What are the symptoms of feline upper respiratory disease complex?  The symptoms of feline upper respiratory disease vary as to which virus, bacteria, etc., is the cause, the age of the animal, and other health factors. A summary of the symptoms as well as other characteristics of rhinotracheitis and calcivirus infections are summarized in the table below.

How is feline upper respiratory disease complex diagnosed?  The diagnosis of feline upper respiratory disease complex is made based on medical history (e.g., vaccination status and possibility of exposure to an infected cat), clinical signs, and rarely through special laboratory tests to determine the exact cause of disease, e.g., isolating the virus. If a cat has recurrent episodes of disease, has signs of disease even though it was vaccinated, or the symptoms last longer than two weeks, the cat should be tested for feline leukemia virus (FeLV) and feline immunodeficiency).

How is feline upper respiratory disease complex treated? The treatment of cats with feline upper respiratory disease complex is basically the same, regardless of cause and includes:

Cats with upper respiratory disease are generally not hospitalized unless their symptoms are severe due to the contagious nature of the disease. In severe cases, fluid therapy, supplemental oxygen, or a tube placed in the stomach for feeding cats who will not eat may be necessary.

What is the prognosis for cats with feline upper respiratory disease complex?  Most cats infected with feline rhinotracheitis virus or calicivirus will become chronic carriers of the virus. This means they will continue to be infected with the virus but not show any signs of the disease. In the case of rhinotracheitis (herpes-1), cats will often shed the virus in secretions from the eyes and nose after they have been stressed, e.g., boarding, moving, new addition to the household, nursing kittens, etc. Cats with calicivirus will shed the virus continually for years. Cats who have been vaccinated for calicivirus and then exposed to an infected cat may become infected with the 'wild' virus (the strain of virus that occurs naturally and can cause disease, not the vaccine strain), never show signs of disease, become carriers of the wild virus, and continue to shed the wild virus.

How is feline upper respiratory disease complex prevented and controlled?  Vaccination is the primary way to prevent feline upper respiratory disease complex. There are several different types of vaccines available: a modified live injectable vaccine, a modified live vaccine that is administered into the nose, and an injectable killed vaccine. The modified live injectable vaccine is often a combination product which includes rhinotracheitis, calicivirus, and panleukopenia, another viral disease of cats. Combination vaccines may also include feline leukemia virus and Chlamydophila. Modified live injectable vaccines should be administered very carefully, so none of the vaccine gets into the eyes, nose, or mouth of the cat, otherwise the vaccine could induce clinical signs of disease. The modified live intranasal vaccine is manufactured differently so it is safe to give in the nose, although, mild sneezing or nasal discharge could occur. The advantages of this vaccine are that it provides better and more rapid protection (within 2-4 days of giving the vaccine), can be given to very young kittens, and is effective even if maternal antibodies are present. It is recommended that this vaccine be used in limited situations in which there is a high but unavoidable risk of exposure. The killed injectable vaccine often comes as a combination product. Some killed vaccines are licensed to be used in pregnant cats so the newborn kittens will be born with more protection. These vaccines are also used in debilitated or immunodeficient cats. Some are licensed for use in very young kittens. Regardless of which vaccine is used, kittens need a series of vaccinations to become protected. Vaccination schedules should take into account the potential of exposure of the kittens to cats who have disease or may be carriers of the viruses. Remember, vaccination is not 100% effective. Vaccinated cats can still become infected with the wild strain of virus, show mild signs of disease and become carriers of the virus. Because vaccination is not 100% effective, and rhinotracheitis virus and calicivirus are wide spread, other control measures are often necessary in areas where cats are in close proximity, e.g., boarding facilities and catteries. Suggested control and prevention measures include:

• Provide regular vaccinations

• Admit only cats who are vaccinated

• House cats individually

• Separate known carriers or cats showing signs of disease from the other cats, and feed and clean their cages last.

