The number and variety of diseases your pet can “catch” is so enormous, they can not possibly all be explained or even enumerated here.  Highlighted will be the most known and the most commonly seen at Fountain City Animal Hospital.


Infectious Diseases In Dogs

Happily, the most common and most serious infectious diseases in dogs are virtually 100% preventable by carefully considered vaccination programs.  At Fountain City Animal Hospital, we recognize that not all dogs require the same number and type of immunizations, but we do strongly believe in the responsible and common-sense use of vaccination throughout your dog’s life.  We have seen far too often the heartbreaking results of ignoring this important part of your pet’s preventive health care.

Canine Distemper Virus is probably the most well-known of infectious diseases in the dog.  What is probably not known by many is that this virus can be found not only in our pet dogs, but in wildlife such as foxes, wolves, coyotes, raccoons, skunks, mink and ferrets and has been reported in lions, tigers, leopards and other wild cats as well as seals.  We haven’t seen this disease in Knox County in some time, but in 2014, there were three outbreaks in Cumberland County, and the Oak Ridge shelter was forced to euthanize 80 dogs after outbreaks there.  In rural areas dogs can catch the virus from wild animals like raccoons and skunks, and since the virus can live free in the environment for several days, our pet dogs don't even need direct contact with the infected wildlife for transmission to take place.

We see the disease most commonly in puppies younger than four months old and in dogs that have not been vaccinated.  They can become infected through airborne exposure to the virus from an infected animal who has coughed or sneezed, or the virus can be transmitted by shared food and water bowls and equipment. Infected dogs can shed the virus for months, and mother dogs can pass the virus through the placenta to their puppies.

Initially, infected dogs will develop watery to pus-like discharge from their eyes. They then develop fever, nasal discharge, coughing, lethargy, reduced appetite, and vomiting. As the virus attacks the nervous system, infected dogs develop circling behavior, head tilt, muscle twitches, convulsions with jaw chewing movements and salivation (“chewing gum fits”), seizures, and partial or complete paralysis. The virus may also cause the footpads to thicken and harden, leading to its nickname “hard pad disease.” 

There is no cure for canine distemper infection.  Treatment typically consists of supportive care and efforts to prevent secondary infections; control vomiting, diarrhea and neurologic symptoms; and combat dehydration through administration of fluids.  Despite heroic efforts, distemper is often fatal, and dogs that survive frequently have permanent, irreparable nervous system damage.

This is definitely a disease we never want to see again, and this is why we so strongly urge our clients to adhere to an appropriate and timely immunization schedule with their puppies, and beyond.

Canine Parvovirus is the most common and most deadly of the infectious diseases we see in dogs.  It is a highly contagious virus that can affect all dogs, but unvaccinated dogs and puppies younger than four months old are the most at risk. Dogs that are ill from canine parvovirus infection are often said to have "parvo." The virus affects dogs' gastrointestinal tracts and is spread by direct dog-to-dog contact and contact with contaminated feces (stool), environments, or people. The virus can also contaminate kennel surfaces, food and water bowls, collars and leashes, and the hands and clothing of people who handle infected dogs. It is resistant to heat, cold, humidity, and drying, and can survive in the environment for long periods of time. Even trace amounts of feces from an infected dog may harbor the virus and infect other dogs that come into the infected environment. The virus is readily transmitted from place to place on the hair or feet of dogs or via contaminated cages, shoes, or other objects.

Typical symptoms of parvovirus include an acute onset of lethargy and loss of appetite, abdominal pain and bloating, fever or low body temperature (hypothermia), profuse vomiting, and severe (often bloody) diarrhea. Persistent vomiting and diarrhea can cause rapid dehydration, and damage to the intestines and immune system can cause septic shock.  Most deaths from parvovirus occur within 48 to 72 hours following the onset of clinical signs so immediate medical intervention is of the utmost importance.

No specific drug is available that will kill the virus in infected dogs, and treatment is intended to support the dog’s body systems until the dog’s immune system can fight off the viral infection. Treatment should be started immediately and consists primarily of intensive care efforts to combat dehydration by replacing electrolyte, protein and fluid losses, controlling vomiting and diarrhea, and preventing secondary infections. Sick dogs must be kept warm and receive excellent nursing care. When a dog develops parvo,  it is possible that he may die despite appropriate intensive care treatment, but with early recognition and aggressive treatment survival rates can approach 90%. 

This disease is still prevalent in our community, and we diagnose and treat these cases far too often despite it’s being virtually 100% preventable.  This is yet another reason why we so strongly urge our clients to adhere to an appropriate and timely immunization schedule with their puppies, and beyond.

