What is wellness testing?

Wellness testing is the term given to a group of tests that is performed specifically to detect signs of early disease in a pet that is apparently healthy.

 

Why do wellness testing?

Pets cannot tell you how they are feeling, and as a result disease may be present before you are aware of it. If a disease or condition can be detected  before a pet shows signs of illness, we can often take steps to manage or correct the problem before irreparable damage is done.

 

When is wellness testing done?

Wellness testing is usually done once yearly, and many pet owners combine wellness testing with their annual visit to the veterinarian for their dog's physical examination, vaccination, or heartworm testing. Your veterinarian may recommend more frequent testing depending on your dog's specific health concerns. Monitoring your pet's health status on a regular basis makes it easier for the veterinarian to detect minor changes that signal the onset of disease.

 

What is involved in wellness testing?

There are four main categories of wellness testing for the young and middle aged dog: complete blood count (CBC), biochemistry profile, urinalysis, and thyroid hormone testing. Within each category, the veterinarian will determine how extensive the testing should be. In younger dogs without noticeable health complaints, relatively simple testing may be adequate. In middle-aged dogs, more comprehensive testing may be beneficial

 

Complete Blood Count - This simple blood test analyses the cellular components in the bloodstream. These include red blood cells, which carry oxygen to the tissues, white blood cells, which fight infection and respond to inflammation, and platelets, which help the blood to clot. The CBC provides details about the number, size, and shape of the various cells types, and identifies the presence of any abnormal cells.

 

Biochemistry Profile - This is a series of tests performed on serum, which is a component of blood.    These tests provide information about how well the various organs of the body are working, and help to detect the presence of some metabolic diseases. There are tests to assess the liver, kidneys, and pancreas, tests to identify the presence of diabetes, and so on. If minor abnormalities are found on the biochemistry profile, the veterinarian may simply request that you repeat the tests at a later time; depending on the abnormality, this may be in a few days, a few weeks, or a few months. In some cases, a more extensive diagnostic workup may be recommended, including an expanded biochemistry profile, or special tests and/or imaging (x-rays, ultrasound).

 

Urinalysis - Urinalysis involves an analysis of the chemical components in urine, as well as a microscopic examination of the cells and solid material present in urine (See handout "Urinalysis"). Urinalysis provides information about how well the kidneys are working, identifies the presence of inflammation or infection, and may detect the presence of underlying metabolic disease such as diabetes. Urinalysis is necessary for a complete assessment of the urinary system. It should be performed routinely as part of wellness testing, and is especially important whenever there is concern about kidney function or underlying metabolic disease.

 

Thyroid testing - The thyroid gland is like a "thermostat", and it "sets" the metabolic rate of the whole body. The most common thyroid disease in the dog is called hypothyroidism, which occurs when the thyroid does not produce adequate amounts of thyroid hormone.  The function of the thyroid gland should be tested if your dog exhibits unexplained weight gain, lack of energy, recurring skin or ear infections, hair loss on the body and tail, or has high cholesterol levels in the blood.

 

Summary

Wellness testing is a simple and effective way of monitoring your dog's health. Early detection and correction of medical problems help to ensure that your pet will have a long, healthy, and active life.

 

 

  This client information sheet is based on material written by Kristiina Ruotsalo, DVM, DVSc, Dip  ACVP &

Margo S. Tant BSc, DVM, DVSc.

 © Copyright 2004 Lifelearn Inc. Used with permission under license. August 22, 2013

 

What is wellness testing?

Wellness testing is the term given to a group of tests that is performed specifically to detect signs of early disease in a pet that is apparently healthy.

 

Why do wellness testing?

Pets cannot tell you how they are feeling, and as a result disease may be present before you are aware of it. If a disease or condition can be detected before a pet shows signs of illness, we can often take steps to manage or correct the problem before irreparable damage is done.

 

When is wellness testing done?

Wellness testing is usually done once yearly, and many pet owners combine wellness testing with their annual visit to the veterinarian for their cat's physical examination and vaccinations. Your veterinarian may recommend more frequent testing depending of your cat's specific health concerns. Monitoring your pet's health status on a regular basis makes it easier for the veterinarian to detect minor changes that signal the onset of disease.

 

What is involved in wellness testing?

There are three main categories of wellness testing for young to middle aged cats: complete blood count (CBC), biochemistry profile, and urinalysis. Within each category, the veterinarian will determine how extensive the testing should be. In younger cats without noticeable health complaints, relatively simple testing may be adequate. In middle aged cats, more comprehensive testing may be beneficial.

