Infectious Diseases in Dogs and Cats
or tissue in the body and is accompanied by a set of symptoms or behavioural
changes in the affected animal. Infectious disease spreads from one animal to
another by various methods. It is hard to know which organism is responsible in a
particular case.
MICRO-ORGANISMS AND DISEASE
Micro-organisms live either in or on the body:
• Oral, nasal and eye discharge
• Urine
• Vomit
• Blood
• Skin surface
Sometimes the disease is passed on by a ‘carrier’ animal. These animals do not
show clinical signs of disease but:
• May have had the disease and recovered – convalescent carriers.
• May never show clinical signs of the disease – healthy carriers.
Both types of carrier will shed the disease-carrying micro-organism into their
environment, putting other animals at risk. Thus, micro-organisms are passed by:
• Direct contact: When parts of the bodies of two animals come into contact, e.g.
nose to nose or nose to anus.
• Indirect contact: The contact is an inanimate object, e.g. bedding, water bowl or
lamp post.
• Aerosol transmission: This occurs through the air, in the form of droplets from
sneezing, coughing, or using air currents.
• Contaminated food or water: When these have been contaminated by urine and
faeces of passing rodents or others.
• Carrier animals: These shed microbes in discharge, urine or faeces although
unaffected themselves, e.g. canine hepatitis.
Incubation
Incubation is the time between the animal receiving the microbe and showing
clinical signs of disease. The incubation time depends on:
• Quantity of microbes: If the microbes enter via the respiratory and/or digestive
tract, the secretions will decrease the ability of the disease to spread unless the
animal is susceptible (see next point).
• Immune status of the animal: If an adequate immune response is not possible
the microbes will overcome the host animal’s resistance.
• General health: If this is not good then the animal is possibly susceptible.
• Age: The immune response of the body is affected in very young and old
animals.
Infection
If the micro-organism has entered the host animal and overcome its resistance,
infection may ensue. Some infections are confined to a restricted area, e.g.
abscesses, whereas others are termed ‘systemic’ because they spread through the
whole body via the bloodstream.
METHODS OF DISEASE CONTROL
• Avoid direct contact between infected and healthy animals.
• Maintain high levels of hygiene/disinfection in the animal’s environment.
• Provide treatment for the infected animal.
• Control parasites to prevent disease passing to healthy animals.
• Maintain vaccination status.
Bacteria
Bacteria are single-celled organisms. Most are large enough to be seen using a
light microscope. Their size and shape (Fig. 8.1) can vary which helps in their
classification. In favourable conditions bacteria reproduce by dividing into two
every 15–20 minutes (binary fission). In conditions unfavourable for growth
some bacteria will form spores with a protective surrounding wall. The bacteria
can remain inside the spores for many years. Passing on of genetic material and
information from a bacterial donor to a recipient bacterium is called conjugation
and is a method of survival of bacteria.
Viruses
Viruses are the smallest of the microbes. They are always parasitic, and reproduce
by replicating themselves. This process happens after the viral DNA or RNA
(genetic information) has gained entry into a living host (the cells in the animal’s
body). Different viruses target different types of body cell.
The viral strand of material takes over control of the host cell’s metabolism and
directs it to manufacture replicas of the viral material. When enough replicas
have been produced, the virus will instruct the host cell to rupture, releasing the
viruses, each of which can then use other host cells for the purpose of replicating.
The virus is not a cell – it consists of a protein coat around a DNA or RNA
strand. Some viruses (Fig. 8.2) are also surrounded by a membrane known as an
envelope, which may have structures like spikes on its surface for attaching to the
host cell before entry.
In many cases, the cycle of viral replication causes no apparent harm to the host.
Disease occurs when large numbers of host cells in a specific tissue are destroyed
leading to disruption of body functions.
Fungi
These are non-chlorophyll-bearing plants. Fungi are divided into:
• Moulds (multi-cellular)
• Yeasts (uni-cellular)
Fungi do not have the ability to make their own food, and so must exist as parasites
or saprophytes. Spread is by spores (Fig. 8.3). Reproduction in fungi is sexual
(hyphae from different strains unite to form a survival spore, awaiting favourable
conditions for growth). There is also an asexual method (spread of spores).
Protozoa
These are single-celled animals and range in size from microscopic to just visible
to the naked eye (Fig. 8.4). They have a cell membrane and organelles for movement
(flagella and cilia). Reproduction is asexual by binary fission and nutrition is
holozoic (capture and assimilation of organic material in their environment).