Leptospirosis is a disease caused by infection with a bacteria which exists worldwide in soil and water, and its occurrence in Knox County has increased significantly since the early 2000s. Leptospirosis is a zoonotic disease, which means it can be spread from animals to people. Infection in people can cause flu-like symptoms and can cause liver or kidney disease. In the United States, most cases of human leptospirosis result from recreational activities involving water. Infection resulting from contact with an infected pet is much less common, but it is possible.

Although any mammal can contract “lepto,” dogs are the most commonly affected in our practice.  Common risk factors include exposure to or drinking from rivers, lakes or streams; roaming on rural properties (because of exposure to potentially infected wildlife, farm animals, or water sources); exposure to wild animal or farm animal species, even if in the backyard; and contact with rodents or other dogs.  The most severe case we’ve ever seen here at Fountain City Animal Hospital was in a tiny house dog who rarely left the owner’s couch and never left her yard.  Even a small mud puddle can be a source for this potentially deadly disease.

Dogs become infected and develop leptospirosis when their mucous membranes (or skin with any wound such as a cut or scrape) come into contact with infected urine, urine-contaminated soil, water, food or bedding.  It is important to note that humans can contract the disease in the same way, so cleaning an infected dog’s urine must be done with utmost care. 

The signs of leptospirosis in dogs vary. Some infected dogs do not show any signs of illness, some have a mild and transient illness and recover spontaneously, while others develop severe illness and death.  The most typical symptoms of leptospirosis include fever, shivering, muscle tenderness, reluctance to move, increased thirst, changes in the frequency or amount of urination, dehydration, vomiting, diarrhea, loss of appetite, lethargy, jaundice (yellowing of the skin and mucous membranes), or painful inflammation within the eyes. The disease can cause kidney failure with or without liver failure. Dogs may occasionally develop severe lung disease and have difficulty breathing. Leptospirosis can cause bleeding disorders, which can lead to blood-tinged vomit, urine, stool or saliva; nosebleeds; and pinpoint red spots (which may be visible on the gums and other mucous membranes or on light-colored skin). Affected dogs can also develop swollen legs (from fluid accumulation) or accumulate excess fluid in their chest or abdomen.

Once diagnosed, leptospirosis is generally treated with antibiotics and supportive care. When treated early and aggressively, the chances for recovery are good but there is still a risk of permanent residual kidney or liver damage.

Leptospirosis is another of the preventable diseases we recommend vaccinating against.  Unlike, canine distemper and parvovirus, the vaccine for leptospirosis needs to be given annually and is recommended for all dogs living in our area.

Infectious Tracheobronchitis or “Kennel Cough” is a highly contagious respiratory disease among dogs. As the name suggests, it is typified by inflammation of the trachea and bronchi and is easily spread through the air, as in a kennel situation. This disease is found throughout the world and is known to infect a high percentage of dogs at least once during their lifetime.  Most often it is nothing more than an unpleasant inconvenience for dog and owner, but it can occasionally be complicated into a more serious condition.  Young puppies often suffer the most severe complications that can result from this disease since they have immature immune systems. Also at increased risk are older dogs, who may have decreased immune capabilities, and dogs with preexisting respiratory diseases.

The most common symptom of infectious tracheobronchitis is a harsh dry cough, often followed immediately by retching or gagging.  Owners often describe their dogs suffering from kennel cough as though they have something stuck in their throats.  In typical mild cases, dogs are often active and eating normally.  In the more severe cases where a secondary pneumonia develops, we will also see inappetence, fever, and lethargy.  Dogs often develop clinical signs associated with kennel cough 3-4 days after exposure to another infected dog.

There are many organisms that can cause the syndrome known as kennel cough, and we vaccinate against all the most common when a dog’s lifestyle puts him at risk. Treatment depends on the severity of the infection. Even if your dog is alert, active, eating well, and has only minor symptoms, he will likely benefit from medications that reduce inflammation and coughing. If a bacterial infection is suspected, antibiotics may help shorten the course of the disease.  If a dog is severely affected with a secondary pneumonia, he might need to be hospitalized for more aggressive treatment - in isolation, of course.

Fortunately, canine infectious tracheobronchitis is rarely a serious illness because this is a disease than can emerge within a community of perfectly vaccinated dogs.  This is a source of deep frustration for owners and veterinarians alike, but there are an unknown number of bacteria and viruses that can cause this clinical syndrome, and we only have vaccines available for the most common.  Nonetheless, appropriate and timely vaccination does decrease enormously your dog’s susceptibility.

