Solving the itchy cat conundrum

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The itchy cat presents a puzzle at every step of the clinical process, from history and diagnosis to successful management. According to Ashley Bourgeois, DVM, DACVD, co-owner of Animal Dermatology Clinic Portland in Portland, Oregon, understanding the uniqueness of feline dermatologic disease is an essential step along that road.

In a case-based presentation at the Fetch dvm360^® virtual conference this week, Bourgeois offered vital tips for approaching these patients, noting that the challenges are many. For starters, some owners don’t recognize that their cat is itchy. Cats tend to isolate themselves, especially when they don’t feel well, so an owner may not witness excessive chewing or licking. And because cats spend large amounts of time grooming anyway, overgrooming may be misinterpreted as normal behavior.

“A lot of these [dermatologic disease signs] can intermix, and allergies can present in different ways,” Bourgeois added, “so whittling down the list of differentials is not always straightforward.”

What to do

Take a good history

“Asking the right questions helps tremendously when deciding which diagnostics to perform,” Bourgeois said. History taking also allows time for the cat to exit the carrier and roam around the room, which can reduce stress associated with the veterinary visit. Other ways to reduce stress include petting the cat and offering a towel or another hiding place.

While taking a medical history, important topics include determining which areas of the body are most affected, when the issue started, whether the problem is seasonal, and which flea control products are being used (if any). Bourgeois also likes to ask which therapies have worked in the past. For example, if the cat’s signs are responsive to steroids, that suggests pruritus instead of psychogenic alopecia, she said.

It’s also useful to ask specific questions. “Don’t just ask whether the cat is itchy. You need to identify what ‘itch’ is,” Bourgeois said, adding that owners may overlook signs such as head shaking or chewing feet. Cats that ask to be scratched more frequently than in the past may also be demonstrating pruritus.

Some pet owners don’t associate increased hairball production with increased ingestion of hair due to overgrooming. “I’ve met owners whose cats only get hairballs in the summer, when they’re overgrooming,” Bourgeois noted, suggesting that determining seasonality is informative in these patients.

Fine-tune your dermatologic exam

Bourgeois suggests incorporating Fear Free handling practices when examining cats. Because dermatologic issues tend to be chronic and require repeat veterinary visits, it’s prudent to make office visits more comfortable. Tips include using synthetic feline pheromone sprays around the office and on towels, incorporating treats and toys to distract or engage with the cat, and performing otoscopic, facial, and oral exams at the end because some cats object to these parts of the exam.

Understanding how certain dermatologic conditions present in cats can facilitate recognition. For example, abdominal/ventral alopecia can have a variety of causes. Try to determine if the hair is falling out on its own, or if the cat is pulling out the hair. Falling out may suggest systemic illness or follicular disease, but overgrooming is more suggestive of pruritus. Scaling and crusting might indicate parasites or infection, but excoriations and plaques may suggest hypersensitivity.

Facial excoriations are another common presentation in cats. Differentials include aural pruritus (eg, ear mites or otitis), adverse food reaction, atopy, systemic illness, fleas, and idiopathic ulcerative dermatitis.

“Adverse food reaction can be dramatically pruritic,” Bourgeois said. However, broaching the topic can be tricky because some pet owners have very strong feelings about their cat’s diet and are reluctant to change. Similarly, some cats are picky eaters and share their owner’s reluctance to try a new food. Bourgeois has had success with hydrolyzed protein diets. “To me, these diets are one of the gold standards in trying to rule out food allergy in pets. Hydrolysis helps with digestibility and helps take away allergenicity.” She commented, noting that owners who are uncomfortable with this approach may accept a novel protein diet.

Eosinophilic granuloma complex is unique to cats, and indicates a hypersensitivity reaction. “It’s not a final diagnosis. It’s a clinical presentation. So, if you see an indolent ulcer or eosinophilic granuloma, that’s something to describe in your findings, but it’s not a true diagnosis,” Bourgeois warned. Cytology is useful in these cases, but histopathology may be needed to rule out other differentials.

