Laurie Anne Walden, DVM
An outbreak of a highly infectious cough has recently been affecting dogs in the Charlotte area. The disease spreads quickly wherever dogs gather: boarding kennels, dog day cares, dog parks, and so forth. Dogs with no symptoms can spread the infection to other dogs.
Most dogs have mild illness and recover at home, but some dogs develop pneumonia and need to be hospitalized. Dogs with pneumonia are at risk of dying.
These are some of the signs of mild illness:
Call your veterinarian if your dog has any of the following signs:
Take your dog to an emergency clinic right away if your dog has signs of trouble breathing:
Many viruses and bacteria cause canine infectious respiratory disease complex (CIRDC), sometimes called kennel cough. Dogs are often infected with more than 1 agent at the same time.
These are some of the agents that cause CIRDC:
Core vaccines (standard for all dogs) give protection against some but not all of the viral agents. Noncore vaccines (optional lifestyle vaccines) are available for canine influenza virus and Bordetella. Vaccines don’t completely prevent CIRDC, but fully vaccinated dogs tend to have shorter and less severe illness. Vaccines also help limit spread of the disease.
Transmission and Risk Factors
The infectious agents spread through respiratory droplets and secretions. Some of the agents stay in the environment and continue to infect dogs for weeks. Dogs are infected by direct contact with an infected dog, by inhaling respiratory droplets, or by licking contaminated objects like bowls, bedding, toys, floors, walls, or people’s hands or clothes.
Because CIRDC can spread silently (by dogs with no symptoms) and some of the agents persist in the environment for a long time, outbreaks can be hard to control.
Any dog that has contact with other dogs or spends time in areas where dogs gather can be infected. Most dogs develop only mild illness and recover within a couple of weeks. Puppies, senior dogs, and dogs with impaired immune function are at higher risk of pneumonia.
Some of the agents that cause CIRDC can also infect cats. The only CIRDC agent known to infect humans is Bordetella, but transmission to people is very rare. Canine influenza is not contagious to people.
Diagnosis and Treatment
The decision to pursue diagnostic tests depends on the individual dog. Dogs with mild illness need physical examination but often don’t undergo other tests if they have symptoms that suggest CIRDC, have been around other dogs (especially in an area with an outbreak of respiratory disease), and are feeling well otherwise. Additional diagnostic tests can include chest radiographs, bloodwork, tests for specific infectious agents, and tests to rule out other causes of coughing.
Treatment can range from just resting at home to being hospitalized for intensive care, depending on the severity of illness. Antibiotics don’t kill viruses, but because CIRDC often involves a combination of organisms, dogs suspected to have a viral respiratory disease (like influenza) might receive an antibiotic as a precaution against bacterial infection.
These are some tips to help keep your dog safe from infectious respiratory disease:
For more information
Image source: https://pixy.org/4653483/
Laurie Anne Walden, DVM
Canine parvovirus is highly contagious among dogs. Infection causes severe illness and is often fatal in dogs that do not receive intensive treatment.
Parvovirus infection is most common in puppies that have not yet completed their initial vaccination series and in adult dogs that are not fully vaccinated against parvovirus. A recent outbreak of parvovirus in Michigan highlighted how quickly the virus can spread, especially in dogs in group housing like animal shelters. All dogs are at risk of infection, but whether a dog becomes ill depends on the dog’s level of immunity to the virus.
Canine parvovirus type 2 (the version responsible for illness) infects domestic dogs and some wild animals, such as foxes, coyotes, wolves, and raccoons. The virus is shed in feces and resists drying, heat, and cold, so it stays in the environment for a long time.
Dogs are infected by ingesting even a tiny amount of feces that contains parvovirus. Dogs can be infected by contact with an infected dog or with contaminated feces, surfaces, or objects. People who have handled infected dogs or contaminated objects can carry the virus on their hands or clothes and infect other dogs. Wild animals might be a source of environmental spread of parvovirus. Animals that have no symptoms can be carriers.
