In this interview with Dr Andrew Rosenberg how to diagnose and then treat feline allergies

Interview with Andrew Rosenberg, DVM, DACVD

Andrew Rosenberg, DVM, DACVD: My name is Andrew Rosenberg, I am a veterinary dermatologist. I working with the Animal Dermatology Group as a clinical dermatologist in both the Wayne, New Jersey, and White Plains, New York, offices. I’m also the director of medical operations for the entire group, which is the largest dermatology group in the world. Additionally, I’m the president of the American College of Veterinary Dermatology, so I’m involved with the organization that board-certifies all veterinary dermatologists.

Sometimes clinicians like to imagine that cats are small dogs, right? But they’re totally different. I think dog allergies are just more straightforward than cat allergies because cats just have a mix of all of these or one of these reaction patterns, and so it can be difficult to accuralty diagnose cats. Cats can also be much pickier eaters, which makes it more difficult to do a food trial with them. Treating allergic cats is much challenging because it’s often harder for owners to medicate them than it is with dogs. So, there are a lot of pitfalls and challenges both with diagnosing and treating cats, 

There could be a whole lecture for that. For treating infections, anything you can do in the office can be helpful, right? So, things like convenia injections to treat skin infections if cats have skin infections as a result of their allergies. Then, as far as you know, diagnosing accurately, that's kind of similar. If these reaction patterns are are non seasonal, you perform food trials, and you just perform food trials with food that that the cat will eat. And so it's always good to have a few different food options in your pocket. So if the cat doesn't like one you can go to another one. I tend to really like the Rayne nutrition brand of foods for novel protein diets. There are some good hydrolyzed diets out there as well

For for diagnosing environmental allergies, right? We don't use allergy tests to actually diagnose allergies, we use allergy tests to formulate immunotherapy. So to really diagnose allergies, it's really a diagnosis of rule outs. You have to make sure the cats are in good flea control, make sure that you're treating all the infections, make sure there's no fungal infection, amke sure there's no ectoparasites. So that's kind of my tip is just make sure that there's you're ruling out every other possible item before you make that diagnosis of allergy. And then it's up to the owner to be able to medicate their cat, which, which can be difficult. 

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Andrew Rosenberg, DVM, DACVD, shares the complexities of diagnosing and treating feline dermatology conditions, and how to make it easier for teams and clients. 

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Overcoming challenges with diagnosing and treating cat allergies

Happy Friday dvm360 readers! Did you know the dvm360 team has spent the past 2 days on site at New York Vet providing readers with conference coverage? Be sure to check in at dvm360.com through today and next week to see more of our coverage and interviews from industry leaders. You can also access all that we have posted so far on the 

Along with our conference coverage, here is what was popular this week on dvm360.com:

To better understand the relationship between clients and specialists or emergency care veterinarians, synchrony 

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 of The Vet Blast Podcast presented by dvm360, our host Adam Christman, DVM, MBA, welcomed Sue Ettinger, DVM, DACVIM, to discuss the importance of cancer awareness, plus the important role general practitioners have with potential oncology patients.

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Ann Hohenhaus, DVM, DACVIM (Oncology, SAIM), 

 the essential components when performing a diagnostic investigation into canine patients with canine mast cell tumors during her lecture at the New York Vet Show.

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Veterinary technicians play an important role in hospice care and the euthanasia process of feline patients. In her lecture “The Technician’s Role in Euthanasia, Hospice and Palliative Care Appointments,” at the 2024 New York Vet Show in New York, New York, Jamie Rauscher, LVT, hospital manager of Animal Hospital of Towne Lake, and president of the National Association of Veterinary Technicians in America (NAVTA), outlined 5-step guidelines for hospice and palliative care that veterinary practices can implement for an effective care plan.

The 5 steps of the Feline Hospice and Palliative Care Guidelines by the Feline Veterinary Medical Association (FelineVMA), formerly the American Association of Feline Practitioners (AAFP), comprise an evaluation of the caregiver’s needs, education about the disease process, development of a personalized plan for the patient and the caregiver, application of hospice or palliative care techniques, and emotional support during the care process and after the death of the cat.

Caregiver needs, beliefs, and their goals for the feline patient will be different for every client, Rauscher explained. Moreover, the severity of the disease will impact the level of caregiving that is necessary. “When we talk about caregiving, how involved we are in our caregiving process is influenced by how severe the disease is,” said Rauscher during her session.

