- Zoonoses in veterinary medicine: The 5 most important transmission routes and how to protect yourself
- 1. Direct contact – when proximity becomes a danger
- 2. Droplets and aerosols – invisible danger through the air
- 3. Needlestick injuries – often underestimated, with serious consequences
- 4. Bite and scratch injuries – small wounds with a high risk
- 5. Fecal-oral transmission – more than just a hygiene problem
- 🦠 Other important zoonoses in small animal practice – what you absolutely need to know
- Zoonoses in small animal practice: How dangerous are they really?
- 🔴 High risk – frequent or particularly dangerous for people
- 🟠 Medium risk – significant depending on the situation, rarely serious
- 🟢 Low risk – rarely dangerous or only dangerous under special circumstances
- Frequently Asked Questions about Zoonoses in Veterinary Medicine
- 🩺 Summary: Zoonoses in veterinary medicine – relevance, risks and protection in everyday practice
- Conclusion: Protection through knowledge and consistent action
Zoonoses in veterinary medicine: The 5 most important transmission routes and how to protect yourself
Inspired by the article by Dr. J. Scott Weese, Ontario Veterinary College, Guelph, Canada
Whether it's a dog, cat, or exotic pet – in every veterinary practice, there's a risk of coming into contact with pathogens that can also make humans sick. These so-called zoonoses range from easily treatable fungal skin infections to life-threatening infections like rabies. What many forget: Even seemingly healthy animals can shed pathogens and endanger others – unnoticed and without showing clinical symptoms.
But there is good news: If we understand the ways in which zoonotic pathogens are transmitted, we can take targeted protective measures – and significantly reduce the risk for ourselves, our team and the animal owners.
This article presents the five most common transmission routes of zoonotic diseases in veterinary medicine. For each route, we highlight the most important risks, identify relevant pathogens, and provide specific tips for prevention. Let's get started:
1. Direct contact – when proximity becomes a danger
Where does the risk lie?
Direct contact with an animal's skin, mucous membranes, saliva, urine, or other bodily fluids can lead to the transmission of a wide variety of pathogens. Often, it is enough for the pathogens to enter the body through even the smallest, invisible skin injuries (microabrasions) or mucous membranes. People with weakened immune systems are particularly at risk—that is, children, pregnant women, the elderly, or individuals undergoing immunosuppressive therapy.
Examples of transmissible pathogens:
- Pasteurella spp., Staphylococcus spp., Escherichia coli (including multi-resistant variants such as MRSA)
- Leptospires through urine contact
- Brucella canis upon contact with amniotic fluid, placenta or sperm
- Dermatophytes (skin fungi) through mere skin contact
What really protects?
- Always wear appropriate personal protective equipment: lab coat, gloves, and, if necessary, safety goggles.
- Wash your hands – regularly, thoroughly, and after every contact with animals.
- Training for all employees on the safe handling of high-risk patients
2. Droplets and aerosols – invisible danger through the air
Where does the risk lie?
Pathogens can also be transmitted through tiny droplets in the air we breathe – for example, when coughing, sneezing, or even speaking. In practice, such aerosols are often generated unnoticed, for instance, during certain diagnostic or therapeutic procedures.
Examples of transmissible pathogens:
- Bordetella bronchiseptica (Kennel cough) – even in asymptomatic animals
- Coxiella burnetii (Q fever), especially in pregnant cats
- SARS-CoV-2 – documented transmission from cat to human
- Yersinia pestis (Plague) – rare, but regionally relevant
What really protects?
- Wear protective masks – ideally FFP2/N95 – if highly infectious agents are suspected.
- Don't forget eye protection – pathogens can also enter through the mucous membranes in the eye.
- Keep your distance, ventilate rooms regularly
- Isolate animals with respiratory symptoms if possible.
3. Needlestick injuries – often underestimated, with serious consequences
Where does the risk lie?