They are capable of pursuing prey by following the trail of a chemical or are stimulated
by movement. They are often found in water. Protozoa form cysts at some
point in their life cycle. This is the form which passes from host to host, and allows
survival outside the host temporarily.
To minimise the risk to people of zoonoses passed by a dog or cat, the following
simple but effective hygiene precautions are recommended to be taken in the
grooming salon:
• Vaccination certificates should be checked prior to admitting animal to a salon
and recorded on owner record.
• Recommend investigation to owner if any signs of illness observed and do not
proceed with grooming.
• Recommend flea and worm control to owner
• Wash hands after handling any animal
• Always wear gloves when handling body discharge
DISEASES OF DOGS
Infectious canine diseases for which there is a vaccine include:
• Canine distemper
• Canine viral hepatitis
• Canine leptospirosis
• Canine parvovirus
• Canine infectious tracheobronchitis (kennel cough syndrome)
• Rabies
Canine distemper
The virus causing distemper attacks the following body systems:
• Central nervous system
• Respiratory system
• Gastrointestinal system
• Skin
The disease is caused by a paramyxovirus that is closely related to the measles
virus of humans. The virus is inactivated by light, heat and most disinfectants.
Distemper is commonly seen in 4–5-month-old puppies when no longer covered
by maternal immunity. Distemper follows a seasonal occurrence (autumn and
winter), due in part to the ability of the virus to survive in cold weather. The
routes of infection are:
• Respiratory tract due to aerosol (airborne) exposure
• Mouth and eye mucous membranes
During the incubation period of 3–10 days, the virus replicates and travels via
the lymphatic system to the lymph nodes, spleen, thymus and bone marrow.
When the virus is in the lymph nodes, the body temperature rises to between 39°C
and 40°C for 2–4 days. About half of all puppies infected are capable of mounting
an adequate response and produce antibodies to clear the infection at this point.
However, if the virus survives, it replicates in the epithelium, other organs and
central nervous system. This allows secondary infection to occur. Clinical signs of
distemper include:
• Lack of appetite (anorexia)
• Nasal and eye discharge
• Coughing
• Diarrhoea and vomiting
• Hardening of the footpads
• Inco-ordination
• Paralysis
• Epileptic-type fits
If the puppy survives the respiratory or gastrointestinal stage of the disease, it
will develop neurological signs up to four weeks later. Older dogs tend to present
with just the neurological signs. This stage is usually fatal; occasionally the dog
will survive but there will be lasting central nervous system damage.
Vaccination gives good protection but is not life-long, so booster vaccinations
are essential.
Canine infectious tracheobronchitis (kennel cough
syndrome)
This syndrome is a complex disease linked to a number of viruses. The microorganisms
causing kennel cough syndrome include:
• Bordetella bronchiseptica
• Canine adenovirus type 2 (CAV2)
• Canine parainfluenza virus (CPIV)
• Canine distemper virus (CDV)
However, the major cause is thought to be the bacterium Bordetella bronchiseptica.
Clinically the syndrome presents as tracheitis, which is usually self-limiting
but which may also develop into bronchitis or pneumonia. Bordetella bronchiseptica,
CAV2 and CPIV are highly contagious and commonly present when dogs
are housed together, as they infect the respiratory tracts of dogs of any age. They
cause nasal and tracheal inflammation lasting 5–14 days and then normally
resolve, with the dog making a good recovery. At this time the dog sheds the
organisms in respiratory secretions. Clinical signs of kennel cough syndrome
include:
• Cough
• Sneezing and nasal discharge
• Depressed but still eating
• Retching after coughing
Transmission from dog to dog can be minimised by isolation of the affected
animal and by improving kennel ventilation and disinfection routines. All dogs
that are going into a boarding establishment should be vaccinated with a mixed
vaccine that includes CAV2 and CPIV.
Canine parvovirus
The canine parvovirus is closely related to the feline panleucopenia virus. The
virus is highly resistant to inactivation by most disinfectants except bleach
and formalin-based chemicals and can survive for months in the environment.
The virus localises in lymphatic tissues and the lining of the intestinal epithelium.
It is found in vast numbers in the faeces and vomit of infected animals and causes
myocarditis and mild to severe haemorrhagic enteritis.