Rauscher explained that to evaluate the caregiver’s needs, it can be beneficial to think about the client’s "personal budget," which consists of the caregiver's available time, financial, emotional, and physical resources. Clients should consider factors such as:

Whether they have the finances needed to care for their cat, and if their feline companion’s medications and treatments could cause a financial strain

Whether caring for the patient will interfere with the client’s physical wellbeing, such as the amount of sleep they get

Whether or not the client can realistically take care of the patient, and if there is anyone that can support or help the client care for the patient

Whether or not the cat is physically able to receive the necessary care (ie., is the cat able to take medication or receive subcutaneous fluids?)

Whether or not the client has the emotional capacity to provide the patient with the required level or care

Quality and duration of life should also be discussed with the client, as well as whether the client prefers euthanasia or hospice-assisted death. When the entire staff is busy, the veterinary technician should take the time to talk to the client, explained Rauscher. “So you’re the technician, you go in that room, and you sit down whoever your client is, [and] start... to ask questions and talk to them about what their personal budget is and what their goals are for cat,” said Rauscher.

Educating the client about the disease process and the delivery of care is just as important as the initial evaluation. The primary aim of caregiver education in hospice and palliative care is to ensure that caregivers fully understand all diagnostic and treatment options to prioritize their cat's comfort while being informed about the disease's progression and prognosis. This education should utilize a variety of instructional methods, including verbal, written, and visual aids, and adopt a “see one, do one, teach one” approach for hands-on tasks like administering subcutaneous fluids, according to Rauscher.

“Take your time to talk to your client and help make them, help them to make an informed decision. Get a stool, sit on that bench with your client, pull the tissues up, because your client is going to be upset with whatever's going on with her pet, but take your time to talk to them,” stressed Rauscher.

“Dr Smith [gave] a whole bunch of medical terms to this client. He has left the room, and this client is looking at you, they have no idea what to do. Or they say, ‘what would you do?’ Right? So sometimes we feel like we can honestly answer them. Other times, we feel like ‘oh my gosh, I cannot, because if I tell her what I would do, she's going to get mad,” continued Rauscher.

“But they do want you to be honest. They're there to talk to you, and they're there to get your opinion. So if you have a client that you have a relationship with, be honest with that client. …As long as your veterinarian or your practice owner— whoever is in charge—as long as they are fine with these things happening, then that's my recommendation for you.”

It is important that the caregiver feels comfortable asking questions and is not rushed into making treatment decisions. No matter what decisions are reached, the client should never feel criticized or judged.

Creating a personalized care plan for both the cat and its caregiver should be a collaborative effort among the veterinary team. This plan should include clear communication of the cat's diagnosis and treatment options, an understanding of the caregiver's responsibilities and capacity to provide care, and a detailed written outline of the expected process, costs, and emotional support resources available to help the caregiver navigate this challenging time. 

The use of hospice and palliative care techniques “empowers [the] caregiver to care for their cat in a homestead,” explained Rauscher. Discussion of these techniques includes instructing caregivers on various therapeutic approaches and how to assess their cat’s responses to treatment. Moreover, it is important for caregivers to recognize signs of decline, even if it is difficult to accept, as this awareness informs their care decisions.

Safe handling techniques and how to create a positive experience during treatments should also be discussed with the client, suggesting that interactions should be enjoyable and supportive to foster a better emotional environment for both the pet and caregiver. Evaluating and adapting the home environment for the safety and comfort of the patient is also essential, making necessary adjustments like ensuring easy access to food and water and providing optimal bedding.

“And then, how can our clients communicate with us?” posed Rauscher. “The goal is for us to be a patient advocate,” she continued. It is important to give the client resources to be able to communicate with the veterinary staff, possibly through telehealth or email, to ensure the cat's needs are continually met.

“We want to help our clients when they first start to realize that they're entering their cat’s end-of-life stage,” emphasized Rauscher. Veterinary technicians and staff should offer emotional support to caregivers during their cat's illness and after the pet's passing. Caregivers often experience intense emotions like denial and grief, and it is crucial for veterinary practices to offer resources such as support groups and counseling to help clients navigate these feelings.

“You're going to reassure your client that it's okay and it's okay for them to cry. It's okay for them to be upset. It's okay for them to want to help out their pet the best they can,” said Rauscher.

Rauscher J. The Technician’s Role in Euthanasia, Hospice and Palliative Care Appointments. Presented at: New York Vet Show; November 7-8, 2024; New York, New York.

