Cats

“In ancient times, cats were worshipped as Gods; they have not forgotten this” – Terry Pratchett, Author

Cats have been domesticated since around 7500 BCE and yet, as any cat owner will tell you, they remain their own masters!

We’ve gathered some useful information about cats, and as always, feel free to give us a call if you have any concerns or questions about your feline companion.

Useful Info about Cats

What do my cat’s kidneys do?

Kidneys have many functions, they principally act to remove nitrogenous waste products from the bloodstream, maintain essential nutrients e.g. potassium at the correct level, maintain hydration and produce urine.

What is chronic renal failure?

The kidneys have a large amount of spare capacity to perform their various functions so at least 70% of the kidneys need to be dysfunctional before clinical signs are seen. In many cases, this means that the damage to the kidneys has been occurring over a number of months or years (chronic) before failure is evident. As chronic renal failure (CRF) is most commonly seen in old cats, early signs of disease such as weight loss and poor coat quality are often put down to normal ageing. In the initial stages of the disease the kidneys cope with their inability to concentrate waste products by excreting them at a lower concentration over a larger volume (compensated renal failure), at some point this is no longer possible resulting in a relatively rapid rise in waste products in the bloodstream and an apparent sudden onset of severe disease.

What are the causes of CRF?

A large number of different disease processes can eventually lead to CRF including:-

  1. Congenital malformations of the kidneys – e.g. polycystic kidneys in long-haired cats.
  2. Bacterial infections (pyelonephritis).
  3. Glomerulonephritis – damage to the filtration membrane.
  4. Neoplasia – various tumours of the kidney are seen, most commonly lymphosarcoma.
  5. Amyloidosis – this is the build-up of unusual material in the kidney which prevents the kidney from functioning normally.
  6. Viral infections e.g. feline immunodeficiency virus or feline infectious peritonitis virus.

CRF is, therefore, the end-stage of a number of different disease processes rather than a specific condition in its own right.

How is the disease diagnosed?

Renal failure is usually diagnosed by looking at the level of two waste products in the bloodstream, blood urea and creatinine. Tests to measure the blood levels of other substances e.g. potassium, phosphorus and calcium, as well as the red and white blood cell counts, can also be important in order to determine the best course of treatment.

Could the renal failure have been diagnosed earlier?

Unfortunately, this is very difficult as neither clinical signs of renal failure nor rises in BUN and creatinine are evident until significant loss of kidney function has occurred. In earlier stages of the disease there are no clinical signs to indicate that sophisticated renal function tests, which can pick up early renal damage, are required.

How does CRF affect my cat?

Because the kidneys perform a variety of different functions, the clinical signs of renal failure can be somewhat variable. The most common changes seen are weight loss, poor hair quality, halitosis (bad breath), a variable appetite which may be associated with mouth ulcers, lethargy and depression. Less commonly cats are seen to drink and urinate more and some will have vomiting and diarrhoea. Rarely renal failure is seen as sudden onset blindness.

What treatments are available?

Depending on the result of blood tests your veterinary surgeon may be faced with several problems which require different treatments.  Don’t worry if the list below seems so long that you will never be able to administer all the medication.  The majority of cats can be effectively managed with diet change including supplementation of one or two other treatments:

  1. Lowering the level of waste products in the bloodstream can be achieved by low protein and low phosphorus diets.  These are readily available from your veterinary practice. The palatability of reduced protein diets is usually not as high as normal cat food, so you may have to persevere for a while before your cat will eat it.
  2. Phosphate binders – despite low phosphate in the diet, blood phosphate levels remain above normal in some cats.  Reducing blood phosphorus can have a major effect on improving your cat’s wellbeing and slowing disease progression.  Phosphate binders eg. Ipakitine is given by mouth to further lower the amount of phosphorus absorbed through the gut wall.
  3. Fortekor- this is a drug that reduces protein loss in urine and lowers the systemic blood pressure and the blood pressure within the kidneys to be able to maintain as much of the kidney function as possible.  It increases your cat’s quality of life.  Some cats might have quite high blood pressure and other drugs can be used to lower that pressure.
  4. Laurabolin – regular administration of an anabolic steroid improves wellbeing.  It has no influence on the kidney function, but it maintains the body condition, maintains weight and increases appetite. It can be given by monthly injection.
  5. Chronic renal failure almost always leads to decreased appetite and weight loss.  Appetite stimulants may be helpful.  The increased levels of toxins can lead to nausea.  They can either act directly on the brain, causing vomiting or they act on the wall of the stomach or gut, causing ulcers.  There are drugs available that can help to stop the vomiting and/or improve the ulcers.
  6. Fluids-since cats with kidney failure have a lot of circulating toxins that make them feel sick, the aim is to reduce them.  Some cats may need intravenous fluids or fluids under their skin to make them feel better

It is important that freshwater is available at all times, as cats with renal failure tend to dehydrate rapidly.

