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Hard Lump After Tick Bite on Dog: Why It Happens

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In addition to the diseases ticks can transmit, they also leave lumps at the bite site. These nodules occur due to either a local allergic reaction or if the tick’s mouthparts remain attached to the skin. The lumps can become infected which requires antibiotic treatment.

Ticks live outside in the grass, trees, or among the leaves. They are attracted to the movement and vibrations humans and animals produce. 

These conditions make them stretch their forelegs in the air, hoping to cling to a host.

While tick bites are often harmless, there are cases where they can cause allergic reactions, hard lumps, or transmit diseases to the bitten host. 

Some of the diseases they transmit can even be fatal for dogs.

Find out what a tick bite looks like on your dog and why your dog has a hard lump after a tick bite.

What Does a Tick Bite Look Like on a Dog?

Tick bites are easy to identify when the tick remains attached to the skin. If the tick has detached, there can be an inflamed area at the bite site. The red spot usually disappears after 2-3 days but can last up to a month.

Ticks do not attack in groups, but there are cases of massive infestations where they are attached in clusters on the skin of an animal. Some ticks are small and not so noticeable compared to large ones.

Dogs that are not allergic to tick bites may only develop a red, slightly inflamed area or show no symptoms at all. Allergic dogs can experience pain, swelling, and rash at the bite site. 

Tick bites are usually similar to mosquito bites and resolve on their own in a few days. In some cases, ticks can leave a hard lump at the bite site.

Related: What Does a Tick Look Like on a Dog?

What Does a Tick Bite Look Like on a Dog
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Why Does My Dog Have a Hard Lump After a Tick Bite?

Hard lumps can appear after a tick bite. These lumps can get infected. They occur due to a local reaction caused by the tick’s saliva or because the mouthparts of the tick are still attached to the skin.

Ticks are among the most common parasites that leave lumps or nodules after biting. The lump you notice on your dog can also be a tick that is still attached. If it is dark in color and has a narrow base, it is probably a tick or a mole, and not a lump.

These hard nodules also appear due to a local reaction. A dog’s body can react when it comes in contact with the substances a tick secretes while feeding (saliva) or fixating (cement-like substance).

Ticks’ saliva has the following properties[1]: 

  • Cytolytic (i.e. destroys cells)
  • Vasodilator
  • Anticoagulant
  • Anti-inflammatory
  • Immunosuppressive

Due to the suppressing nature of tick bites, dogs can’t always feel when they are bitten. They also don’t bleed.

The salivary glands of a tick secrete a cement-like substance in addition to saliva. This substance helps the tick attach firmly to the skin of its host. The saliva and cement-like substance usually cause a local reaction, resulting in inflammation. 

Ticks can also cause local inflammation when they cut into the tissue to insert their feeding tube.

After removing a tick, the bite area must be carefully inspected for any residual parasite parts. The mouthpiece of the tick can break and remain attached to the skin if a tick is improperly removed. This can lead to granuloma (a hard lump) and infections.

Inflammation

Inflammation

If you find a tick on your dog, do not panic and take action. All you have to do is to remove the tick correctly and disinfect the bitten area. 

As with any insect bite (although ticks are not insects), the tick leaves behind a small red bump (inflammation) that resolves on its own in a few days. This reaction occurs when the dog’s body comes in contact with the tick’s saliva.

Granuloma

A granuloma is an inflammatory nodular skin formation that occurs after the accumulation of a large number of large phagocytic cells (immune cells).[2]

In other words, a granuloma is a bunch of white blood cells that causes a lump to appear on the skin (or in the body). It occurs as a result of the body’s defense reaction to the mouthparts that remain attached to the skin after the tick has been removed.

Tick-bite granuloma can cause excessive itching to your pet and persist for months or years[3]. In some cases, surgery may be needed to remove it.

Infections

Infections
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Due to intense scratching, a granuloma can become infected. Infected granuloma can turn into a red, inflamed, hot area where the bite occurred. The hard lump can enlarge as it fills with pus.

The infection occurs a few days after the appearance of the granuloma. The infected nodule can be painful to the touch, and the pus can burst when the pressure builds up inside, leaving a crust behind.

For such cases, local antibiotic treatment is often recommended combined with pus drainage.

Allergy

Signs of Ticks on Dogs
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An allergic reaction can occur when sensitive dogs are bitten by ticks. These dogs scratch intensely, which causes the bite site to become inflamed. As a result, the skin will turn red.

The most common symptoms of a tick bite allergy:

  • Red, dry, or irritated skin
  • Excessive itching and scratching
  • Hot spots
  • Dermatitis

In other cases, ticks of the species Ixodes muris can trigger an inflammatory reaction.  

This reaction[4] resolves on its own within three days after the tick has been removed and is manifested by several symptoms:

  • Lethargy
  • Anorexia
  • Pain
  • Fever
  • Swelling at the bite site

Allergic reactions are alarming when they affect your dog’s airways or blood circulation. Contact a veterinarian if this occurs.

Tumor

Tumors are abnormal multiplications of cells that occur as a result of a mutation in the dog’s tissue[5]. These can be malignant (cancerous) or benign (non-cancerous). Malignant tumors grow and spread (metastasize) very quickly, unlike benign ones.

A tick never produces a cancerous tumor at the bite site. Granulomas can appear to be cancerous, but they are benign.

Should I Take My Pet to the Vet if It Has a Lump on Its Skin?

Yes, if your dog has a lump on his skin, it is best to go with it to the vet for a correct diagnosis. After the diagnosis, the doctor will establish therapeutic conduct.

The urgency of taking your pet to the vet if a lump has appeared on its skin depends on several factors:

  • How long the nodule has been present.
  • Overall health.
  • If the lump has changed its shape, size, or consistency since you first noticed it.
Tick Bite Diseases in Dogs

The diagnosis similarly depends on several things:

  • Fat
  • Lipomas
  • Cysts
  • Granulomas
  • Tick bites or other insect bites
  • Abscess
  • Cancer
  • And others

Treatment is administered or recommended depending on the diagnosis.

Your veterinarian may recommend you give your dog an antibiotic if the lump is infected.

If the lump doesn’t pose a risk to your dog’s health, your doctor may ask you to monitor it in the future. Do a weekly checkup and note if it changes in color, size, shape, and texture.

Conclusion 

Ticks usually leave an inflamed area at the bite site. If the tick has not been completely removed and the mouthparts have remained attached to your dog’s skin, it can lead to the formation of a hard lump (granuloma). If your dog scratches excessively, the granuloma can become infected and form pus.

Visit your veterinarian if the hard lump persists for more than a few days.

FAQs

Does a Tick Bite Leave a Hard Lump?

Yes, it is normal for a tick to leave a hard lump after it bites. The hard lump represents the body’s reaction to the tick’s saliva or attached mouthparts.

How Long Does a Tick Bump Last on a Dog?

A tick bump lasts a few days to a few weeks. It depends if your dog scratches it a lot or not. If the bump is excessively itchy, you can apply topical antihistamine creams.

Why Does My Dog Have a Lump After Tick Removal?

If you are sure the tick’s mouthparts have been completely removed with the tick, your dog is possibly allergic to its saliva, or the lump is infected. Consult your veterinarian for proper treatment.

About Iulia Mihai (DVM)

Dr. Iulia is a certified veterinarian with more than 10 years of experience in the field. With extensive knowledge of diet, care, and medication, she helps Misfit Animals provide readers with accurate knowledge on technical topics.

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