Laurie Anne Walden, DVM  Kennel cough, the common term for canine infectious respiratory disease (or infectious tracheobronchitis), is a contagious disease that causes a hacking cough. The infection spreads quickly among dogs. Kennel cough is usually a mild illness, but some dogs develop more serious disease.
Causes Many bacteria and viruses cause canine infectious respiratory disease. Most dogs with the disease are infected with more than 1 organism at the same time.[1,2] Some of the organisms involved are the following:
Risk Factors Not all dogs get sick after being exposed to an agent that can cause respiratory disease. Some of these organisms are unlikely to cause illness on their own but can cause symptoms when combined with other organisms.[3] Whether a dog develops respiratory disease is also affected by environmental factors (such as crowding and poor ventilation) and the dog’s immune system. Kennel cough spreads through respiratory secretions from an infected dog. Dogs with no symptoms at all can spread the infection. Droplets containing bacteria or viruses become airborne after a dog coughs or sneezes and are deposited on surfaces, water bowls, toys, and other objects. The higher the number of dogs housed together, the higher the chance of a dog coming into contact with infected respiratory secretions. Crowding increases stress, which reduces a dog’s protective immune response against infection. Some infectious agents can hinder the immune response, making infection with additional organisms more likely. Bordetella bronchiseptica can infect cats and possibly humans. Infection in humans is probably of most concern in people with impaired immune function. Symptoms Because of the variety of organisms and differences in individual dogs, symptoms can vary. Typical symptoms of the mild form of disease include the following:
Some dogs, especially young puppies, elderly dogs, and dogs with poor immune function, develop more severe bronchitis and pneumonia. These dogs have more serious symptoms:
Diagnosis For dogs with mild disease, kennel cough is usually presumed from physical examination findings and history of exposure to other dogs. Dogs with a persistent cough or signs of more serious disease need diagnostic testing, which can include chest radiographs, blood tests, and (in some cases) tests to identify the organisms involved. Treatment Treatment decisions are based on the severity of the illness and the dog’s environment. Mild cases of kennel cough often resolve on their own, so dogs with mild disease might need only supportive care (good nutrition, limited activity, and a warm place to rest indoors). Some dogs benefit from treatment with an antibiotic active against Bordetella. Most dogs with kennel cough should not receive cough suppressants. Dogs with more severe disease need more intensive treatment. The treatment for dogs in an environment with a high risk of disease spread (like a shelter) may be different from the treatment chosen for a pet living at home. Prevention Vaccines help control canine infectious respiratory disease. No single vaccine can entirely prevent kennel cough, but vaccinations protect dogs against some of the organisms and reduce the severity and spread of disease. A combination vaccine including canine distemper virus, canine adenovirus type 2, and sometimes canine parainfluenza virus is recommended for all dogs.[5] Puppies receive this vaccine as part of the puppy vaccine series. Adult dogs should have booster vaccinations (or antibody titer tests). A vaccine against Bordetella bronchiseptica, sometimes also including canine parainfluenza virus, is recommended for dogs whose lifestyle puts them at risk for infection. The Bordetella vaccine is given in the nose, in the mouth, or by injection, depending on the formulation. Vaccines against canine influenza virus are also available. The decision to give a dog Bordetella and flu vaccines depends on the dog’s lifestyle and possibly on geographic area. Talk to your veterinarian about these vaccines if your dog goes to boarding kennels, doggie daycare, dog parks, dog shows, groomers, shelters, or other areas where dogs gather. Because infectious respiratory disease is so contagious, dogs with symptoms should be kept away from other dogs as much as possible. Washing hands, bowls, dog toys, and clothing can reduce the risk of spreading the infection to other dogs. References 1. Schulz BS, Kurz S, Weber K, Balzer HJ, Hartmann K. Detection of respiratory viruses and Bordetella bronchiseptica in dogs with acute respiratory tract infections. Vet J. 2014;201(3):365-369. 2. Hurley K, Aziz C. Canine infectious respiratory disease complex (CIRDC) - diagnosis and treatment; prevention and management. Pacific Veterinary Conference 2015. Veterinary Information Network website. https://www.vin.com/doc/?id=6789809. Accessed December 6, 2019. 3. Canine infectious respiratory disease complex (CIRDC, a.k.a. “kennel cough”). University of Wisconsin-Madison Shelter Medicine website. https://www.uwsheltermedicine.com/library/resources/canine-infectious-respiratory-disease-complex-a-k-a-kennel-cough. Published July 2015. Accessed December 6, 2019. 4. Kuehn NF. Tracheobronchitis in small animals. Merck Veterinary Manual website. https://www.merckvetmanual.com/respiratory-system/respiratory-diseases-of-small-animals/tracheobronchitis-in-small-animals. Accessed December 6, 2019. 5. 2017 AAHA canine vaccination guidelines. American Animal Hospital Association website. https://www.aaha.org/aaha-guidelines/vaccination-canine-configuration/vaccination-canine/. Published September 7, 2017. Updated February 3, 2018. Accessed December 6, 2019. Photo by Hannah Lim Laurie Anne Walden, DVM  Leptospirosis is a disease caused by infection with Leptospira bacteria. The disease is zoonotic, meaning that it can pass from animals to humans. The bacteria are spread through the urine of infected animals and can remain in water or soil for months.