What is the cost of treatment?

Treatment costs will vary somewhat with each individual case. In the majority of cases, long term management is unlikely to cost more than a few dollars a week.

How long can I expect my cat to live?

Unfortunately, once damaged the kidneys have a very limited ability to recover but the progress of the disease may be very slow so, with treatment, your cat may have several years of good quality, active life ahead.

What is cystitis?

Cystitis is a general term referring to inflammation in the urinary bladder.  The term cystitis does not imply a specific underlying cause.

In cats, diseases of the lower urinary tract (the bladder and urethra) are grouped under the term ‘feline lower urinary tract disease’ (FLUTD) as it can be difficult sometimes to distinguish between diseases of the bladder and urethra, and many diseases will affect both structures.

What are the signs of FLUTD?

Typical signs in cats with FLUTD are those of inflammation and irritation of the lower urinary tract.  The common signs are therefore:-

  • Increased frequency and urgency of urination.
  • Difficulty in urinating (spending a long time straining on the litter tray while passing only small quantities of urine).
  • The presence of blood in the urine or blood spots in the litter tray.
  • Occasionally complete obstruction to the passage of urine (straining persistently without producing any urine).

With the latter sign particularly (straining without the passage of any urine), it is important to seek urgent veterinary attention as complete blockage to the flow of urine can be a life-threatening complication if left untreated.

What causes FLUTD?

There are a vast number of potential causes of FLUTD, but in many cats there may be severe inflammation of the bladder and/or urethra without an identifiable underlying cause (so called ‘idiopathic’ FLUTD).  These idiopathic cases have to be differentiated from other potential causes of the clinical signs though so that appropriate treatment can be given.  Some of the potential causes of FLUTD are listed below:

  • Idiopathic (inflammation for no known cause) but possibly caused by unrecognised viruses or bacteria or even stress
  • Urinary calculi (‘bladder stones’)
  • Bacterial infections
  • Neoplasia (tumour)
  • Anatomical abnormalities
  • Urethral plugs (blockage of urethra with a mixture of crystals or small calculi/stones, mucus and inflammatory material)

How is FLUTD diagnosed?

The initial diagnosis of FLUTD is based on the identification of signs of lower urinary tract inflammation.  The clinical signs displayed by the cat are often characteristic of FLUTD, but where there is doubt, analysis of a urine sample will confirm the presence of inflammation or blood.

Initially, a cat with uncomplicated FLUTD may be treated symptomatically by a veterinary surgeon (for example with a short course of tablets).  However, if the signs do not respond to this treatment, or if there is a recurrence of the clinical signs further investigation may be required to identify the underlying cause of the FLUTD.

What further investigations are required to diagnose the cause of FLUTD?

Where clinical signs are persistent or recurrent, a number of investigations may be required to differentiate idiopathic FLUTD from the other known causes of urinary tract inflammation.

These investigations may include:

  • Laboratory analysis of a urine sample
  • Bacterial culture of a urine sample
  • Blood samples to look for other evidence of urinary tract disease or other systemic disease
  • Radiographs (x-rays) and/or ultrasound examination of the bladder and urethra

The information from these investigations should help to identify a specific treatable underlying cause if one is present.

What is the treatment for FLUTD?