Injuries from needles and other sharp instruments are unfortunately common in the hectic daily routine of veterinary practice. Besides the injury itself, there is a risk of introducing pathogens directly into the tissue – in both animals and humans.
Examples of transmissible pathogens:
- Staphylococcus aureus (also MRSA)
- Bartonella spp. – known through cat scratch disease, but also transmissible via needle bites
- Leishmania spp., Blastomyces spp. – especially in aspiration procedures
What really protects?
- Do not recap needles by hand – if necessary, use a one-handed technique or tools.
- Dispose of directly after use in tested safety containers
- Document and analyze all needlestick injuries.
- Use of safety-optimized instruments (e.g., self-closing needles)
4. Bite and scratch injuries – small wounds with a high risk
Where does the risk lie?
A bite or scratch can happen quickly – whether during a blood draw or nail trimming. The mechanical injury is one thing, but the much greater risk lies in the pathogens that can be transmitted.
Examples of transmissible pathogens:
- Rabies virus (Rabies) – always take precautions in affected regions
- Capnocytophaga canimorsus – can be fatal in immunocompromised individuals
- Streptobacillus moniliformis – Pathogen of rat-bite fever
- Various fungi and bacteria from the animal's oral flora
What really protects?
- Recognize bite risks and take early de-escalation action.
- After a bite: Immediately and thoroughly rinse the wound and seek medical attention.
- Prophylactic antibiotic administration in high-risk patients or specific locations
- Always document everything and inform the health department if necessary.
5. Fecal-oral transmission – more than just a hygiene problem
Where does the risk lie?
Feces are a significant vector for zoonotic pathogens – especially in young animals or animals with diarrhea. Transmission often occurs indirectly: via contaminated hands, surfaces, or even pens, smartphones, or food.
Examples of transmissible pathogens:
- Campylobacter spp., Salmonella spp. – common in young animals
- Giardia spp. – often not zoonotic, but potentially transmissible
- Echinococcus multilocularis – especially in case of contact with foxes
- Multidrug-resistant intestinal bacteria – increasingly problematic
What really protects?
- Gloves and protective clothing if necessary in case of contact with feces
- Isolate animals with diarrhea, clean and disinfect them thoroughly.
- Do not store human food near animal samples.
- Do not touch any devices (e.g., pens, phones) with contaminated gloves.
🦠 Other important zoonoses in small animal practice – what you absolutely need to know
In addition to the five main transmission routes, there are numerous zoonotic diseases that can occur in small animal practice – some rare, but with potentially serious consequences for humans. Below you will find an overview of all other zoonoses from the specialist document:
🦜 Avian influenza („bird plague“)
Pathogen: Highly pathogenic avian influenza viruses
Transmission: Aerogen from close contact with infected birds
Frequency: Rarely
Symptoms in humans: Severe flu-like illness with a potentially fatal outcome
Remark: Highly contagious animal disease – particularly relevant in bird keeping and animal welfare.
🦠 Tularemia („rabbit fever“)
Pathogen: Francisella tularensis
Transmission: Transmission occurs through ticks, direct contact with animals, and inhalation of infectious particles.
Frequency: Very rare, but increasingly so due to imports
Symptoms in humans: Ulceroglandular form, pneumonia, abdominal pain, fever, swollen lymph nodes
Remark: Dogs and cats can also transmit pathogens – intensify protective measures if infection is suspected.
🧬 Tuberculosis
Pathogen: Mycobacterium tuberculosis, M. bovis
Transmission: Aerogen, contact with excretions
Frequency: Very rare
Symptoms in humans: Lung involvement, pyogranulomatous inflammation in various organs
Remark: Zoonotic risk from contact with infected exotic animals or birds, especially in animal welfare facilities
🧫 Yersiniosis
Pathogen: Yersinia enterocolitica, Y. pseudotuberculosis
Transmission: Fecal-oral transmission, primarily through rodents, cats, and birds
Frequency: Rarely
Symptoms in humans: Lymphadenitis, fever, pharyngitis, in severe cases also arthritis, iritis, skin rashes
Remark: Hygiene measures are particularly important when handling excrement.