• Use pens, cages, litter boxes, and bowls that can be easily disinfected

• Soak used items, e.g., bowls, in a 1:32 solution of bleach for several hours and then do not reuse for at least 24 hours

• Have solid partitions between pens and provide an aisle between the fronts of the cages at least 4 feet wide

• Design pens so dishes and litter can be removed from the pen without opening the door.

• Wash and disinfect hands between handling cats, or use individual pairs of rubber gloves for each cat

• If a cat is permanently removed from a pen or cage, disinfect the cage and allow it to remain empty 2 days before reusing it

• Provide adequate ventilation and control humidity and temperature

• Prepare food in a separate area away from the cats

• Vaccinate female cats before breeding or during pregnancy (killed or inactivated vaccine only)

• Attempt to keep animals as stress-free as possible

• Do not breed female cats who had previous litters of kittens with respiratory disease

• Separate pregnant cats from other cats starting at least three weeks before giving birth

• Keep kittens separate from other cats until a week after their second vaccination (usually at 12 weeks)

Feline leukemia is a cancerous disease caused by feline leukemia virus (FeLV). FeLV causes diseases other than leukemia including immunodeficiency and additional cancers. Cats may not start to show signs of disease for months or years after being infected with FeLV. Infection with FeLV is a major cause of illness and death in domestic cats.

What are the characteristics of feline leukemia virus?

FeLV is a type of virus called a retrovirus. That puts it in the same family as feline immunodeficiency virus (FIV) and human immunodeficiency virus (HIV, the virus that causes AIDS).

Retroviruses are species-specific. This means a feline retrovirus will only infect cats; a human retrovirus will only infect humans.

Retroviruses are made up of RNA. In the host, the RNA is transcribed into DNA and incorporated into the DNA of the host's cells.

Retroviruses are fragile, being easily inactivated by ultraviolet light, heat, detergents, and drying.

Retroviruses are widespread in nature. As a matter of fact, they have been around for so many millions of years, parts of a feline retrovirus are actually incorporated into every cat's DNA. This is called "endogenous" FeLV DNA. This is passed from generation to generation.

There are three subgroups of FeLV and each tends to cause a different type of disease:

1. FeLV-A is found in all naturally infected cats and is easily transmitted. For this reason, this is the FeLV we use for making vaccines against FeLV.

2. FeLV-B is found in about ½ of naturally infected cats. It is formed when FeLV-A combines with the endogenous FeLV DNA.

3. FeLV-C is rare. FeLV-C results from mutations of FeLV-A.

How common is FeLV infection?

It is estimated that 2-3% of healthy cats are infected with FeLV. Approximately ¼ to ½ of the healthy cats living in infected multi-cat households and catteries are infected.

How is the FeLV transmitted?

Large amounts of FeLV are excreted in the saliva. Therefore, the most common mode of transmission is through nose-to-nose contact, mutual grooming, and shared food and water bowls. Bites are a very efficient way to transmit FeLV.

FeLV can also be found in lesser amounts in tears, urine, and feces. Thus litter boxes could be a source of infection in multi-cat households or catteries.

FeLV can also be transmitted across the placenta (in utero) and through the milk.

It takes large amounts of virus to infect an adult cat, so usually prolonged contact is necessary for transmission.

What happens to a cat after being exposed to FeLV?

If the cat becomes infected from the exposure, 2-4 weeks later, in the acute stage of infection, large numbers of the virus can be found in the bloodstream (viremia). Cats in the acute phase usually do not show signs of disease. If they do, the signs are usually mild fever, slight lethargy, and swollen lymph nodes (lymphadenopathy). When an adult cat is exposed to FeLV, four things can happen:

1. Approximately 30% of adult cats will not be infected due to inadequate exposure.

2. 30-35% of adult cats have a transient infection; over the course of 6 months or so, the cats will eventually kill all of the virus.

3. 5-10% of adult cats will develop latent infections; these cats will not be able to kill all the virus, but will be able to hold it in check. This is called a latent infection. These cats usually show no signs of infection and usually do not shed virus in their saliva or other body secretions. Queens, however, may still pass the virus in utero or through the milk.

