13 Signs of Rat Parasites and What To Do ASAP

If you plan on keeping pet rats for awhile, you will need to know how to treat intestinal and external parasites. This is necessary for the well-being of your rats and will help lower the risk of contracting rat parasites that are transferable to humans.

There are two forms of parasites, intestinal and external. Both are highly contagious between rats and require care from a qualified veterinarian.


Intestinal Parasites in Rats: Symptoms

Intestinal parasites like worms and protozoa can invade a rat’s gastrointestinal system when a rat is exposed to unsanitary living conditions or through contaminated feces.

Worms are organisms that consist of more than one cell. The most common types of worms are tapeworms, roundworms, and pinworms. Protozoa consist of one cell and are known for their rapid reproduction.

Intestinal parasites can spread easily between rats because their eggs are released through the affected rat’s feces. Some eggs are known to become airborne and subsequently inhaled. Unsanitary living conditions will increase the likelihood of worms spreading between rats and can go undetected without regular veterinary care.


1. Diarrhea

Diarrhea is a common symptom of intestinal parasites and be accompanied by blood in some cases.


2. Weight Loss

Weight loss can accompany an intestinal infection because parasites consume necessary energy required to maintain a healthy weight. Alternatively, your rat might experience a loss of appetite resulting in a noticeable weight loss.


3. Intestinal Blockage

A severe intestinal infection can lead to a blockage developing in your rat’s intestines.


4. Change in Appetite

A change in appetite can refer to both an increase or decrease in appetite. When a rat is affected with an internal parasite, the parasite can consume a lot of energy requiring your rat to eat more food. Parasites can decrease your rat’s appetite if eating worsens other symptoms like diarrhea or nausea.


5. Excessive licking or chewing of rectal area

Infected rats will excessively lick or chew their rectal area because the infection causes localized discomfort and itching.


6. Visible Worms in Feces

Visible worms in your rat’s feces is a sure sign of an intestinal parasite infection. When you have multiple rats living in the same cage, it can be difficult to determine which rat is infected. Worms are highly transmissible through feces, so you might need to treat your entire mischief to eliminate the infection.


7. Enlarged Liver

A tapeworm infection can cause cysts to develop on your rat’s liver. This infection might develop into an enlarged liver.


8. Distended Abdomen

A distended addomen is another sign that something is wrong with your poor little pal.


9. Lethargy

Intestinal parasites can take a toll on your rat’s energy, especially during severe infestations. You might notice an infected rat appearing sluggish or sleeping more often. Lethargy can be a sign of many serious ailments, so you will need to rule out other causes with your veterinarian before establishing a treatment.


External Rat Parasites

Parasite prevention in rats

External parasites refer to organisms that affect a rat’s fur and skin. The most common external parasite is mites, but rats can be affected by lice, fleas, and ticks too.

Sources of external parasites are poor living conditions, commercial small animal bedding, and any object that has come in contact with an infected rat like cage accessories or toys.


10. Excessive Itching of Fur

Itchiness is one of the most common symptoms when it comes to external parasites. If you notice excessive itching in your entire mischief, they probably all are infected by mites. Scabbing of the skin accompanies excessive itching and is another good indicator of mites.


11. Loss of Fur

After periods of excessive itching, you might notice patches of hair missing from your rat’s fur. This could be a stress response or fur being tugged out from itching.


12. Scabby Ears, Nose, Tail, and Feet

A common symptom of ear mange mites is the appearance of scabs over the ears, nose, tail, and sometimes the feet. Ear mange mites are less common than fur mites and infect rats by burrowing into the skin.


13. Inflamed Skin and Sores

Excessive itching caused by mites can irritate your rat’s skin. If your rat has sharp toenails, their itching can break the skin causing self-inflicted scratches and wounds. Untreated, these injuries can develop into skin infections.


Treatment of Rat Parasites

Treatment for your rat’s parasite infection will be different based on whether it is caused by an intestinal or external parasite.

Veterinarians will diagnose intestinal parasites from identifying worms and eggs during the fecal examination. Protozoa can be diagnosed after analyzing a rat’s stool for the presence of this single-celled organism.

For intestinal infections, the medication prescribed will be an anti-protozoal (protozoa) or anti-helminthic (worms) based on the type of infestation. Metronidazole is a common treatment for protozoa infections. Ivermectin, Fenbendazole, and Piperazine are commonly prescribed treatments for worms.

External parasites on rats can be difficult to diagnose because skin samples don’t always show the presence of mites under microscopic observation. Instead, most veterinarians will observe for signs of excessive scratching and scabs and prescribe treatment without a confirmed diagnosis.

Revolution is the most common medication prescribed to treat mites. It is formulated for cats, but it is a safe and effective treatment for rats, too. Depending on the type of infection and the severity, Ivermectin or Mitabin might be prescribed instead of Revolution.


Preventing Rat Parasites

Maintaining the cleanliness of your rats’ cage is one of the most effective preventative measures you can take for avoiding external and internal rat parasites. You should always wash your hands before and after handling your rats.

If you are planning on bringing home a new rat, look for signs of external and internal parasites. Visible worms in feces, diarrhea, excessive itching and scabbing, are a strong indicator that the rats are suffering from parasites. It’s recommended that you always quarantine a new rat for at least three weeks before introducing them to your mischief and look for signs of infection.

Freezing pre-packaged commercial small-animal bedding and dry food for 72 hours, is an effective method for destroying external parasites.

Annual veterinary check-ups are recommended for rats because veterinarians will look for signs of parasites and might help you catch symptoms before a major infestation occurs.



Parasites are a common ailment affecting pet rats. Sometimes, infections are minor and exist unnoticed for long periods of time.

Major infestations can occur when parasites transfer to new hosts from infected feces. It’s important to do regular check-ups at home to observe for signs of parasites before they become a major problem.

Please note: This page is intended for educational purposes only and is NOT a replacement for professional medical advice, and not intended to diagnose any health issues with your rat. If you’re concerned that your rat may be sick, PLEASE take them to visit a vet!


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