Canine Influenza (CIV) is an emerging viral disease which leaves virtually all dogs, regardless of breed or age, susceptible to infection.  There are presently two known strains of canine influenza (compared to the dozens of human influenza strains identified).  The first recognized outbreak of H3N8 canine influenza occurred in racing greyhounds in January 2004 at a track in Florida. From June to August of 2004, outbreaks of respiratory disease were reported at 14 tracks in 6 states (Florida, Texas, Alabama, Arkansas, West Virginia, and Kansas). Between January and May of 2005, outbreaks occurred at 20 tracks in 11 states (Florida, Texas, Arkansas, Arizona, West Virginia, Kansas, Iowa, Colorado, Rhode Island, and Massachusetts). Since then, the H3N8 canine influenza has been documented in 40 states (including TN), and Washington, DC. The first recognized U.S. outbreak of H3N2 canine influenza occurred in 2015, starting in Chicago and spreading to other Midwestern states. Since March 2015, outbreaks have occurred in a number of areas throughout the U.S. and thousands of dogs have been confirmed positive for the H3N2 virus. 

Outbreaks are more commonly seen in situations where groups of susceptible dogs are in close contact, such as shelters, kennels, dog day care facilities, grooming or boarding facilities, and even dog parks.  The disease is spread via aerosolized respiratory secretions (coughing, barking, sneezing), via contaminated objects (kennel surfaces, food and water bowls, collars and leashes), and via and people moving between infected and uninfected dogs. The virus can remain viable (alive and able to infect) on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours.  Because this disease is most contagious during the two to four days prior to an infected dog’s showing symptoms, it is extremely hard to contain once an outbreak has begun.

Like human influenza viruses, canine influenza virus causes an acute respiratory infection in dogs. However, unlike human influenza, CIV is not a "seasonal" flu – infections can occur year-round. Canine influenza virus infection often resembles the illness associated with canine infectious tracheobronchitis ("kennel cough") but is generally considered more severe.  In the mild form, the most common clinical sign of canine influenza is a cough that persists for 10 to 21 days despite treatment with antibiotics and most cough suppressants. Affected dogs may have a soft, moist cough or a dry cough similar to that induced by kennel cough.  Thick nasal and/or ocular discharge, sneezing, lethargy, and inappetence are common.   In dogs with more severe cases, high fever in the range of 104-106o F are not uncommon, and they often experience an increased respiratory rate and effort.

Veterinary expertise is required to establish the best course of treatment or treatment options. As for all viral diseases, treatment is largely supportive.  Most dogs recover from canine influenza within 2-3 weeks, but complications are not unexpected and in the worst of scenarios the disease may be fatal.


Infectious Diseases in Cats

Feline Leukemia Virus (FeLv) is an immuno-suppressant disease and is recognized as a contagious virus which can even be responsible for certain cancers, the two most common being lymphosarcoma and leukemia. The virus is also responsible for several other conditions known as FeLV-related diseases. Noncancerous conditions associated with FeLV infection include anemia, reproductive problems, and secondary infectious diseases.

Feline leukemia is spread in moist secretions, such as saliva, urine, blood, and placental fluids. Behaviors such as grooming/licking, biting, sharing litterboxes, and sharing feeding bowls can allow for transmission of the disease. The disease is usually easily diagnosed through a blood test. A positive test means that a cat is infected with FeLV and thus contagious to other cats; however, presence of the virus is not a disease in itself, but rather only a confirmation of the presence of a potential disease-causing agent. A negative test means that no virus was detected in the blood at the time the sample was collected, but the cat could be in the early stage of infection when no virus is detectable. A negative test in no way suggests that a cat is immune to the virus, and if there is any reason to suspect a particular cat could be infected despite a negative test, we always suggest repeating the test in a few months.

If your cat's test is positive, we believe he should be isolated from any potentially non-vaccinated cats, both for their protection and his.  He could potentially spread his infection to another who might not be as fortunate as he and come down with fatal disease, or your own cat might be immunosuppressed enough that a fairly innocent infection carried by the other cat could result in severe illness in yours.  However, if your cat is positive and all the other cats in his community (your home) are vaccinated, it is possible for him to live a happy life and not be a threat to the others in the household.  If your cat's test is negative, he should still be kept strictly isolated from strange cats and vaccinated annually against FeLV if he might have any contact with cats of unknown vaccination or health status. The vaccination is of no value to a cat already infected with FeLV, but has proved to be virtually 100% protective if boosted regularly.

It is recommended that all cats receive an initial series of two FeLV vaccinations when they are kittens and yearly boosters if they go outside or might have contact with cats of unknown health or vaccine status. Adult cats should be tested for feline leukemia before a vaccination schedule is considered because if the cat happens to already be an asymptomatic carrier there is no benefit in vaccinating, and if he is to be an inside only cat, he may not need vaccination.