Jamie Rauscher, LVT, president of NAVTA, outlined 5 essential steps veterinary technicians should follow for an effective care plan for a cat in their end-of-life stage

The heartfelt role of veterinary technicians in feline hospice and palliative care

What should veterinarians know about the diagnostic investigation of a canine mast cell tumor (MCT)? At the 2024 New York Vet Show—happening November 7 to November 8—Ann Hohenhaus, DVM, DACVIM (Oncology, SAIM), director of Pet Health at the Schwarzman Animal Medical Center (AMC) in New York, talked about several components of a diagnostic investigation of canine MCTs, including the presurgical evaluation and diagnostic imaging. According to Hohenhaus, the second most common tumor seen on canine skin is the MCT, and it is the most common malignant skin tumor in dogs.

In her lecture “Mast Cell Tumors Part 1: The Diagnostic Investigation,” Hohenhaus delved into fine-needle aspiration and the preanesthetic evaluation—both essential components of a presurgical evaluation for patients with suspected MCTs.

Regularly aspirating cutaneous tumors is crucial, as these tumors can often be MCTs, and performing a fine-needle aspirate of a skin mast is the first step in the presurgical evaluation. “Aspiration cytology is critical for identifying mast cell tumors because when you have a mast cell tumor, you need to be sure that you're going to have adequate surgical margins,” emphasized Hohenhaus during her lecture.

 “So, to not know that a tumor is a mast cell tumor and go in and just cut a little bit around the mast is going to end up having that pet have to have a second surgery to get adequate margins. So that's the critical reason to aspirate skin masses.”

In dogs, skin masses generally look like pimples. However, on an aspirate, identifying a MCT is not a difficult feat. When aspirating, Hohenhaus recommends using a needle without a syringe on the hub, stabbing the mast several times, and then attaching a needle and squirting the material in the hub of the needle onto the slide. “That's sometimes a little bit more friendly to the cells in the mast cell tumor, because sometimes if you suck them into a syringe and squash them onto a slide, they just explode, and the pathologist can't really tell what it is,” explained Hohenhaus.

Aspirating the regional lymph nodes and looking at the patient’s complete blood count (CBC) and biochemical profile are also important components of the presurgical evaluation and should be routinely done.

Treatment for a canine MCT consists of surgery, most importantly. As such, a preanesthetic evaluation should be conducted as part of the diagnostic evaluation—this will aid in the planning of anesthesia.

A preanesthetic evaluation is especially important for older canines and those undergoing tumor removal or other nonelective procedures, as these groups have a higher risk of anesthetic death.

 Additional risk factors for anesthetic death in patients include having an abnormal hematocrit (Hct) level and being underweight. Foregoing conducting or not recording a physical exam and pulse oximetry can also put a patient at risk for anesthetic death. Moreover, feline patients are at a higher risk of anesthetic death than their canine counterparts.

In canines, a buffy coat is not a discriminator for mast cell disease, said Hohenhaus. “Cats are a different story,” Hohenhaus continued. “If a cat has a positive buffy coat, then that cat highly likely has a mast cell tumor…somewhere.”

In discussing diagnostic imaging for MCTs, Hohenhaus emphasized that although chest X-rays can be useful for managing a patient with cardiac or respiratory disease, this method is generally not effective for detecting MCTs. “I've seen a lot of dogs with mast cell tumors over the years, and only 1 dog had a mast cell tumor in its thorax, and that dog, we found it on necropsy—it was not visible on a chest X ray, so a chest X ray in a dog with a mast cell tumor doesn't really help me manage that mast cell tumor better,” said Hohenhaus.

An abdominal ultrasound should likely be done if the patient has enlarged popliteal or inguinal lymph nodes as this imaging will show lymphadenopathy associated with metastatic mast cell disease.

“If you have a dog with a grade 3 or a high-grade tumor, you probably want to look at that liver and spleen because those are the dogs that are at high risk for visceral metastasis,” said Hohenhaus, “And if you've got a dog with a whole bunch of mast cell tumors all over, you might want to think about imaging the abdomen and considering cytology for the liver and spleen”

For dogs with low-grade cutaneous mast cell tumors, imaging is often unnecessary, as studies show a low incidence of visceral metastasis in these cases.

 Hohenhaus recommended waiting to do preoperative imaging until after biopsy results come back, suggeting that only dogs exhibiting signs of more aggressive tumors—such as edema or ulceration—should undergo further imaging.