Newcastle Disease
Pathogen: Newcastle disease virus
Transmission: Aerogenic, contact with conjunctival secretions of infected birds
Frequency: Very rare in humans
Symptoms in humans: Conjunctivitis, local lymph node swelling
Remark: Highly contagious for birds, notifiable disease – wear protective goggles if in contact with the disease.
📉 Canine Brucellosis
Pathogen: Brucella canis
Transmission: Contact with abortifacient material or genital secretions, rarely also via airborne transmission
Frequency: Very rare in Central Europe – often due to imports
Symptoms in humans: Often asymptomatic; possible symptoms include fever, organ swelling, and flu-like symptoms.
Remark: Especially with animals from abroad, consider the differential diagnosis.
This list clearly shows that even rare zoonoses should not be underestimated in small animal practice. Many of these diseases only occur in certain regions or in certain animal species – but in the age of globalization, animal imports and animal welfare transports, they are also gaining importance in Central European practices.
🧾 Recommended protection strategies for everyday practice
- Isolate suspected cases and involve as few people as possible.
- Wear protective equipment consistently (gown, gloves, mask and safety goggles if necessary)
- Regularly train and monitor hygiene and disinfection plans.
- Actively inquire about the animals' travel history, origin, and living conditions during the anamnesis interview.
- Protect particularly vulnerable individuals in the team (pregnant women, immunocompromised individuals) or adapt tasks.
🧑⚕️ Zoonoses in small animal practice: How dangerous are they really?
Veterinary practice involves a certain degree of daily health risk – many of these risks can be managed routinely, while others are underestimated or even overlooked. Zoonoses are among the most misunderstood dangers. Although serious incidents are rare, transmission can occur rapidly, especially in hectic practice environments, with inadequate protective clothing, or insufficient hygiene.
Below you will find a practical guide. Assessment of the danger posed by zoonotic diseases – divided into three relevance categories:
🔴 High risk – frequent or particularly dangerous for people
These pathogens represent a clear danger in everyday practice that is important – either because they occur regularly, are highly contagious, or can be fatal in certain cases.
| disease | Hazard | remark |
|---|---|---|
| Rabies (Lyssavirus) | Life-threatening, no cure | Fortunately very rare in Central Europe, but relevant for imported animals. Always take bites seriously. |
| Leptospirosis (Leptospira spp.) | Severe systemic illness possible | Transmission via urine – high risk in infected, asymptomatic dogs. |
| Q fever (Coxiella burnetii) | Highly infectious via aerosols | Especially transmissible in pregnant cats and rodents – even without symptoms. |
| Psittacosis (Chlamydia psittaci) | Pneumonia, myocarditis, severe course possible | Highly relevant in case of bird contact – protective measures urgently needed. |
| Bartonellosis (cat scratch disease) | Common, especially dangerous in immunocompromised individuals | It happens regularly – don't underestimate scratches and bites. |
| Salmonellosis / Campylobacteriosis | Gastrointestinal diseases with complications | Particularly problematic for reptiles, young animals, and patients with diarrhea. |
| Toxoplasmosis (T. gondii) | Danger to pregnant women (miscarriage, birth defects) | High relevance when in contact with cat feces. |
👉 Practical recommendation:
These diseases should always be considered in daily practice when dealing with high-risk patients and situations. Protective measures such as gloves, masks, isolation, and consistent hygiene are not optional, but essential.