Who’s at Risk Many different animals can carry Leptospira. Rodents are the most common sources of infection in people. Farm animals, wild animals, and dogs can also be carriers. (Cats are very rarely infected.) Leptospirosis is a public health hazard for people around the world. People are most often infected through contact with contaminated water, including recreational contact like swimming. Heavy rainfall and flooding increase the risk. Other routes of infection are direct contact with animal urine and contact with contaminated soil or food.[1,2] Dogs are infected the same way as people: through contact with urine, contaminated soil, or contaminated objects. Dogs can also be infected by eating infected animals. Pregnant dogs can pass the infection to puppies through the placenta.[3] Dogs are at increased risk for leptospirosis if they have access to any of the following:
Leptospirosis was once considered a disease mostly of working dogs and other outdoor dogs. But small-breed dogs that live in cities and have no access to outdoor water sources are also at risk because rodents carry the disease.[3] Symptoms Leptospirosis causes a wide range of problems, including kidney failure, liver failure, lung disease, eye damage, blood clotting disorders, and death. Some dogs infected with Leptospira have mild disease or no symptoms at all. The severity of disease depends on the Leptospira strain and the dog’s immune system, among other factors. Symptoms of leptospirosis in dogs vary but can include the following:
Leptospira infection can be diagnosed with blood tests. Dogs suspected of having leptospirosis generally also need other tests, such as urinalysis, x-ray examination, and ultrasound.[3] Treatment Dogs with leptospirosis are treated with antibiotics. Most require hospitalization for supportive care and intravenous fluid treatment. The prognosis is good for most dogs that are treated early in the course of disease. Dogs with kidney failure that is not aggressively treated and those with lung complications have a poorer chance of survival. Dogs with leptospirosis can infect people and other dogs. People handling infected dogs should take precautions like wearing protective clothing and avoiding contact with the urine. Prevention Leptospira vaccines are available for dogs. Talk to your veterinarian about your dog’s risk for leptospirosis. In some geographic areas, veterinarians recommend leptospirosis vaccination for all dogs, including those that live mostly indoors. Other precautions to reduce the risk of infection are washing hands after handling dogs, wearing gloves when cleaning or collecting dog urine, and using antibacterial solutions to clean surfaces that might be contaminated with urine. The Centers for Disease Control and Prevention recommends avoiding contact with contaminated water (don’t wade barefoot in floodwater!) or wearing protective clothing around potentially contaminated water or soil.[1] References 1. Leptospirosis. Centers for Disease Control and Prevention website. https://www.cdc.gov/leptospirosis/index.html. Accessed July 9, 2019. 2. Leptospirosis. World Health Organization website. https://www.who.int/zoonoses/diseases/leptospirosis/en/. Accessed July 9, 2019. 3. Sykes JE, Hartmann K, Lunn KF, Moore GE, Stoddard RA, Goldstein RE. 2010 ACVIM small animal consensus statement on leptospirosis: diagnosis, epidemiology, treatment, and prevention. J Vet Intern Med. 2011;25(1):1-13. Photo by Matt Jones on Unsplash Laurie Anne Walden, DVM  Fleas don’t just cause itching. They also carry infectious diseases that can be contagious to people. Controlling fleas on your pets protects your whole family’s health.