Atopy in cats can be seasonal or nonseasonal, with a variety of presentations, including overgrooming, increased hairball production, alopecia, excoriations, and even signs of asthma. However, atopy is a diagnosis of exclusion, which makes it even more challenging to recognize and address appropriately. “Usually, we’ve already had [these cats] on good flea control,” Bourgeois said. “Either they’re completely seasonal, or we’ve done a diet trial to rule that out as a component. And then we’re working up atopic dermatitis.”

Don’t dismiss fleas

“Good flea control is essential in any pruritic cat,” Bourgeois cautioned, even in cats that live exclusively indoors. “I’ve seen indoor-only cats that live on the fourth floor of an apartment building respond to flea control alone. I tell clients that fleas are sneaky. They can jump on people, and onto elevators. So, let’s just rule out the easy things first and see if that makes a difference for your cat, before we set them up for testing and other medications that we may not need.”

Bourgeois prefers completing a few months of treatment with a rapid-kill product to help rule out flea allergy, noting that flea allergy may only be one component of the patient’s problem, so flea control should be continued while other differentials are being investigated and treated.

Don’t be fooled

Bourgeois cautioned that psychogenic alopecia tends to be overdiagnosed. “Excessive grooming is much more often from pruritus than obsessive-compulsive disorder, being clean, or being stressed.” In a 2006 study of cats referred to behaviorists for presumptive psychogenic alopecia, 19 of 21 cats had a problem unrelated to behavior, and were instead diagnosed with problems like food allergy or flea allergy.¹

It’s also wise to avoid being fooled by corticosteroids. These agents are frequently used in cats because they’re effective and overall options are still limited. However, Bourgeois cautioned that asking the owners about the timing of long-acting steroid injections, such as methylprednisolone, can be important. Long-acting steroid injections can sometimes provide 2 or 3 months of relief. However, if the cat stops scratching for that period, the owners may falsely assume that the problem cleared up and recurred, without realizing that a medication was in effect that entire time. Bourgeois warned that effective steroid therapy can “mask” seasonality, pruritus due to diet changes, and other historical information that can help identify the underlying problem.

Giving a long-acting methylprednisolone injection with an antibiotic can also create confusion for owners. If the cat’s signs resolve for 2 or 3 months, owners may presume that the antibiotics cleared up the problem, instead of understanding that the long-acting steroid may have been responsible.

The workup is worthwhile

“I perform cytology on almost every case that walks in the door, because it tells us a lot of information. Even if the cytology was boring, that’s good for us to know,” Bourgeois said. She also recommends skin scrapings, dermatophyte culture, and trials with parasiticides.

“Sometimes, you need a few months of having these patients on good, high-quality, fast-speed-of-kill parasite control to know whether flea allergy is a component, or whether mites or lice (that we couldn’t find on scrapings) are an issue,” she said. Bloodwork to investigate systemic illness is appropriate in some cases. Bourgeois also recommends paying particular attention to claw and claw fold lesions, as autoimmune disease (eg, pemphigus foliaceus) can cause these. Cytology is informative, and biopsy can confirm this diagnosis.

Treatment options are still limited, but improving

Glucocorticoids remain a cornerstone of dermatologic treatment for itchy cats. However, Bourgeois is encouraged by the efficacy of some other products, including cyclosporine (available in tablets or liquid, and FDA approved for use in cats) and oclacitinib (which is currently off-label in cats). Bourgeois also a proponent of allergen-specific immunotherapy (ASIT) for cats with atopic dermatitis. “It’s the only thing we know that can reverse the underlying immunopathogenesis [of atopy],” she said, noting that ASIT is a safe, long-term option that can reduce reliance on steroids and other medications.

Whichever treatment is administered, Bourgeois noted, “communication and frequent rechecks are foundational to success. We can manage these cats to have a good quality of life if we work them up appropriately and get the owners on board with us.”

Karen Todd-Jenkins, VMD, is a medical writer, technical director with animal health marketing agency Shepherd, and member of the American Medical Writers Association and One Health Initiative. She has been in clinical practice for over 20 years.

Reference

1. Waisglass SE, Landsberg GM, Yager JA, Hall JA. Underlying medical conditions in cats with presumptive psychogenic alopecia. J Am Vet Med Assoc. 2006;228(11):1705-1709.doi:10.2460/javma.228.11.1705