Hubert is a guinea pig, and an exceptionally cute pig, at that. When his owners brought him in for skin problems, he made adorable, indignant huffing noises as I examined him. “How long have you had Hubert?” I asked, noting the thick layer of white, flaky dandruff down his back.
“Six months,” they replied.
“Is he an only pig?” I queried, inspecting the scabby scratches and bald patches on his neck. Sometimes when guinea pigs are housed together, the dominant pig will bite the fur of those lower on the “pecking order.” This is called “barbering” and the treatment is to separate the pigs. But, no, this wasn’t barbering. Hubert was the lone guinea pig in the house. According to my guinea pig texts, hair loss also may occur in juvenile pigs around weaning time, but Hubert was more than a year old. They had purchased him six months ago and he had been perfectly healthy until recently, when the scratching began.
Now I am mostly a dog and cat veterinarian. If something is seriously wrong with a “pocket pet” or “exotic,” I often offer referral to someone with more experience than me, but I do know the first thing to check is basic husbandry. In other words, do owners know how to feed and house this particular species of animal correctly? It’s not uncommon for people to lack adequate knowledge to properly care for such critters. I have seen iguanas with bone disease because their owners fed nothing but iceberg lettuce, rabbits with gastrointestinal disease from too many pellets and not enough hay and greens, rodents with respiratory disease from poorly tended cages, and so on.
“What are you feeding?” I inquired. Hubert’s diet was good, including pellets, fresh veggies, hay, and Vitamin C supplements critical for guinea pigs. Like humans, guinea pigs cannot manufacture their own Vitamin C but need to regularly eat foods rich in C or take a supplement. Otherwise they can get scurvy, just like people do. Hubert’s bedding was being changed and cage thoroughly cleaned weekly. Although there were dogs and cats in the house, I found no evidence of fleas. He did not go outside where he might contract other infectious conditions. What could be causing this sudden, severe itchiness?
Despite Hubert’s sheltered life, his clinical signs still pointed to some type of external parasite or infection. Donning a magnifying headset to assist my middle-aged eyes, I sifted carefully through his fur. Having been through two (count ‘em, two) bouts of head lice with two daughters both of whom have unbelievable amounts of long curly hair, I am extraordinarily adept at finding lice and nits. Hubert was clean. No lice.
What about mites? Mites are microscopic critters related to ticks that can infest the skin, causing intense pruritus — that’s the technical term for itching. Or maybe ringworm? Contrary to the name, ringworm is not actually a worm. It’s a fungus that is ubiquitous in the environment. Cats, dogs, children, and other critters can carry the organism, sometimes without any clinical signs. Up to 15 percent of guinea pigs may be asymptomatic ringworm carriers. Maybe Hubert had been one such carrier and then some type of stress led to a clinical outbreak. But ringworm usually starts on the head and isn’t particularly itchy.
“We’d better do a few tests,” I announced. I plucked a tuft of hair from the margin of one of the more spectacular lesions and carefully placed it into a small glass vial of orange culture media. “This checks for ringworm,” I explained, loosely screwing the top back on the vial. “If anything grows over the next three weeks, the lab will identify it and see if it’s causing Hubert’s problem.”
Next I grabbed a scalpel blade and microscope slides. “Hold him steady,” I asked my assistant, Elise, who had been happily cuddling him throughout the visit. Gently scraping debris from several spots on Hubert’s back, I deposited the scurf onto the slides. One sample, mixed in a drop of mineral oil, I examined immediately, looking for those microscopic mites. Other samples we diluted with saline, dried, and stained. These I searched for microscopic yeast, bacteria, or ringworm spores or hyphae. Nada.
“So far I can’t find the cause,” I said. “But everything I have read says that with this degree of self-inflicted scratching, the most likely explanation is a mite infestation, even if I don’t see them on these slides.”
Guinea pigs are susceptible to infestation with a mite named Trixacarus cavie. Caviae is the scientific family of a group of rodents native to South America that includes capybaras, wild cavies, and domestic guinea pigs. So you can see this mite’s name reflects its specificity for Hubert and his kin. With a presumptive diagnosis of mites, we started weekly injections of ivermectin to kill the bugs. “Disinfecting the environment is also key,” I explained, handing them a bottle of stuff to kill mites in Hubert’s living quarters. “Put Hubert somewhere else, then toss all his bedding, completely clean the cage daily, and spray this product.”
The following week Hubert returned for his second injection, but he wasn’t improving. We ordered a special topical dip called lime-sulfur. “Let’s continue the injections and start antibiotics for secondary bacterial infection, until the dip arrives,” I said.
A few days later, the owners called frantically. “He had a terrible night,” they lamented. “He won’t eat. He’s crying and scratching himself bloody.” The guinea pig gurus again assured me that this level of pruritus was almost surely mites and they had seen Trixacarus infections cause such intense itchiness that owners mistook the extreme scratching for seizures. Poor Hubert.
Luckily our dip had just arrived. We prescribed antihistamines to calm the itch, continued the other medications and began lime-sulfur treatments. Thankfully, Hubert responded immediately. He stopped scratching. Soon his dandruff disappeared. His scabs healed. His coat improved.
At his last visit, Hubert was again making adorable snuffling sounds, but this time I think he sounded more grateful than indignant.