4. 30% of adult cats will become persistently infected; these cats will not develop an adequate immune response and will remain permanently infected with FeLV. These are the cats who will become ill and die of FeLV-related diseases, usually within 2-3 years of infection. These cats will shed large amounts of virus in their saliva.

Age is a very important factor in determining what will happen after a cat is exposed to FeLV. Almost all FeLV-exposed kittens less than 8 weeks of age will have persistent viremia and show signs of disease during the acute phase. As kittens get older, there is the probability of becoming persistently infected after exposure lessens, until it reaches approximately 30% in adulthood.

The prevalence of FeLV infection is highest in cats between 1 and 6 years of age, with a mean age of 3 years. Males are 1-½ times more likely to be infected than females. This may be due to the frequency in which intact males roam and fight.

Rabies is one of the best known of all the viruses. Fortunately, through active vaccination and eradication programs, rabies only accounted for 4 human deaths in the United States in 1997, one in 1998, and none in 1999. In other parts of the world, however, human cases and deaths from rabies are much higher. In fact, some estimates claim that human death rates may be over 10,000 a year in southern Asia.

If you want to completely avoid coming into contact with a rabid animal you should move to Australia, the British Isles, or Antarctica where there is no rabies virus. When traveling around the world, you will encounter certain animals that are much more likely to be carriers of the disease. After leaving the safety of the British Isles and heading eastward into Europe, the fox is the primary carrier. If you dip south into Africa, you will encounter it in jackals in the north, cats and dogs in the central countries, and mongooses in the southern part of the continent. Heading into the Himalayans, you can see it in wolves and in Russia it is seen in dogs. The arctic fox is the main carrier in all parts of the Arctic. If you venture into Indonesia and Malaysia, the cat and dog are again common carriers. When you come back to South America, the cat and dog are again common sources of exposure as well as vampire bats. In Mexico, insectivorous bats cause the most problems. In the United States, the mountain states have the lowest incidence of humans contacting animals with rabies. When you hit the Plains, the Midwest, and Texas the striped skunk is the big carrier. As you work your way to the east, raccoons become important carriers. Fox and bats also cause some human exposures, but very rarely, especially the bat who gets blamed more than it should. If the squirrel or rabbit in the back yard bites you, do not panic, there has never been a reported case of someone contracting rabies from one of these species.

Who is at risk?

People that work closely with wildlife, veterinarians, and travelers are at the highest risk of exposure. Fortunately, there is a vaccine that is available to protect high-risk people. Animals that come into contact with wildlife and are not vaccinated are at a higher risk of infection. While the risk of coming into contact with the virus is very low, it nevertheless does exist. When I started my first job in rural Wisconsin, a veterinarian I worked with told me that in over twenty-five years of practice he had never seen a case of rabies. Two years later, I was exposed to two dogs and a cow in one three-week period that all had, and died from, rabies. Because of the movement of carriers, there is always the risk of exposure. In my three cases, there was known contact with raccoons by both dogs and a skunk by the cow.

Transmission of the disease

The transmission of the disease almost always occurs as a result of an infected animal biting a non-infected animal. There have been a few reported cases of infection resulting from aerosolization occurring in caves where large quantities of infected bats reside. Rabies virus does not live very long outside the host and remains viable in the carcass of an infected animal for less than 24 hours. The rabies virus is shed at high levels in saliva. However, being bitten by a rabid animal does not necessarily mean that the bitten animal (or human) will become infected. It has been speculated, that only around 15% of exposed people will contract the disease. Humans, cats, and dogs are only mildly susceptible to the disease unlike skunks, raccoons, foxes, and bats that are much more susceptible to the virus.

Symptoms

After coming in contact with the virus, the bitten animal may go through one or all of several stages. If the bitten animal is a skunk it may not show any symptoms at all but could become a lifelong carrier. With most animals, however, the virus will spread through the nerves of the bitten animal towards the brain. The virus is relatively slow moving and the average time of incubation from exposure to brain involvement is between 3 to 8 weeks in dogs, 2 to 6 weeks in cats, and 3 to 6 weeks in people. However, incubation periods as long as 6 months in dogs and 12 months in people have been reported. After the virus reaches the brain it then will move to the salivary glands where it can be spread through a bite. After the virus reaches the brain the animal will show one, two, or all of the three different phases.

