Infectious Diseases



Brucellosis is caused by the bacteria Brucella canis. The disease is spread from one dog to another via breeding or oral contact with vaginal discharges, aborted fetuses, placentas, semen or urine. Although it is contacted most frequently in breeding kennels, family pets may become infected also. Pregnant females that contract brucellosis abort their puppies, while nonpregnant bitches may fail to conceive. Infected male testicles may swell and usually become sterile. Some dogs do not appear ill, yet are infected and capable of spreading the disease. Diagnosis is afforded via blood culture and/or serology (blood testing). Multiple blood samples are usually required.


Feline calicivirus is a virus that can cause mild to serious respiratory illness. Cats become infected by inhaling or swallowing the virus. Signs of illness develop within 2-10 days of exposure. Young kittens are most affected. Early signs include eye and nose discharge, sneezing, depression and poor appetite. Ulcers may develop on the tongue and hard palate. Most infected cats drool heavily. Illness lasts from 1 to 4 weeks. Most cats recover but fatalities do occur. Some cats that recover from the initial disease can continue to shed the virus for weeks or even years. Calicivirus vaccine is available.

Chlamydia (Pneumonitis in Cats)

Feline pneumonitis is an infectious upper respiratory disease of cats caused by the organism Chlamydia psittaci. The disease is spread by contact with discharges from the eye, nose or mouth. Signs develop 5-10 days after exposure and may include sneezing, coughing and discharge from the eyes and nose. The disease may reappear in recovered cats after stress or other illness. Diagnosis is afforded via physical exam, conjunctival cytology and serology. Annual vaccination is the best means of preventing pneumonitis.

Chronic Rhinitis

Chronic rhinitis is a long-standing inflammation of the nasal passage lining. It can develop in pets of any age and frequently follows a mild infection of the upper respiratory system. Causes include viruses, fungi, foreign bodies, neoplasia, irritating fumes and allergies. Signs may include nasal discharge, ocular discharge, sneezing, coughing and diminished appetite. Diagnosis is afforded by physical exam, complete blood count, cytology, rhinoscopy, x-rays, serology, culture and sensitivity. Treatment may include anti-inflammatories, antibiotics, antifungals, foreign body removal, flushes and the treatment of any other underlying disorder.

Coronavirus (Cats)

Feline coronaviruses may cause feline infectious peritonitis (FIP) or only a mild intestinal disease (coronavirus enteritis). The viruses differ, but cannot be differentiated by the current blood tests. A positive blood test can signal the possibility of these diseases.

FIP is relatively uncommon but generally fatal. It occurs primarily in cats of multicat households between the ages of 6 months and 5 years or greater than 10 years of age. Two forms of FIP occur: (1) a disease affecting the the abdomen and/or chest cavities, in which massive fluid accumulates (“wet” FIP), and (2) a disease of various organs, such as the liver, lymph nodes, kidneys, eye and brain (“dry” FIP).

Feline enteric coronaviruses cause mild intestinal disease in kittens up to 12 weeks of age. The infection is common and may exist in most homes with multiple cats. It may recur, but is rarely serious.

Coronavirus (Dogs)

Canine coronavirus (CCV) affects the intestinal tract of dogs. CCV is transmitted through feces. The length of time between infection and signs of illness is 1-5 days. Illness may continue for 2-10 days and dogs may shed the virus for 2 weeks after signs of infection have ended. Signs include anorexia, depression, vomiting and diarrhea. Dogs that have recovered from CCV develop some immunity, but the duration is unknown. Diagnosis of the disease is made via physical exam, serology, endoscopic biopsy and the process of ruling out other more serious diseases (eg. parvovirus). Treatment is supportive. Vaccination is available for prevention of CCV infection. Annual boosters are recommended.


Distemper is a highly contagious disease of dogs caused by a virus that is easily spread via air and contaminated objects. The disease occurs more often in young dogs, but those of any age may contract distemper. Signs range from mild respiratory problems, such as ocular and nasal discharge, to anorexia, depression, fever, severe diarrhea, vomiting and seizures. Diagnosis is afforded via complete blood count, virology, cerebral spinal fluid analysis and serology. Treatment is symptomatic and supportive. Vaccination is available to prevent canine distemper. Annual boosters are recommended.

