What is the difference between disinfection and sterilisation?

Sterilisation is the removal of all forms of microbial life from an environment, and is very difficult to achieve in the home. Disinfection is the selective elimination of certain undesirable micro-organisms in order to prevent their transmission. In terms of the home with pet cats, disinfection is necessary to prevent the spread of infectious diseases from one cat to another, or, in a few cases, to humans.

What are the important types of micro-organisms to consider?

A number of different organisms can infect cats - protozoa such as Toxoplasma gondii and Giardia, yeasts and fungi, bacteria, and viruses. Of these, viruses are generally considered to be the most important pathogens of cats. The viruses include the ‘cat flu’ viruses feline herpesvirus (FHV) and feline calicivirus (FCV), feline parvovirus (FPV) the cause of enteritis and panleukopenia, feline leukaemia virus (FeLV), feline immunodeficiency virus (FIV) and feline coronavirus, the cause of feline infectious peritonitis (FIP). FPV and FCV are the two viruses which are most resistant to disinfectants, and are two of the most infectious, so a disinfectant that is effective against these two viruses is desirable.

What types of disinfectants are available?

Chemical disinfectants can broadly be divided into liquid and gaseous types, but only the former are a viable prospect for home disinfection. Many different types of chemicals have disinfectant properties, the most common ones being listed below:-

Phenolic compounds

These compounds, derived from coal tar, include ‘Lysol’ (cresol and soap solution), ‘Stericol’(xylenol-rich cresylic acid and soap solution), and ‘TCP’. They are sometimes mixed with pine disinfectants, e.g. ‘Dettol’. Phenolic compounds are effective against viruses, but must NOT be used where there are cats (see below).

Biguanides

Such as chlorhexidine are commonly used disinfectants, but are not active against viruses. Antiseptics such as ‘Savlon’ contain chlorhexidine and cetrimide.

Surface active agents(surfactants)

Come in four types, cationic, anionic, non-ionic and amphoteric. Of these, only cationic and amphoteric have appreciable disinfectant properties, but are not very effective against FCV or FPV, although they will kill FHV, FeLV and FIV efficiently. Examples are cetrimide (cationic, in ‘Savlon’) and ‘Tego’ (amphoteric).

Aldehydes

Two aldehydes, formaldehyde and glutaraldehyde are very important disinfectants with broad disinfectant properties.

Halogens

Sodium hypochlorite solution eg ‘Chloros’, ‘Domestos’ is effective against viruses, but loses activity in heavily soiled situations.

What disinfectants are safe to use for cats?

Particular care must be taken in the choice of a disinfectant for use in a home with cats. Cats are generally fastidious creatures and their washing habits will leave them open to ingesting anything they get on their bodies. Cats have low levels of the liver enzyme called glucuronide transferase, which is responsible for detoxifying phenolic compounds. Consequently, phenolic disinfectants must NEVER be used where there are cats resident. The other disinfectants listed above are safe for cats provided that the instructions on the label are strictly observed. Most disinfectants need to be diluted before using and it is important NOT to use a stronger solution than recommended. The disinfectant should be rinsed away thoroughly before cats are allowed access to the disinfected area. Although individual disinfectant compounds can be used, better results are likely using proprietary mixtures such as ‘Parvocide’, ‘Peratol’, ‘Virkon’, ‘Trigene’ or ‘GPC-8’ which have all been shown to be safe for cats and are effective against all of the common viruses.

FOR FURTHER INFORMATION AND ADVICE CONSULT YOUR VETERINARY SURGEON.

'Cat flu' is a common disease in cats of all ages despite widespread vaccination, but tends to be particularly severe in young and old cats. A number of infectious agents have been found to cause 'cat flu' but the vast majority of cases will be caused by one of two viruses, feline herpes virus type 1 (FHV-1) and feline calicivirus (FCV). FHV-1 is also known as feline rhinotracheitis virus.

What are the clinical signs of 'cat flu'?

Signs of 'cat flu' are similar to colds and flu in people. FHV-1 tends to cause more severe disease, the major signs are inflammation of the lining around the eye (conjunctivitis) and nose (rhinitis). This causes a clear discharge from the nose and eyes which becomes thickened and purulent as the disease progresses due to secondary bacterial infection. Cats tend to be dull and depressed with a raised temperature, sneezing and are reluctant to eat. Coughing is also a feature in some cases. Rarely the virus will cause skin lesions and invade the lungs causing pneumonia. Without treatment signs usually resolve in 2-3 weeks but some cats are left with a chronic, intermittent nasal discharge or eye disease.

FCV tends to cause less serious disease, but clinical signs are dependent on the strain of virus that is involved. Mouth ulceration can be a prominent feature of the disease causing severe inappetance. Ulcers may also sometimes occur on the tongue, nose and hard palate. Some strains of FCV cause a lameness and fever syndrome in young kittens. FCV is commonly isolated from cats with long-standing (chronic) inflammation of the gums (gingivitis) but the precise role of the virus remains unclear.

