Parasitic Blood Infection in Cats

Brittany Kleszynski, DVM
By Brittany Kleszynski, DVM on Jan. 26, 2024
A cat is held with their vet.

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What Is Parasitic Blood Infection in Cats?

Parasitic blood infections are not overly common in cats, but they are important diseases for pet parents to be aware of.

External parasites—such as fleas, ticks, and flies—can cause infection in the blood of cats when they bite or are swallowed. They transmit blood parasites, such as mycoplasma, that are harmful to cats.

When a flea, tick, or fly bites or is swallowed by a cat, the blood parasite it transmits may enter the cat’s red or white blood cells and reproduce, causing infection. These blood parasites change the normal function and number of these cells and may travel to different organs in a cat’s body.

Damage to the cells and organs leads to extreme sickness in affected cats.

Parasitic blood infections should be treated quickly, and many of the symptoms they cause, such as pale gums and breathing difficulties, are considered medical emergencies.

If you notice any abnormal behaviors or new concerning symptoms in your cat, bring them to the veterinarian promptly to be checked.

While most cats recover well from parasitic blood infections, they can be fatal depending on the type and severity of the infection. Your cat has the best chance for recovery from a parasitic blood infection when treatment is started early.

Symptoms of Parasitic Blood Infection in Cats

Blood infections in cats can cause a variety of symptoms, which may include the following:

Cats with a weakened immune system or those with an underlying immune function disorder—such as FeLV or FIV—may have more severe symptoms than healthy adult cats.

Causes of Parasitic Blood Infection in Cats

Cats most commonly develop blood infections after being bitten by a parasite, such as a flea, tick, or fly. Cats who are allowed outside are more likely to get these infections, as they spend more time around parasites that could infect them.

Male cats more commonly develop infections compared to females. This is because male cats are more likely to escape outdoors where they may encounter fleas and ticks.

Also, cats who are not on monthly parasitic protection and those with a weakened immune system are more at risk for bloodborne infections. Certain blood infections—such as mycoplasmas—can also pass from mother to kitten during pregnancy.

How Veterinarians Diagnose Parasitic Blood Infection in Cats

To diagnose a parasitic blood infection, a veterinarian will start with a head-to-toe check of the cat to find any abnormalities, such as pale gums, dehydration, or visible parasites.

Pet parents should share the cat’s thorough medical history to help with a diagnosis. This includes any medications the cat is taking, when symptoms started, if the cat is indoor or outdoor, and if the cat is taking any parasite prevention.

Other testing may include the following:

  • Complete blood count—A veterinarian takes a small sample of blood from the cat’s vein. This test finds changes to red blood cells, white blood cells, and platelets. A special slide called a blood smear can be viewed under a microscope to identify blood parasites.

  • Serum chemistry—Using a small sample of blood from the cat’s vein, a veterinarian can look for problems in liver and kidney function, glucose levels, and other measurements that may change with an infection.

  • PCR/serology—A special laboratory can use a sample of blood or serum to diagnose a blood infection through specific testing.

  • SNAP® 4Dx—A few drops of blood are mixed with a special solution and then added to a test that finds several parasitic blood infections, including Anaplasma and Ehrlichia in cats.

Other diagnostics, such as imaging or other laboratory testing, may be recommended by the veterinarian as well.

Treatment of Parasitic Blood Infection in Cats

Parasitic blood infections in cats are treated primarily with antibiotics, antiparasitic medications, and supportive care.

Oral doxycycline is an antibiotic that is often used to treat mycoplasma infections in cats. However, it’s been associated with narrowing of the esophagus—so the dose must be followed by a syringe of water. Pet parents should follow their veterinarian’s instructions closely when giving this medication.

Many cats can be treated on an outpatient basis at home. However, if the infection has gone untreated for a while and the cat is very sick, hospitalization and supportive care will be needed.

Supportive care may include fluids given by vein or underneath the skin, anti-inflammatories, steroids, and oxygen therapy depending on the needs of the cat. In cats who are severely anemic, a blood transfusion may be needed for recovery.

Parasitic blood infections can be cured in most cases, but they must be treated right away.

Sometimes treatment cures the acute infection but leaves the cat a chronic carrier of the bacteria. In these cats, less stress and regular preventative veterinary care are important to stop a relapse of symptoms.

Recovery and Management of Parasitic Blood Infection in Cats

Recovery can take several weeks in affected cats. Sometimes cats will become chronic carriers, especially those with mycoplasma infections, and will later experience a recurrence of symptoms during times of stress.

Although most cats will fully recover with quick treatment and supportive care, one type of blood infection—cytauxzoonosis—is often fatal.

To help with recovery, pet parents should offer a private, quiet space for cats getting treatment for a parasitic blood infection.

Some cats like going to their carrier for quiet time, so pet parents can also try keeping a cat carrier opened and easily accessible for recovering cats to spend time in. Keeping the affected cat in one area of the home and away from other pets can help lower stress and make recovery faster.

Prevention of Parasitic Blood Infection in Cats

Pet parents should keep their cats on monthly flea and tick prevention year-round to lower the risk of blood infections caused by these parasites. These products are available by prescription through your veterinarian and include Bravecto®Plus and Revolution® Plus.

Additionally, keeping cats indoors lowers the risk that they will encounter fleas, ticks, and other insects that could cause disease.

Featured Image: megaflopp/iStock / Getty Images Plus via Getty Images

Brittany Kleszynski, DVM


Brittany Kleszynski, DVM


Dr. Brittany Kleszynski is a veterinarian and freelance medical writer who specializes in creating meaningful content that engages readers...

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