This depends on the underlying cause.  For example:

  • Cases of the idiopathic disease may respond to treatment with anti-inflammatory or analgesic (‘pain-relieving’) drugs, but it is crucial that you only use drugs specifically prescribed by your veterinary surgeon, as may human products are extremely dangerous to use in cats.
  • Bacterial infections of the lower urinary tract, although uncommon in cats, will usually respond well to antibiotic therapy.
  • If a cat develops a blocked urethra (this almost exclusively occurs in males), emergency treatment is required to remove the blockage, which may require flushing of the urethra while the cat is given a short anaesthetic.
  • If bladder stones (calculi) are present they may have to be removed surgically or, depending on their type, they may be able to be dissolved by using a special diet, or dietary additive

There is no universal treatment for FLUTD.  Each case has to be investigated to determine the underlying cause, and then the treatment has to be tailored to the individual cat.  Sometimes despite appropriate investigation and treatment clinical signs may still recur, requiring further therapy.

How can FLUTD be prevented?

It is impossible to completely prevent diseases of the lower urinary tract occurring.  However, FLUTD is more common in cats that have a lower water consumption, and in cats that are inactive and obese or suffer from stress.  All these factors may relate, at least in part, to the frequency with which a cat urinates.  Avoidance of obesity and encouraging exercise may be of some help in preventing FLUTD, and as cats tend to drink very little the feeding of at least some tinned/wet food rather than exclusively a dry cat food product will help to maintain a higher water intake.  Some cats get FLUTD whenever they eat dry cat food.

Products like Feliway help reduce stress as does simple things such as having a couple of litter trays inside, clean and easily accessible.

If a cat develops urinary calculi stones), the feeding of special diets (available from veterinary surgeons) may help to prevent recurrence of stone formation.

Your cat will be admitted and weighed on the day of surgery; this allows us to calculate exactly how much premedication and anaesthetic will be needed. If you have elected for us to run a pre-anaesthetic blood profile then we will take a blood sample from your cat’s neck. This will be run through our in-house Idexx blood machine – this will let us ensure that your pet’s internal organs are functioning well and that it is safe to give an anaesthetic.

Your cat is then sedated using a combination of drugs, including pain control, which will make your cat feel relaxed and make the induction phase of the anaesthetic smoother and easier.

After about 15 minutes we will then go to the next stage of induction where an intravenous anaesthetic is injected into a vein in your cat’s front leg. This is very short acting and allows us to place an endotracheal tube into your cat’s wind pipe. This allows us to deliver oxygen and anaesthetic gas to your pet, this gas keeps your pet asleep while we perform the surgical procedure.

Once asleep and stable we attach monitoring machines that allow us to measure your pet’s heart rate and also blood oxygen levels. We also place an oesophageal stethoscope that allows us to very simply listen to your cat’s heart rate.

Your cat is then taken into our sterile theatre where her skin is cleaned again and made ready for surgery.

The surgeon scrubs their hands and then puts on a sterile gown and gloves and is ready to start the surgery. We place a sterile drape over the cat and then make a small incision about 1 to 2 cm in the midline of the cat’s tummy that starts very close to the umbilicus.

We then use a hook to locate and pull up the uterus which is clamped and tied off using vicryl – an absorbable but very strong suture material – both uterine horns are tied off first and then the body of the uterus. Finally the muscle layer is sutured closed and then the subcutaneous fat and finally the skin is closed with one or two sutures using nylon. These are the sutures that we remove 7 – 10days after the surgery.

Upon recovering from the anaesthetic the cat is placed on a very soft bed with a heated pad and given further pain medication that will last for 24 hours after the surgery.

Because we use a sterile theatre we do not routinely give antibiotics pre or postoperatively.

How common are ear infections in cats?

Infections of the external ear canal (outer ear) by bacteria or yeast are common in dogs but not very common in cats.  We call this otitis externa.  The commonest cause of feline ear disease is ear mite infestation.  Some cats have similar signs due to excessive wax in their ears that are not infected.

What are the symptoms of an ear infection?

A cat with an ear infection is uncomfortable and its ear canals are sensitive.  The cat shakes its head trying to get the debris and fluid out and scratches its ears.  The ears often become red and inflamed and develop an offensive odour.  A black or yellow discharge commonly occurs.

Don’t these symptoms usually suggest ear mites?

Ear mites can cause several of these symptoms including a black discharge, scratching and head shaking.  However, ear mite infections generally occur most commonly in kittens. Ear mites in adult cats occur most frequently after a kitten carrying mites is introduced into the household.  Sometimes ear mites will create an environment within the ear canal which leads to a secondary infection with bacteria or yeast.  By the time the cat is presented to the vet, the mites may be gone but a significant ear infection remains.