🟠 Medium risk – significant depending on the situation, rarely severe
These zoonoses are coming occasionally before, are usually easily treatable, but require increased attention in certain patient groups or circumstances.
| disease | Hazard | remark |
|---|---|---|
| Dermatophytosis (skin fungi) | Mostly harmless, but annoying and time-consuming. | Common in cats and young animals – easily transmitted through contact or environment. |
| Echinococcosis (E. multilocularis) | Slow but potentially fatal progression | Transmission occurs primarily through contaminated environments or fur. |
| Yersiniosis | Usually mild, but complications are possible. | Fecal-oral – especially in cats, birds, and rodents. |
| Cryptosporidiosis / Giardiasis | Diarrhea, dehydration | More common in young animals; immunocompromised people are particularly affected. |
| Sporotrichosis | Skin and lymph node involvement | Rare, but with a prolonged course in immunocompromised individuals. |
👉 Practical recommendation:
Targeted hygiene measures (e.g., cleaning, gloves for patients with diarrhea) are usually sufficient. However, special caution is advised for immunocompromised employees or pet owners.
🟢 Low risk – rarely dangerous or only dangerous under special circumstances
These pathogens are either very rarely or only under certain conditions These factors are problematic for humans. Nevertheless, they should be known in the background – especially in travel histories or animal imports.
| disease | Hazard | remark |
|---|---|---|
| Canine brucellosis (B. canis) | Often asymptomatic | Mostly import-related – consider brucellosis in cases of unexplained abortions. |
| Tularemia (Francisella tularensis) | Severe course possible | Hardly relevant to practice – v. a. in lagomorphs. |
| Newcastle Disease Virus | Mild conjunctivitis | Harmless to humans, but highly contagious to birds. |
| Avian influenza (HPAI) | A severe course is theoretically possible. | Isolated cases so far in Europe – protection against contact with birds is recommended. |
| Tuberculosis (M. bovis / tuberculosis) | Organ involvement, rare | The risk increases with exotic animals, wild animals, and animals from abroad. |
👉 Practical recommendation:
These diseases should be considered in the differential diagnosis if there is a specific suspicion (e.g., animal welfare import, travel, unusual symptoms). They are relatively rare in everyday practice, but important to recognize during outbreaks.
Frequently Asked Questions about Zoonoses in Veterinary Medicine
How can I tell if an animal is carrying a zoonotic disease if it shows no symptoms?
This is one of the biggest challenges in small animal practice – because many animals that shed zoonotic pathogens show no clinical symptoms whatsoever. This is referred to as... asymptomatic carriers. Examples include cats with Toxoplasma gondii, dogs with Leptospira spp. or parrots with Chlamydia psittaci. These animals appear healthy, but can spread pathogens via urine, feces, saliva, or aerosols.
In practice, therefore, the medical history is a key factor in risk assessment:
Did the animal come from abroad, from an animal welfare organization, or from a group of animals kept together?
Have there been any recent births, abortions, or cases of uncleanliness?
Is any other animal in the household showing symptoms?
Does the pet owner have a known immunodeficiency or is she pregnant?
Additionally, an assessment based on... Husbandry conditions, animal species and age (e.g., young animals are more likely to shed toxins) Campylobacter spp. or Giardia spp.In cases of suspected zoonosis – even without symptoms – the application of standard hygiene measures such as gloves, protective clothing and disinfection is essential.
What should I do if I am bitten or scratched by a patient?
Bites and scratches are not only painful, but also pose a high risk of infection – both bacterial and viral. Even small, superficial injuries can lead to serious complications, especially in immunocompromised individuals.
The following measures should be taken immediately:
First aid:
Rinse the wound immediately and thoroughly under running water (for at least 5 minutes).
Disinfect the wound with an antiseptic solution (e.g., PVP-iodine, octenidine).
Do not apply any ointments or wound dressings until a medical assessment has been carried out.
Documentation:
Document the incident: time, animal details, type of injury.
Check reporting requirements (e.g., in case of possible rabies exposure).
Medical consultation:
In cases of deep wounds, high-risk patients, or unclear vaccination status of the animal, a medical examination is advisable.
Post-exposure prophylaxis (e.g., in case of suspected rabies) may be necessary.
Tetanus protection & other vaccinations:
Check your tetanus protection – get a booster if necessary.