Feline Leukemia Virus

Feline leukemia virus (FeLV) is one of the most common and destructive of cat viruses. It is highly contagious and is spread by saliva, blood, urine and feces. Kittens may become infected within the womb or during nursing. Not all cats exposed to the virus become infected. Approximately 40% of exposed cats destroy the invading virus while the remainder of exposed cats become persistently infected (30%) or develop a latent infection (30%). The latter group has inactive virus in their bone marrow which may become active if the cat is severely stressed or becomes ill. Of the persistently infected cats, about 25% will die within 1 year and 75% will die within 3 years. Some may live a normal life span but tend to have various recurrent illnesses.

There are no specific signs for FeLV infection. Disorders commonly associated with FeLV infection include: anemia, lymphosarcoma (neoplasia), chronic respiratory disease; chronic infection of the mouth, gums and tongue; chronic eye disease; frequent or chronic skin disease; reproductive disease (abortions, stillbirths and kitten deaths); frequent or chronic urinary tract infections; chronic digestive tract disease; and other systemic diseases (infectious peritonitis, haemobartonellosis toxoplasmosis, polyarthritis). Diagnosis is afforded via physical exam, complete blood count, blood chemistries, serology and bone marrow cytology. Treatment is only supportive. A vaccination is available.


Haemobartonellosis is a contagious disease caused by the blood parasite Haemobartonella felis (cats) and Haemobartonella canis (dogs). The organism attacks red blood cells, resulting in their destruction and subsequent development of anemia.

Feline infectious anemia (Haemobartonella felis) is spread by contact with infected blood through injuries or the bites of blood-sucking insects, such as fleas and ticks. Kittens may become infected before birth or while nursing. Time from infection to appearance of the parasite on the red blood cells varies from 8 to 23 days. Some infected cats show no signs of illness until stressed by illness, injury or severe emotional upset. Recovered cats can become carriers and experience relapses. Signs include lethargy, anorexia, weakness and possible death. Diagnosis is afforded via complete blood count, serology and cytology. Treatment includes antibiotics and supportive therapy.


Canine herpesvirus (CHV) infection is a contagious disease. Adult dogs may harbor the virus in the nose, throat, lungs and genital tract without showing signs of illness unless they are stressed by illness or injured. Puppies can become infected before or after birth. Infected puppies under 10 days of age usually die while puppies over 3 weeks of age may only show mild respiratory signs. These puppies can shed the virus for about 3 weeks after recovery in their secretions. People can not contract CHV infection.

Infectious Hepatitis

Infectious canine hepatitis (ICH) is a serious viral disease that is acquired through oronasal exposure. It is found in all tissues of infected pets and is shed in all secretions during acute infection and in the urine up to 9 months after recovery. The disease affects the liver, kidneys, lymph nodes, eyes and other organs. Signs range from mild, unnoticed disease to cloudy eyes, vomiting, diarrhea, abdominal pain, fever, bleeding, disorientation, depression, seizures and death. Nearly all dogs are exposed to ICH virus at some time during their lives. Diagnosis is via physical exam, complete blood count, blood chemistries, serology and biopsy (eg, liver). Treatment is supportive. Vaccination is available to prevent ICH. All dogs should be receive annual immunization.

Kennel Cough (Infectious Tracheobronchitis)

Kennel Cough (Infectious Tracheobronchitis) is a very contagious disease of the upper respiratory tract, which includes the trachea (windpipe) and bronchi (large air passages of the lungs). Both viruses and bacteria are usually involved (eg. primarily Parainfluenza virus and Bordetella bronchiseptica bacteria). The most common sign of kennel cough is a harsh, dry cough that is often followed by gagging and coughing up foamy mucus. Otherwise the patient appears bright, alert and generally healthy. Severe infections may produce nasal discharge, anorexia, fever, depression and rarely death. Diagnosis is afforded via accurate history, physical exam, cytology and the rule out of other diseases. Treatment may include antibiotics, anti-inflammatories and supportive care.