Effects on the Body and Signs of Infection
Canine parvovirus targets the lining of the small intestine, bone marrow, heart, and other organs. Destruction of the intestinal lining causes vomiting, bloody diarrhea, dehydration, loss of barrier protection against bacteria, and inability to absorb nutrients. Some infected animals develop intussusception, a potentially life-threatening condition in which a section of intestine folds into itself like a telescope. White blood cells (part of the immune system) are produced in the bone marrow, so infected animals have low white blood cell counts and impaired immune function. Because of decreased intestinal barrier protection and immune function, infected animals are at risk of septic shock caused by bacterial infection. Young puppies sometimes develop myocarditis, or inflammation of the heart muscle.
These are some of the signs of parvovirus infection:
Death can occur within 3 days after symptoms begin.
Parvovirus infection is often suspected on the basis of the patient’s symptoms, age, and vaccination history. Tests of fecal samples confirm the infection. A rapid test at a veterinary clinic is convenient but sometimes returns a false result, which can delay the diagnosis (this was the case with the outbreak in Michigan). A polymerase chain reaction (PCR) test at a diagnostic laboratory is accurate but takes longer. A blood test showing a low white blood cell count supports a diagnosis of parvovirus, especially in a sick puppy still awaiting a PCR test result.
Dogs with parvovirus infection usually also receive other tests, such as x-ray imaging or ultrasound of the belly.
For most dogs with parvovirus infection, the best chance for recovery is hospitalization for intensive care very soon after symptoms start. No antiviral drug that kills parvovirus is currently available, so treatment consists of measures to reverse dehydration, minimize vomiting and diarrhea, prevent bacterial infection, reduce pain, and restore nutrition. Intensive care for parvovirus infection can be expensive.
Most dogs that receive prompt intensive treatment in the hospital survive. Most dogs that are not treated die. For dogs whose owners can’t afford hospitalization, the success of outpatient treatment depends on the individual dog (illness severity and immune status), type of treatment, and ability of the owners to provide care at home.
The parvovirus vaccine is effective and is one of the core vaccines recommended for all dogs. This vaccine is part of the initial series of puppy vaccines. Puppies need to receive the entire initial vaccine series to have the best chance of being protected. The current recommendation is for puppies to be vaccinated every 2 to 4 weeks from the ages of about 6 weeks to at least 16 weeks. The vaccine is given again 1 year later and then every 3 years throughout the dog’s life. Some dogs never mount an immune response to vaccination (this is not common). Vaccinating all dogs helps keep puppies and vulnerable adult dogs safe.
Limiting a puppy’s exposure to other dogs and to places where other dogs gather reduces the risk of infection. However, this approach can hinder a puppy’s social and emotional development. In general, puppy classes and establishments that have protocols to reduce disease transmission (like requiring vaccines, proper disinfection and hygiene, and isolation of sick dogs) are relatively safe, especially when weighed against the risk of behavior problems in puppies that are not socialized. Exposure to dogs of unknown vaccination and health status, as in dog parks, is riskier. Ask your veterinarian about safe activities for your puppy, and keep your puppy away from sick dogs and other dogs’ feces.
For More Information
Public domain photo by C. E. Price
Laurie Anne Walden, DVM
Monkeypox is a zoonotic disease; it spreads between animals and humans. In the United States, the chance that a person will catch monkeypox from a pet or give monkeypox to a pet is very low. Transmission between people and pets is possible, though, so the Centers for Disease Control and Prevention (CDC) has developed monkeypox guidance for pet owners.
This article summarizes information from the CDC and the American Veterinary Medical Association (AVMA) and is current as of August 24, 2022. See these links for updates:
How Monkeypox Spreads
Monkeypox was first discovered in 1958 in monkeys and since then has been found in many animal species. Rodents and other small mammals (not monkeys) are thought to be the reservoir species that maintain the virus.
Human infection was first reported in 1970 in Africa, and monkeypox has occasionally appeared in other parts of the world. The United States had an outbreak in 2003 after pet prairie dogs were housed with infected animals from Ghana. The 2022 global monkeypox outbreak has involved at least 75 countries.
The monkeypox virus is related to the virus that causes smallpox. The virus infects the host through the respiratory tract, mouth, eyes, or broken skin. These are some of the ways people and animals are infected:
Most transmission during the 2022 outbreak has been through close, direct contact with an infected person.