The infection spreads by faecal or oral contact. Damage to the bone marrow
results in lack of white cells and the infection spreads from lymph cells in the gut
tissues. The incubation period is 5–10 days. Clinical signs of canine parvovirus
infection include:
• Dull and depressed
• Anorexia
• High temperature (up to 41°C)
• Vomiting
• Bloodstained gastric juices
• Bloodstained diarrhoea 24 hours later
• Rapid dehydration
Vaccination as a puppy should be followed by annual boosters for protection.
Canine viral hepatitis
This is caused by the canine adenovirus type 1 (CAV1). Transmission occurs
through oral and nasal passages after exposure to infected materials. The virus is
resistant and survives outside the body for up to 11 days in bedding, feeding
bowls, urine and faeces. It is resistant to freezing, ultraviolet light and most disinfectants
but is destroyed by heat. Following exposure, the virus localises in the
tonsils and lymph nodes where primary replication occurs. The virus travels in
the lymph and gains access to the bloodstream. It is attracted to the cells of the
liver and kidneys, where further replication occurs, before it is shed in urine and
faeces. The incubation period is 5–9 days. Animals can shed the virus for several
months after recovery.
Puppies may develop high temperature and death occurs within hours. Older
dogs survive the viraemic stage but may have blood-stained vomit and diarrhoea,
and acute abdominal pain. In some dogs, ‘blue eye’, clouding of the cornea of the
eye, can occur up to three weeks after acute infection. Vaccination and annual
boosters are essential.
Leptospirosis
Leptospirosis is also known as Stuttgart disease or Weil’s disease in humans
and is caused by a filament-like bacterium, Leptospira icterohaemorrhagiae, which
causes a zoonotic disease in humans. Leptospira strains that cause the disease in
dogs are:
• Leptospira icterohaemorrhagiae: Primary host is the rat, attacks mainly the liver.
• Leptospira canicola: Primary host is the dog, attacks mainly the kidney.
These bacteria are easily destroyed by sunlight, disinfectants and temperature
extremes. The disease spreads by direct contact, bite wounds or ingestion of
infected food or water. Rodents such as rats are frequently carriers, shedding
the bacteria in urine and thus contaminating water. The incubation period is
7–21 days, with severity of the disease depending on the susceptibility of the
host animal and the strain. Clinical signs of leptospirosis include:
• High temperature
• Shivering and muscle pain
• Vomiting and diarrhoea
• Dehydration
• Shock
• Jaundice (mucous membranes of mouth and eye appear yellow)
Animals continue to shed the bacteria via the urine for some time after
recovery. Strict isolation must be observed. Both veterinary surgeon and doctor
can provide advice and information regarding how to prevent a human carer
becoming infected. An annual booster after initial vaccination is essential.
Rabies
Rabies is caused by a rhabdo virus. The virus is fragile, surviving for only a short
time in the environment, and is destroyed by most disinfectants, heat and light.
It is transmitted in the saliva of infected animals, and replicates in the muscle
cells at the site of infection. Then it travels via the peripheral nerves to the spinal
cord and the brain. When it has invaded the central nervous tissues, neurological
signs are observed. The virus also travels to the salivary glands, where it is shed
to infect other mammals, both human and animal. Rabies is therefore a zoonotic
disease.
The incubation period ranges from 10 days to four months, the time depending
on how close to the central nervous system the virus initially enters the host.
There are three phases or stages of the disease. However, all will not necessarily
occur in all affected animals.
(1) Preclinical stage: This lasts 2–3 days. There is a raised body temperature, slow
eye reflexes and signs of irritation at the site of the original injury.
(2) Excitable stage: This lasts up to one week with the animal becoming irritable,
aggressive and disorientated, having difficulty standing and epileptic-type
fits.
(3) Dumb stage: This lasts 2–4 days during which the animal’s throat and
skeletal muscles becomes progressively paralysed, leading to salivation,
difficulty breathing, coma and death.
In some cases the preclinical stage can last for several months during which
the virus is shed in the saliva. The diagnosis is confirmed on post-mortem
examination of the brain and spinal cord for signs of the virus. A vaccine is available
for dogs that live in countries where rabies is endemic or in case of travelling
to a country with rabies in the wild or domestic animal population. The vaccine is
given at three months of age with annual boosters.
If a human is bitten by an animal suspected of having rabies, the wound should
be cleaned immediately using soap or antiseptic solution and medical attention
should be sought straight away.