Leptospirosis is a serious contagious bacterial disease that infects dogs, people and several other types of animals. There are numerous serotypes of leptospira. These bacteria attack the kidneys, liver and nervous system. Infected wild animals and rats are common sources of leptospirosis. Signs may include fever, depression, anorexia, vomiting, general muscle pain, pain over the kidneys, excessive urination, meningitis, hemorrhage and death. Diagnosis is afforded via physical exam, complete blood count, blood chemistries, serology and urinalysis. Treatment may include antibiotics, fluid therapy, diet, omega 3 fatty acids, phospate binders, acid blockers and other supportive therapy. Animals that recover may shed the organism in their urine for up to 1 year. Vaccination is the best prevention for leptospirosis. All dogs should be vaccinated annually. The vaccine is commonly combined with the distemper, hepatitis, parvovirus and parinfluenza vaccines.

Panleukopenia Virus (feline distemper)

Feline distemper is a severe, very contagious viral disease. It occurs most often in kittens under 6 months of age but cats of any age may become infected. The virus survives in the environment for long periods. Signs develop 2-5 days after exposure to the virus and may include anorexia, depression, fever, vomiting, diarrhea, dehydration and death. The death rate is highest in kittens and elderly cats. The disease may run its course in 2-14 days. Feline panleukopenia virus is shed in all body excretions, especially feces, for up to 6 weeks. Cats that contract the virus during pregnancy pass it to their kittens (in utero) possibly causing these kittens to be born with brain defects. Diagnosis is afforded by physical exam, complete blood count, blood chemistries and serology. Treatment is via support therapy. All cats should be vaccinated for feline distemper and boostered yearly.


Parvovirus is a severe, highly contagious disease of dogs. They become infected with parvovirus through contact with the stool of an infected dog or contaminated environment. The virus is very hardy and remains infective in the environment for a long periods of time. Puppies are most susceptible to parvovirus infections. Signs of parvovirus may include anorexia, depression, fever, severe and often bloody vomiting and diarrhea. Infected animals rapidly dehydrate, and may progress to shock and death. Fatalities occur mostly in puppies less than 12 weeks of age. The virus may also attack the heart muscle of puppies, and can cause sudden death. Diagnosis is afforded via accurate vaccine history, physical exam, complete blood count, blood chemistries and serology. Treatment may include long hospitalization, fluid support, blood transfusions, hyperimmune plasma, antiemetics, antidiarrhea therapy, antibiotics and dietary restriction. A vaccine is available for prevention of canine parvovirus infection. All dogs should be vaccinated annually.


Rabies is a fatal viral disease. All warm-blooded animals are susceptible. The virus primarily attacks the nervous system and is shed in saliva. The bat, skunk and fox are the most commonly infected wild animals while dogs and cats are the most commonly infected domestic animals.

Signs of rabies vary, making diagnosis very difficult while the animal is alive. Rabies progresses through three phases. Early in the disease, affected animals may show subtle changes in behavior or temperament. As the disease progresses, the animal may become restless, excitable and may have a tendency to roam or eat unusual objects. Frequently the animal becomes vicious. Convulsions may occur. The animals may then have trouble swallowing and begin to drool excessively. This is followed by depression, coma and death from respiratory paralysis. The only positive diagnosis of rabies is by laboratory examination of brain and salivary tissue. Early confirmation of animal rabies is necessary in order that exposed humans can receive proper prophylaxis as expediently as possible. There is no treatment for rabies. Proper vaccination against rabies is essential for prevention of the disease. Vaccination is the best means of rabies control. All pets should be vaccinated. Consult your veterinarian regarding the proper vaccination regiment for your pet. Keep rabies vaccinations current. Wild animals should not be kept as pets, nor vaccinated for rabies. There is no approved rabies vaccine available for wild animals. If a suspected rabid animal bites a person, contact your local health department and quarantine the animal for 10 days. If the animal develops signs of rabies or dies, tissues must be immediately sent to the proper (eg. state) laboratory for examination. Since rabies is such a threat to people and other animals, affected animals should not be treated. Euthanasia is mandatory.