 

Complete Blood Count - This simple blood test analyzes the cellular components in the bloodstream. These include red blood cells, which carry oxygen to the tissues, white blood cells, which fight infection and respond to inflammation, and platelets, which help the blood to clot. The CBC provides details about the number, size, and shape of the various cells types, and identifies the presence of any abnormal cells.

 

Biochemistry Profile - This is a series of tests performed on serum, which is a component of blood. These tests provide information about how well the various organs of the body are working, and help to detect the presence of some metabolic diseases. There are tests to assess the liver, kidneys, and pancreas, tests to identify the presence of diabetes, and so on. If minor abnormalities are found on the biochemistry profile, the veterinarian may simply request that you repeat the tests at a later time; depending on the abnormality, this may be in a few days, a few weeks, or a few months. In some cases, a more extensive diagnostic workup may be recommended, including an expanded biochemistry profile, or special tests and/or imaging (x-rays, ultrasound).

 

Urinalysis - Urinalysis involves an analysis of the chemical components in urine, as well as a microscopic examination of the cells and solid material present in urine (See handout "Urinalysis"). Urinalysis provides information about how well the kidneys are working, identifies the presence of inflammation or infection, and may detect the presence of underlying metabolic disease such as diabetes. Urinalysis is necessary for a complete assessment of the urinary system. It should be performed routinely as part of wellness testing, and is especially important whenever there is concern about kidney function or underlying metabolic disease.

 

Summary

Wellness testing is a simple and effective way of monitoring your cat?s health. Early detection and correction of medical problems help to ensure that your pet will have a long, healthy, and active life.

 

 

 

  This client information sheet is based on material written by Kristiina Ruotsalo, DVM, DVSc, Dip  ACVP &

Margo S. Tant BSc, DVM, DVSc.

 © Copyright 2004 Lifelearn Inc. Used with permission under license. August 22, 2013

 

Recent advances in veterinary medical science have resulted in an increase in the number and type of vaccines that are available for use in cats, and improvements are continuously being made in their safety and efficacy. Some vaccines are more or less routinely advocated for all cats ("core" vaccines) whereas others are used more selectively according to circumstances. However, in all cases the selection of the correct vaccination program for each individual cat, including the frequency of repeat, or booster, vaccinations, requires professional advice.

 

Currently cats can be vaccinated against several different diseases:

      

"Core" Vaccines, as recommended by the American Association of Feline Practitioners (AAFP) for all kittens and cats:
      

1. Feline panleukopenia, FPV or FPL (also called feline infectious enteritis) caused by FPL virus or feline parvovirus
2. Feline viral rhinotracheitis, FVR caused by FVR virus, also known as herpes virus type 1, FHV-1
3. Feline caliciviral disease caused by various strains of Feline caliciviruses, FCV
4. Rabies caused by Rabies virus

 

"Non-core" or discretionary vaccines, recommended for kittens and cats with realistic risk of exposure to specific diseases:

 

1. Feline chlamydial infection
2. Feline leukemia disease complex caused by Feline leukemia virus, FeLV
3. Feline Infectious Peritonitis (FIP) caused by FIP virus or Feline Coronavirus
4. Giardiasis caused by the protozoal parasite Giardia
5. Bordetellosis caused by the bacterium Bordetella bronchiseptica
6. Ringworm
7. Feline Immunodeficiency Virus (FIV)

 

How do vaccines work?

Vaccines work by stimulating the body's defense mechanisms or immune system to produce antibodies to a particular microorganism or microorganisms such as a virus, bacteria, or other infectious organism. The animal's immune system is then prepared to react to a future infection with that microorganism(s). The reaction will either prevent infection or lessen the severity of infection and promote rapid recovery. Thus, vaccination mimics or simulates the protection or immunity that a pet has once it has recovered from natural infection with a particular infectious agent.

 

The immune system is complex, involving interaction of various cells and tissues and organs in an animal. The main cells involved in an immune reaction are the white blood cells and the main tissues are the lymphoid tissues such as the lymph nodes.

 

One of the most important functions of the immune system is the production of specific protein molecules called antibodies. A specific microorganism, such as Feline Panleukopenia Virus, has components called antigens that induce the immune system to produce antibody that specifically binds and neutralizes that organism and no other.

 

Antibodies work together with other white blood cells such as lymphocytes that are able to identify and kill cells that have become infected by the microorganism. The activity of lymphocytes and other immune system cells is called cell-mediated immunity.

 

 After vaccination, just as after recovery from natural infection, the body 'remembers' the particular antigens so that when they are encountered again it can mount a rapid and strong immune response preventing the cat from developing the disease. The duration of this response varies with the disease, the type of vaccine and other variables. The likely duration will determine the recommended revaccination date.