Since these symptoms are similar can I just buy some ear drops?

No, careful diagnosis of the exact cause of the problem is necessary to enable selection of appropriate treatment.  There are several kinds of bacteria and fungi which might cause an ear infection.  Without knowing the kind of infection present we do not know which drug to use.  In some cases, the ear infection may be caused by a foreign body, tumour or polyp in the ear canal.  Treatment with medication alone will not resolve these problems.  Also, the cat must be examined to be sure that the eardrum is intact.  Administration of certain medications can result in loss of hearing if the eardrum is ruptured.  This determination is made by the vet and must be done at the surgery.

How do you find out what is causing the ear problem?

The vet may examine the ear canal with an otoscope, an instrument that provides magnification and light.  This permits a good view of the ear canal and allows him to determine whether the eardrum is intact and if there is any tumour or foreign material in the canal.  When the ears are extremely painful and the cat refuses to allow ear examination, sedation or general anaesthesia may be necessary.  The vet may then examine a sample of the material from the ear canal under the microscope.  This is called cytology and is very important in helping the vet choose the right medication.  Some cats have such a heavy build-up of debris that sedation or anaesthesia are needed to cleanse the canal and examine it completely.

How are ear infections treated?

The results of the otoscopic examination and cytology tell the vet. what to do.  If there is a foreign body lodged in the ear canal the cat can be sedated so that it can be removed.  Specific medication can be prescribed for bacteria or fungi; sometimes more than one type of infection is identified and this situation requires the use of multiple medications.

An important part of the evaluation of the cat is the identification of the underlying disease.  If an underlying disease is found it can be treated.  If this cannot be done the cat is less likely to have a favourable response to treatment; the cat might respond temporarily but relapse when the medication is discontinued.

Since primary ear infections are uncommon in cats should I be concerned that something else is going on?

Normal cats are very resistant to ear infections.  Therefore finding otitis externa in a cat signals us to look for an underlying cause such as an ear mite infestation, an unusual shape of the ear canal or for a disease affecting the cat’s immune system.

What is the prognosis?

In the cat, nearly all ear infections that are properly diagnosed and treated can be cured.  However, if an underlying cause remains unidentified and untreated the outcome will be less favourable.

My cat’s ear canal is nearly closed.  Is this a problem?

Closing of the ear canal occurs when an infection becomes very chronic.  There are medications that can shrink the swollen tissues and open the canal in some cats.  However, some cases may eventually require surgery.

How should I apply medication to my cat’s ear?

It is important to get the medication into the horizontal part of the ear canal.  This is best done by following these steps:-

  • Prior to instillation of the medication, clean the outer part of the ear canal and the inside of the ear flap with a ball of cotton wool.  Do not use cotton-tipped applicators to do this as they tend to push debris back into the vertical ear canal
  • Warm the medication by standing the bottle in a bowl of warm water for a few minutes.
  • Gently pull the ear flap straight up and hold it with one hand.
  • Apply a small amount of medication in the vertical part of the ear canal while continuing to keep the ear flap elevated.  Hold this position long enough for the medication to run down to the turn between the vertical and horizontal ear canal.
  • Put one finger in front of and at the base of the ear flap and put your thumb behind at the base
  • Massage the ear canal between your finger and thumb.  A squishing sound tells you that the medication has gone into the horizontal canal
  • Release the ear and let your cat shake its head.  If the medication contains a wax solvent debris will be dissolved so it can be shaken out
  • If another medication is to be used apply it in the same manner

In some circumstances, your vet may suggest that you should consider having your pet ‘put to sleep’ (euthanased) such as if your pet has a terminal illness from which it cannot recover or if it has incurable pain. This will enable your pet to die in peace, with dignity and without further suffering. It can be a very hard decision to make, but it is one of the kindest things an owner can do for a suffering pet.

What happens when a pet is ‘put to sleep’?

The vet will often give your pet a sedative first, so there will be less stress and a calm environment is created. When it’s feeling a bit sleepy, the nurse will often be called in to assist the vet. A lethal injection will be given in the vein of the front leg. In some pets, this vein is not easily accessible and the injection might need to be given in the kidney or heart. Loss of consciousness and death will happen very quickly. This is a very controlled and painless method of euthanasia. Your pet’s eyes will remain open afterwards.