Consider hepatitis or rabies vaccinations depending on the region and occupation.
Pro tip: In practice, a standardized procedure for bite injuries should always be in place, including first aid materials, contact details for reporting, and medical facilities.
Which zoonoses are particularly dangerous for pregnant women or immunocompromised individuals?
Pregnant women, older people, children and immunosuppressed patients (e.g. due to illness or medication) are at increased risk. increased risk of severe or atypical courses of zoonotic infections. Some pathogens that only cause mild symptoms in healthy adults can be life-threatening or lead to complications in these groups.
Highly relevant zoonoses in this context are:
Toxoplasmosis: A first-time infection during pregnancy can lead to miscarriage, malformations, or neurological damage in the fetus.
Listeriosis & Leptospirosis: Severe systemic infections with fever, sepsis, and organ involvement are possible.
Bartonellosis „Cat scratch disease“ can lead to chronic courses with fever, hepatitis or endocarditis in immunocompromised individuals.
Cryptosporidiosis & Giardiasis: Prolonged diarrhea, severe fluid loss and weight loss are possible.
Echinococcosis Long-lasting asymptomatic, but potentially life-threatening due to organ cysts.
Practical recommendation:
As soon as it is known that a female employee is pregnant or that someone in the team or among the pet owners is immunocompromised, these persons should not with high-risk patients (e.g., animals with diarrhea, unexplained wounds, giving birth, animals from abroad). Additionally, they should strictly hygienic training be and do not perform any activities involving direct contact with feces, blood or mucous membranes.
Which protective measures are truly effective in everyday practice – even when things need to happen quickly?
Daily life in the Veterinary practice It's often hectic – so protective measures can sometimes feel like an additional burden. But it's precisely in such moments that most incidents occur. The good news: Already simple measures can one big difference make.
These protection strategies have proven to be particularly effective:
Disposable glovesAlways wear when in contact with bodily fluids, diarrhea, wounds, or when collecting stool.
Hand hygieneThorough handwashing or alcoholic hand disinfection between each patient – even if gloves were worn.
Protective gowns & overshoesEspecially in wards, laboratories, or with patients suspected of having an infection.
Masks & protective goggles: In patients with respiratory diseases, during childbirth, or when a zoonotic risk is suspected.
Separation of human and animalNever bring food, drinks, or personal items into treatment rooms.
Regular cleaning & disinfectionSurfaces, tables, instruments – especially after infectious patients.
Information flow within the teamWho is at risk? Who had contact with which animal? Who needs special caution?
Tip: Standard operating procedures (SOPs) in practice create clarity – especially for new employees or in stressful situations.
When do I have to report a zoonotic disease – and to whom?
In Germany (and also in Switzerland and Austria), some zoonoses are subject to the Reporting obligation under the Infection Protection Act (IfSG) or veterinary regulations. This means: If there is a suspected case, a confirmed infection, or a positive test result, Certain departments need to be informed, usually the responsible health or veterinary office.
The following are subject to mandatory reporting (depending on the region):
rabies – immediate reporting obligation in case of suspicion or contact
Psittacosis (Ornithosis) – must be reported in case of suspected bird contact
Q fever, Tularemia, salmonellosis, Leptospirosis – relevant to humans and animals
Echinococcosis – especially when detected in slaughter samples, but also clinically
Campylobacteriosis, Toxoplasmosis – depending on pathogen detection in humans
Message to:
Public Health Department (in case of human illness or contact)
Veterinary Office (in case of animal detection or suspicion in practice)
Note the laboratory results: Laboratories are often required to report, but medical practices should still consider this as well.
Important: The obligation to report does not automatically mean that quarantine or business closures will follow – but primarily serves the purpose of Protection of humans and animals as well as the Infection control in public health.