Tapeworms Tapeworms are parasites that live in the intestines. They shed small body segments called proglottids that pass out of the host animal’s body in the feces. Tapeworm segments in the stool look like whitish rice grains. Fleas transmit a type of tapeworm that commonly infects dogs and cats. Dogs and cats become infected by swallowing a flea. Tapeworms rarely cause significant disease in dogs and cats. The dog and cat tapeworm that is carried by fleas, Dipylidium caninum, can also infect humans (usually children) who swallow a flea.[1] Bartonellosis (Cat Scratch Disease) Bartonella species are bacteria that cause a variety of diseases in humans and other animals. Cat scratch disease and endocarditis (heart valve infection) are just 2 of the serious illnesses caused by Bartonella infection.[2] Fleas are the most common insect vector for Bartonella henselae, the species that causes cat scratch disease.[3] Fleas can also carry other Bartonella species. Infected cats and dogs might or might not have any symptoms of infection. Bartonellosis is a human health risk. Treating your cat with a cat-safe flea preventive reduces the risk of cat scratch disease for people in contact with your cat. Rickettsial Diseases Rickettsiae are a group of bacteria responsible for diseases such as typhus and Rocky Mountain spotted fever. Rickettsiae are spread by arthropods, including fleas and ticks. The types of fleas that infest dogs and cats transmit Rickettsia typhi (which causes murine typhus) and Rickettsia felis. Both of these bacteria can also cause disease in people.[1,4] Yersiniosis (Plague) Plague, including bubonic plague and the Black Death, is caused by infection with the bacterium Yersinia pestis. The Oriental rat flea (Xenopsylla cheopis) transmits the bacterium usually to rodents but sometimes to cats, dogs, other animals, and humans. Rat fleas in the western United States and other parts of the world still harbor Yersinia.[3] Mycoplasma Infection Cats infected with certain types of Mycoplasma bacteria develop anemia (low red blood cell count). Fleas are thought to be a source of infection for cats.[5] Noninfectious Diseases Fleas cause skin disease in animals that scratch or chew themselves to relieve the itch. Just a few fleas can set off intense itching in an animal with a flea allergy. Because fleas feed on blood, animals with lots of fleas can develop anemia from blood loss. This anemia can be life threatening. References 1. Fleas. Companion Animal Parasite Council website. https://capcvet.org/guidelines/fleas/. Updated September 19, 2017. Accessed May 7, 2019. 2. Bartonella infection (cat scratch disease, trench fever, and Carrión’s disease). Centers for Disease Control and Prevention website. https://www.cdc.gov/bartonella/index.html. Updated December 14, 2015. Accessed May 7, 2019. 3. Shaw SE. Flea-transmitted infections of cats and dogs. World Small Animal Veterinary Association World Congress Proceedings, 2008. Veterinary Information Network website. https://www.vin.com/doc/?id=3866578. Accessed May 7, 2019. 4. Little SE. Feline fleas and flea-borne disease (proceedings). DVM360 website. http://veterinarycalendar.dvm360.com/feline-fleas-and-flea-borne-disease-proceedings. Published April 1, 2010. Accessed May 7, 2019. 5. Lappin MR. Update on flea and tick associated diseases of cats. Vet Parasitol. 2018;254:26-29. Photo of Oriental rat flea (Xenopsylla cheopis) by James Gathany, CDC Laurie Anne Walden, DVM  Adult heartworms grow up to a foot long, block blood flow around the heart, and cause inflammation within blood vessels. The damage continues as long as the heartworms remain in the body.