Ultimately, understanding whether there is metastatic involvement is crucial for determining prognosis and appropriate treatment, including the potential need for chemotherapy and long-term histamine blockers to manage symptoms. “Benadryl and famotidine would be the 2 that we would typically use,” said Hohenhaus, of the long-term histamine blocking agents that would be used in those cases.

Hohenhaus A. Mast Cell Tumors Part 1: The Diagnostic Investigation. Presented at: 2024 New York Vet Show; November 7- 8, 2024; New York, NY.

Rinaldi V, Crisi PE, Vignoli M, et al. The role of fine needle aspiration of liver and spleen in the staging of low-grade canine cutaneous mast cell tumor. 

. 2022;9(9):473. doi:10.3390/vetsci9090473

Ann Hohenhaus, DVM, DACVIM (Oncology, SAIM), delved into essential components of a diagnostic investigation of dogs with MCRs, including fine-needle aspiration and diagnostic imaging methods during her session at the NY Vet Show in New York, New York

Presurgical evaluation and diagnostic imaging for canine mast cell tumors 

When it comes to feline patients, diagnosing them can be tricky due to their nature to hide that they are hurt or sick, and this also rings true for diagnosing skin diseases in a pruritic cat. The signs of skin disease can sometimes be unintentionally overlooked because they may not scratch but overgroom instead. Besides overgrooming, these patients may also have hair loss due to self-induced biting or licking, but clients may bring them in thinking the hair loss is spontaneous.

During his lecture “Unique Considerations in Feline Dermatologic Disease” at the 2024 New York Vet Show in New York City, New York, Andrew Rosenberg, DVM, DACVD, director of medical operations for the Animal Dermatology Group, explained to attendees multiple skin reaction patterns as well as what veterinary professionals can recommend for diagnostic options.

Feline atopic syndrome has 4 reaction patterns, miliarydermatitis, facial neck and pruritus, Eosinophilic Dermatoses, and Self-Induced Alopecia, but they are not a diagnosis. Each of the patterns is a recognized manifestation of skin diseases that feline patients will exhibit and can be caused by a plethora of differentials, but the most common are hypersensitivity reactions.

Papulocrustous dermatitis, also known as miliary dermatitis, is often pruritic, widespread, small, erythematous, crusted papules that tend to be nonfollicular. The disease usually presents itself on the dorsum but can be located anywhere on the feline patient. This pattern is often seen with allergies, however underlying causes can produce this same type of reaction pattern as well.

“What's interesting about these is they aren't associated with follicles, so these are nonfollicular, crusted papules [and] very often they're infected. So if you see these, do a cytology, look for bacteria,” explained Rosenberg.

“This is very commonly seen on the dorsum of a cat, especially the caudal dorsum. Besides allergies, ectoparasites can do this, especially flea allergy can do this. Dermatocytosis can do this. Different types of cancer can look like this as well. And then certainly autoimmune diseases, pemphigus foliaceus is the most common, widespread crusting on a cat, and you can get these little papulocrustous lesions with pemphigus very frequently. I f that's the case, on the if it's pemphigus, most commonly seen on the face and sometimes seen on the ventral abdomen,” he continued.

Eosinophilic dermatoses is the new proposed term that covers the group of skin diseases that were formerly known as eosinophilic Granuloma Complex (EGC) and includes eosinophilic plaques, granulomas, and indolent ulcers. Rosenberg explained they present as pink to yellow pruritic lesion that are raised, erythematous, and exudative. The lesions usually develop in the inguinal region and ventral abdomen of the feline patient but can sometimes be found on the neck or face.

They could present as linear or as nodular firm lesions that occur within the chin or oral cavities. In severe cases, indolent ulcers can affect the upper lip of cats and could affect their nasal planum. When it comes to eosinophilic dermatoses, it is almost always are aligned with hypersensitivity reactions.

According to Rosenberg, none of the reaction patterns he listed during his lecture are pathognomonic for hypersensitivity reactions or feline atopic syndrome specifically. Because of this, veterinary professionals need to rule out other diseases that are differentials for reaction patterns. Diagnosing feline atopic syndrome is based on compatible clinical signs once other different diagnosis is ruled out such as ectoparasites, such as fleas and lice, 

as well as dermatophytic infections. Rosenberg also explained to attendees that in past years, psychogenic alopecia/pruritus was assumed to be common, but now it is exceedingly rare, meaning it should only be considered once teams have ruled out all other possible causes of the patient pruritus, including feline atopic syndrome.