DISEASES OF CATS
Infectious feline diseases include:
• Rabies (see Rabies in the dog above)
• Feline leukaemia
• Feline panleucopenia or feline infectious enteritis
• Chlamydiosis or feline pneumonitis
• Feline viral respiratory disease:
(a) Feline herpesvirus
(b) Feline calicivirus
• Feline infectious anaemia
• Feline infectious peritonitis
• Feline immunodeficiency
Feline leukaemia
The retrovirus causing feline leukaemia (FLV) affects approximately 2% of cats
worldwide. It is contagious and, once symptoms appear, almost always fatal.
Most cats are exposed to this virus during their life and it is most commonly
found where cats are in close contact.
Evidence of the virus is obtained from testing blood samples using the FLV
enzyme-linked immunosorbent assay (ELISA) test. The effect of the virus on the
host cat depends on the age of the cat when it is infected and the quantity of virus
received.
Some cats become ill and apparently recover whereas others do not become ill
and develop immunity to the disease. Yet others develop the disease symptoms
after an incubation period of weeks to several years. Young kittens are most
susceptible to the virus. Most die within 2–3 years of exposure or as a result
of FLV-related conditions including anaemia (lack of red blood cells) and
lymphosarcoma (tumours of the lymph system). Clinical signs of FLV include:
• High temperature
• Vomiting and diarrhoea
• Weight loss
• Kidney disease
• Enlargement of the spleen
The virus is shed in:
• Saliva
• Faeces
• Urine
• Milk to offspring
The virus is easily destroyed by disinfectants and cannot live long outside a
host. Infection can be passed via saliva in bite/fight episodes, contact with other
cats or from the mother to the kittens before or after birth via the milk. Initially,
the virus replicates in the lymphatic tissues, then moves on to target other
systems containing lymphatic tissue, such as the intestines, causing enteritis, the
salivary glands and the urinary and reproductive systems, causing infertility or
abortion in pregnant animals. The disease is controlled by:
• Testing. Testing for evidence of microbes in other cats in a multi-cat household
may need to be done several times to confirm the result because the cat is
euthanised if it is a true result.
• Isolating animals testing positive.
• Disinfection and maintenance of hygiene in cat areas.
• Re-testing 12 weeks after positive test to ensure result is correct.
• Testing all new cats that join a household.
After two positive tests, the safe option is to permanently isolate the infected cat
or perform euthanasia. Cats are vaccinated from nine weeks of age with a second
dose 2–4 weeks later followed by an annual booster. Before vaccination, all cats
are tested for presence of the virus in the blood.
Feline panleucopenia or feline infectious enteritis
Feline panleucopenia is a highly infectious disease of cats. It is also known as:
• Feline parvovirus
• Feline distemper
• Feline infectious enteritis
The disease is caused by a parvovirus, similar to the canine parvovirus. The
disease can affect cats of any age and is mainly responsible for deaths in young
kittens. The virus is stable and capable of surviving in the environment for
months to years and is resistant to most disinfectants. The incubation period is
2–10 days following direct contact with an infected animal or ingestion of the
virus. The virus targets rapidly dividing cells and tissues of the small intestines,
lymph and bone marrow. It is shed in saliva, vomit, faeces and urine. Clinical
signs of infection with the feline parovirus include:
• Diarrhoea, often bloodstained
• Dull and listless behaviour
• Abdominal pain
• Fever and dehydration
Blood tests show a typical reduction in white blood cells (leucopenia), particularly
neutrophils. The virus can cross the placenta during pregnancy and affects
the fetus by targeting the brain tissue (cerebellum), causing death or abnormal
nervous system development. Affected kittens show balance difficulties and incoordination
at about 2–3 weeks of age. If the cat survives the first week of
clinical disease, careful nursing can lead to recovery but the intestine may suffer
permanent damage, evident as poor absorption of nutrients and frequent diarrhoeal
episodes. Vaccination, using either live or inactivated vaccine (in pregnant
cats), provides good immunity with a booster required every 1–2 years.
Chlamydiosis or feline pneumonitis
Chlamydial infection is caused by an organism which lives within cells. Chlamydia
are therefore treated like a virus, although in appearance they resemble bacteria.
Chlamydia cati or C. psittaci affects the conjunctiva of the eye in cats, causing severe
conjunctivitis with eye discharge, sneezing and nasal discharge. The conjunctivitis
may affect one or both eyes. Transmission is thought to be via contact with
eye/nose discharge, or genital or gastrointestinal secretions from carrier animals.