 

It is important to realize that most vaccines work by preventing your cat from becoming ill during a subsequent exposure to specific disease-causing organisms, but vaccination may not prevent the cat from becoming infected. In such cases the cat, while itself protected against disease, may shed the organism for a period of time after exposure and be capable of infecting other susceptible animals. This is not a major consideration in the pet cat but may be important in the breeding colony.

 

What is the difference between the various types of vaccine?

Three major types of vaccine are produced for use in cats.

1. Modified live vaccines - these vaccines contain live organisms that are weakened (attenuated) or genetically modified so that they will not produce disease but will multiply in the cat's body. Live vaccines are generally considered to cause a stronger, longer lasting immunity than inactivated vaccines. It is not advisable to use modified live vaccines in pregnant queens or cats whose immune system is not working properly (cats infected by feline immunodeficiency virus (FIV), etc.).
2. Killed (inactivated) vaccines - these vaccines are prepared using fully virulent organisms or genetically modified organisms that have been killed by various treatments. Because, on their own, they do not give as high a level of protection as the live, replicating type of vaccine, killed vaccines may have an "adjuvant" added to enhance immune stimulation.
3. Subunit vaccines - These are most commonly what are called recombinant-DNA vaccines. These are vaccines in which the infectious organism has been broken apart and only certain parts are included in the vaccine. In some cases this is achieved by using genetic engineering techniques prior to the fragmentation.

 

Also vaccines come in various combinations, so that protection against more than one disease is achieved in a single injection or administration. Some vaccines are given by drops into the nose rather than by injection. Your veterinarian will advise you on the most appropriate vaccines for your cat.

 

When should my kitten be vaccinated?

Generally kittens are vaccinated for the first time at between six and eight weeks of age and a second dose is given at ten to twelve weeks. A kitten will not be fully protected until seven to ten days after the second vaccination. Under specific circumstances your veterinarian may advise an alternative regime.

 

How often should booster vaccinations be given?

Booster vaccination has generally been carried out yearly, but as vaccines and knowledge change, recommendations for frequency of boosters evolve. The appropriate interval for boosters will vary with individual circumstances. Your veterinarian will discuss this with you. All cats should be examined and appropriate vaccines administered regularly. Senior cats are particularly susceptible to these infections as they grow old and their immune system becomes less efficient.

Many adult cats that have been vaccinated as kittens will be vaccinated every one to three years based on lifestyle risk assessment. That is, if your cat is at higher risk for realistic exposure to a disease, the frequency of vaccination may be increased. It is important to thoroughly discuss your cat's lifestyle with your veterinarian and determine the appropriate vaccinations and vaccination schedule for your cat.

 

The AAFP vaccination guidelines recommend that low-risk adult cats be vaccinated every three years for the "core" vaccines and then as determined by your veterinarian for any "non-core" vaccinations. It is important to note that feline leukemia virus (FeLV) vaccine is recommended by some AAFP members to be a "core" vaccine while other experts classify it as a "non-core" vaccine. Your veterinarian is the ultimate authority on  how your cat is vaccinated

 

Will vaccination always protect my cat?

Vaccination will protect the vast majority of cats but under some circumstance vaccine breakdowns will occur. Reasons for such breakdowns or apparent "vaccine failure" include:

 

1. Variations between different strains of viruses - This is particularly a problem for example with FCV infections, where, like the 'common cold' in people, there are a large number of different strains. Available vaccines may only partially cross-protect against some of these strains.
2. Maternally derived antibodies - When a kitten is born and after it suckles its mother, it is acquires a proportion of antibodies from the mother. A well vaccinated queen cat will pass on some antibodies to the diseases she has been vaccinated against, and any others she has acquired naturally. Such antibodies protect the kitten against those diseases for the first two or three months of life, arguably the most critical period. However, during this same period, the maternally-derived antibodies can block the effects of vaccination of the kitten. This blocking effect decreases as the maternal antibodies gradually disappear over those two to three months. A point in time is reached when vaccination can be successfully given. Unfortunately, this point varies between kittens, mainly because the amount of maternal antibodies that each kitten receives is variable. This is part of the reason that vaccinations are usually given two to four weeks apart in the kitten vaccination program.
3. The cat was stressed or not completely healthy at the time of vaccination - Stress can prevent a good response to vaccination. For this reason it is better to let a kitten settle into its new home for five to seven days before a vaccination is given.  A physical examination is always given before vaccinating to help ensure the cat is healthy at that time.
4. The cat has been exposed to an excessive challenge dose of virus or bacteria in its environment and this has been sufficient to overwhelm the immunity.
5. The immune system of the cat is under-performing or incompetent because of some other disease, or complications associated with advanced age.