Prodromal phase

The first is the prodromal phase and usually lasts for 2-3 days in dogs. Apprehension, nervousness, anxiety, solitude, and a fever may be noted. Friendly animals may become shy or irritable and may snap, whereas, aggressive animals may become affectionate and docile. Most animals will constantly lick the site of the bite. In cats, the prodromal phase lasts for only 1-2 days and they usually develop more fever spikes and erratic behavior than dogs.

Furious phase

From the prodromal phase, animals may enter the furious stage; cats are particularly prone to developing this phase. The furious stage of the disease in dogs usually lasts for 1 to 7 days. Animals become restless and irritable and are hyperresponsive to auditory and visual stimuli. As they become more restless, they begin to roam and become more irritable and vicious. When caged, dogs may bite and attack their enclosures. Animals progress to become disoriented and then have seizures and eventually die.

Paralytic (dumb) phase

Animals may develop the paralytic phase either after the prodromal or furious stage. The paralytic phase usually develops within 2 to 4 days after the first signs are noted. Nerves affecting the head and throat are the first to be involved and animals may begin to salivate as a result of their inability to swallow. Deep labored breathing and a dropped jaw may result as the diaphragm and face muscles become increasingly paralyzed. Animals may make a choking sound and many owners think that there is something lodged in the dog’s throat. This was the case with both dogs I was exposed to (as mentioned earlier) and the owners were also exposed as they had been looking in the dog’s mouth for a foreign object. The animal will get weaker and eventually go into respiratory failure and die.

As a side note, many of the dogs with rabies that I encountered while in Central America also presented with the dumb form. The one cow that I saw bellowed incessantly and staggered aimlessly. Many animals present with a combination of the above symptoms and phases.

Diagnosis

The current way to diagnose rabies in animals is to submit the brain for microscopic examination. Some new testing techniques utilizing skin and or blood samples are being studied and used in a few research settings and show promise as a way of testing potentially exposed humans and animals. They are not routinely being used at this time.

Treatment

There is no treatment. Once the disease develops in humans, death is certain. There have been several reported cases of dogs surviving the infection, but they are very rare.

Vaccination and prevention

Vaccination is the best way to prevent infection and properly vaccinated animals stand very little chance of contracting the disease. While rabies vaccination for dogs is mandatory for all states, it is estimated that up to half of all dogs are not vaccinated. Some communities are also requiring cats to be vaccinated, which is very important because there are currently more cases of cat rabies than dog rabies. Some people estimate that less than ten percent of the cat population is vaccinated thus leading to the high incidence of rabies in cats. The standard vaccination protocol is to vaccinate cats and dogs at three or four months and then again at one year of age. A year later, a three-year rabies vaccination is recommended. The three-year shot has been tested and shown to be very effective. A few counties, states, or individual veterinarians require yearly or once every two-year vaccination for a variety of reasons that need to be explored more closely.

There is a three-shot series of Human Diploid Cell vaccine that can be used to vaccinate people at high risk. There are some vaccines available for large animals also. The question of vaccinating exotic animals is a common one. There are no approved products for most exotics, however, canine vaccine is used on some species to offer some protection. Vaccinating exotics or wolf hybrids should be dealt with individually in cooperation with your local veterinarian. Keeping a wild animal that is at high risk of being a carrier such as a skunk or raccoon is never recommended.

Human exposure

If an animal bites a human, the animal will be either quarantined or observed for a period of at least ten days to ensure that it does not have rabies. Whether or not the animal was currently vaccinated the community that you live in will dictate the requirements of the quarantine. People that do become exposed to a rabid animal can be given a five-shot post exposure series of Human Rabies Immune Globulin to protect them against being infected.