flora of the conjunctiva and upper respiratory tract of cats. However, some of these mycoplasmas can cause feline diseases such as feline conjunctivitis, lower respiratory tract infections, and polyarthritis. Among them, Mycoplasma felis has been shown to be one of the probable causes of feline conjunctivitis and respiratory diseases. It is imperative that the Mycoplasma species be correctly identified so that the appropriate treatment is given earlier. For example, there are many causes of feline conjunctivitis and discharge from the eyes. These include allergy, bacterial infections (especially Chlamydia psittaci), fungal infections and other viral infections (especially feline calicivirus). Treatment of viral or fungal infection with antibiotics will not aid recovery.
Conventional detection of Mycoplasma felis in cases of feline conjunctivitis and ulcerative keratitis has been based on clinical presentation, which is not entirely reliable because of overlapping symptoms with other pathogens. Staining of corneal scrapings to detect small basophilic inclusion bodies in epithelial cells is not specific for Mycoplasma; culture of clinical specimens is not a very sensitive test because these bacteria do not remain viable for very long after specimen collection. Identification of M. felis in clinical samples is usually performed by initial cultivation of "fried egg-shaped” colonies on mycoplasma-specific media in 2–3 days. This is followed by biochemical testing to confirm glucose fermentation, absence of arginine hydrolysis, digitonin sensitivity and phosphatase activity. Confirmation of M. felis identification to the species level is then achieved by either growth inhibition with specific anti-sera, fluorescent antibody staining, or use of an immunobinding assay. Additional serological testing can confirm a recent or active infection by detecting rising antibody titers to M. felis with an indirect haemagglutination assay. These testing methodologies are cumbersome and expensive when all costs are added up. However, molecular detection by PCR is the most sensitive and specific way of detecting the bacteria. It is also much faster than culture.
Conventional detection of Mycoplasma felis in cases of feline conjunctivitis and ulcerative keratitis has been based on clinical presentation, which is not entirely reliable because of overlapping symptoms with other pathogens. Staining of corneal scrapings to detect small basophilic inclusion bodies in epithelial cells is not specific for Mycoplasma; culture of clinical specimens is not a very sensitive test because these bacteria do not remain viable for very long after specimen collection. Identification of M. felis in clinical samples is usually performed by initial cultivation of "fried egg-shaped” colonies on mycoplasma-specific media in 2–3 days. This is followed by biochemical testing to confirm glucose fermentation, absence of arginine hydrolysis, digitonin sensitivity and phosphatase activity. Confirmation of M. felis identification to the species level is then achieved by either growth inhibition with specific anti-sera, fluorescent antibody staining, or use of an immunobinding assay. Additional serological testing can confirm a recent or active infection by detecting rising antibody titers to M. felis with an indirect haemagglutination assay. These testing methodologies are cumbersome and expensive when all costs are added up. However, molecular detection by PCR is the most sensitive and specific way of detecting the bacteria. It is also much faster than culture.
Bordetella bronchiseptica (Bb)
Bordetella bronbchiseptica (B bronchispetica) is a bacterium that can cause disease in a number of animals, and also rarely in humans.
This bacterium can be a cause of upper respiratory disease in cats, but is mainly a problem where cats are kept together in large groups such as rescue shelters and some breeding households. Bordetella bronchispetica infections can be treated successfully with antibiotics, and for situations where it causes significant ongoing problems, an effective vaccine is available in many countries.
What is Bordetella bronchispeticaBordetella bronchispetica is a bacterium that causes respiratory disease in a number of animals. It is related to Bordetella pertussis and Bordetella parapertussis, which are the cause of ‘whooping cough’ in humans. B bronchispetica is a cause of disease in dogs (one of the important causes of ‘kennel cough’), cats, pigs, rabbits and can occasionally cause disease in humans. B bronchispetica is therefore classified as a rare zoonosis (disease transmissible from animals to humans).
How is B bronchispetica spread?Cats infected with B bronchispetica shed bacteria in saliva and nasal secretions (and in droplets when they sneeze) so direct contact between cats or inhalation of infectious sneeze droplets is an effective means of transmission. Although the bacteria are susceptible to disinfectants, it is likely that they can survive for 1-2 weeks in the environment, so unless kept scrupulously clean, the environment, bedding, feeding bowls, grooming utensils etc may also be sources of infection. B bronchispetica can also be spread between dogs and cats. Cats can also remain infected with B bronchispetica for many months after clinical signs of infection have subsided, so recovered cats can also be a potential source of infection to others.