Animals at Risk
One pet dog has contracted monkeypox, most likely from direct contact with its owners (this was the first reported case of human-to-animal transmission). Chinchillas, prairie dogs, and some types of rabbits, mice, and rats can be infected with the monkeypox virus. Many wild mammals are also susceptible to infection. Cats, guinea pigs, hamsters, and cows can be infected with other viruses in the same genus as monkeypox, but whether they can also be infected with the monkeypox virus is not yet known. The CDC says that it’s best to assume that any mammal can be infected. There have been no reports of infection in animals that are not mammals.
Signs of Monkeypox in Animals
These are some of the signs that infected animals have developed:
These symptoms are nonspecific. Many conditions that are much more common than monkeypox cause the same symptoms in animals. Diagnosing monkeypox requires laboratory tests.
Precautions for Pet Owners: CDC Guidance
If You Think Your Pet Has Monkeypox: CDC Guidance
Monkeypox. American Veterinary Medical Association. Accessed August 24, 2022. https://www.avma.org/resources-tools/one-health/veterinarians-and-public-health/monkeypox
Monkeypox in animals. Centers for Disease Control and Prevention. Updated August 17, 2022. Accessed August 24, 2022. https://www.cdc.gov/poxvirus/monkeypox/veterinarian/monkeypox-in-animals.html
Monkeypox: pets in the home. Centers for Disease Control and Prevention. Updated August 17, 2022. Accessed August 24, 2022. https://www.cdc.gov/poxvirus/monkeypox/specific-settings/pets-in-homes.html
Seang S, Burrel S, Todesco E, et al. Evidence of human-to-dog transmission of monkeypox virus. Lancet. 2022:S0140-6736(22)01487-8. doi:10.1016/S0140-6736(22)01487-8
Image source: CDC
Laurie Anne Walden, DVM
Lyme disease is the most common tick-borne disease in humans in the United States. Dogs can be infected with the bacteria that cause Lyme disease but are much less likely than people to develop symptoms.
Lyme disease is caused by infection with Borrelia burgdorferi bacteria, which are transmitted through tick bites. The tick responsible for infection in the eastern United States is Ixodes scapularis, the deer tick (also called the blacklegged tick). Deer ticks persist in the environment because they’re maintained in populations of deer and other wild animals. For this reason, Lyme disease is endemic—always present in the environment—in some parts of the country.
Deer ticks are smaller than American dog ticks and can be hard to see on animals with fur. The immature nymph stage, which can also transmit B burgdorferi, is tiny and even harder to spot.
Ticks live in woods, grassy areas, and underbrush. Ticks can’t jump or fly; they wait on the tip of a branch or grass blade until a person or animal brushes past, then they latch on. Adult deer ticks can be active when the weather is cool, so Lyme disease isn’t just a summertime risk.
Ticks transmit bacteria to the host animal while they’re taking a blood meal. It takes a day or two for B burgdorferi to pass from a tick into a host, so removing ticks within 24 hours reduces the risk of Lyme disease.
Humans and dogs don’t spread Lyme disease directly to each other, but dogs can bring ticks into the home. Infection in one host species also means that another host species living in the same environment is at risk. If a dog has a positive test for B burgdorferi, for example, that means the dog has been exposed to ticks carrying the bacteria, and people in the dog’s household are at risk for Lyme disease from the same ticks.
Most dogs (95%) infected with B burgdorferi don’t develop any symptoms. In dogs that become ill, symptoms start 2 to 5 months after infection and include fever, loss of appetite, and lameness that can shift from one leg to another. Some infected dogs develop kidney disease.
Cats can be infected with B burgdorferi, but whether they actually get sick from the infection is unknown.
Many dogs are routinely tested for B burgdorferi antibodies at the same time as their annual heartworm test. Antibody tests show whether a dog has been exposed to the bacteria. The American College of Veterinary Internal Medicine recommends yearly antibody tests for all dogs living in or near areas where Lyme disease is endemic. Dogs that test positive have further blood and urine tests to check kidney function and uncover other problems. A positive antibody test in a healthy dog also indicates a possible risk of Lyme disease for people living in the same environment.