Deaths following respiratory virus infections are rare, usually occurring in young kittens or old cats that have advanced disease before being presented for treatment.

How is 'cat flu' diagnosed?

In most cases the diagnosis is made on clinical signs but in cases where there is recurrent disease or in vaccinated cats a specific diagnosis may be required. This can be achieved by swabbing the cat's mouth and sending the swab in viral transport medium to a laboratory where the virus can be grown in culture and identified.

What treatments are available?

As for colds and flu, specific anti-viral treatments are not generally available. Treatment is aimed at controlling secondary bacterial infection (with antibiotics) and stimulating eating and drinking as, particularly dehydration, is a major cause of worsening disease. Anti-viral ointment (e.g. acyclovir) used to treat herpes virus infections in people (cold sores) has been used in cats, but the response is not very good. Another type of antiviral ointment is sometimes used if cats have developed severe eye ulcers as a result of the herpes virus.

What can be done to help treatment?

Your cat can be encouraged to eat and drink using drugs such as multivitamins and mucolytics (help dissolve secretions) but good nursing plays a crucial role. The eyes and nose can be kept clear of secretions by gently bathing the area with cotton wool and by steaming. Steaming needs to be undertaken carefully, the cat is placed in a wire basket and a bowl of steaming water is placed outside the basket, the two are then covered by a towel and the cat left for up to 5 minutes. The steam acts to loosen secretions making the cat feel better, oils such as eucalyptus should be avoided as they can cause ulceration of the nose in cats. Your cat can be encouraged to eating by providing highly flavoured foods e.g. sardines warmed to body temperature. Hand feeding can also help.

Severely ill cats may need nursing in hospital, this allows rehydration with intravenous fluids and feeding by naso-oesophageal tube.

How can 'cat flu' be prevented and controlled?

For most households, with a few cats, vaccination is sufficient. Vaccination will not usually prevent your cat becoming infected but will reduce the severity of the disease, often to the point that all that is noticed is mild lethargy and inappetance for a few days. Unfortunately, however the vaccines are not 100% effective and some cats can still develop severe disease, despite being vaccinated. A variety of vaccines are available depending on the circumstances. Neither virus is very hardy, FHV-1 will survive for a maximum of 48 hours in the environment, FCV lasting 7-10 days.

In multi-cat households, particularly where new cats are continually arriving (rescue or breeding), vaccination alone may not be sufficient to control the problem. In these households isolation and quarantine is also required. Disinfection, whilst an important part of disease control generally, is of limited value in respiratory virus control as most cats become infected by aerosol droplets sneezed or coughed out by infected cats. Clinically ill cats or those suspected of being carriers should be isolated and handled last, their food bowls and litter trays disinfected and your hands, face and boots washed before handling other cats. Where possible separate clothing or overalls should be worn. New arrivals to the group should be quarantined for 7-10 days in case they are incubating 'cat flu'. Unfortunately, quarantine will not identify carrier cats. In households where 'cat flu' is endemic, queens should be kittened in isolation from other cats and, where possible, the kittens remain in isolation until vaccinated.

What are carrier cats?

Carriers are animals that are infected with 'cat flu' but are not showing any clinical signs. Carriers are only infectious to other animals when shedding the virus. Viral shedding can be continual or intermittent. Around 80% of cats that have been infected with FHV-1 become carriers, they shed the virus intermittently usually during periods of stress e.g. rehoming, lactation and remain carriers for life. About 50% of cats infected with FCV are still excreting virus 3 months after they were originally unwell, some of these cats continue to excrete for up to 18 months or even longer. FCV carriers excrete continually so are always potentially infectious to other cats.

Can I check to see if my cat is a carrier?

In some special circumstances it may be helpful to identify carriers but this is not usually important for pet cats. A swab can be taken from your cat's mouth which will show if it is a FCV carrier. FHV-1 carriers are only diagnosed if they are excreting the virus at the time the swab is taken which is unlikely.

What should I do if my cat is a carrier?

Nothing can be done to change the carrier status of your cat. Therefore it is important that your cat does not come into contact with particularly susceptible cats (eg unvaccinated cats, kittens, old cats, cats with other diseases, or cats receiving immunosuppressive treatments). All cats that have had FHV-1 infection should be assumed to be carriers.

My cat has had 'cat flu' should I bother to vaccinate it?

YES! Your cat is likely to have been infected with only one of the viruses so will still be susceptible to infection with the other.

FOR FURTHER INFORMATION AND ADVICE CONSULT YOUR VETERINARY SURGEON

What is cardiomyopathy?

Cardiomyopathy is a term used to describe diseases of the heart muscle (cardio = heart, myo = muscle, pathy = disease). In cats, various different types of cardiomyopathy have been described. The 3 mostly widely recognised forms are hypertrophic cardiomyopathy (HCM, the most common type), restrictive cardiomyopathy (RCM, the second most common) and dilated cardiomyopathy (DCM, rarely diagnosed).