Heartworm treatment protocols for dogs are designed to remove the worms while reducing the risk of treatment complications. No safe heartworm treatment exists for cats and ferrets. Your veterinarian can recommend appropriate heartworm preventives for your dog, cat, or ferret. Initial Tests Heartworm infection is diagnosed with a blood test. Your veterinarian might confirm the diagnosis with another test before proceeding with treatment. Other tests, like x-ray imaging, echocardiography (heart ultrasound), and other blood tests, are used to assess the extent of damage. The results can affect the treatment plan, so your veterinarian might recommend these tests even if your dog isn’t showing any symptoms of infection. Dogs with blood clotting problems or signs of heart disease need a full diagnostic workup before treatment starts. Exercise Restriction Any activity that increases the heart rate and blood pressure can worsen the problems caused by heartworms. Dogs with heartworms need to stay as quiet as possible to limit the damage. Once treatment begins, pieces of dead worms can break off and lodge in small blood vessels, potentially causing serious problems and even death. Strict exercise restriction is the best way to reduce the risk. The American Heartworm Society (AHS) recommends restricting activity from the time heartworms are diagnosed until 6 to 8 weeks after the last dose of heartworm treatment. Dogs should ideally stay indoors in a small area where they can’t run or jump. Some dogs need to be confined to a crate. They should go outdoors on a leash only long enough to pee and poop. Ask your veterinarian about the level of confinement your dog needs. Before Killing the Heartworms Before dogs begin receiving adulticide (medication that kills adult heartworms), they may need treatment for heartworm-related problems. They should receive a certain type of heartworm preventive to remove larvae, or immature worms, from the bloodstream. They also benefit from a monthlong course of doxycycline, an antibiotic, to eliminate a bacterium that lives inside heartworm cells. This bacterium is partly responsible for the inflammation that occurs when heartworms die. The AHS recommends that dogs start adulticide treatment 2 months after receiving a heartworm diagnosis (30 days after the last dose of doxycycline). Dogs should have limited activity during these 2 months. Adulticide Treatment The only adulticide currently approved for use in the United States is melarsomine. This drug is given by injection in a veterinary hospital. Your dog may need to stay in the hospital for observation after a melarsomine injection. The number and timing of injections may vary depending on the situation. The current AHS recommendation is to give a series of 3 injections: 1 injection followed by a 30-day wait, then 2 injections given 24 hours apart. Your veterinarian will suggest a protocol that’s appropriate for your own dog. Complete exercise restriction is crucial during adulticide treatment and for several weeks after the last dose. Your veterinarian may also prescribe medications to reduce adverse effects of treatment. Retesting Your dog can be retested for heartworms several months after the last melarsomine injection. The goal of treatment is to remove all stages of heartworms. “Slow-Kill” Methods Protocols to manage heartworm infection without using melarsomine are sometimes called “slow-kill” treatments. These protocols consist of giving doxycycline for a month and beginning a specific type of heartworm preventive to remove larvae. Heartworms take from several months to a year or more to die with these protocols. The disadvantage of slow-kill treatment is that it allows adult heartworms to remain in the body for much longer than with adulticide treatment. The worms continue to damage the heart and blood vessels during this time. For this reason, the AHS does not recommend this method as standard treatment. Dogs receiving slow-kill treatment should also have exercise restriction for as long as adult heartworms remain in the body. The advantage of slow-kill treatment is that it costs much less than melarsomine. Slow-kill methods have been proposed for dogs that would otherwise go untreated or be euthanized, like those in shelters or in areas where melarsomine is not available. Slow-kill treatment also offers an option for dogs at high risk of complications from adulticide treatment. For More Information See these resources from the American Heartworm Society: Battling Boredom: Tips for Surviving Cage Rest (PDF) Heartworm Positive Dogs: What Happens if My Dog Tests Positive for Heartworms? Heartworm Treatment Guidelines for the Pet Owner (PDF) Photo by Ryan McGuire Laurie Anne Walden, DVM  Roundworms are some of the most common internal parasites in dogs and cats. They can also infect humans. According to the Centers for Disease Control and Prevention (CDC), 13.9% of people in the United States have antibodies to roundworms, meaning they have been exposed to the parasite at some point in their lives.