Diagnosing Lyme disease in dogs with symptoms is not always straightforward. The same symptoms are caused by many different conditions. A positive antibody test means that at some point the dog was bitten by a tick carrying B burgdorferi, not necessarily that the infection is causing the current symptoms. A diagnosis is usually based on antibody test results (possibly more than 1 type of test), symptoms consistent with Lyme disease, lack of evidence of other causes of symptoms, and response to treatment.
Dogs with symptoms of Lyme disease are treated with antibiotics. Dogs that develop kidney disease need additional treatment.
Tick control is the best way to prevent Lyme disease. Many tick preventives are available for dogs; some are given by mouth and others are applied to the skin. Your veterinarian can suggest products best suited to your dog. Some products are available only by prescription.
The CDC website has lots of information about preventing tick bites in people and pets. See “Preventing Tick Bites” in the Lyme disease section of the CDC website: https://www.cdc.gov/lyme/prev/index.html
Vaccines for Lyme disease are available for dogs. Your veterinarian can advise you on whether you should consider having your dog vaccinated.
1. Lyme disease. Centers for Disease Control and Prevention. Accessed June 25, 2022. https://www.cdc.gov/lyme/index.html
2. Littman MP, Gerber B, Goldstein RE, Labato MA, Lappin MR, Moore GE. ACVIM consensus update on Lyme borreliosis in dogs and cats. J Vet Intern Med. 2018;32(3):887-903. doi:10.1111/jvim.15085
Ixodes scapularis image source: CDC
Laurie Anne Walden, DVM
Yeast skin infection (dermatitis) is common in dogs and also affects cats. Animals with allergies to pollen, grass, and other substances are especially prone to yeast dermatitis and yeast ear infections, so watch for the signs of infection if your pet gets itchy when the seasons change.
Yeast dermatitis is caused by Malassezia organisms on the skin. Malassezia yeasts are part of the normal collection of microorganisms that live on the skin and in the ears of animals. Yeast dermatitis occurs when something about the host animal—skin condition or immune function—causes Malassezia to overgrow or results in an abnormal immune response to Malassezia organisms. Examples of skin conditions that lead to yeast overgrowth are inflammation and increased moisture. Some animals are allergic to Malassezia and develop yeast dermatitis even when the number of organisms on the skin is relatively low.
These are some of the things that increase the risk of yeast dermatitis:
The most commonly affected areas are the face, neck, armpits, belly, inner thighs, feet, and ears, although yeast dermatitis can affect any part of the skin. Yeast dermatitis typically causes these signs:
Samples from affected areas are taken with various methods (tape pressed to the skin, a microscope slide pressed to the skin, cotton swabs, scraping with a blade, or possibly skin biopsy) and examined under a microscope. Animals with yeast dermatitis might have very few Malassezia organisms visible with a microscope. In animals with long-term or recurring yeast dermatitis, other tests are often done to look for an underlying cause.
Yeast dermatitis is treated with topical medication, oral medication, or both. Topical antifungal products include shampoos, mousses, wipes, creams, and so forth. Topical products need enough skin contact time to be effective, so shampoos usually come with instructions not to rinse the lather off for at least 10 minutes. A number of prescription oral antifungal medications are also used.
The choice of treatment type—topical, oral, or both—depends on the individual animal, the part of the body affected, the response to earlier treatment, and the ability of the animal’s owner to apply topical treatments. Not everyone has a place to bathe a large shaggy dog twice a week, for instance. Treatment for yeast dermatitis typically needs to continue for weeks.
For animals with recurring yeast dermatitis, the underlying cause also needs to be treated.
1. Bond R, Morris DO, Guillot J, et al. Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats clinical consensus guidelines of the World Association for Veterinary Dermatology. Vet Dermatol. 2020;31(1):28-74. doi:10.1111/vde.12809
Public domain image source: CDC/Janice Haney Carr
Laurie Anne Walden, DVM
As COVID-19 cases increase, more pets are exposed to the virus, so it’s time to review what we know about COVID-19 and animals. The content of this article is current as of February 7, 2022.
Can animals get COVID-19?
A number of mammal species, including dogs and cats, can be infected with SARS-CoV-2 (the virus that causes COVID-19). Infection in animals is rare compared with infection in people. Most animals infected with the virus have had close contact with people who had COVID-19. Some species have been experimentally infected under controlled conditions; these species might or might not be able to get infected naturally. The virus has not been found in birds, reptiles, amphibians, or fish.