Is it usual for the owner to stay with their pet when it is ‘put to sleep’?

It is best to do what you feel comfortable with. It is possible to stay during the whole procedure or only a part of it. Some people like to stay until the sedation has set in, so their last memory can be of their pet while it was alive. Others might not want to be present at all or only after the procedure has finished.

The decision of whether to stay or not is a very personal one, which should preferably be made in advance to avoid further distress.

Can I have my pet ‘put to sleep’ at home or is it better to take him to the surgery?

It is possible for the vet and a nurse to come to your house. This involves a bit more planning since there will be a period of time they will be away from the clinic. If there are difficulties arranging an appropriate time, then it is usually also possible to book an appointment at a quiet time in the clinic to avoid undue stress to both pet and owner.

What can I do with my pet’s remains?

  • home burial
  • cremation
  • Individual cremation with return of the pet’s ashes. This can be arranged via the clinic.

Grieving for your pet

It is very natural to feel upset and emotional when your pet dies. Don’t be afraid to show your feelings in front of your vet, he/she will understand. Feel free to ask all the questions you like and take your time to say goodbye.

It’ll take time to get over your loss and it often helps to talk about it. Counselling is also available. It’s quite normal to feel angry, this is part of the process of coming to terms with your loss. Try not to feel guilty or blame yourself for your pet’s death. Try to focus on remembering the good times and what you loved most about your pet.

Helping children to cope

The death of a pet is often a child’s first experience of death. Tell them the truth and encourage them to talk about their feelings and let them know how you feel yourself. Help them understand that they are not to blame and talk to them about the good times you have had with your pet.

The basic elements of care that are needed for owning a cat for all of its life are the same – a warm, safe environment; good food; clean water; companionship and the ability to know and respect your friend’s behaviour.

As your cat ages, these elements remain the same, however, your ability to read these and observe for changes are more important.

The things to look for are changes in routine;

  • does the cat drink more?
  • urinate inside? (when they never have),
  • eat more?
  • eat less?
  • sleep more?
  • seem stiff/sore?
  • groom less?

The types of illnesses that older cats get are:

  • Kidney disease
  • Liver disease
  • Hyperthyroidism (overactive thyroid)
  • Heart disease
  • Cancer
  • Diabetes
  • Arthritis

Early detection of these diseases is essential in their successful treatment. Diseases such as kidney disease are really hard to detect early on and it is often not until 75% of the kidneys are damaged, we start to see the common symptoms of drinking and urinating excessively.

As with human medicine, the advances that have occurred have immensely helped our ability to diagnose and treat many of these diseases. There are great new insulins that allow better management of diabetes plus several new drugs that allow us to treat heart disease and help with kidney disease. Tools such as ultrasound machines give us a view into the heart and allow us to directly measure changes in such things as blood flow through the heart and also the thickness of the muscular walls of the heart itself. Heart disease can be accurately diagnosed and then treated appropriately. Blood pressures can be easily measured and treatments administered.

We have one patient that comes to see us who had a large abdominal cancer, the owners had been told, by another vet clinic, that there was nothing that could be done and the cat should be taken home to die. We saw the cat’s blood tests were favourable and chest x-rays clear, so surgery was done and the mass biopsied. The cancer was treatable and the cat referred to a referral centre for chemotherapy. This cat was still alive a good 6 months later and is stable in remission and a very happy cat.

Chemotherapy always stirs emotions in animal owners and is definitely not for every owner or patient.

People often say Fluffy is thirteen he is just old, yes he is old, but that should be an excuse to say let’s make sure that he is well, rather than just use the excuse of his age as a reason to do nothing.

So on top of your caring for your cat at home, there is a huge amount that can be done, diet, pain control for arthritis, supplements for tired joints the list goes on. So if your feline friend is “old and tired” get them checked as there may be a reason for the tired component that could be treatable and lead to both an increase in the quality and also the length of their lives.

Recommendation – if your cat loses weight rapidly, has an increase or decrease in appetite, changes behaviour suddenly such as less active or can’t jump up on the furniture, drinks more or from unusual places (like the shower) get them checked, as the sooner we act the easier it is to help with some of these problems.

Don’t just rationalize things away with the old “old” excuse!

Is your cat at risk?