In all cases, the heart disease may cause heart failure. Cardiomyopathy may be seen as a disease on its own or secondary to another disease. For example, hyperthyroidism (an overactive thyroid gland) can cause hypertrophic changes to the heart and feeding a diet lacking in taurine can cause dilated cardiomyopathy. All commercial cat foods contain correct amounts of taurine for cats.

What are the clinical signs seen with cardiomyopathy?

In the early stages of disease, the cat may be able to cope and hence show no signs of disease. This situation is referred to as compensated heart disease. Often the cats will alter their activity levels to those that they can cope with which makes it difficult to diagnose cardiomyopathy until it is quite advanced. Affected cats may be noticed to be less active, spending more time asleep although this is often considered to be normal behaviour for a cat!

The major longterm concerns with all types of cardiomyopathy are:-

1. Development of congestive heart failure: Breathlessness and lethargy are the most frequently noticed signs of congestive heart failure. These signs are caused by a failure of the heart to efficiently pump blood causing fluid to accumulate in the lungs (pulmonary oedema) or around the lungs (pleural effusion). In some cases, fluid accumulates in the abdomen (ascites).

2. Thromboembolic disease: Altered flow of blood in enlarged heart chambers predisposes to the formation of a blood clot within the chambers of the heart. This becomes organised and is known as a thrombus. If parts of the thrombus become dislodged they can travel in the bloodstream and become lodged in blood vessels. These particles of dislodged thrombus are called emboli and the most common place for them to lodge is at the bottom of the aorta which is the biggest artery in the body. This cuts off the blood supply to the back legs which is usually very painful and the back legs become paralysed and cold to the touch. This is a potentially fatal complication of any cardiomyopathy. In some cats, a partial recovery which may take a long time, is seen. Unfortunately even if cats do recover, the risk of another thromboembolism is extremely high.

How is cardiomyopathy diagnosed?

Heart disease may be suspected in cats showing clinical signs of heart failure such as breathlessness. In other cases, a routine check-up may identify a heart murmur or abnormal heart rhythm as cause for concern. Further tests are needed to assess the cause and severity of the heart disease. Chest x-rays are helpful particularly in looking for signs of congestive heart failure such as the build up of fluid within or around the lungs, and may also be useful in assessing the size and shape of the heart; electrocardiography (ECG) may identify an abnormal heart rhythm that may arise as a consequence of cardiomyopathy. Cardiac ultrasound scans are required to distinguish between the different types of cardiomyopathy.

Blood pressure can be measured if suitable equipment is available, to exclude high blood pressure as a cause of the cardiomyopathy, and to ensure that blood pressure is not too low as a consequence of the reduced cardiac function. Examination of the eyes may provide evidence of high blood pressure in those practices where facilities to measure blood pressure are not available.

Specific tests may be done in order to check that the cardiomyopathy is not secondary to some other disease. (see below).

What causes cardiomyopathy?

There are many causes of secondary cardiomyopathy, however, in older cats thyroid disease (hyperthyroidism) is the most commonly recognised cause. A rare cause is dietary deficiency of taurine, an essential nutrient. This is not seen in cats fed a commercial cat food. The cause of primary cardiomyopathy is unknown.

How is cardiomyopathy treated?

In cases where an underlying cause of the heart disease is found, then treatment of this may result in improvement or reversal of the heart disease. Hyperthyroidism is the most treatable cause of heart disease since complete resolution of the heart disease is possible if treated early. In cases of primary cardiomyopathy, where no cause is identified, and in cases where disease remains following treatment for an underlying cause then medication may be needed. In most cases, the cat is likely to need medication for the rest of its life.

Treatment varies according to each case but may include:-

1. Diuretics if congestive heart failure is present. Cats with congestive heart failure have too much fluid in their circulation; diuretics are drugs which cause fluid loss from the body into the urine.

2. Beta blockers to reduce the heart rate where this is excessive.

3. Calcium channel blockers to help the heart muscle relax and hence help more effective filling of the heart.

4. ACE inhibitors - these drugs help to control congestive heart failure and may be useful in treating cats with restrictive cardiomyopathy.

5. Aspirin may be used for its effects at reducing the risk of thrombus formation and hence thrombo-embolic disease. Dosing of aspirin should always be as advised by a veterinary surgeon since aspirin may be toxic to cats. Aspirin poisoning, which occurs if the dose or frequency of aspirin administration is too high, may cause vomiting and internal bleeding. If your cat shows these signs, goes off their food or is sick then aspirin therapy should be stopped and you should consult your vet.

The longterm outlook for a cat with cardiomyopathy is extremely variable depending on the cause and severity of this disease. Some cats with cardiomyopathy may remain stable for several years.

Does a cat with cardiomyopathy need a special diet?

Other than in cases of taurine deficiency, no specific diet is recommended although excessively salty foods should be avoided since these will predispose to fluid retention. This may increase the risk of congestive heart failure and hypertension developing. Proprietary cat foods are usually adequate although special low salt diets are available and may be recommended by your veterinary surgeon in specific cases. Cat treats are often quite salty and probably should be avoided.

FOR FURTHER INFORMATION AND ADVICE CONSULT YOUR VETERINARY SURGEON.