Animals infected with SARS-CoV-2 don’t necessarily get sick. Domestic cats, large cats, dogs, ferrets, hamsters, mink, and gorillas have developed symptoms after being infected. Infection with no symptoms has been found in rabbits, bats, white-tailed deer, and many other species.
Symptoms of SARS-CoV-2 infection in animals are usually mild and nonspecific (lots of other things cause the same symptoms):
Can pets spread COVID-19 to people or other animals?
The risk of catching COVID-19 from a pet is very low. There is no evidence that animals are a significant source of infection for people or that animals carry the virus on their fur. An exception is that SARS-CoV-2 was found to spread in both directions between mink and humans on mink farms in Denmark.
Some animals can infect other animals of the same species. For example, SARS-CoV-2 spreads among white-tailed deer populations without causing symptoms.
Someone in my household has COVID-19. How should I protect my pets?
People with COVID-19 can spread the virus to dogs, cats, and ferrets, although serious illness is rare in animals. The CDC recommends that people with COVID-19 avoid close contact with pets, stay in a room away from pets as much as possible, and wear a mask if they need to be near pets. People carrying the infection should also wash their hands before and after handling animals, avoid sharing food with animals, and avoid kissing their pets or letting their pets lick them in the face. There is no reason to remove pets from the home unless their caregiver is unable to take care of them.
Don’t put a mask on an animal or do anything else that might block its airflow. Increase ventilation or use air filters instead. Don’t use hand sanitizer, disinfecting wipes, or surface cleaners on an animal.
I think my pet might have COVID-19. What should I do?
If your pet has symptoms that seem similar to COVID-19, call your veterinarian. If you have COVID-19, don’t take your pet to the clinic yourself. Your veterinarian will advise you on whether your pet should be seen at the clinic.
Can I have my pet tested for COVID-19?
Don’t use a home test on an animal. Routine animal testing for COVID-19 is not currently recommended because infection is rare in animals, the symptoms are more likely to be caused by something else, and animals aren’t a significant source of SARS-CoV-2 infection in humans. Decisions about animal testing are made by a veterinarian in consultation with public health officials. A veterinarian will need to rule out more common causes of the symptoms before considering SARS-CoV-2 testing. Testing might be done for animals that meet criteria like having exposure to an infected person and having symptoms compatible with SARS-CoV-2 infection (with no other cause found).
Can my pet be vaccinated for COVID-19?
Vaccines for dogs and cats are not available. According to the World Organisation for Animal Health, vaccines are being developed for some animal species that are susceptible to SARS-CoV-2 infection. An experimental COVID-19 vaccine has been given to zoo animals at risk of getting sick from the infection. Mink will likely also be a priority species for vaccine development because of their potential to spread the infection to humans.
Please see these sources for updates and more information:
Public domain image credit: National Institute of Allergy and Infectious Diseases, NIH. Source: NIH Image Gallery
Laurie Anne Walden, DVM
Reptiles and amphibians can carry germs that infect humans and other animals. Zoonotic diseases are diseases that spread from animals to humans. Most of the zoonotic diseases of reptiles and amphibians are caused by bacteria.
Reptiles and amphibians that carry harmful bacteria often have no symptoms and seem completely normal. If you have a reptile or amphibian pet, assume that it is harboring bacteria and use safe handling practices to keep everyone healthy.
Stress, poor nutrition, and an unclean environment increase the chance of a bacterial infection in a reptile or amphibian. Learn all you can about your pet’s husbandry and be sure you’re providing everything it needs: the right food, temperature, humidity, water quality, type and timing of lights, sanitation, and opportunities to engage in normal activities for its species (like climbing, burrowing, or hiding).
Salmonella infection is the most common disease that reptiles and amphibians spread to humans. People most often contract salmonellosis from contaminated food but can also be infected through the many animal species that carry Salmonella. With reptiles and amphibians, sources of infection are the animal itself, the animal’s food (including frozen or live rodents), water, habitat (terrarium or tank), and items inside the habitat.
Any reptile or amphibian can carry Salmonella. Outbreaks in humans in the last decade have been linked to turtles, bearded dragons, and crested geckos. The risk is especially high with very small turtles, which is why it’s illegal in the United States to sell turtles with shells less than 4 inches long.