🩺 Summary: Zoonoses in veterinary medicine – relevance, risks and protection in everyday practice
Zoonoses in veterinary medicine are a ubiquitous, often underestimated risk that affects veterinarians and their entire practice team on a daily basis. The term "zoonoses in veterinary medicine" encompasses a wide range of diseases that can be transmitted between animals and humans – many of them even when the animal appears outwardly perfectly healthy. Therefore, a sound understanding of zoonoses in veterinary medicine is essential for safe practice in everyday veterinary medicine.
Zoonoses in veterinary medicine can be caused by various pathogens such as bacteria, viruses, parasites, or fungi. Their transmission routes are equally diverse: direct contact, respiratory droplets, bodily fluids, stings, bites, scratches, or fecal-oral transmission are among the most common. For this reason, knowledge of zoonoses in veterinary medicine is important not only for veterinarians but also for veterinary assistants, cleaning staff, trainees, and even pet owners.
Zoonoses in veterinary medicine deserve special attention when it comes to high-risk individuals: pregnant women, children, the elderly, and immunocompromised people are often more susceptible to infections. The importance of zoonoses in veterinary medicine is therefore steadily increasing, particularly in the areas of animal welfare, companion animal husbandry, and the importation of animals from abroad. With increasing travel and animal imports, the geographical boundaries for zoonoses in veterinary medicine are continuously expanding.
Among the most relevant zoonoses in veterinary medicine are rabies, leptospirosis, psittacosis, Q fever, toxoplasmosis, and campylobacteriosis. Many of these diseases are severe or chronic in humans – especially if they are not detected in time. Dermatophytoses and cat scratch disease are further examples of zoonoses in veterinary medicine that, while common in everyday life, are easily controlled with consistent hygiene.
A systematic approach to protection is crucial for the safe handling of zoonoses in veterinary medicine: personal protective equipment, standardized hygiene measures, regular training, and a thorough medical history help to detect and prevent transmission early. Standard Operating Procedures (SOPs) play a central role here, providing safety and clarity in the management of zoonoses in veterinary medicine.
Even in cases of needlestick or bite injuries, the following applies: Zoonoses in veterinary medicine should never be underestimated. Even the smallest skin injuries can be entry points for dangerous pathogens. Therefore, professional practice organization should include an emergency plan that regulates the correct handling of incidents related to zoonoses in veterinary medicine – including wound care, documentation, tetanus status, and, if necessary, reporting.
Many zoonotic diseases in veterinary medicine are also notifiable. Depending on the federal state or country of origin, different reporting requirements may apply – for example, for psittacosis, Q fever, or brucellosis. Transparent communication with health and veterinary authorities is therefore essential when zoonotic diseases are detected or suspected in veterinary medicine.
The topic of zoonoses in veterinary medicine is essential for training and continuing education. A well-trained team can identify at-risk animals early, pay attention to warning signs, and act proactively – both in the treatment room and during cleaning or when handling infectious material. Therefore, zoonoses in veterinary medicine belong in every training manual, on every team meeting agenda, and in every hygiene plan.
Especially today, as One Health – the close connection between veterinary, environmental, and human medicine – gains increasing importance, zoonoses in veterinary medicine symbolize the necessity of interdisciplinary thinking. Because protecting against zoonoses in veterinary medicine protects not only ourselves, but also our fellow human beings – and ultimately the entire healthcare system.
Whether as a practicing veterinarian, veterinary assistant, or cleaning professional – anyone working in veterinary medicine will sooner or later come into contact with zoonoses. Being prepared protects both yourself and others. Zoonoses in veterinary medicine are not uncommon – but with knowledge, structure, and teamwork, they are very manageable.
Conclusion: Protection through knowledge and consistent action
Zoonoses are an everyday risk in veterinary medicine – but they don't have to become a danger to you, your team, or your clients. Understanding the transmission routes allows you to significantly reduce the risks through simple yet effective measures. Personal protective equipment, hygiene, documentation, and team awareness training form the basis for a safe daily practice.
Ultimately, the following applies: Only those who protect themselves can protect others.