The incubation period is 3–10 days. Clinical signs of chlamydiosis include:
• Initial watery discharge in one eye, spreading to both
• Inflamed conjunctiva
• Fever
• Rubbing eyes and signs of discomfort
• Diarrhoea in kittens
During pregnancy, chlamydiosis may lead to abortion or stillbirth. Chlamydiosis
may last for 2–3 weeks or longer, especially as a part of the feline viral
respiratory disease complex. Animals may shed the responsible organism for
several weeks so any treatment given usually continues for three weeks after
recovery. The organism is killed by most disinfectants during routine cleaning.
Vaccination is available with annual boosters.
Feline viral respiratory disease
This is also known as:
• Cat flu
• Feline upper respiratory disease (FURD)
• Feline viral rhinotracheitis (FVR)
The two main viruses involved are:
• Feline herpesvirus
• Feline calicivirus
Cats are particularly susceptible to infections (both bacterial and viral) of
the nose and throat. Due to their location, these infections are called upper
respiratory infections or cat ‘flu. While it is essential to vaccinate, as with the
‘human flu’, vaccines do not protect against some strains of this disease, especially
feline calicivirus.
Calicivirus is easily destroyed outside the host by disinfectants. Transmission
of the virus is by aerosol or direct contact. As a result of this, any grouping of cats
may lead to infection, e.g. shows, boarding, breeding kennels and veterinary
surgeries. Many cats that survive the infection become carriers, shedding the
virus for several years. It is possible to have suspected carrier animals tested by a
veterinary surgeon for the presence of the calicivirus. The incubation period is up
to ten days after exposure to high-risk situations (groups of cats) or stress caused
by a change in the environment which may lower the cat’s resistance. Clinical
signs of the infection include:
• Ulcers on the tongue
• Inflammation of the gums
• Unwilling to eat, but producing excess saliva
• High temperature
• Depressed and listless
• Loss of voice
The presence of ulcers may allow bacteria normally present to add to the cat’s
original symptoms and recovery time.
Feline herpesvirus can survive outside the host for up to eight days. This virus
attacks and replicates in the tissues of the respiratory tract and conjunctiva of the
eye, causing viral rhinotracheitis. The tissues from the nose (rhino) to the trachea
(tracheitis) are affected and inflamed, causing breathing difficulties, sneezing
and coughing. Animals can act as carriers after recovering from the infection,
shedding the virus particularly when stressed.
Viral rhinotracheitis is the most serious form of upper respiratory disease, often
leaving animals after recovery with damage to the nasal passages. This causes the
affected cat to periodically sneeze, snuffle and have a runny nose, the discharge
occasionally being thick with pus. The incubation period lasts for 2–10 days
following exposure. Clinical signs of the infection include:
• High temperature
• Discharge from eyes and nose, later becoming thickened due to bacterial
infection
• Depressed and listless
• Loss of appetite
• Sneezing
• Conjunctivitis
• Mouth ulcers
• Pneumonia
• Abortion in pregnant queens
A vaccine is available, requiring an annual booster. It is administered
intranasally. In high-risk situations, six-monthly administration is advisable.
Feline infectious anaemia
Infectious anaemia is the direct loss of red blood cells caused by a blood parasite
called Haemobartonella felis or Eperythrozoon felis. It is thought to be transmitted via
blood-sucking parasites, e.g. the flea. Cats of all ages can be affected. When the
disease is linked to feline leukaemia, affecting white blood cell numbers, chances
of recovery are poor.
The single-celled parasite responsible for the infection can be demonstrated on
a blood smear in the laboratory. Discussion with a veterinary surgeon is essential
at this time. Products to safely remove fleas from the affected household will be
required and other cats in the same household may need to be examined and
treated. The incubation period is up to 50 days, with recovered or carrier animals
often shedding the parasite for months. Clinical signs of the infection include:
• Pale mucous membranes (mouth and gums)
• Breathing difficulty
• Listless and loss of appetite
• Third eyelid up as a sign of ill health
• High temperature
• Weight loss
Animals respond well to treatment using specific antibiotics. There is no vaccine
against this virus.
Feline infectious peritonitis
Infectious peritonitis is also called feline infectious vasculitis and is caused by a
coronavirus which affects mostly young cats under three years of age. It causes
the lining membrane of the abdomen (peritoneum) and contents to become
inflamed (peritonitis). The effects of this disease are not limited to the organs of
the abdomen and it may also affect the nervous system and eyes.