Humans are infected by getting the bacteria in their mouths, so good hygiene—such as washing hands and keeping habitats clean—helps prevent infection. Symptoms of infection in people include diarrhea, vomiting, cramps, and fever. The risk of severe illness is highest for young children, elderly people, and people with impaired immune systems.
Animals that carry Salmonella are often not sick, so they have no symptoms. Reptiles and amphibians that are sick with salmonellosis might have decreased appetite, decreased energy, and diarrhea.
Mycobacterium bacteria are transmitted through contact with an infected animal or contaminated water. In people, infection causes skin sores and can spread throughout the body, especially in those with weakened immune systems. Reptiles and amphibians carrying Mycobacterium can have no symptoms at all or symptoms related to whichever part of the body the bacteria have infected: skin, lungs, joints, etc.
Aeromonas bacteria live in water and spread through skin wounds or ingestion of contaminated water or other material. Fish, amphibians, and reptiles in aquatic environments can be infected. Symptoms of infection in people include wound infections, vomiting, and diarrhea. As with other types of infection, people with lowered immunity have the highest risk of severe disease. Infected animals can develop discolored limbs, bleeding disorders, and blood infections.
Other Bacteria and Parasites
Like all animals, reptiles and amphibians harbor a huge variety of bacteria, some of which could potentially infect humans. Reptiles and amphibians can also be infected with parasites like Giardia and Cryptosporidium that might pose a risk to people.
Safe Handling Practices
For More Information
See the Reptiles and Amphibians section of the CDC website: https://www.cdc.gov/healthypets/pets/reptiles.html
Photo by Vitya Lapatey on Unsplash
Laurie Anne Walden, DVM
Ringworm (dermatophytosis) is a skin infection caused by fungi. It’s called ringworm because in humans it sometimes looks like a small circular skin rash. Ringworm isn’t caused by a worm, despite the name.
Ringworm is zoonotic: it spreads between animals and people. Many animal species carry ringworm. The infection is transmitted by contact with an infected host or with contaminated soil, bedding, or other objects in the environment.
Causes and Risk Factors
Many types of fungi cause ringworm in different host species (animals and people). The most common fungi that infect cats and dogs are Microsporum canis and Trichophyton mentagrophytes, whose natural hosts are animals, and M gypseum, which is found in soil.
Fungi tend to infect abraded skin, not healthy intact skin, so scratches and scrapes—for example, from scratching itchy skin—make ringworm more likely.
The pet animals most likely to have ringworm are young puppies and kittens, free-roaming animals, and animals living in warm or humid climates. Working and hunting dogs are more likely than indoor dogs to encounter fungal spores in the environment.
Signs of Infection
In dogs and cats, ringworm doesn’t typically cause the ringlike skin lesion that it causes in humans. Ringworm in animals mimics other skin diseases and can’t be diagnosed just by its appearance. Some animals have no visible signs at all. These are some of the signs of ringworm in dogs and cats:
Ringworm isn’t usually itchy. However, skin conditions that an animal might have at the same time as ringworm could cause itchy skin, and these conditions can also make a fungal infection more likely.
A combination of diagnostic tests might be needed to confirm a fungal infection and monitor the response to treatment. M canis infection causes hairs to glow fluorescent green under a Wood’s lamp, a type of ultraviolet light source, although the fluorescence can be difficult to see in some patients. Samples collected by plucking hairs or brushing affected skin can be submitted for fungal culture or polymerase chain reaction testing.
In animals and people with normal immune function, ringworm can clear on its own without treatment, although this can take weeks or months. The goals of treatment are to clear the infection more quickly and prevent the infection from spreading to others.
In dogs and cats, treatment often involves both topical treatment and oral medication. Topical treatment (like antifungal shampoos) reduces the risk of disease transmission and environmental contamination. Oral medication treats the fungal infection at its source.
Decontaminating an infected animal’s surroundings might be part of the treatment plan. Environmental decontamination prevents false-positive culture results (caused by noninfective fungal spores carried on the fur) that might lengthen the course of treatment.
