Photo courtesy of Nancy Hinkle

Clients with delusional infestation by proxy sometimes bring veterinarians samples of what they believe are bugs, similar to these fragments, shown 15 times magnified, that were received by Nancy Hinkle, a veterinary entomologist at the University of Georgia in Athens. Close inspection shows such bits to be inanimate scraps such as scabs, hairs and lint.

The day the elderly client came in with flecks of detritus labeled by where they’d come from her body, the support staff at Daisy Hill Animal Hospital was at a loss to respond. But the hospital co-owner, Dr. Nancy Irvine, calmly gloved up and inspected the bits under a microscope.

None of them was a bug, as the client believed. Irvine shared the result, then gently asked for permission to speak with the woman’s family physician.

That sort of respectful, compassionate approach is exactly what a team of researchers recommends in a new study on a curious psychological condition called delusional infestation by proxy. In this manifestation of the disease, clients have the mistaken belief that their pets are infested with parasites, and bring them to the veterinarian for help. Oftentimes, the pet owners likewise believe themselves infested. The conviction stands in spite of a lack of clinical evidence.

The research paper, “Delusional infestation by proxy — What should veterinarians do?” published in the September issue of the Canadian Veterinary Journal, provides the first formal advice for veterinarians confronted with the delicate situation of a mentally ill client whose condition may be causing harm to him or herself as well as to the pet.

“Certainly there’s nothing in the veterinary curricula that would teach you how to deal with this,” said Dr. Mark Rishniw, lead author of the paper. Rishniw is a visiting scientist at the Cornell University College of Veterinary Medicine and director of clinical research for the Veterinary Information Network. VIN is an online community for the profession and parent of the VIN News Service.

Together with Peter Lepping and Roland Freudenmann, psychiatrists and world experts on delusional infestation, Rishniw offers a series of steps to follow that are guided by the goal of caring for the pet and client alike.

The recommendations include taking the client’s concern seriously and looking diligently for the suspected pathogen; refraining from treating the pet simply to appease the client; and building trust with the client in order to be able to help him or her obtain appropriate medical attention.

Rishniw’s interest in the subject was sparked by a chance conversation with a colleague who related the story of a woman who believed that her entire family, including the dog, had filaments growing from their skin, a condition popularly dubbed Morgellons disease. Rishniw posted a synopsis on a VIN message board and asked whether other veterinarians had ever encountered similar cases.

The outpouring of responses led Rishniw to look further into the phenomenon of imaginary dermal afflictions involving veterinary clients and patients. Working with Lepping, a consultant psychiatrist in North Wales and visiting professor at Glyndwr University, and Nancy Hinkle, a veterinary entomologist at the University of Georgia, Rishniw then formally surveyed VIN members on their experiences with the condition. (Freudenmann, a psychiatrist at the University Clinic of Ulm in Germany, joined the research group later.)

Seven hundred twenty-four veterinarians responded to the survey from several countries, primarily the United States and Canada. The results provided the basis for two scientific papers. A descriptive report of the 700 instances is in press in the British Journal of Psychiatry. The second paper is in the current issue of the Canadian Veterinary Journal.

Consistent with previous studies on delusional parasitosis, the researchers found that the majority of instances involved women. In three out of four cases where data were available, the client perceived herself to be affected along with her pet, a variant of the condition that the researchers term “double delusion.”

A little more than half of those showed their respective veterinarians the lesions on their own bodies, or the veterinarians observed lesions that appeared to be self-inflicted, such as by scratching or picking. The researchers suggest one clue to self-trauma is finding lesions only in areas that the person can reach easily, such as on the side of the body opposite the dominant hand. “… commonly, the middle of the back will be devoid of such lesions,” the researchers note.

Similarly, lesions on a pet may be caused by its owner picking the animal’s skin. As reported by the VIN News Service last year, one veterinarian had a case in which a dog’s owner picked at larvae he perceived under the dog’s skin, causing wounds to which he applied a solution of flea-killer. That worsened the sores, causing the owner to pick further.