How dogs and cats are infected Almost all puppies are born with roundworms. The type of roundworm that most often infects dogs, Toxocara canis, transfers from a mother dog to unborn pups through the placenta. T canis can also pass to puppies through the mother’s milk. Infected animals excrete roundworm eggs in their stool, so dogs can be infected by eating feces or swallowing roundworm eggs in the environment. Dogs can also become infected by eating a small animal (like a rodent) that is carrying roundworms. The most common roundworm in cats is Toxocara cati. Cats and kittens are usually infected by swallowing roundworm eggs in the environment or by eating an infected animal. T cati does not pass to unborn kittens through the mother’s placenta. Ingested T canis and T cati eggs hatch into larvae in the intestines. The larvae migrate through body tissues to the lungs, are coughed up and swallowed, grow into adult worms in the intestines, and begin producing eggs that pass into the environment through the feces. Roundworm larvae can remain dormant in body tissues of adult animals instead of maturing in the intestines. These arrested-development larvae can’t be detected by fecal tests for worm eggs because they don’t produce eggs. Dormant larvae in a pregnant dog can become active and move through the placenta to the pups. In other words, a female dog with a negative test for roundworms can pass roundworms to her puppies anyway. Signs of infection Infected animals often have no symptoms at all. Dogs and cats (especially puppies and kittens) with lots of roundworms may develop a potbelly, vomiting, diarrhea, weight loss, or dull coat. Heavily infected animals sometimes vomit worms, which look a bit like spaghetti noodles, or pass worms in the stool. Treatment and prevention in pets Young puppies and kittens should receive multiple doses of deworming medication. The Companion Animal Parasite Council recommends deworming puppies and kittens every 2 weeks starting at age 2 weeks for pups and 3 weeks for kittens, continuing until they are about 2 months old, and then beginning monthly parasite preventives. Many heartworm preventives also prevent roundworm infection. To reduce the chance your pets will be infected, remove feces from the environment and try to keep them from eating rodents or other wild animals. Have your veterinarian regularly test your pets for parasites, and give them parasite preventives all year round. Infection in humans People can be infected by T canis or T cati if they ingest contaminated dirt or feces. Toxocara eggs can survive in the soil for years. Children and people who own dogs or cats have an increased risk of infection, says the CDC. Many people with Toxocara infection don’t develop serious disease and have no symptoms. But T canis and T cati larvae can migrate through the bodies of humans, as they do in dogs and cats. Larvae that migrate to internal organs (such as the liver) damage these tissues, a disease process called visceral larval migrans or visceral toxocariasis. Symptoms depend on the organs affected. Sometimes larvae migrate to the eye, causing a disease known as ocular larval migrans or ocular toxocariasis. People with this condition may develop retinal inflammation and vision loss. Prevention in humans The CDC recommends these steps to prevent toxocariasis:
For more information Ascarid (Companion Animal Parasite Council) Cat Owners: Roundworms and Dog Owners: Roundworms (Pets and Parasites) Toxocariasis FAQs (CDC) Photo by Berkay Gumustekin Laurie Anne Walden, DVM  Are you tempted to skip your pets' heartworm and flea medicines during the winter? Dogs and cats actually need parasite prevention all year round. Year-round parasite control for pets helps keep the whole family safe from parasite-transmitted disease.
Warm spells during the winter are common in North Carolina, so we can’t count on cold temperatures to suppress insects that carry disease. Mosquitoes, fleas, and ticks can also live through the winter in areas that are protected from the cold. Heartworms Heartworms are transmitted by mosquitoes. Mosquitoes become active when the temperature rises above about 50°F (which happens routinely in North Carolina during the winter). But occasional warm winter days aren’t the only reason pets need year-round heartworm prevention. Heartworm preventives work by killing tiny heartworm larvae that are already in an animal’s bloodstream. These larvae came from mosquitoes that bit the animal in the past month or more. Skipping a month of heartworm prevention could mean that your dog isn’t protected from heartworm larvae that he was exposed to when it was warmer. The American Heartworm Society recommends giving heartworm preventives all year round. Intestinal parasites (worms) Some heartworm preventives also control intestinal parasites like hookworms and roundworms. These parasites can infect humans too. Giving parasite prevention to your pets throughout the year is a sensible safety measure. Fleas Fleas don’t just causing itching. They also transmit diseases like cat scratch disease, tapeworms, and plague. Fleas lay eggs that drop off the infested animal into the environment. This means that flea eggs are present everywhere the animal has been, including inside a home. After the eggs hatch, the larvae and pupae (intermediate stages) can stay dormant for weeks to months before becoming adult fleas. Because fleas can go through their life cycle indoors, they don’t need to wait for warm weather to develop into adult fleas. Flea infestations are easier to prevent than to treat, so the best chance of avoiding a flea problem is to give your pets year-round flea prevention. Ticks Ticks carry many diseases that affect both pets and people. Some tick species, including the type that transmits Lyme disease, are active during the winter when the temperature is above freezing. Ticks tend to live in leaf litter, crevices of buildings, and underbrush. When they’re ready to take a blood meal, they move to grassy areas or shrubbery near paths and latch onto a passing animal or person. Ticks can be hard to see through fur, so you might not realize that your dog has picked up a tick. Because of the risk of serious disease, the safest approach is to limit tick exposure: control ticks around your home and give your pets tick preventives recommended by your veterinarian. Photo by Justin Veenema Laurie Anne Walden, DVM  Both indoor and outdoor cats need vaccines. Vaccination protects cats against infectious diseases that cause serious illness or death. This article describes the vaccines that veterinarians commonly recommend for cats.
