Rats dying from disease is more common than most people realize—especially in the case of pet rats or large wild populations.
This article explains the most common diseases that kill rats, how they spread, what symptoms to watch for, and what you can do to prevent illness and sudden death—especially if you care for pet rats.
Can Rats Die from Disease?
Yes, rats can die from various diseases, especially respiratory infections, viral outbreaks, and internal parasites. Infections often go unnoticed until it’s too late because rats hide illness as a survival instinct.
Whether it’s wild rats in your area or pet rats in your care, knowing what diseases affect them and how they work is key to prevention and early treatment.
Common Diseases That Kill Rats
1. Respiratory Infections (Mycoplasma Pulmonis)
This is the number one cause of chronic illness and death in rats—especially pet rats. Caused by a bacteria called Mycoplasma pulmonis, it attacks the lungs and airways.
Symptoms:
- Wheezing or sneezing
- Labored breathing
- Hunched posture or lethargy
- Loss of appetite
Without quick veterinary treatment, it can turn into pneumonia and kill the rat in a matter of days.
2. SDA Virus (Rat Coronavirus)
SDAV (Sialodacryoadenitis virus) is a highly contagious viral disease that spreads quickly through rat colonies. It can cause severe damage to the respiratory system and immune system, leading to death in vulnerable rats.
Symptoms:
- Swollen lymph nodes or jaw area
- Eye or nose discharge
- Breathing difficulties
- Sudden weakness
There’s no cure—only supportive care. Infected rats need to be isolated to protect others.
3. Tumors and Cancer
Older rats, especially females, are prone to mammary tumors. While not always deadly, untreated tumors can lead to infection, weight loss, and eventually death.
Some tumors grow internally and may not be noticed until the rat shows signs of pain or lethargy.
4. Rat Bite Fever
This is a bacterial infection that rats can both carry and contract. It spreads through bites, scratches, or contact with rat droppings.
While often discussed as a disease passed to humans, rats can also suffer from it internally, especially in overcrowded or unsanitary living conditions.
5. Parasites and Internal Worms
Parasites can slowly weaken a rat’s immune system until it becomes vulnerable to other illnesses.
These include:
- Mites and lice (external)
- Tapeworms and roundworms (internal)
- Fleas (can transmit other infections)
In severe infestations, parasites can cause sudden death, especially in young or weak rats.
Why Are My Rats Getting Sick So Easily?
Rats are highly sensitive to their environment. Small issues like poor ventilation, dirty bedding, or cramped cages can quickly lead to disease outbreaks.
Common causes of frequent sickness include:
- Dirty cages that promote bacteria growth
- Poor diet lacking vitamins and nutrients
- Overcrowded cages causing stress and spreading illness
- Exposure to drafts, extreme cold, or heat
Cage size matters too. Small cages increase stress, reduce airflow, and lead to more fighting—all of which weaken the immune system.
Not sure if your rat cage is big enough? Use this free tool to Calculate their Rat Cage Size Requirements instantly.
How Do Diseases Spread Among Rats?
Rats can catch diseases through direct contact, contaminated food, or even airborne particles.
Here’s how infections typically spread:
- Touching an infected rat or its waste
- Sharing food bowls or water bottles
- Exposure to unclean cages and bedding
- Being stressed or injured—weakening their immune system
New rats introduced into a group can also bring diseases if not quarantined first. Always isolate new arrivals for 2 weeks before introducing them to others.
Signs Your Rat May Be Sick
Early symptoms are easy to miss, but if caught in time, many diseases can be treated successfully.
Look out for:
- Red discharge around the eyes or nose
- Hunched or puffed-up posture
- Labored or noisy breathing
- Lack of interest in food or play
- Scratching or fur loss
If you notice any of these signs, take your rat to a vet with experience in rodents. Rats hide symptoms well, so any visible sign means the illness is already serious.
What to Do If a Rat Dies from Disease
When one rat dies, others may be at risk too—especially if they shared the same cage.
Here’s what you should do immediately:
- Remove the body using gloves
- Clean the cage completely with pet-safe disinfectant
- Quarantine any other rats and monitor for symptoms
- Wash all toys, food bowls, and water bottles
- Consult a vet, especially if you plan to adopt more rats
Can You Prevent Rat Diseases?
Yes, with the right care, you can prevent most illnesses and greatly reduce the risk of death from disease.
Here’s how to protect your rats:
- Clean the cage at least once a week
- Feed a healthy, varied diet—not just pellets
- Provide fresh water daily
- Keep the cage in a dry, well-ventilated area
- Avoid overcrowding—make sure each rat has enough space
Don’t guess when it comes to housing. Use the Rat Cage Calculator to get the right cage size based on how many rats you own.
Conclusion
Diseases are one of the most common causes of rat death—especially in poor conditions or overcrowded environments. While not every illness is preventable, early care, good hygiene, and proper space can keep most rats healthy and happy.
If you want to protect your rats from deadly diseases, start with their environment. A clean, spacious cage is the first and best step. Calculate their Rat Cage Size Requirements today and give them the life they deserve.
Healthy rats start with informed care—stay alert, act early, and don’t overlook the little signs.