If you are unfortunate enough to lose a cat to FeLV, we recommended that you wait 1 - 3 months before bringing a new cat into your home. It is important to evaluate the new cat’s FeLv status and consider whether or not vaccination is appropriate for him.  We also recommended disposing of or thoroughly cleaning any litter boxes, food bowls or toys that were used by the previous cat. All areas of the house should be cleaned with bleach, especially the areas where the previous cat spent the most time.

Sadly, even now, once a cat has begun to show symptoms of disease associated with FeLv,  treatment is limited to supportive care as well as treatment of symptoms. We continue to study the use of anti-cancer drugs, but sadly there is still no cure for feline leukemia.

Feline Upper Respiratory Infections (URIs) are most commonly caused by one of several common viruses and occasionally by bacteria.  Feline calicivirus and feline herpesvirus account for 80 to 90 percent of all contagious upper respiratory problems, and are prevalent in shelters, catteries and multi-cat households. These viruses can be transmitted from cat to cat through sneezing, coughing, or while grooming, or by sharing food and water bowls. Once infected, cats can become carriers for life, and though they may not show clinical signs, they can still transmit the viruses to others. Cats often develop bacterial infections secondary to these common viral infections, or in less frequent cases, a bacteria can be the primary cause of the disease; Chlamydia felis and Bordetella bronchiseptica being the most common and Mycoplasma spp also occasionally being responsible.

The typical upper respiratory infection involves some combination of coughing, sneezing, and conjunctivitis (inflammation of the membranes lining the eyelids). There is frequently a discharge from the nose or eyes, and it may be clear or become thick and mucousy.  With certain viruses, the cat may also develop ulcers in the mouth. Less specific symptoms of an upper respiratory infection include lack of appetite, lethargy, fever, enlarged lymph nodes and blepharospasm (squinting). In severe cases, the cat may have difficulty breathing.

Upper Respiratory Infections in cats are highly contagious.  Susceptible cats can get an infection by direct contact with another infected cat or by environmental exposure to objects that have been contaminated with infectious secretions, including human hands.  In the majority of cases however, a cat becomes infected by direct contact since the viruses and bacteria can only survive for a short period of time in the environment, and are readily destroyed by proper disinfection procedures.  The facts that several of these diseases can cause a carrier state in cats and that female carrier cats can pass the infection on to their newborn kittens are what make these conditions so difficult to eradicate once they have invaded a cattery.

Once a cat is exposed to an infectious agent, it will go through an incubation period of 2-10 days before developing symptoms. If the infection is uncomplicated, it will typically last for 7-21 days, depending on the particular disease agent. During this entire time, the cat will potentially be infectious to other cats.  In cases of feline herpes virus, all infected cats become chronic carriers, meaning that they will have the disease essentially for life. In some cats who carry this virus, stress may cause the virus to become repeatedly reactivated. In cases of calicivirus, about half of the cats that are infected will become carriers of disease. In some of these cats the carrier state may only last for a few months, but in a small percentage of cats the carrier state may persist for life. These persistent carriers may be free of symptoms but serve as a constant source of virus to susceptible cats.

Most cats with an uncomplicated upper respiratory infection can be treated symptomatically at home. Your cat might need an eye medication to be applied topically if she has a purulent eye discharge. Although viral infections do not respond to antibacterial drugs, broad spectrum antibacterial drugs may be prescribed in an effort to prevent secondary bacterial infections from complicating the disease, particularly in kittens. Primary bacterial upper respiratory infections caused by Bordetella or Chlamydia will be treated with specific antibiotics that are effective against these diseases.

Cats with nasal or airway congestion may benefit from increased environmental humidification, such as being taken into a steamy bathroom for 10-15 minutes several times per day. To minimize irritation from discharges, we recommend gently wiping the cat's face or eyes with a moist tissue or cotton ball. Since cats with a respiratory infection often have a decreased sense of smell, they may have a decreased appetite, so feeding a highly palatable canned food may help. If a patient’s appetite is seriously compromised, we may prescribe an appetite stimulant.  If a cat is dehydrated, depressed, or has a severe case of illness, we will occasionally recommend hospitalization in our isolation unit for more intensive treatment, including intravenous fluids and other supportive treatments.