One factor that affects vaccination protocols for cats—but not dogs—is the risk of injection-site sarcomas. Some cats develop these malignant tumors at the injection sites of vaccines or other substances. These cancers are uncommon (estimated to occur in 1 to 10 of every 10,000 cats vaccinated) but can be devastating. Although the vast majority of cats do not develop injection-site sarcomas, feline vaccination protocols are designed to balance the tumor risk with the need to keep cats protected from infectious disease. Recommendations include giving cats only the vaccines that are necessary, vaccinating cats no more often than necessary, and using vaccine formulations that are less likely to cause sarcomas. Rabies virus Rabies vaccination is mandated by law for dogs and cats in the United States. In North Carolina, all cats, dogs, and ferrets aged 16 weeks and older must be vaccinated against rabies. Rabies vaccination laws are one reason this fatal disease is very rare in humans in the United States. Around the world, rabies kills tens of thousands of people every year. Cats in North Carolina can and do get rabies. In 2017, cats were 1 of the 5 most common species to test positive for rabies in this state (after raccoons, skunks, foxes, and bats). The total number is low, but the risk is real. Cats that live 100% indoors need rabies vaccines too. Cats sometimes escape outside. And sometimes the unexpected happens, like a bat getting into the house. The presence of a bat indoors is considered a rabies exposure unless the bat is caught and tests negative. A cat that is exposed to rabies but does not have a current rabies vaccination is subject to quarantine for up to 6 months. Also, a cat that bites a person must be quarantined for 10 days; cats without current rabies vaccinations typically spend this quarantine at a facility instead of at home. For more information, see the post about NC rabies laws. In North Carolina, the first rabies vaccine a cat receives lasts for 1 year, and subsequent vaccines can legally be given every 3 years (as long as the vaccine is labeled for 3-year use). If your veterinarian recommends giving your cat a rabies vaccine every year instead of every 3 years, it’s probably because the clinic uses a feline rabies vaccine that is designed to reduce the sarcoma risk and is labeled for 1-year use. Most 3-year rabies vaccines on the market are killed-virus vaccines that contain adjuvants, substances that enhance the immune response. Killed, adjuvanted rabies vaccines have been associated with injection-site sarcomas in cats. A different type of rabies vaccine, a recombinant vaccine, does not contain adjuvants. The most common version of the recombinant rabies vaccine is a 1-year vaccine. Ask your veterinarian which type of rabies vaccine the clinic uses for cats. Feline herpesvirus 1 (rhinotracheitis), calicivirus, and panleukopenia virus Vaccines for feline herpesvirus 1, calicivirus, and panleukopenia virus are often included in a single combination vaccine. The American Association of Feline Practitioners (AAFP) recommends that all cats be vaccinated against these viruses as kittens (in a series of boosters), again 1 year later, and then every 3 years. In past decades, cats received these vaccines every year, but annual vaccination is no longer considered necessary. Feline herpesvirus 1 and calicivirus are 2 of the main causes of feline respiratory disease complex. This illness spreads easily from cat to cat. People can also carry the infectious agents on their clothing, which is how indoor cats can be infected. Infection causes sneezing, discharge from the nose and eyes, conjunctivitis (pinkeye), fever, mouth ulcers, and eye ulcers. Some combination vaccines also cover Chlamydophila (Chlamydia) bacteria, which cause conjunctivitis in cats. Feline panleukopenia virus is very contagious among cats, and infection can be fatal. The virus is similar to canine parvovirus. Like parvovirus, it destroys cells lining the intestine and impairs immune function. In kittens, it can also damage the part of the brain that regulates coordination and balance. Feline leukemia virus Feline leukemia virus is a retrovirus that suppresses immune function and causes cancer. Because the virus impairs immunity, infected cats develop a wide variety of medical problems. Most infected cats die within 3 years of diagnosis. There is currently no cure. Vaccines against feline leukemia virus have been associated with injection-site sarcomas. For this reason, the decision to vaccinate an adult cat usually depends on the cat’s lifestyle and risk factors. However, the AAFP recommends vaccinating all kittens against feline leukemia virus. A nonadjuvanted recombinant vaccine is available. Photo by Sticker Mule on Unsplash Laurie Anne Walden, DVM  Dogs often receive vaccines during their veterinary wellness visits. But what are all of those shots for? This article describes the diseases that canine vaccines help prevent.