These are not the only reasons for vaccination failure but they are the most common.

 

If you feel your cat has contracted an infection for which it has been vaccinated then let your veterinarian know so tests can be undertaken to try and establish why vaccination has failed to be protective.

 

What are the risks of vaccination?

There are very few risks to vaccination. Your veterinarian will be able to advise you on specific details concerning your pet. You may notice your cat has a temporary loss of appetite or is less lively a day or two after a vaccination, but this should resolve within twenty-four to forty-eight hours. A very few cats may be allergic to one or more components of the vaccine and have more serious side effects such as difficulty in breathing, vomiting or diarrhea. If these signs occur, let your veterinarian know immediately. A rare form of soft tissue sarcoma has been associated with a reaction to vaccine or vaccine components in a very small number of cats. This association is controversial, and studies are in progress to investigate whether the association is real. The benefits of vaccination greatly outweigh these small risks in most situations.

 

Which are the most important vaccinations to have?

This is a difficult question and will depend on individual circumstances, including the area you live in and the lifestyle of your cat. As mentioned before, certain vaccines are more routinely given and are regarded as "core" vaccines. Others may or may not be advised depending on the particular situation of your cat. Your veterinarian will be able to advise you of the most appropriate vaccination schedule for your cat.

 

Feline panleukopenia infection - FPV or FPV

 

This is an uncommon disease today because of widespread vaccination, but the risk remains widespread. When disease occurs it is a severe and often fatal gastroenteritis, with profound depression, dehydration and collapse. It is very contagious to other cats. Vaccination provides a high level of long lasting protection.

 

Feline respiratory virus infection

 

Disease is caused by FVR virus (FHV-1) or the caliciviruses (FCV) - sometimes simultaneously. The syndrome is commonly termed Upper Respiratory Infection (URI) or sometimes, erroneously, ?Cat Flu?. While not usually very serious, except in young kittens, it is a very common infection in unvaccinated cats and can cause long-term problems. Vaccination is only moderately effective as solid immunity to these viruses is not long term, and may be overcome by a high dose of virus in the immediate environment. Vaccination does significantly reduce the severity and duration of URI.

 

Feline chlamydial infection

 

This tends to be a particular problem in colony cats or in certain geographical locations. Chlamydiosis is a bacterial infection causing a painful inflammation and swelling of the conjunctiva or the membrane around the eye as well as upper respiratory infections.  It has also been associated with infertility in queens. Infection in colonies of cats can last for long periods because protection against re-infection (immunity) is relatively short lived. Vaccination can help to prevent infection becoming established in a colony and can be used in conjunction with treatment where infection is already present.

 

Feline leukemia virus (FeLV) infection

 

This virus is widespread and infection of outdoor cats or cats in infected catteries is common. The vast majority of persistently infected cats will die either from tumors or as a consequence of the immunosuppression caused by the viral infection. Current vaccines provide a good level of protection and do not interfere with routine testing for the virus in breeding colonies. Because the virus tends to take many months before it causes disease, infected cats can appear completely normal and healthy. For this reason your veterinarian may suggest your cat have a blood test to make sure it is not infected before vaccination. Despite vaccination, a few cats will still become infected with the virus.

 

Feline Infectious Peritonitis (FIP)

 

FIP is caused by a coronavirus.  Infection with the causative or related viruses is common, but the disease is uncommon, although cases occur from time to time almost everywhere.  We do not understand why some infections lead to fatal disease whereas the majority of infections cause only minor illness. Vaccines are advised in some high-risk cases. Discuss usage with your veterinarian.

 

Rabies

 

This is such an important disease because of the almost 100% fatality rate of cases once symptoms occur, and because of its potential transmission to people by bites from infected animals. Rabies vaccination is an essential part of the vaccination program for all cats. Your veterinarian will discuss the frequency of booster vaccinations needed for your cat.

 

 

 

 

  This client information sheet is based on material written by Ernest Ward, DVM

© Copyright 2005 Lifelearn Inc. Used with permission under license. August 22, 2013

What is a vaccine?
The word vaccine comes from the discovery of an English country doctor, Dr. Edward Jenner. Dr. Jenner discovered that people given a preparation or vaccine of material from the common cattle disease, cowpox or vaccinia, developed only a mild skin infection, but when those vaccinated individuals were exposed to the deadly smallpox virus (a virus closely related to cowpox) they remained healthy. They were immune. More than one hundred years after Jenner?s findings, the great French scientist Louis Pasteur and his colleagues found that they could protect animals and people against a variety of diseases including rabies by administering injections of the infectious microorganism in an altered form. The two main alterations of these microorganisms were "inactivated vaccines" using killed virus or "attenuated vaccines" using still living virus but changed into a harmless form.