What clinical disease does B bronchispetica cause in cats?Infection with B bronchispetica in cats usually results in mild sneezing, coughing, nasal and ocular discharge and fever. Signs typically last 7-10 days. However, in occasional cases (especially in young kittens, and with severe stress) infection may be more severe and can sometimes result in life-threatening pneumonia.
The frequency with which B bronchispetica causes disease in cats is not well understood. Studies have shown that exposure to the bacterium is relatively common, especially in colony situations (such as rescues and some breeding establishments). However, sub-clinical and mild infections are likely to be common. Pet cats kept on their own or as part of a small group are much less likely to be infected. Most clinical problems arise in colonies where B bronchispetica may sometimes be an important part of the upper respiratory infection (URI) complex of diseases.
How is B bronchispetica infection diagnosed?A diagnosis of infection is made by detecting the organism in the laboratory from swabs taken from the pharynx (throat). The organism can be detected by bacterial culture (using specific culture medium) or by PCR (polymerase chain reaction – a molecular technique to detect the genetic material of the organism).
How are B bronchispeticainfections treated?Treatment with antibacterial drugs is usually very effective in managing B bronchispetica infections. However, the bacteria can be resistant to some antibiotics so in general it is better to carry out sensitivity testing in the laboratory (from bacterial culture) to determine which antibiotics are most effective. In general, treatment with doxycycline (or possibly a fluoroquinolone antibiotic) is likely to be most successful.
If infection is severe, further supportive care and hospitalisation may be required.
How can B bronchispetica infections be prevented or controlled?In most cases, B bronchispetica is considered a minor infection and no specific precautions are necessary for most pet cats as the risk of infection and serious disease is low. In shelters and breeding colonies it is important to try to minimise the risk by:
This bacterium can be a cause of upper respiratory disease in cats, but is mainly a problem where cats are kept together in large groups such as rescue shelters and some breeding households. Bordetella bronchispetica infections can be treated successfully with antibiotics, and for situations where it causes significant ongoing problems, an effective vaccine is available in many countries.
What is Bordetella bronchispeticaBordetella bronchispetica is a bacterium that causes respiratory disease in a number of animals. It is related to Bordetella pertussis and Bordetella parapertussis, which are the cause of ‘whooping cough’ in humans. B bronchispetica is a cause of disease in dogs (one of the important causes of ‘kennel cough’), cats, pigs, rabbits and can occasionally cause disease in humans. B bronchispetica is therefore classified as a rare zoonosis (disease transmissible from animals to humans).
How is B bronchispetica spread?Cats infected with B bronchispetica shed bacteria in saliva and nasal secretions (and in droplets when they sneeze) so direct contact between cats or inhalation of infectious sneeze droplets is an effective means of transmission. Although the bacteria are susceptible to disinfectants, it is likely that they can survive for 1-2 weeks in the environment, so unless kept scrupulously clean, the environment, bedding, feeding bowls, grooming utensils etc may also be sources of infection. B bronchispetica can also be spread between dogs and cats. Cats can also remain infected with B bronchispetica for many months after clinical signs of infection have subsided, so recovered cats can also be a potential source of infection to others.
What clinical disease does B bronchispetica cause in cats?Infection with B bronchispetica in cats usually results in mild sneezing, coughing, nasal and ocular discharge and fever. Signs typically last 7-10 days. However, in occasional cases (especially in young kittens, and with severe stress) infection may be more severe and can sometimes result in life-threatening pneumonia.
The frequency with which B bronchispetica causes disease in cats is not well understood. Studies have shown that exposure to the bacterium is relatively common, especially in colony situations (such as rescues and some breeding establishments). However, sub-clinical and mild infections are likely to be common. Pet cats kept on their own or as part of a small group are much less likely to be infected. Most clinical problems arise in colonies where B bronchispetica may sometimes be an important part of the upper respiratory infection (URI) complex of diseases.
How is B bronchispetica infection diagnosed?A diagnosis of infection is made by detecting the organism in the laboratory from swabs taken from the pharynx (throat). The organism can be detected by bacterial culture (using specific culture medium) or by PCR (polymerase chain reaction – a molecular technique to detect the genetic material of the organism).
How are B bronchispeticainfections treated?Treatment with antibacterial drugs is usually very effective in managing B bronchispetica infections. However, the bacteria can be resistant to some antibiotics so in general it is better to carry out sensitivity testing in the laboratory (from bacterial culture) to determine which antibiotics are most effective. In general, treatment with doxycycline (or possibly a fluoroquinolone antibiotic) is likely to be most successful.
If infection is severe, further supportive care and hospitalisation may be required.
