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Can Fleas Kill a Dog?

Dog wearing anti-flea collar in field to answer question can fleas kill a dog
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If you’ve ever dealt with fleas, you know exactly how unpleasant and tenacious they can be. Thin, wingless, and only a few millimeters long, these tiny parasites can cause huge problems for animals and people alike. 

More than 15 flea species have been found in domestic dogs over the years—and it turns out canines may actually be the perfect hosts for bringing flea-borne diseases into homes [1].

We all know that fleas can cause itchiness and rashes, and that they’re incredibly tough to get rid of. But can fleas kill a dog? Can these pesky parasites actually lead to a dog’s death? We asked a veterinary expert to set the record straight.

Can Fleas Kill a Dog?

Dog scratching due to fleas for article that is about can fleas kill a dog

“The short answer is yes,” says Dr. Tyra Davis Brown, who practices at Hammond Animal Hospital and Pet Lodge in Louisiana, “and I’ve seen it happen in a patient.”

What Brown is referring to is a dangerous condition called flea anemia, which can actually lead to a dog’s death if left untreated. 

In the warm South, where there are rarely hard freezes to kill off outdoor fleas, Brown says they are common year-round. At work, she saw a group of small dogs who continued to come in covered with fleas—even after Brown brought it up to the owner multiple times. On one visit, she noticed that one of the flea-ridden dogs was feeling sick. Brown ordered blood work, which revealed severe anemia. She advised the owner to address the flea issue immediately. When the dog returned a few weeks later, the fleas were still there, and his blood work was even worse. 

Dog scratching back due to having fleas wondering can fleas kill a dog

Brown referred him to a specialist, but the dog died shortly afterward. “It was the fleas,” she says. “There was nothing else going on with him medically, except for the severe flea infestation. His anemia was a direct result of that.”

“We don’t see it often,” Brown says of flea anemia that’s severe enough to kill a dog, “however, as in this case, it can and does happen.”

And anemia isn’t the only concern when it comes to flea-borne diseases and dogs. Fleas can also cause Bartonella—an infection from bacteria that fleas may carry. While treatable with antibiotics, Bartonella that goes unaddressed can lead to fatal heart inflammation in dogs, Brown says, and it can even transmit to humans, too.

A Closer Look at Flea Anemia

Sad sick looking dog

In dogs, anemia occurs when the body lacks sufficient red blood cells, hemoglobin, or both. It can be caused by any number of diseases, injuries, or conditions—including blood loss due to fleas. That’s because, as parasites, fleas don’t just bite and cause an itchy feeling. Each adult flea actively sucks blood from their host several times every day. The more fleas there are on a dog, the more blood it’s losing. And as we all know, sufficient blood is crucial to a healthy body.

“If you have parasites constantly sucking your blood, your body can compensate for a while,” Brown says. “But after that, if you don’t have enough blood, things are going to shut down. Your cells will start to die. Your immune system can get out of whack.”

Small dog lying sick in bed wanting to see if can fleas kill a dog

She says flea anemia is particularly dangerous in small dogs. “A big dog could get anemia from fleas, but the likelihood of death is slimmer compared to a tinier dog,” she says. The reason is simple—big dogs have more blood, so it’s easier for their bodies to survive losing some. Little dogs have much less blood to spare.

According to Brown, the symptoms of anemia to look for in dogs include 

  • Pale gums (instead of the usual bubblegum-pink color)
  • Increased fatigue and loss of stamina
  • Loss of appetite
  • Panting or gasping for breath
  • Some dogs may also begin seeking warmth in ways they didn’t before

If you notice any fleas on your dog, Brown suggests getting them treated immediately. “When you see one flea on your dog, you should know there are probably a hundred more,” she says. And if you can’t get those fleas under control quickly—or if you spot any symptoms of anemia—bring them to a veterinarian immediately. 

Other Flea Diseases

Sick dog being held by owner

While other diseases fleas carry or conditions they cause may not lead directly to a dog’s death, they can still make a pup sick or very uncomfortable. 

Flea allergy dermatitis is a common cause of skin disease in dogs. It happens when the body reacts to the saliva that fleas inject when they bite. “All it can take is one flea to set the skin off,” Brown says. “And if that one flea becomes a hundred fleas, or even 10 fleas, the reaction is going to be worse.” In some dogs, a single flea bite can cause itching for days, and may eventually result in hair loss down the middle of the back to the base of the tail. 

Fleas can also cause tapeworms in dogs. This happens when a dog is licking itself and swallows a flea that’s harboring a tapeworm. The good news: “I’ve never seen a dog die from a tapeworm infestation,” Brown says. But if you see any signs of tapeworms in your dog’s feces, be sure to contact your veterinarian right away.

Flea Prevention Tips

Dog getting flea prevention

“Every animal should be on some type of [flea] preventative 12 months out of the year—especially if you live in a warmer climate where you don’t get hard freezes a lot,” Brown says. There are numerous options out there, from topical treatments to oral medications. Just be sure that whatever you use explicitly states it will combat fleas.

The CDC suggests limiting how much time your pet spends outside, giving frequent baths, and regularly checking for fleas [2]. It also recommends cleaning pet bedding often with soap and water.

Brown says it’s vital to vacuum your home at least every other day and immediately empty the bag. You should also sweep and mop bare floors, because eggs can hide in the cracks between planks. 

“We can’t make fleas vanish entirely,” Brown adds, “but you can keep them out of your home and off your pet.”

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