These steps help prevent ringworm from spreading to people and other animals:
1. Moriello KA, Coyner K, Paterson S, Mignon B. Diagnosis and treatment of dermatophytosis in dogs and cats. Clinical Consensus Guidelines of the World Association for Veterinary Dermatology. Vet Dermatol. 2017;28(3):266-e68. doi:10.1111/vde.12440
2. Ringworm. Centers for Disease Control and Prevention. Accessed September 9, 2021. https://www.cdc.gov/healthypets/diseases/ringworm.html
Image source: CDC Public Health Image Library
Laurie Anne Walden, DVM
Vaccines for dogs and cats are safe, especially compared with the risk of disease. Most animals don’t have any untoward symptoms after receiving a vaccine. But vaccines, like any other medicine, can have some side effects.
Vaccination produces an immune response, and inflammation is part of the immune response. Most of the symptoms (if any) that animals have after vaccination are caused by normal inflammation, meaning that the immune system is acting the way it’s supposed to act when it’s stimulated.
Allergic (hypersensitivity) reactions to vaccines are uncommon in dogs and cats but can be serious. These reactions are caused by an inappropriate immune response. The most severe type of hypersensitivity reaction is anaphylaxis, which can be life threatening.
In one study of dogs in the United States, the rate of vaccine-associated adverse events, including everything from normal inflammatory responses to anaphylaxis, was 0.38% (38 events per 10,000 vaccine doses). Anaphylaxis accounted for 1.7% of the adverse events. The risk of adverse events was highest in small-breed dogs and dogs who received multiple vaccines at the same time.
These are some of the common mild vaccine effects you might notice in your dog or cat. In most cases it’s safe to monitor these symptoms at home. If any of these symptoms last longer than a day or if your pet seems very uncomfortable, contact your veterinarian.
More Serious Symptoms
Allergic reactions to vaccines appear minutes or several hours after vaccination. Anaphylaxis can start with these symptoms and is a medical emergency. Seek veterinary care right away if your pet has any of these symptoms.
Lumps at Injection Sites
Most small, firm lumps at vaccine injection sites are caused by inflammation and resolve in a couple of weeks without treatment. An injection-site lump or swelling that is still present after 3 weeks or is enlarging should be checked by a veterinarian. Injection-site cancer is rare but can happen in cats (vaccine protocols and formulations for cats minimize this risk as much as possible).
Vaccines could—at least in theory—be linked to autoimmune diseases, in which the immune system targets cells of the body. Immune-mediated hemolytic anemia (affecting red blood cells) and thrombocytopenia (affecting platelets) occur in animals, but the association of these disorders with vaccination isn’t clear. The presence of an autoimmune disease would affect future vaccination decisions for the animal, though.
If Your Pet Has Had a Vaccine Reaction
Tell your veterinarian if your pet has had any vaccine-related symptoms. Your veterinarian will determine if your pet most likely had a normal inflammatory response or an allergic reaction. The decision on how to proceed with future vaccinations depends on the symptoms, the animal’s overall health, and the animal’s individual risk for vaccine-preventable diseases.
Depending on the circumstances, options for future vaccinations might include dividing vaccines among several visits instead of giving multiple vaccines all at once, giving medication (like an antihistamine) before vaccination, using a different type of vaccine, or discontinuing a vaccination. Vaccine titers—levels of antibody in the blood—indicate whether an animal is likely to still be protected by earlier vaccines, so titer testing can replace vaccination in some cases.
Some of these options don’t apply to rabies vaccination, which is mandated by law. In North Carolina and South Carolina, as in many states, veterinarians cannot give medical exemptions for rabies vaccination, and rabies antibody titers can’t be used instead of vaccination.