One mode of transmission is contact between cats via urine and faeces. Carrier
animals may carry the virus for years, with mothers possibly passing the disease
to their kittens. The virus is unstable outside the body and easily destroyed by
disinfectants. Diseased cats are sometimes affected by feline leukaemia, which
may make them susceptible to the peritonitis virus. The form taken by the disease
will vary depending on the ability of the animal’s immune system to mount a
response to the viral challenge. Clinical signs of the disease include:
• Lack of appetite and gradual weight loss
• Fever
• Swollen abdomen due to fluid accumulation
• Diarrhoea and vomiting
Later signs include:
• Organ failure
• Neurological signs including inability to stand, paralysis and convulsions
• Inflammation within the structure of the eye, affecting the sight
Depending on the form taken by the disease, it is often further described as
wet (fluid in body cavities) or dry (tumour-like masses called granulomatous
lesions forming in organs). The disease is controlled by observing strict hygiene
measures and disinfection particularly in multi-cat households or where groups
of cats are housed. There is no vaccine available in the UK at present.
Feline immunodeficiency
Feline immunodeficiency is caused by a virus of the lentivirus group. The disease
is often characterised by a long incubation period from four weeks to several
years; as a result, it is unusual to find the infection in cats under two years of age.
The disease attacks the lymph system, causing the body’s immune response to be
suppressed. Initially the disease was known as T-lymphotrophic T cell lentivirus,
due to the effect on the cells of the immune system (T cells and B cells).
The virus is carried in the saliva of the infected animal and transmitted by bite.
Therefore cats that have access to outdoor life are more at risk than those living
completely indoors. Male cats are more commonly infected due to territorial
fighting.
Commercial screening kits are available for detection of antibodies to the virus
in a blood sample from the animal. After the initial response to the virus, the cat
shows signs of the disease in a few weeks. These signs are very similar to those of
feline leukaemia and include:
• Conjunctivitis and nasal discharge
• Enlarged superficial lymph nodes (lymphadenopathy)
• Mouth and gum inflammation
• Diarrhoea
• Skin problems
• High temperature
• Neurological signs that include difficulty in walking and change in
temperament
The animal then appears to recover but due to gradual suppression of its
immune responses, it will frequently suffer from recurrent or ongoing infections
of various kinds, often failing to respond to veterinary treatment. The cat will
suffer weight loss, becoming inactive and listless. There is no vaccine available so
owners are advised to castrate male cats and limit exposure to other neighbourhood
cats to avoid contact with an infected animal.
IMMUNITY
Immunity is the body’s natural protection against life-threatening diseases.
Immunity may be acquired by passive or active means.
Passive immunity results from the transfer of maternal antibodies to the
newborn via the colostrum and the milk. The degree of passive immunity
depends on the quantity of the colostrum and the quality of the mother’s own
antibodies resulting from her recent vaccinations. Passive immunity lasts only as
long as the antibodies remain active in the blood – from three to 12 weeks. After
this time the body eliminates the antibodies.
Active immunity develops as a result of either the animal becoming infected
with a micro-organism, developing the disease and recovering or by vaccination.
Both cause the body to react in much the same manner by stimulating the production
of antibodies, which are specific for particular microbes (pathogens or
antigens).
The purpose of vaccination is to prevent the disease by averting or limiting the
infection in a host animal. Vaccines stimulate the immune system, which in turn
produces antibodies. The cells of the immune system responsible for producing
this protection are the B lymphocytes (B cells) and these in turn are assisted by the
T lymphocytes (T cells). Both are white blood cells, which may be targeted and
destroyed by certain viruses. Antibodies recognise specific viruses or bacteria and
prevent or limit their ability to produce disease in the host animal. Vaccines are
prepared from live or inactivated (killed) preparations of micro-organisms.
At the time of vaccination, the veterinary surgeon will fully examine the animal
to ensure that adverse conditions which may influence the manner in which the
body responds to the vaccine are not present, such as a raised body temperature.
Many factors influence an animal’s ability to respond to vaccination. These
include:
• Antibodies from the mother’s milk which could interfere with the vaccine.
• Type of vaccine.
• Route of administration (subcutaneous or intranasal).
• Animal’s age.
• Medication that could interfere with the vaccine, e.g. anti-inflammatory drugs.
• Diet.
• Infection already present.