How can B bronchispetica infections be prevented or controlled?In most cases, B bronchispetica is considered a minor infection and no specific precautions are necessary for most pet cats as the risk of infection and serious disease is low. In shelters and breeding colonies it is important to try to minimise the risk by:
- Keeping cats individually or in small isolated groups
- Maintaining excellent hygiene, with use of appropriate disinfectants
- Isolate any cats showing signs of clinical disease
Chlamydophilia (feline chlamydophilosis)
Feline chlamydophila disease refers to infection with a bacterium called Chlamydophila felis. This was formerly known as Chlamydia pistachio var felis.
Many different strains of chlamydia-type bacteria exist, most of which are highly species-specific (each strain usually only infects one or a small number of different animals/species).
The bacterium that infects cats is specifically adapted to them, where it primarily causes ocular infections and conjunctivitis. Appropriate treatment can eliminate the organism and resolve all the clinical signs. Where the disease is problematic in colonies of cats, vaccination is also available and can be helpful as part of a control plan.
In keeping with other similar organisms, Chalmydophila felis (or C felis) is a very fragile bacterium and cannot survive for any significant time in the environment. Infection is therefore mainly through direct contact between animals.
What disease does C felis cause in cats?Chlamydophila felis is mainly a cause of conjunctivitis (infection and inflammation of the delicate membranes – conjunctiva – that cover the inner surface of the eyelids and the white part of the eye itself).
The bacteria invade and infect the cells of the conjunctiva itself causing inflammation and ocular discharge. Clinical signs usually develop within a few days of infection, and starts off as a watery ocular discharge. At first only one eye may be involved, but within a few days the disease invariably affects both eyes. Pain and discomfort means affected cats may hold their eyelids partially closed (blepharospasm) and as the disease progresses, severe swelling and reddening of the conjunctiva may be seen. The discharge changes to a thicker yellowish nature and occasionally the eye infection is accompanied by mild sneezing and nasal discharge. Occasionally there is alao a mild fever which can result in lethargy and inappetence but cats usually remain bright and eat well.
If left untreated, the conjunctivitis can often persists for two months or more, and cats may continue to shed the bacteria in ocular secretions for many months (and thus be a potential source of infection to other cats).
Although C felis mainly causes conjunctivitis, the organism can also be found in the lungs, gastrointestinal tract and reproductive tract. There is some speculation that it may occasionally contribute to infertility in breeding queens.
Which cats are at risk of infection?Chlamydophila infection is relatively common in cats, and it may be a cause of up to 30% of cases of chronic (long-term) conjunctivitis. However, the organism requires direct contact between cats to spread so disease is much more common where larger groups of cats are kept together (multi-cat households, breeding households, catteries and shelters).
Although cats of all ages can be infected, disease is seen most commonly in kittens 5-12 weeks of age. Chlamydophila also has to be distinguished from other potential causes of conjunctivitis such as feline herpesvirus, feline calicivirus and mycoplasmas. Conjunctivitis may also occur as a result of trauma, allergies or other non-infectious reasons.
Diagnosis of Chlamydophila felis infectionDiagnosis of feline chalmydophilosis requires detection of the organism in the conjunctiva of a cat showing typical signs. Examination of smears from an eye swab under the microscope may give an indication of the presence of infection through observation of typical changes in the conjunctival cells. However, for definitive diagnosis swabs from the eyes of affected cats should be sent to a veterinary laboratory where the organism can be identified through culture or through molecular diagnostic techniques, such as polymerase chain reaction (PCR).
Treatment of Chlamydophila felisA number of antibiotics can be used to treat C felis infections. A group of antibiotics known as tetracyclines are considered the treatment of choice, being most effective. Doxycycline is one of these antibiotics and only has to be administered once daily to infected cats. Some other antibiotics may also be effective, but these are generally not as good and have to be given for longer to achieve the same results as doxycycline.
Oral treatment with tablets or a suspension is best, as the organism can be present at sites other than the eye, but topical treatment with eye drops or ointments are also helpful - they may enhance recovery and also make the cat feel more comfortable.
Treatment is usually continued for 3-4 weeks to ensure the organism is eliminated (sometimes longer with other antibiotics) and all cats in a house should be treated.
A vaccine is available in many countries to protect cats against chlamydophila conjunctivitis. This does not always prevent infection, but is helpful in preventing severe clinical disease. Although not generally suitable for the majority of pet cats, it can be useful in high risk situations such as catteries with persistent problems with the organism.
