Myiasis or Maggots in Dog and Cat

Dog encounter bot fly larvae in outside or in the field and hunting the rodents. Free Free-roaming cats are more likely to develop lesions than indoor cats. 

Adult flies lay eggs on blades of grass or in nests, and they hatch and crawl onto the skin of the passing host. The small maggot enter to the wound or opening of the skin or any orifice of the body like mouth, nose and especially to the genitalia when there is soak urine and feces to the matted hair attract flies to producing myiasis. This is common for the double coated hair like chow chow.

When maggots developed in warbles the migration from different tissues start and creates a fistula. Common system affected is integumentary, ophthalmic and respiratory system respiratory system. After ~30 days, the larvae exit the skin, fall to the soil and pupate.

Signs and Symptoms

Warbles or myiasis are common during summer. Skin lesions and swelling in the skin, pustules and pain in the affected area. Visible hole in the skin and the hole enlarged when warble has fully developed. Purulent material exudes from the lesion. Ocular and nasal discharge present. Seizures, blindness and other neurologic disorder appear when the CNS is affected. 

Prevention 

Prevent the dog and cat roaming outside or hunting the rodents, regularly check and inspect the skin after roaming or walking outside.

Treatment 

Covering the lessions with white petroleum jelly for 10−15 minutes before grasping the parasite can make it easier to remove.  Don't squeeze the lesion because when the larvae ruptured allergic reaction may occur.

Broad spectrum antibiotic indicated to combat the secondary bacterial infection. antihistamine like cetirizine or diphenhydramine administered 2 hours before the administration of ivermectin.

Prognosis

Prognosis is poor if the patient manifested a neurological sign and infected with multiple warbles.