 

What is "immunity"?
Immunity is a complex series of defense mechanisms by which an animal is able to resist an infection or, minimally, resist disease and the harmful consequences of the infection. The main components of these defenses are the white blood cells, especially lymphocytes and their chemical products, antibodies and cytokines such as interferon. All infectious disease organisms (viruses, bacteria, protozoa, fungi, etc.) have specific components called antigens. These antigens cause lymphocytes to respond in a specific way such that each antigen stimulates the production of a mirror-image antibody as well as non-antibody responses called cellular immunity. Immunity has memory, so that a subsequent exposure to the same antigen results in a much more rapid response. This rapid "boost" of immunity usually stops the new infection before it can cause illness. The animal is then said to be "immune" against this infection. Such immune memory can fade with time, sometimes quite rapidly, depending on the specific antigen-antibody relationship.

Immunity is not absolute. Immunity can sometimes be overcome when there is an overwhelming exposure to a high dose of a virulent or particularly harmful strain of the microorganism or when the animal is unduly stressed or its immune system is otherwise depressed known as immunosuppression by other infections or certain drugs.

 

What is a modified-live vaccine?
In a modified-live or live-attenuated vaccine the causative organism (virus, bacterium, etc.) has been altered so that it is no longer harmful or virulent but upon injection or other administration it will stimulate protective immunity.

 

What is a killed vaccine?
The organism has been killed or inactivated to render it harmless. Killed vaccines often need a helper or adjuvant included in the vaccine to stimulate a longer-lasting immune response.

 

Which is better: a live or killed vaccine?
Both have advantages and disadvantages. Your veterinarian takes many circumstances into account in making the choice.

 

Why are vaccines administered by injection?
Some vaccines are given locally, for example into the nose, but most require injection so that the maximum take-up of vaccine by the white cells and stimulation of the immune system is achieved. Some vaccines are injected subcutaneously or just under the skin, others are injected into the muscles or intramuscularly. Injections look easy but there are a number of precautions a veterinarian is taking.

 

Which vaccines are needed in dogs?
Depending on your locality some infections may be more or less likely. Your veterinarian will assess the relative risks based on your circumstances and advise you accordingly. The range of vaccines available includes: rabies, distemper, adenovirus/ infectious canine hepatitis, parvovirus, leptospirosis, parainfluenza, coronavirus, Lyme disease, and Bordetella bronchiseptica (see Kennel Cough). For details on these diseases see the specific topic. These vaccines are often available in combinations given in one dose. These combination vaccines are convenient and avoid extra injections for your dog, but sometimes separation of vaccines is advisable. Your veterinarian will advise you on the appropriate vaccines for your pet based on your dog's specific lifestyle requirements.

 

"Core" Vaccines - Recommended for all puppies and dogs by the American Animal Hospital Association (AAHA) Canine Vaccine Task Force

1. Canine distemper virus
2. Canine parvovirus
3. Canine adenovirus-2
4. Rabies virus

 

"Non-Core" Vaccines - Recommended for puppies and dogs in special circumstances, dependent on the exposure risk of an individual dog by the American Animal Hospital Association (AAHA) Canine Vaccine Task Force

1. Distemper-measles virus
2. Leptospira spp.
3. Borrelia burgdorferi or Lyme disease
4. Canine parainfluenza virus
5. Bordetella bronchiseptica or "Kennel Cough

 

What is maternal immunity?
Newborn animals have not yet had a chance to make their own immunity so they need protection against infections present in their environment. They receive this immunity from their mother, partly across the placenta while in the uterus with most of the maternal antibody transferred to them in the first milk or colostrum. Maternal immunity is only temporary. It declines steadily over the first few weeks of life and is largely gone by twelve weeks. The rate of decline is variable depending on many factors.

 

Why is more than one dose of vaccine given to pups?
There are two reasons. First, without complicated testing it is impossible to know when a pup has lost the immunity it gets from its mother called maternal immunity. An early decline in a puppy's maternal antibody can leave it susceptible to infection at a very young age but a strong maternal immunity can actually interfere with early vaccination (see Vaccination Failure). Second, particularly with killed vaccines, the first dose is a "priming" dose, and the second dose is needed to boost the response to a higher, longer-lasting level of immunity.