Feline immunodeficiency virus (FIV) or Feline AIDS is a common feline retrovirus infecting New Zealand cats. It is similar to Human AIDS or HIV causing immunosuppression which leads to diseases such as oral infections and cancer. Caught through bite wounds in fighting cats, New Zealand has one of the highest rates of FIV positive cats in the world.  High-risk animals would include tom cats, breeds that tend to fight (Abyssinians, Burmese, Rex) and potentially all outdoor cats. In New Zealand infection rates vary, current research estimates 5-15% of New Zealand cats become infected with this life-threatening disease.

A new vaccine

Recently a new vaccination, Fel-O-Vax FIV (Fort Dodge), has been developed to protect against Feline AIDS.  This vaccine is a very important model in the fight against HIV.
The vaccine was developed to protect against FIV Subtype A and D (there are 5 different Subtypes of FIV: A, B, C, D and E). In New Zealand, the most common subtypes found are Subtype A and C.  With a high prevalence of Subtype C in NZ research is currently being undertaken to assess the efficacy of FIV vaccination. As Subtypes A and C are closely related it is expected that good cross-protection should occur and no evidence of vaccine breakdown has occurred in NZ to date.

The decision to vaccinate

For all at-risk cats we recommend vaccination. A simple and quick antibody test will be run in-clinic prior to vaccination for all adult animals. Kittens may be vaccinated straightaway. If the test is negative a microchip to identify your cat as vaccinated (as well as enabling us to track you as an owner) will be inserted and the first vaccine given. A course of 3 vaccinations spaced 2-4 weeks apart is necessary for full protection, with an annual booster given at the same time as your regular vaccine.

What if my cat tests positive?

A small percentage of cats will have a false-positive antibody test.  A laboratory PCR blood test to identify the virus will double-check the in-clinic result. If your cat has feline AIDS we will discuss ongoing treatment. Many cats can go on to live full and happy lives carrying the virus, although remain a risk to other animals if fighting.

At-risk animals

If your cat has recently been in a catfight it is best to wait 2 months before testing and vaccination. It takes a while for the body to produce antibodies to the virus and produce a positive test. In all at-risk pets we recommend vaccination due to the high prevalence of FIV, the safety of the vaccine and the fact is it’s too late once they have the virus.

Our protocol

For kittens under 6 months, we can vaccinate without testing.  There needs to be one vaccination done with a vet check-up, then two boosters done two weeks apart which will be performed by a nurse.  From there, they just require an annual booster, much like their normal vaccinations.

In cats and kittens over 6 months we would need to perform the in-house antibody test.  This would involve leaving your cat with us for the day, so we can run the test, then start the vaccination protocol as above if the result is negative.  If we get a positive result, we would then send the blood to the external lab for confirmation and reassess where we go from there.

What is hyperthyroidism?

Hyperthyroidism is the most common endocrine (hormonal) disorder of cats.  It is rarely seen in cats under eight years of age, and there is no sex or breed predisposition.  It is due to an increase in production and secretion of thyroid hormone by the thyroid gland in the neck.

What are the clinical signs of hyperthyroidism?

Cats may present with a combination of the following clinical signs which tend to develop gradually:

  1. Weight loss
  2. Increased appetite
  3. Hyperactivity and restlessness
  4. Increased heart rate, with a variety of cardiac rhythm irregularities and murmurs
  5. Increased frequency of defecation, with abundant, bulky stools
  6. Increased thirst and urination
  7. Occasional vomiting

How is hyperthyroidism diagnosed?

In hyperthyroidism, a nodule may be palpable in one or both of the thyroid lobes.  As the enlarged lobe may be freely movable and can slide along and behind the trachea, it may be difficult to detect and require careful palpation.  In the normal cat, the thyroid lobes are either not palpable or small and symmetrical.

Once hyperthyroidism is suspected on the basis of clinical signs, the diagnosis is confirmed by detecting elevated serum thyroid hormone levels.  Other laboratory tests may also be abnormal, such as elevation of the liver enzymes, or changes on an electrocardiograph (ECG).

How can hyperthyroidism be treated?

There are two common therapeutic options for the treatment of hyperthyroidism.  Which treatment option is most suitable for your cat depends on a number of factors and your vet will discuss this with you.