Respiratory Disease Complex in Cats

Various infectious organisms inhabit the respiratory tract of cats. These organisms include rhinotracheitis virus, calicivirus, Chlamydia psittaci, reoviruses, Mycoplasma and various bacteria. Respiratory diseases are transmitted by direct contact with discharges from the eyes, nose, mouth or other body fluids of infected cats. Some of these organisms are spread by contaminated clothing hands, feeding utensils, grooming equipment and other articles. The most common signs of respiratory disease are sneezing, cough, discharge from the eyes, nose or mouth, difficult breathing, gagging, lack of appetite and weight loss. Infections may last only a few days or be present for weeks to months. Some of these disease agents exist in a carrier state within apparently healthy cats. Most of these organisms are contagious, and some can even cause fatal disease. Diagnosis is afforded by physical exam, complete blood count, blood chemistries, cytology, serology and imaging studies. Treatment may include antimicrobials, support therapy and anti-inflammatories.


Rhinotracheitis is a herpesvirus infection of the eyes, nasal passages and windpipe (trachea) of cats. Signs include sneezing, coughing, discharges of the eyes and nose, hypersalivation and possible corneal ulceration. Infection is spread via direct contact of discharges from the eyes, nose or mouth of infected cats as well as contaminated clothing, hands, feeding bowls, etc. Signs occur 2-5 days after infection. Mild cases recover in 1-2 weeks, while more severe infections may last for several weeks. The disease is more severe in kittens. Diagnosis is afforded via physical examination, cytology, serology, immunology testing and/or virus isolation. Treatment is directed toward secondary disorders (eg. bacterial infections) and supportive care.


Salmonellosis is a bacterial disease of the intestinal tract caused by Salmonella. Pets are infected by ingesting substances contaminated with the bacteria. The organism can survive long periods in the environment and up to 6 weeks in the feces of animals after recovery. Signs include vomiting, diarrhea, fever, anorexia, lethargy, abdominal pain, dehydration and even death. Diagnosis is afforded via physical exam, complete blood count and fecal or blood cultures with sensitivities. Treatment may include antibiotics, fluid and electrolyte therapy and supportive care as well as frequent bathing of the pet to minimize reinfection. Salmonella is a zoonotic disease (humans can contract the disease)! Take precautions!

Systemic Fungal Disease

Fungi are microscopic organisms found throughout the environment. Only a few types of fungi cause disease in pets via either inhalation or contaminated wounds. Systemic infections multiply and cause infection throughout the body. Organs infected may include the lungs, lymph nodes, spleen, kidneys, eyes, skin, brain and intestinal tract. Systemic fungi include blastomycosis, coccidiomycosis, cryptococcosis and histoplasmosis. Signs may include skin lesions, respiratory disorders, enlarged lymph nodes, eye lesions, gastrointestinal disorders, anorexia and weight loss. Diagnosis is afforded via physical exam, cytology, biopsy, complete blood count, blood chemistries, imaging studies, serology and fungal culture. Treatment includes antifungal medications, supportive care and treatment of secondary disorders.


Toxoplasmosis is caused by the protozoa (very small organism) Toxoplasma gondii. The organism can infect pets as well as people by their eating infected raw meat or infective eggs within cat feces. Carrier cats may or may not show signs of illness but can pass infective eggs in their feces! Signs of the disease include anorexia, diarrhea, abdominal pain, jaundice, stiff gait, ataxia, seizures, fever, labored breathing, enlarged lymph nodes, eye inflammation, abortions and even death. Diagnosis is afforded via physical exam, complete blood count, blood chemistries, imaging studies, special fecal floats and serology. Treatment may include clindamycin, other antimicrobials and supportive therapy.

Viral Enteritis

Viral enteritis is an inflammation of the intestinal tract caused by a virus. Viruses that cause enteritis include astrovirus, enterovirus, coronavirus, herpesvirus, parvovirus and reovirus. Some produce mild disease while others may cause life threatening illness. Puppies/kittens, old pets and pets weakened by concurrent illness are most susceptible. Transmission is by direct contact of infected feces, saliva or vomit or by contact with contaminated clothing, feeding bowels, etc. as well as some insects and birds. Signs may include anorexia, vomiting, diarrhea, fever, depression, hypothermia, jaundice and death. Diagnosis is afforded via physical exam, complete blood count, blood chemistries, imaging studies, serology, virology and biopsy. Treatment may include fluid and electrolyte therapy, antibiotics, dietary restriction, antiemetics, antidiarrheals, hyperimmune plasma, whole blood, immunotherapy and supportive care.