Cuterebrosis

Pet Tales
by Barry B. Burtis D.V.M.

Cuterebrosis

His name was Lucky and he was only eight weeks old. He had arrived in his new home just 2 weeks ago, having been born in a house just a few doors up the street. His new owners were determined that he would live as an inside cat, unlike his mother who was quite well known in the neighbourhood as a bit of a wanderer. She did have an official residence but she enjoyed the hand-outs and the affections of several other families on the street. She had also enjoyed, over the years, the affections of various male cats who visited the area and, of course, that's how Lucky came to be, but that's another story.

At this particular moment, Lucky could be pardoned, if he was perhaps, doubting the appropriateness of his name. Here he was, at such a tender age, back at the animal hospital for the second time in his life. His first visit, just a few days after arriving in his new home, had resulted in a thorough examination and vaccinations to start protection against some common feline diseases. His new family had been told by the veterinarian that Lucky was a healthy little kitten.

However, here he was again on the examination table. His owners had noticed that Lucky had a small wound just below his ear on the left side of his face. It had appeared quite suddenly and they had no idea what had caused it. The only other pet in the house was a dog and although it had seemed largely to ignore Lucky so far, they wondered if perhaps, in a moment of frustration, it had bitten Lucky.

On examination of the affected area, the veterinarian agreed that the wound certainly resembled a bite wound infection but something did not quite fit. It did not look like a dog bite. Usually, much more damage would result when that kind of injury is inflicted on such a fragile little fellow as Lucky. It could have been caused by a cat bite or another puncture wound of that sort but Lucky had lived quite a protected life so far and had likely not been exposed to those circumstances. It would be very unlikely a bite from his mother or siblings would cause something like this.

Well, fortunately the cause was quickly revealed when the wound was more closely examined. The hair over the wound was shaved and the affected area gently washed. Now at the center of the 1.5 cm. diameter, raised, mildly inflamed, thickened skin, a tiny hole, a few mm. wide could be seen. When that tiny hole was carefully observed with a good light source and the examination made a bit easier with small magnification, something could be seen moving in that skin bump beneath the opening. The experienced veterinarian knew immediately Lucky was infected with a Cuterebra maggot.

 Flies of the genus Cuterebra found in this part of Ontario and throughout North America are parasites of rabbits and rodents. Adult flies lay eggs on blades of grass or in nests of these animals. These eggs hatch and crawl onto the skin of the passing host animal. These maggots enter a body orifice, migrate through internal tissues and eventually make their way to the skin where they establish a warble - a firm lump in the skin. The mature maggot which may be up to 2.5 cm. (1 inch) in length, crawls out through the hole that develops in the skin, falls to the ground and after pupating in the soil becomes an adult fly to complete the life cycle. Dogs and cats or sometimes kittens, like Lucky, can become infected as accidental hosts when a tiny infective maggot enters their body.

Lucky was most likely infected when his mother brought back, after one of her outside excursions, one of these tiny larvae riding along on her haircoat. After transferring to Lucky, the larvae invaded his body and now he was showing the end result of that infection. The problem is usually very seasonal with most cases occurring in late summer and early fall when the adult flies are active.

As it turns out, Lucky was actually lucky. With infection in a location such as his, after local freezing of the skin and surrounding tissue, a small incision will allow the maggot to be removed. Owners and even seasoned veterinary care providers never fail to be abhorred by the sight of such a fat, stocky, grub-like creature, still alive and moving after removal, that so recently had infested the pet. The affected area, with minimal after care and medication, should promptly heal. Maggots can also be removed from the eyes or nostril when they occur in these locations but they can be more difficult to diagnose and treat if they cause problems in internal organs such as the lungs or the central nervous system.

Lucky was back in his home the same day with owners even more convinced that his life should be lived in an inside environment thus avoiding, hopefully, any future exposure to Cuterebrosis.