Why a Dog Has a Lump After Tick Removal

Ticks are parasites that feed on animal blood.

Dogs that live in warm, wooded areas are especially susceptible to the bites of ticks — tiny arachnids that feed on blood. Though most tick bites are only minor inconveniences, ticks carry a host of illnesses. A tick bite can also cause infections and allergic reactions. A small amount of localized swelling is a normal inflammatory reaction to tick removal. However, if the swelling grows or remains present for more than a day, it could indicate something more serious.

Retained Head

A retained tick head is among the most common risks of tick removal. When you remove a tick from your dog, always check to enure the tick's head is present. If you squeeze a tick or use heat when removing it, you may have only partially removed the tick, leaving the head inside the dog. If you're not sure that you fully removed the tick, take your dog to the vet. If the tick's head is still inside your dog, your veterinarian will excise the head and treat your dog with antibiotics.


Removing tick frequently leaves a small wound behind. When the tick is extremely engorged, it has often been attached to the dog for an extended period, increasing the likelihood of infection at the bite site. If you notice a lump on the site from which you removed the tick that gets larger the day after removal, your dog may have an infection. Other signs of infection include pus, oozing, fever and lethargy. Contact your vet, who will treat the infection with antibiotics.

Allergic Reaction

Ticks inject a variety of potentially disease-spreading fluids into dogs when they bite. Even when dogs are not exposed to diseases, however, they may exhibit allergic reactions to the tick's saliva. If the area around the bite becomes swollen or red, if your dog has a rash or if your dog has a history of allergies, it may be experiencing an allergic reaction. Your vet may treat the wound with a cortisone injection or antibiotics.


The most serious potential cause of a lump at a tick bite site is Lyme disease. The symptoms of Lyme disease are frequently similar to a mild infection during the first days of the illness. Rocky Mountain spotted fever, which has similar symptoms to those of Lyme disease, may also begin with a small lump after you remove the tick. Your veterinarian will perform tests to determine whether your dog has a serious illness or just irritation at the wound site.