Vaccines save lives and are safe, but your dog might not need every vaccine available. Vaccination is a medical procedure, and the choice of vaccines to use is specific to each dog. Talk to your veterinarian about your dog’s risk factors. The American Animal Hospital Association (AAHA) lifestyle-based vaccine calculator is a good starting point. Canine vaccines fall into 2 categories: core vaccines, which are recommended for all dogs, and noncore vaccines, which are recommended for dogs whose lifestyle and environment put them at risk of infection. Core vaccines Rabies Rabies vaccination is mandated by law in the United States. In North Carolina, all dogs, cats, and ferrets older than 4 months must be vaccinated against rabies. Rabies is caused by a virus that is spread through the saliva of infected mammals. After an incubation period that can last up to several months, the virus attacks the brain. Infection is almost always fatal once symptoms begin. The rabies vaccine is an example of an animal vaccine that also protects human health. Read more about rabies in the blog post about NC rabies laws. Canine distemper virus, canine adenovirus 2, and parvovirus Vaccines against canine distemper virus, adenovirus 2, and parvovirus are included in a single combination vaccine. Canine distemper virus infection causes fever and respiratory symptoms (runny nose and coughing) before it proceeds to the nervous system, resulting in seizures and possibly death. Dogs that survive the initial infection can have nervous system abnormalities for the rest of their lives. Canine adenovirus 1 causes infectious canine hepatitis, a potentially fatal liver disease that also affects blood clotting ability. The vaccine against adenovirus 1 can have unwanted effects, so the currently recommended vaccine targets canine adenovirus 2, a variant that causes respiratory illness. The adenovirus 2 vaccine protects against both virus variants. Canine parvovirus is a highly contagious, sometimes fatal infection spread through the feces of infected animals. Puppies and incompletely vaccinated dogs are most likely to be infected. Parvovirus causes severe intestinal disease (diarrhea and vomiting) and disrupts immune function. Antibody tests (vaccine titers) are available for canine distemper virus, adenovirus 2, and parvovirus and may be an alternative to vaccination for some dogs. Noncore vaccines Bordetella bronchiseptica and canine parainfluenza virus Infectious tracheobronchitis, or kennel cough, is a highly contagious respiratory disease caused by a variety of viruses and bacteria. Bordetella bronchiseptica (a bacterium), canine parainfluenza virus, canine distemper virus, and canine adenovirus 2 are some of the organisms that cause kennel cough. Kennel cough is usually mild, but some dogs develop more serious illness. Kennel cough vaccines target Bordetella and sometimes parainfluenza virus. Parainfluenza virus vaccine is also included in some combination distemper/parvovirus vaccines. Leptospira Leptospirosis is caused by infection with Leptospira bacteria. This infection is zoonotic: it can spread between animals and humans. Leptospira are carried by many animal species, including wildlife and farm animals, and are usually transmitted through urine. Animals become infected through any contact with infected urine, including exposure to contaminated water or soil. Leptospirosis ranges from mild illness to kidney failure, liver failure, and death. Canine influenza virus Like kennel cough, canine influenza is a very contagious respiratory illness. Most dogs develop the mild form of flu, but the disease progresses to pneumonia in some dogs and can be fatal. Two strains of influenza virus are known to cause canine flu. AAHA recommends vaccinating at-risk dogs against both strains. Borrelia burgdorferi The bacterium Borrelia burgdorferi is responsible for Lyme disease, a tick-borne disease that causes fever and lameness in many animal species, including dogs and humans. North Carolina is currently on the border of one of the geographic areas with a high risk for Lyme disease. For more information Canine vaccination guidelines (AAHA) Vaccinations (American Veterinary Medical Association) Photo by Jay Wennington Laurie Anne Walden, DVM  Are dogs’ mouths really cleaner than humans’ mouths? Definitely not! You may have read the recent news story of a Wisconsin man who required multiple limb amputations after contracting a bacterial infection from dog saliva. This type of severe infection is extremely rare, but dogs' (and cats’) mouths do harbor quite a variety of bacteria, some of which can make people sick.