 

Why does my dog need to be revaccinated?
In most properly vaccinated dogs, the immunity should last more than a year, and often several years. However, immunity does decline with time and this decline rate varies with individuals. To maintain the best immunity in a reasonable way, revaccinations have proven very successful. Because improvements are continuously made in the vaccines we use, some do not need to be given so often, depending on individual circumstances of the pet. Most dogs with low-risk lifestyles will be vaccinated every three years with the "core" vaccines and then as needed for any "non-core" vaccines. Your veterinarian will discuss the need and frequency of booster vaccinations for your dog based on your pet's needs and lifestyle.

 

How long does it take for a vaccine to produce immunity?
Within a few hours of vaccination the earliest phases of the immune response are being stimulated. It usually requires ten to fourteen days before a reasonable level of protection is established. Killed vaccines may not provide adequate protection until after the second dose. Also in young puppies maternal antibody may hinder protection until later in the vaccine series. Therefore it is advisable to keep a recently vaccinated pup away from dogs or pups of unknown vaccination history until it has finished its vaccination course.

 

What happens if my dog is sick when vaccinated?
The veterinary check-up prior to vaccination and sometimes blood tests pre-vaccination help prevent this situation. In most cases it would not have disastrous consequences, but it is important that an animal is healthy when vaccinated, to ensure proper development of immunity.

 

Will vaccination make my dog sick?
It is not unusual to detect some lethargy in the day or so after vaccination. In the case of killed vaccines containing an adjuvant, some thickening or lump formation may occur at the vaccination site. If this is painful or persists for more than a week or so with no decrease in size, consult your veterinarian. A few dogs will develop more severe reactions that are forms of hypersensitivity (allergy). These will usually occur within minutes but may be delayed for a few hours. The dog may have difficulty breathing, salivate, vomit, and have diarrhea. In these situations consult your veterinarian immediately.

 

Do vaccines provide 100% protection?
Vaccines have been highly successful in protecting the majority of dogs against diseases such as distemper that were once common but now rare, but there are situations in which the immunity conferred by a vaccine may be overcome and a vaccinated dog may still develop disease. In such cases the disease is generally milder than it would have been had the dog not been vaccinated. Some causes for apparent "vaccine failure" are:

1. Maternally derived antibodies - As mentioned above, when a puppy is born and after it suckles its mother, it acquires a proportion of any antibodies that the mother has. So a well-vaccinated female will confer antibodies to the diseases she has been vaccinated against and any others she has acquired naturally to her puppies. Such antibodies protect the pup against those diseases for the first two or three months of its life, the most critical period of its life. However during this same period the maternally derived antibodies can block the effects of vaccination of the pup. This blocking effect decreases as the maternal antibody gradually disappears over those two to three months. A point in time is reached when vaccination can be successfully given. Unfortunately this point varies between pups, mainly because the amount of maternal antibodies that each pup receives is variable. This is part of the reason that two vaccinations are usually given, two to four weeks apart, in the puppy vaccination program. Maternal antibody interference has been a particular problem with canine parvovirus vaccination.
2. Incomplete immune response - There is variation between dogs in their immune system. Some respond less well to vaccination, so immunity may be incomplete or shorter-lived than normal. Certain breeds and genetic lines have a tendency for such problems.
3. Declining immunity - Without booster vaccinations, or without natural boosting of immunity by sporadic exposure to the infectious agent in nature, immunity to the specific organism declines over time, particularly in older age. There may come a time when if there is a particularly heavy dose of the organism from the environment the declining immunity may be insufficient and overwhelmed, disease resulting.
4. Immune suppression - Certain infections and some drugs, such as anti-cancer drugs, may cause a suppression of the immune system so that an otherwise well-vaccinated dog becomes susceptible to infection and disease if exposed.
5. New strains of organism - Some infectious agents exist in different strains or new strains evolve, that are not directly covered by the vaccines given. There may be some "cross-protection" but it may not be complete.

The above are not the only reasons for vaccination failure but they are the most likely explanations.

If you feel your dog has contracted an infection for which it has been vaccinated then let your veterinarian know so tests can be undertaken to try and establish why vaccination has failed to be protective.
 

What causes heartworm disease?

Heartworm disease or dirofilariasis is a serious and potentially fatal disease in dogs. It is caused by a blood-borne parasite called Dirofilaria immitis.

Heartworms are found in the heart and adjacent large blood vessels of infected dogs. The female worm is 6 to 14 inches long (15 to 36 cm) and 1/8 inch wide (5 mm). The male is about half the size of the female. One dog may have as many as 300 worms.

 

How do heartworms get into the heart?