1. Moore GE, Guptill LF, Ward MP, et al. Adverse events diagnosed within three days of vaccine administration in dogs. J Am Vet Med Assoc. 2005;227(7):1102-1108. doi:10.2460/javma.2005.227.1102
2. Tizard IR. Adverse consequences of vaccination. Vaccines for Veterinarians. 2021;115-130.e1. doi:10.1016/B978-0-323-68299-2.00019-8
3. AAHA canine vaccination guidelines: vaccine adverse reactions. American Animal Hospital Association. Accessed August 27, 2021. https://www.aaha.org/aaha-guidelines/vaccination-canine-configuration/frequently-asked-questions/how-can-adverse-reactions-be-managed/
4. Rabiesaware.org. Accessed August 27, 2021. http://www.rabiesaware.org/
Photo by Raghavendra V. Konkathi on Unsplash
In March and April 2021, outbreaks of Salmonella infection linked to wild songbirds, ground turkey, and small turtles were reported, and several brands of dog and cat food were recalled because of possible Salmonella contamination.[1,2]
Dogs and cats are at risk of illness from salmonellosis. However, healthy adult animals infected with these bacteria often become carriers with no symptoms. Salmonella are zoonotic—they spread between humans and other animals—so a major concern with Salmonella infection in animals is that it increases the risk for people.
Salmonella are spread through the feces of infected animals. These are some of the animals that carry Salmonella and expose people to infection:
Contaminated Food and Water
People and animals are most often infected with Salmonella by eating food or drinking water contaminated with feces. Handling contaminated food is also a risk if you don’t wash your hands thoroughly afterward to avoid bringing the bacteria to your mouth. Potential sources of Salmonella infection in humans, dogs, and cats include the following:
Animals carrying Salmonella shed the bacteria into their environment. Animals that seem completely healthy can be Salmonella carriers. It’s safest to assume that Salmonella are present anywhere an animal of a high-risk species spends time: reptile habitats, terrariums, aquariums, chicken coops, animal pens, and so forth. Bedding and water tanks or bowls (especially in reptile and amphibian habitats) can also be contaminated.
Bird Feeders and Birdbaths
Wild songbirds aren’t just Salmonella carriers; sometimes they get sick and die of Salmonella infection. The type of Salmonella that birds carry, S typhimurium, is contagious to people and other animals. Cats who hunt birds or hang out under bird feeders and birdbaths can be infected.
Many adult dogs and cats exposed to Salmonella don’t get sick but can still spread the bacteria. Puppies, kittens, stressed animals, immunosuppressed animals, and animals with other diseases are more likely to become ill with salmonellosis. Symptoms include lethargy, loss of appetite, vomiting, fever, and diarrhea. The infection can be fatal in fetuses and newborns.
Salmonellosis in cats infected by birds is called songbird fever. Symptoms are similar to salmonellosis in other animals: vomiting, bloody diarrhea, lethargy, and loss of appetite.
As with most diseases, specific treatment depends on the individual animal’s needs. Salmonella can develop resistance to antibiotics, so animals with mild symptoms might be treated only with supportive measures. In some cases, the choice of antibiotic is based on results of culture and antimicrobial sensitivity tests.
Be aware that raw meat pet diets are a common source of Salmonella. The CDC recommends these measures to prevent Salmonella infections:
1. Reports of selected Salmonella outbreak investigations. Centers for Disease Control and Prevention. Accessed April 20, 2021. https://www.cdc.gov/salmonella/outbreaks.html
2. Recalls, market withdrawals, & safety alerts. US Food & Drug Administration. Accessed April 20, 2021. https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts
3. Salmonella infection. Centers for Disease Control and Prevention. Accessed April 20, 2021. https://www.cdc.gov/healthypets/diseases/salmonella.html
4. Kukanich KS. Update on Salmonella spp contamination of pet food, treats, and nutritional products and safe feeding recommendations. J Am Vet Med Assoc. 2011;238(11):1430-1434. doi:10.2460/javma.238.11.1430
5. Marks SL, Rankin SC, Byrne BA, Weese JS. Enteropathogenic bacteria in dogs and cats: diagnosis, epidemiology, treatment, and control. J Vet Intern Med. 2011;25(6):1195-1208. doi:10.1111/j.1939-1676.2011.00821.x
6. Salmonella outbreak linked to wild songbirds. Centers for Disease Control and Prevention. April 1, 2021. Accessed April 20, 2021. https://www.cdc.gov/salmonella/typhimurium-04-21/index.html
Image source: Shenandoah National Park (photo by N. Lewis, NPS)
Laurie Anne Walden, DVM
The contents of this blog are for information only and should not substitute for advice from a veterinarian who has examined the animal. All blog content is copyrighted by Mallard Creek Animal Hospital and may not be copied, reproduced, transmitted, or distributed without permission.