1. Anti-thyroid drug therapy

Anti-thyroid drugs are one course of treatment.  They do not destroy the thyroid gland but act by interfering with production and secretion of thyroid hormone.  Their use does not result in a cure but rather controls the condition.  These drugs need to be given orally and sometimes even twice daily dosage is required, so this can be difficult especially with a cat that isn’t easy to medicate.

Mild (and often transient) side effects are seen quite commonly in cats on this medication (~15% of patients) and can include poor appetite, vomiting and lethargy.  More serious side effects are seen less frequently (~5% of patients) and can include a fall in the number of white blood cells, clotting problems, or liver disorder.  Blood should, therefore, be tested routinely to monitor for potential side effects, and in some patients, the occurrence of severe adverse reactions may necessitate withdrawal of the drug.

2.Surgical thyroidectomy

Surgical thyroidectomy (removal of the thyroid glands) has the immediate advantage over drug therapy in that it provides a cure.  This treatment is readily available, although surgical skill and experience are necessary to minimise potential side effects.

Anaesthesia can be problematic in hyperthyroid patients both as a direct result of the condition being treated, and also because a number of patients have other concurrent diseases e.g. chronic renal failure.  To reduce hyperthyroid-related surgical risks, patients should be pre-treated with anti-thyroid drugs for 3 to 4 weeks prior to surgery to reduce their thyroid hormone levels back to normal.  Any associated cardiac disease should be carefully controlled.

Side effects of the surgical procedure may include nerve damage, or hypoparathyroidism (lack of the hormone that controls the level of calcium in the blood).  The parathyroid glands are located very close to the thyroid glands, and so can be easily damaged when the thyroid glands are being removed.  The resultant hypocalcaemia (low blood calcium level) can result in muscle twitching, weakness and convulsive seizures.  Patients in the veterinary practice are observed closely for the first 2-3 days after surgery.

3. 131I (radioactive iodine) therapy

This uses radioactive iodine (I131) which is administered subcutaneously (injected under the skin) or given by mouth, and is selectively concentrated within the follicles of the thyroid gland.

131I selectively destroys the affected thyroid tissue, including any areas of thyroid tissue which may be inaccessible to surgery, and spares adjacent normal tissue, including the parathyroid glands.

An initial tracer-dose of 131I may be given in order to precisely calculate the correct treatment-dose of 131I for any individual.  However, recent experience suggests that a standard dose (150-250MBq/cat) is likely to be curative in around 90% of cases.  Where hyperthyroidism persists after treatment, a second dose can be given.  Very occasionally permanent hypothyroidism (lack of thyroid hormone) has been seen after 131I treatment, but this can be easily managed with thyroid hormone replacement therapy.

The primary advantages of 131I treatment are that it is curative, has no serious side-effects (no toxicity, no hypoparathyroidism), does not require an anaesthetic or sedation, is associated with a low recurrence of hyperthyroidism and the location of the tumour is unimportant.  The cost of treatment is comparable to surgical treatment but depends in part on the length of hospitalisation.  Additionally, large doses of 131I are the only effective treatment for thyroid adenocarcinoma, which is responsible for around 1 to 2% of feline hyperthyroid cases.

The problems of 131I treatment include:-

a) Poor availability, due to safety regulations that cover the use of radioactive products so there may be a “wait time” for this procedure

b) Cats need to be referred for this service and will need to be hospitalised for approximately 1 week following treatment, which is necessary to allow adequate decay of the 131I.

c) It is not suitable for use with patients requiring intensive care as, particularly in the early days following treatment, excessive handling of the cat must be avoided.

What is solar dermatitis?

Solar dermatitis is a skin disease which is caused by exposure to the sun.  It occurs mainly in cats with white non-pigmented area. The ear flaps, nose and lower eyelids are most commonly affected areas.  In the early stages the skin may look pink and scaly with some degree of hair loss but as the condition progresses the area becomes crusted and eroded.  The cat is often irritated by the lesions and if the ears are affected it may shake its head and cause bleeding from the ear tips.  If left untreated some cases progress and a malignant tumour (squamous cell carcinoma) can develop at the site. New Zealand is one of the worst countries in the world for this problem.

What can be done to prevent the condition from progressing?