Since upper respiratory infections can be caused by a variety of different disease agents, it is not always possible to prevent upper respiratory disease in cats. However, the standard vaccines that are given to cats provide protection against all of the most common culprits in causing these conditions.  Even if these vaccines don’t completely prevent an infection from occurring if your cat is exposed, they will significantly reduce the severity of the infection and shorten the length of the illness.  Upper Respiratory vaccines need to be boostered on a regular basis, and we have changed to a three year schedule for most of our patients at Fountain City Animal Hospital.

Panleukopenia (feline distemper) is an infectious disease of cats that we rarely see any more, thanks do decades of adherence to effective vaccine programs. This highly transmittable disease travels from one cat to another through contact with infected saliva, urine or feces. Clinical signs can vary and may include depression, fever, weight loss, diarrhea, vomiting, dehydration, loss of appetite, swollen lymph nodes, anemia, or persistent chronic infection. If the animal does not receive prompt supportive care he can die within days, and sometimes even with aggressive medical intervention, cats may still succumb to this aggressive infection.  Initial vaccinations and regularly scheduled boosters are available to prevent this disease.

Feline infectious peritonhis (FIP) is another serious disease we (happily) rarely see in cats who have always lived here in North Knoxville.  The few cases we have diagnosed over the years have been in cats from other neighborhoods in Knoxville or from shelters or neighborhoods out of town, but because it is easily spread among cats in any population, we are always on the alert and keep this disease on our differential list when evaluating any sick cat with symptoms compatible with this illness.

The disease spreads through contact with saliva or feces of an infected animal, but the virus can also live in the environment for several weeks.  The most common transmission of this disease occurs when infected female cats pass along the virus to their kittens, usually when the kittens are between five and eight weeks of age.  Most cats who develop FIP are under two years of age, but it can occur in cats of any age.

Two types of this disease have been identified. “Wet FIP,” or the effusive form, is characterized by some combination of weight loss, fever, depression, enlarged belly, or labored breathing.  In this form, FIP is a relatively straightforward diagnosis to make because of the classic accumulation of a specific type of fluid in either the abdomen and/or thorax. Symptoms of “Dry FIP” include some combination of weight loss, anemia, chronic and unresponsive fever, depression and inactivity, liver failure, renal insufficiency, pancreatic disease and eye lesions.

The only vaccine available is of questionable value, and previous administration of the vaccine can complicate the diagnosis in a patient if the disease is ever suspected. Cats with this disease usually do not do well for long, despite even heroic efforts, and FIP is very sadly usually fatal.

Feline Immunosuppressive Virus, sometimes called, “Kitty AIDS,” is caused by a virus in the same family as the Feline Leukemia Virus, but they differ in many ways.  The virus is found in cat populations worldwide, and in the U.S., it is estimated that between 1.5 and 3% of healthy cats actually are carrying the virus.  As with the human AIDS virus, it is quite possible to carry the virus and never actually become ill.

The primary mode of transmission of this disease is through bite wounds, so free-roaming aggressive male cats are most frequently infected.  Casual non-aggressive contact does not appear to be an efficient route of spreading FIV, so cats in households with stable social structures where housemates do not fight are at little risk of spreading FIV, even if one among the household is a carrier.

Infected cats most commonly appear normal for many years, but once the disease becomes active it acts to hinder the cat’s ability to fight even the most common infection.  Something that would be a mere inconvenience for a healthy cat can be fatal for one whose immune system is compromised by FIV.  More subtle symptoms of FIV infection can include poor coat condition, persistent fever, lack of appetite, inflammation of the gums and mouth, chronic or recurrent infections of the skin or urinary tract, recurrent upper respiratory infections, persistent diarrhea, and weight loss.  Even certain types of cancer and blood diseases are more common in FIV infected cats, and infrequently these cats can even experience seizures, behavior changes, and other neurological disorders.

There is a vaccine to help protect against FIV, but since even these are not 100% effective, preventing exposure by keeping your cats indoors is far and away the best way to protect them from FIV.  Vaccinating for the disease can also have an impact on future FIV test results, so if you’re considering vaccination, please consult with us first. 

If your cat is diagnosed with FIV, we always recommend that she be confined to living 100% indoors.  This is both for her protection since she is susceptible to every infectious disease she might contact in the outside world, and also to try to minimize the possibility of her spreading the disease to others with whom she might have an unfriendly encounter and altercation.

Please remember that a positive test is not a death sentence for your cat.  Nonetheless, it is important to always remember that the potential for severe secondary infections exists if he is carrying the virus, and to always be appropriately attentive to any sign of infection you might see in him.  Your FIV positive cat can live a long and healthy life, but this virus behaves differently in different cats, so erring on the side of over-caution is always best.  Call us if you have even the slightest suspicion that your FIV positive kitty isn’t feeling his absolute best.