Adult heartworms live in the heart and pulmonary arteries of infected dogs. They have been found in other areas of the body, but this is unusual. They live up to five years and, during this time, the female produces millions of offspring called microfilaria. These microfilariae live mainly in the small vessels of the bloodstream. The immature heartworms cannot complete their life cycle in the dog. The mosquito is required for some stages of the heartworm life cycle. The microfilaria are not infective (cannot grow to adulthood) in the dog - although they do cause problems.

 

As many as 30 species of mosquitoes can transmit heartworms. The female mosquito bites the infected dog and ingests the microfilariae during a blood meal. The microfilariae develop further for 10 to 30 days in the mosquito and then enter the mouthparts of the mosquito. The microfilariae are now called infective larvae because at this stage of development, they will grow to adulthood when they enter a dog. The mosquito usually bites the dog where the hair coat is thinnest. However, having long hair does not prevent a dog from getting heartworms.

 

When fully developed, the infective larvae enter the bloodstream and move to the heart and adjacent vessels where they grow to maturity in two to three months and start reproducing, thereby completing the full life cycle.

 

Where are heartworms found?

Canine heartworm disease occurs all over the world. In the United States, it was once limited to the south and southeast regions. However, the disease is spreading and is now found in most regions of the United States and Canada, particularly where mosquitoes are prevalent.

 

How do dogs get infected with them?

The disease is not spread directly from dog to dog. An intermediate host, the mosquito, is required for transmission. Spread of the disease therefore coincides with mosquito season. The number of dogs infected and the length of the mosquito season are directly correlated with the incidence of heartworm disease in any given area.

 

It takes a number of years before dogs show outward signs of infection. Consequently, the disease is diagnosed mostly in four to eight year old dogs. The disease is seldom diagnosed in a dog less than one year of age because the young worms (larvae) take up five to seven months to mature after infection.

 

What do heartworms do to the dog?

Adult heartworms: Adult heartworms cause disease by clogging the heart and major blood vessels leading from the heart. They interfere with the valve action in the heart. By clogging the main blood vessels, the blood supply to other organs of the body is reduced, particularly blood flow to the lungs, liver and kidneys, leading to malfunction of these organs.

 

Most dogs infected with heartworms do not show any signs of disease for as long as two years. Unfortunately, by the time clinical signs are seen, the disease is well advanced. The signs of heartworm disease depend on the number of adult worms present, the location of the worms, the length of time the worms have been present, and the degree of damage to the heart, lungs, liver, and kidneys from the adult worms and the microfilariae.

 

The most obvious signs are a soft, dry cough, shortness of breath, weakness, nervousness, listlessness, and loss of stamina. All of these signs are most noticeable following exercise, when some dogs may even faint.

 

Listening to the chest with a stethoscope will often reveal abnormal lung and heart sounds. In advanced cases, congestive heart failure may be apparent and the abdomen and legs will swell from fluid accumulation. There may also be evidence of weight loss, poor condition, and anemia.

 

Severely infected dogs may die suddenly during exercise or excitement.

 

Microfilariae (Young heartworms): Microfilariae circulate throughout the body but remain primarily in the small blood vessels. Because they are as wide as the small vessels, they may block blood flow in these vessels. The body cells being supplied by these vessels are deprived of the nutrients and oxygen normally supplied by the blood. The lungs and liver are primarily affected.

 

Destruction of lung tissue leads to coughing. Cirrhosis of the liver causes jaundice, anemia, and general weakness because this organ is essential in maintaining a healthy animal. The kidneys may also be affected and allow poisons to accumulate in the body.

 

How is heartworm infection diagnosed?

In most cases, diagnosis of heartworm disease can be made by a blood test that can be run in the veterinary hospital or by a veterinary laboratory. Further diagnostic procedures are essential to determine if the dog can tolerate heartworm treatment. Depending on the case, we will recommend some or all of the following procedures before treatment is started.

 

Serological test for antigens to adult heartworms: This is a test performed on a blood sample. It is the most widely used test because it detects antigens (proteins) produced by adult heartworms. It will be positive even if the dog does not have any microfilaria in the blood. This occurs in about 20% of the cases. Dogs with less than five adult heartworms will not have enough antigen to give a positive test result, so there may be an occasional false negative result in dogs with early infections. Because the detected antigen is only produced by the female heartworm, a population of only male heartworms will also give a false negative. Therefore, there must be at least five female worms present for the most common heartworm test to diagnose heartworm disease.