Sunlight should be avoided.  This is best achieved by keeping the cat indoors between the hours of 9.00 am and 4.00 pm on sunny days.  If this is not possible then one can try using sunblock cream on the affected areas.  Unfortunately, cats will rapidly groom or lick this off.  Some products may actually be toxic to cats so it is advisable to check with your vet before you start using a cream.  There is one sunblock (Filtabac) cream available specifically formulated for cats.

How will I know if my cat has squamous cell carcinoma?

If your vet is at all concerned that the condition may be progressing to squamous cell carcinoma he will advise that a biopsy (a small tissue sample) is taken from the affected area.  The cat will need to have a general anaesthetic in order to do this.  The biopsy will be sent away to a histopathologist who will examine it under a microscope to see if malignant cells are present.

How is squamous cell carcinoma treated?

The treatment of choice is the surgical removal of the affected area and a wide surrounding margin.  This usually straightforward if the ears are affected.  Complete removal of the ear flaps may be necessary; this has no detrimental effect on the cat and the final appearance is usually quite acceptable.  Surgery can be more difficult if the nose or eyelids are affected. In advanced cases with nose involvement, removal of the nose is possible as a last resort.

What is the likely outcome following surgery for squamous cell carcinoma?

The prognosis is usually good especially when the ears are involved and particularly if the disease is discovered early.  If all the diseased tissue is not adequately removed the tumour will recur at the operation site; this can be a problem if the nose or the eyelids are affected.  This type of tumour can be locally invasive but often does not commonly spread to other areas of the body.

Core Vaccinations (Strongly Recommended for All Cats)

Feline Herpesvirus, Calicivirus and Panleukopaenia. We recommend vaccinating kittens at 9 weeks and again at 12 weeks with a combined vaccine for these three diseases.  This is repeated 12 months after the last vaccine and then again once every 3 years, but some cats will require this more frequently (see below “Cats at high risk”)

Feline herpesvirus and calicivirus are two of the main causes of “cat flu/snuffles.”  These may cause sneezing, runny eyes & nose, mouth & eye ulcers, loss of appetite and in severe cases death. Infected cats can become lifelong “carriers” of herpesvirus in which case signs may recur when the cat is under stress of any kind.  Vaccination will not prevent or cure the carrier state, it will, however, reduce the chance of infection, the severity of the disease and possibly reduce the amount of virus shed.

Feline panleucopaenia is now thankfully uncommon in New Zealand due to vaccination.  It is a highly contagious disease causing loss of appetite, diarrhoea, vomiting, extreme lethargy, dehydration and frequently death.  Vaccination is very effective at preventing the disease.

Cats at “High Risk”– Cats are at a higher risk of infection particularly with cat flu viruses if they come into boarding catteries, go to cat shows, or have frequent contact with stray cats.  These cats may benefit from a more frequent vaccination against herpesvirus and calicivirus – we recommend an annual booster vaccination or booster at least 2 weeks before going into a cattery.

Optional Vaccination

FIV = Feline Immunodeficiency Virus  This is an infectious disease transmitted most commonly by deep bite wounds.  It affects the cat’s immune system making it unable to respond properly to infections. It is a very dangerous disease, but is not as contagious as the flu and panleukopenia, and can take a long time to become apparent, some infected cats will not show any clinical signs for many years.  Also, the vaccine available has not been made specifically for New Zealand and has not been proven (though it is accepted to be) protective against the main subtype of the disease present in New Zealand.

We recommend vaccination against FIV only for cats who are likely to be outdoors in areas with many other cats/cats that fight a lot.  Vaccination involves an initial series of 3 injections 3 weeks apart then 1 vaccination once yearly.

We recommend the cat be microchipped if it is being vaccinated (this is so it can be identified as being vaccinated – the most common test for the disease will not distinguish between vaccinated and infected cats).

If the cat is over 6 months of age at the initial vaccination it will need a blood test first to make sure it is not already carrying the disease.

Other diseases

Vaccines are available but we do not recommend them unless cats are deemed at specific risk for :

Feline Leukaemia Virus – because it is extremely rare in New Zealand.

Chlamydia – because the vaccination for it carries a higher risk of side effects, and the disease is quite easily treated if it does occur

We hope this has been useful to you, please do not hesitate to discuss any questions you may have with one of our veterinarians.  Information last updated October 2010

As always, please don’t hesitate to call us if you have any questions regarding your cat.