Ear canal

Psoroptes cuniculi is an ectoparasitic cause of ear mite infection in several different host species particularly rabbits, horses, goats, antelopes, sheep and cattle. This disease should not left untreated as when it became worst, the parasite may spread and infest the head, the neck, legs, ventral abdomen and they may loss the ear pinnas and even cause fatal meningitis. Psoroptes mites do not infect human. EPIDEMIOLOGY This condition is common in captive rabbits and can infect any aged rabbits. Psoroptes cuniculi can survive off the host for 4-21 days at temperatures between 5?

C-31? C and relative humidities between 20%-99%. Survival of this mite is greatest at low temperatures and a high humidity. Temperatures greater than 40? C and a humidity less than 75 % are lethal to the mite within two days. It has five stages life cycle which are the egg, larva, protonymph, tritonymph and adult. Within 4 days, the mite egg hatches to release a larva. The larval mite feeds and grows and sheds its exoskeleton, emerging from it as a slightly larger stage called a protonymph (both larva and protonymph stages have only 6 legs) the case of the unhealthy hospital.

Again, the protonymph mite stage feeds, grows and sheds its exoskeleton, emerge to eight-legged stage called a tritonymph. The tritonymph mite stage grows and sheds its exoskeleton, emerging from it as an adult mite (eight-legged also). The adult mite feeds and lays more eggs and the cycle last about 3 weeks. PATHOGENESIS Psoroptes cuniculi rabbit ear mites do not burrow down into epidermal layers of the rabbit's skin like certain other species of mange mites. They live feeding and breeding on the surface of the rabbit's skin.

The mites feed upon the rabbit's lymph by piercing the rabbit's ear skin with their needle-like mouthparts. It produces and secretes waste products like feces and mucus which are highly allergenic and antigenic to the rabbit's skin. Then, the rabbit's immune system reacts against the waste product which results in moderate to severe inflammatory reaction occurring within the rabbit's ear canal. This inflammatory reaction are redness, heat, swelling and itchiness of the ear canal, as well as the oozing of inflammatory fluids (serum) and white blood cells onto the surface of the irritated skin.

The thick, grayish crusts and scale produce when the inflammatory serum ooze engulfs and entraps the white blood cells, mite feces, mites and surface epithelial cells on the surface of the skin and the whole lot dries out. It usually tend to take up their feeding positions at the edges of the crusts, causing yet more inflammation and scab formation to occur, and thus the entire infestation of mites and their associated crust tends to spread and expand outwards, eventually leaving the dark depths of the external ear canal (where the infestation tends to begin) and spreading out across the pinna and body skin.

Rabbit ear mites tend to initially invade the deeper regions of the rabbit's external ear canal and cause hard to be seen for early infestations of ear mites in rabbits. Owners may only notice very occasional symptoms of ear-scratching and head-shaking by the rabbit during these early stages of ear mite infestation. Besides that, hair thinning or hair loss around the edges of the pinnas may also be recognized. Early infestation may involve only one ear or both ears of the rabbit but when fully infested by mite population, both ears will be infected.

If no treatment, mite infestation will increase in population number causing more crust and scale and may reach up to 2 cm thick. The infestation and inflammatory process expands and grows, eventually extending from the passage-like ear canal of the rabbit and out onto the outer ear flap (pinna). At this point, the infestation is obvious to the rabbit owner. With moderate to advanced ear mite infestations, the rabbit ear pinna appears crusty and scabby with large quantities of thick, grayish, flaky, crusts clinging to the pinna.

These crusts can be so thick and heavy that the infected ears flop. The rabbit is often extremely irritated and itchy by this stage and scratches and chews at its ears frequently, often making the skin bleed. Left untreated, the ears can become so traumatized by the rabbit that secondary bacterial infections of the damaged skin can set in, resulting in the rabbit becoming feverish, lethargic (sleepy) and sick. Allowed to progress, bacterial infection can sometimes invade the middle and inner compartments of the rabbit's ear/s producing severe neurological signs (e.g. head tilt, loss of balance, incoordination of the gait) and even a fatal meningitis.

When it worst, long-term cases of ear mites result in the loss of the rabbit's ear pinnas and spread across the rabbit's body, infesting in particular the head, neck and belly of the rabbit as well as thick, grayish crusts and scale produce when the inflammatory serum ooze engulfs and entraps the white blood cells, mite feces, mites and surface epithelial cells on the surface of the skin and the whole lot dries out.

It usually tend to take up their feeding positions at the edges of the crusts, causing yet more inflammation and scab formation to occur, and thus the entire infestation of mites and their associated crust tends to spread and expand outwards, eventually leaving the dark depths of the external ear canal (where the infestation tends to begin) and spreading out across the pinna and body skin. Rabbit ear mites tend to initially invade the deeper regions of the rabbit's external ear canal and cause hard to be seen for early infestations of ear mites in rabbits.

Owners may only notice very occasional symptoms of ear-scratching and head-shaking by the rabbit during these early stages of ear mite infestation. Besides that, hair thinning or hair loss around the edges of the pinnas may also be recognized. Early infestation may involve only one ear or both ears of the rabbit but when fully infested by mite population, both ears will be infected. If no treatment, mite infestation will increase in population number causing more crust and scale and may reach up to 2 cm thick.

The infestation and inflammatory process expands and grows, eventually extending from the passage-like ear canal of the rabbit and out onto the outer ear flap (pinna). At this point, the infestation is obvious to the rabbit owner. With moderate to advanced ear mite infestations, the rabbit ear pinna appears crusty and scabby with large quantities of thick, grayish, flaky, crusts clinging to the pinna. These crusts can be so thick and heavy that the infected ears flop.

The rabbit is often extremely irritated and itchy by this stage and scratches and chews at its ears frequently, often making the skin bleed. Left untreated, the ears can become so traumatized by the rabbit that secondary bacterial infections of the damaged skin can set in, resulting in the rabbit becoming feverish, lethargic (sleepy) and sick. Allowed to progress, bacterial infection can sometimes invade the middle and inner compartments of the rabbit's ear/s producing severe neurological signs (e.g. head tilt, loss of balance, incoordination of the gait) and even a fatal meningitis.

 When it worst, long-term cases of ear mites result in the loss of the rabbit's ear pinnas and spread across the rabbit's body, infesting in particular the head, neck and belly of the rabbit as well as the lesions. Dissolving the ear crust samples in KOH solution will help to break down and dissolves the thick crusts of the scab, which make the mites easily visualized.