From the survey responses, the researchers were heartened to see that most veterinarians took their clients’ complaints seriously. “The vets didn’t seem to dismiss it out of hand, saying, ‘You’re just plain nuts,’ ” Rishniw said in an interview. “They made an honest attempt, a reasonably vigorous attempt, at diagnosis. That’s the right thing to do.”

For one thing, he said, the pet genuinely may have a parasite. Maybe not fleas, but perhaps something less common.

Even if it seems unlikely to turn up a parasite, a full diagnostic workup is valuable, Rishniw said: “It’s not going to prove to the client that there’s nothing there. … There’s nothing you can do to prove to the client that there’s nothing there. What you’re doing with the diagnostic testing is to buy their trust that they’re taken seriously and to prove to yourself that you’re not overlooking something.”

The survey found that one common response by veterinarians to a client’s delusion is to offer some form of relatively benign treatment. While understandable, they write, that is not advisable, as it serves only to reinforce the delusion.

Moreover, they say, “No animal should undergo treatment purely for the benefit of the vet or the owner. Treatment, even when it is unlikely to cause harm, should always be directed at a treatable illness.”

Instead, the researchers advise establishing rapport with the client by treating his or her concerns with respect, and then consulting with the client’s family members. (They note that because the client is not the veterinarian’s patient, the veterinarian is not prevented by patient-doctor confidentiality rules from sharing information with the client’s family.)

Depending on the relationship between the veterinarian and client, the veterinarian may directly suggest to the client to see his or her physician, or obtain permission to consult with the client’s physician.

That is the path Irvine, a clinic owner in Ohio, took when a client in her 80s came in with her cat and her husband, claiming that all three were plagued by bugs.

One of the survey respondents, Irvine elaborated in an interview with the VIN News Service that she spent about four months trying to help the woman.

The client had come to the clinic previously for preventive care after she’d adopted the adult cat. Then one day, she brought the cat in for a skin condition. “That’s not an unusual complaint, to present a cat for itchiness,” Irvine said. “We searched the cat. She was concerned about white bugs she was seeing. We assured her those were scale.”

The client returned about a month later to report that now she, too, was infested. She showed the doctor spots on her legs and belly. Irvine saw them as self-trauma, though she didn’t say that to the client. The client’s husband also had a lesion on his head. Whether it was his or his wife’s doing, Irvine couldn’t tell; the husband was quiet and seemed willing to go along with whatever his wife said.

The situation came to a head the day the client came in with samples of the bugs she said she’d captured. “She … had them all labeled as to where they had come from: ‘This one crawled out of my robe. This one was on its way to my rectum.’ My staff just hit the floor,” Irvine recalled. “But I gloved up and I looked at them all.”

Under the microscope, Irvine saw a variety of things, but “there wasn’t anything of a life form,” she said. “I think there were bits of feces.

“She talked about why the bugs smelled awful. It was at that point that I asked her more, and she was pretty open about talking to me. She was frustrated that her (dermatologist) wasn’t believing her.”

Irvine asked the client about her family physician, who, as it turns out, was someone Irvine knew personally. She suggested that it would be a good idea to consult the physician. The client gave the veterinarian permission to contact him.

“I found he was very aware of what was going on, and was not at all surprised,” Irvine said. “His simple comment to me was that her medication needed to be adjusted.”

The clinic didn’t hear from the client again for a year. When she returned, it was to report that the cat was drinking water excessively and losing weight. “We diagnosed the cat with diabetes,” Irvine said. “Completely different (situation). We didn’t bring up itchiness and bugs, and she didn’t either.”

Looking back, Irvine estimates she spent untold hours on the perceived parasite problem, “not time that’s paid by any stretch of the imagination,” she said. But she doesn’t begrudge the time.

The daughter of a family-practice doctor, Irvine grew up hearing her father’s stories about people’s health situations. “That probably provided me with training,” Irvine mused. “I remember my mother saying that the main thing he did was listen to people.”

Now in her own practice as a veterinarian, Irvine said, “I think that compassion is just part of what we do that’s perhaps a very important part of what we do.”