Grubs (Cuterebriasis) and dogs

Grubs are the larvae of a large botfly that has a wide seasonal distribution in the United States. This fly lays its eggs near the burrows of rodents and rabbits. Dogs acquire the disease by direct contact with infested soil.

Newly hatched larvae penetrate the skin to form cystlike lumps with small openings, which allow the grubs to breathe. Several grubs may be found in the same area of the dog’s body. In such cases, they form large nodular masses. Typical infestation locations are along the jaw, under the belly, and along the flanks. Inch-long (2.5 cm) grubs may protrude from these breathing holes. In about one month, the grubs emerge and drop to the ground.

Treatment: Veterinary assistance is best. The veterinarian will clip away hair to expose the breathing holes. Grasp each grub with a fine-tipped forceps and gently draw it out. Do not crush or rupture the grub. This can produce anaphylactic shock in the dog.

If the veterinarian is unable to grasp the grub, a small incision must be made under local anesthesia to remove the parasite. Grub wounds are slow to heal and often become infected. Antibiotics may be required.