Risk to humans from feline chlamydophilosisHumans can be infected with Chlamydia psitacci, but the bacterium that infects cats (Chlamydophila felis) is highly adapted to this species. There have been one or two reports of human conjunctivitis following contact with a cat harbouring C felis, but the risk appears to be extremely low. Routine hygiene precautions are recommended when handling and treating infected cats (washing hands after stroking or giving medications, and avoiding close face-to-face contact until the infection has resolved).
Many different strains of chlamydia-type bacteria exist, most of which are highly species-specific (each strain usually only infects one or a small number of different animals/species).
The bacterium that infects cats is specifically adapted to them, where it primarily causes ocular infections and conjunctivitis. Appropriate treatment can eliminate the organism and resolve all the clinical signs. Where the disease is problematic in colonies of cats, vaccination is also available and can be helpful as part of a control plan.
In keeping with other similar organisms, Chalmydophila felis (or C felis) is a very fragile bacterium and cannot survive for any significant time in the environment. Infection is therefore mainly through direct contact between animals.
What disease does C felis cause in cats?Chlamydophila felis is mainly a cause of conjunctivitis (infection and inflammation of the delicate membranes – conjunctiva – that cover the inner surface of the eyelids and the white part of the eye itself).
The bacteria invade and infect the cells of the conjunctiva itself causing inflammation and ocular discharge. Clinical signs usually develop within a few days of infection, and starts off as a watery ocular discharge. At first only one eye may be involved, but within a few days the disease invariably affects both eyes. Pain and discomfort means affected cats may hold their eyelids partially closed (blepharospasm) and as the disease progresses, severe swelling and reddening of the conjunctiva may be seen. The discharge changes to a thicker yellowish nature and occasionally the eye infection is accompanied by mild sneezing and nasal discharge. Occasionally there is alao a mild fever which can result in lethargy and inappetence but cats usually remain bright and eat well.
If left untreated, the conjunctivitis can often persists for two months or more, and cats may continue to shed the bacteria in ocular secretions for many months (and thus be a potential source of infection to other cats).
Although C felis mainly causes conjunctivitis, the organism can also be found in the lungs, gastrointestinal tract and reproductive tract. There is some speculation that it may occasionally contribute to infertility in breeding queens.
Which cats are at risk of infection?Chlamydophila infection is relatively common in cats, and it may be a cause of up to 30% of cases of chronic (long-term) conjunctivitis. However, the organism requires direct contact between cats to spread so disease is much more common where larger groups of cats are kept together (multi-cat households, breeding households, catteries and shelters).
Although cats of all ages can be infected, disease is seen most commonly in kittens 5-12 weeks of age. Chlamydophila also has to be distinguished from other potential causes of conjunctivitis such as feline herpesvirus, feline calicivirus and mycoplasmas. Conjunctivitis may also occur as a result of trauma, allergies or other non-infectious reasons.
Diagnosis of Chlamydophila felis infectionDiagnosis of feline chalmydophilosis requires detection of the organism in the conjunctiva of a cat showing typical signs. Examination of smears from an eye swab under the microscope may give an indication of the presence of infection through observation of typical changes in the conjunctival cells. However, for definitive diagnosis swabs from the eyes of affected cats should be sent to a veterinary laboratory where the organism can be identified through culture or through molecular diagnostic techniques, such as polymerase chain reaction (PCR).
Treatment of Chlamydophila felisA number of antibiotics can be used to treat C felis infections. A group of antibiotics known as tetracyclines are considered the treatment of choice, being most effective. Doxycycline is one of these antibiotics and only has to be administered once daily to infected cats. Some other antibiotics may also be effective, but these are generally not as good and have to be given for longer to achieve the same results as doxycycline.
Oral treatment with tablets or a suspension is best, as the organism can be present at sites other than the eye, but topical treatment with eye drops or ointments are also helpful - they may enhance recovery and also make the cat feel more comfortable.
Treatment is usually continued for 3-4 weeks to ensure the organism is eliminated (sometimes longer with other antibiotics) and all cats in a house should be treated.
A vaccine is available in many countries to protect cats against chlamydophila conjunctivitis. This does not always prevent infection, but is helpful in preventing severe clinical disease. Although not generally suitable for the majority of pet cats, it can be useful in high risk situations such as catteries with persistent problems with the organism.
Risk to humans from feline chlamydophilosisHumans can be infected with Chlamydia psitacci, but the bacterium that infects cats (Chlamydophila felis) is highly adapted to this species. There have been one or two reports of human conjunctivitis following contact with a cat harbouring C felis, but the risk appears to be extremely low. Routine hygiene precautions are recommended when handling and treating infected cats (washing hands after stroking or giving medications, and avoiding close face-to-face contact until the infection has resolved).
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