The organism responsible for the Wisconsin patient’s infection was Capnocytophaga canimorsus, which is common in dog and cat saliva. Many different Capnocytophaga species normally live in the mouths of healthy dogs, cats, and humans. Up to 74% of dogs and 57% of cats have Capnocytophaga in their mouths. The types of Capnocytophaga that live in human mouths are usually different from those in dogs and cats. Capnocytophaga canimorsus is one of the bacteria that cause infections in people who are bitten by dogs. Although it is usually spread through bites, it’s possible for a person to contract the infection after being licked by a dog. The Wisconsin man was reportedly licked, not bitten. A case report published in 2016 described an older woman who developed serious illness from Capnocytophaga canimorsus that likely came from contact with her own Italian greyhound. She recovered fully after 2 weeks of intensive care and antibiotics. The vast majority of people exposed to this bacterium do not become ill. (Think of all the times you’ve been licked by a dog and haven’t gotten sick.) People who have had their spleen removed, use alcohol to excess, or have compromised immunity (from cancer or HIV infection, for example) are at increased risk of Capnocytophaga infection. Infection can cause severe sepsis (blood infection), gangrene, and inflammation of the heart lining, eyes, lymph nodes, and brain membranes. Infection in a pregnant woman can spread to the fetus. A 2015 review article reported a fatality rate of about 26%. Of course Capnocytophaga are not the only bacteria in our pets’ mouths. Oral cavities—everyone’s, humans included—contain hundreds of different species of bacteria. Most of these bacteria are not zoonotic; that is, they are not spread between animals and people. The ones that do cause illness in people are usually transmitted by bites. However, one study found that several oral bacteria species could potentially be transmitted by close contact between pet dogs and their owners. Prevention For most people, the risk of contracting a severe infection after being licked by a dog is incredibly low. But if your dog has zoonotic parasites like hookworms or roundworms, eats a raw meat diet, or eats feces (including foraging for snacks in the cat’s litter box), it would be a very good idea not to let him lick you in the face. The Centers for Disease Control and Prevention recommends taking extra precautions around animals if you have an increased risk of infection. And everyone should take steps to prevent dog bites, which are much more likely than doggie kisses to cause an infection. Photo by James Barker Laurie Anne Walden, DVM  Zoonotic diseases, or zoonoses, are infections spread from animals to people (and vice versa). Many zoonotic diseases are transmitted by insects, wildlife, and livestock, and some are carried by pets.
Controlling zoonotic disease is a cornerstone of One Health, the concept that human health, animal health, and the environment are all linked. July 6 is World Zoonoses Day and is also the anniversary of the day Louis Pasteur administered the first successful rabies vaccination to a person (July 6, 1885). How to reduce your risk Preventive care for pets helps keep everyone in the family safe. The chance of contracting a zoonotic disease from a dog or cat is low if you take proper precautions. Zoonotic infections are also spread by contaminated food, insects, ticks, farm animals, birds, reptiles, and rodents. Young children, older adults, and people with compromised immune systems are at higher risk than others. These measures can lower your risk:
Find out more at the Centers for Disease Control and Prevention (CDC) website. Zoonoses in companion animals Many zoonotic diseases have been identified, and the CDC estimates that 75% of emerging infectious diseases originated in animals (often insects). Some of the most common zoonotic diseases in companion animals are listed below. Bacteria
Parasites
Other infectious agents
For more information: Zoonotic diseases (CDC) Zoonotic diseases and pets FAQ (American Veterinary Medical Association) Photo by Lydia Torrey |
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