Blood test for microfilariae: A blood sample is examined under the microscope for the presence of microfilariae. If microfilariae are seen, the test is positive. The number of microfilariae seen gives us a general indication of the severity of the infection. However, the microfilariae are seen in greater numbers in the summer months and in the evening, so these variations must be considered. Approximately 20% of dogs do not test positive even though they have heartworms because of an acquired immunity to this stage of the heartworm. Because of this, the antigen test is the preferred test. Also, there is another blood parasite that is fairly common in dogs that can be hard to distinguish from heartworm microfilariae.

 

Blood chemistries: Complete blood counts and blood tests for kidney and liver function may give an indication of the presence of heartworm disease. These tests are also performed on dogs diagnosed as heartworm-infected to determine the function of the dog's organs prior to treatment.

 

Radiographs (X-rays): A radiograph of a dog with heartworms will usually show heart enlargement and swelling of the large artery leading to the lungs from the heart. These signs are considered presumptive evidence of heartworm disease. Radiographs may also reveal the condition of the heart, lungs, and vessels. This information allows us to predict an increased possibility of complications related to treatment.

 

Electrocardiogram:  An electrocardiogram (EKG or ECG) is a tracing of the electric currents generated by the heart. It is most useful to determine the presence of abnormal heart rhythms.

 

Echocardiography: An ultrasonic examination that allows us to see into the heart chambers and even visualize the heartworms.

 

How are dogs treated for heartworms?

There is some risk involved in treating dogs with heartworms, although fatalities are rare. In the past, the drug used to treat heartworms contained arsenic so toxic effects and reactions occurred more frequently. A newer drug is now available that does not have the toxic side-effects, allowing successful treatment of more than 95% of dogs with heartworms.

 

Some dogs are diagnosed with advanced heartworm disease. This means that the heartworms have been present long enough to cause substantial damage to the heart, lungs, blood vessels, kidneys, and liver. A few of these cases will be so advanced that it will be safer to treat the organ damage rather than risk treatment to kill the heartworms. Dogs in this condition are not likely to live more than a few weeks or months.

 

Treatment to kill adult heartworms: An injectable drug to kill adult heartworms is given. It kills the adult heartworms in the heart and adjacent vessels. These injections may be divided and given thirty days apart.

 

Complete rest is essential after treatment: The adult worms die in a few days and start to decompose. As they break up, they are carried to the lungs, where they lodge in the small blood vessels and are eventually reabsorbed by the body. This can be a dangerous period so it is absolutely essential that the dog be kept quiet and not be allowed to exercise for one month following treatment. The first week after the injections is critical because the worms are dying. A cough is noticeable for seven to eight weeks after treatment in many heavily infected dogs.

 

Prompt treatment is essential if the dog has a significant reaction in the weeks following the initial treatment, although such reactions are rare. If a dog shows loss of appetite, shortness of breath, severe coughing, coughing up blood, fever, and/or depression, you should notify us. Response to antibiotics, cage rest, and supportive care and intravenous fluids is usually good in these cases.

Treatment to kill microfilaria: Approximately one month following treatment to kill the adults, the dog is returned to the hospital for administration of a drug to kill the baby heartworms or microfilariae. Your dog needs to stay in the hospital for the day. Your dog is started on heartworm preventive after this treatment.

 

Other treatments: In dogs with severe heartworm disease, it may be necessary to treat them with antibiotics, special diets, diuretics to remove fluid accumulations, and drugs to improve heart function prior to treatment for the heartworms.

 

Dogs with severe heart disease may need lifetime treatment for the heart failure, even after the heartworms have been killed. This includes the use of diuretics, heart drugs, and special low salt, low protein diets.

 

Response to treatment: Dog owners are usually pleasantly surprised at the change in their dog following treatment for heartworms, especially if the dog had been showing signs of heartworm disease. The dog has a renewed vigor and vitality, improved appetite, and weight gain.

 

Are changes made in the treatment protocol for dogs that have severe heartworm disease?

Yes. The state of heart failure is treated as described above. However, we also treat the adult heartworms in a two-stage process. Only one treatment with the drug to kill the worms is given initially. This causes the death of approximately half of the worms. One month later, the full treatment is given to kill the remaining worms. By killing them in two stages, the severe effects on the lungs are much less likely to occur. This protocol is also used in moderate cases to provide a safer treatment.

 

How can I prevent this from happening again?

When a dog has been successfully treated for heartworms, it is essential to begin a heartworm prevention program to prevent future recurrence. With the safe and affordable heart preventives available today, no pet should ever have to endure this dreaded disease.

 

 

  This client information sheet is based on material written by Ernest Ward, DVM.

© Copyright 2005 Lifelearn Inc. Used with permission under license. August 22, 2013

Double-click to add copy here.

Hover over the other text and images to view your editing options.