To help veterinary professionals with diagnosing feline atopic syndrome, criteria was created to help diagnosing patients. The criteria is:

Presence of at least 2 affected body sites

Presences of at least 2 of the 4 reaction patterns

Presence of erosions or ulcerations on the neck or chin

Absence of nonsymmetrical alopecia on rump and tail

With the criteria, if 5 out of the 8 are present, there is a sensitivity of 75% and specificity 76% for diagnosing nonflea hypersensitivity dermatitis (feline atopic syndrome).2 Once veterinary professionals can use the following additional criteria when a flea hypersensitivity reaction is ruled out:

At least 2 of the 4 reaction patterns are present 

There is a presence of miliary dermatitis as a dominant pattern

Eosinophilic dermatitis or symmetrical alopecia or erosions/ulcerations are present on the ears, face, head, lips, or neck

Nonsymmetrical alopecia is present on the hindlimbs, tail, or rump

Symmetrical alopecia is present on the abdomen

There is an absence of erosions/ulcerations on the forelimbs

Absence of lesions on the sternum or axilla

When 6 of the 10 criteria above are met, there is a sensitivity of 90% and specificity 83% for the diagnosis of nonflea hypersensitivity dermatitis (feline atopic syndrome).

Flea allergy dermatitis (FAD) is the most common type of allergic dermatitis in feline patients, so it is a mandatory first step to be ruled out according to Rosenberg. Often clients will not see fleas and make the assumption their pet is not suffering from a flea allergy.Affected cats can be a tricky to diagnose for even clinicians because they are fastidious groomers, so they typically groom the fleas off during a mild infestation, so no fleas or flea feces is observed during the exam.

[Cats] are also not like dogs in the sense that they're not just effective in the caudal rump if they have a flea allergy. Verry often it's miliary dermatitis and self-induced alopecia as a reaction pattern, and very often it is the lumbosacral malaria and the caudal medial thighs. But it doesn't have to be. And I actually think when I do see flea allergic cats, they have more of those indolent ulcers and my guess is that that's burning those fleas off, the reaction in their mouth from self-burning themselves,” Rosenberg continued.

Along with ruling our FAD, it is important to rule out dermatophytes, even though they are not technically on the diagnostic criteria list, and food allergies. If all other common causes of pruritus are ruled out, veterinary teams can conduct a skin biopsy in order to diagnose other potential conditions like feline herpes ulcerative dermatitis, or pemphigus.

Rosenberg A . Unique Considerations in Feline Dermatologic Disease. Presented at: New York Vet Show; November 7-8, 2024; New York, NY.

Favrot C, Steffan J, Seewald W, et al. Establishment of diagnostic criteria for feline nonflea-induced hypersensitivity dermatitis. 

. 2012;23(1):45-e11. doi:10.1111/j.1365-3164.2011.01006.x

The unique feline dermatological cases veterinary professionals can see at the clinic, plus how to approach them 

Feline atopic syndrome: What it is and how to diagnostically approach it 

Andrew Rosenberg interview at NY vet regarding cat allergies

Recognizing cat allergies

: So, my name is Andrew Rosenberg. I am a veterinary dermatologist. I work with Animal Dermatology Group, both as a clinical dermatologist in the Wayne, New Jersey, and the White Plains, New York offices. I'm also the director of medical operations for the entire group, which is the largest dermatology group in the world. I'm also the president of the American College of Veterinary Dermatology, so I'm involved with the association that board certifies all veterinary dermatologists.

So, cats with allergies can exhibit one or a combination of all four of these skin reaction patterns. None of them are pathognomonic for one particular type of allergy versus another. The first one is called miliary dermatitis, and miliary dermatitis consists of these crusted papules that you can see on the back—I mean, you can see them anywhere—but they're very often infected with bacteria; they're these crusted papules.

The second reaction pattern is called eosinophilic dermatoses. These include things like indolent ulcers or eosinophilic plaques or granulomas that cats develop, and they can present in a variety of situations. They're frequently seen on the ventral abdomen, with indolent ulcers obviously on the lip. Those are also known as rodent ulcers. If you do a cytology, you'll typically see a lot of eosinophils under the microscope.

The third reaction pattern is called self-induced alopecia, also known as self-barbering. So that's when these cats literally will just pull their hair out, and the underlying skin actually isn't even inflamed, but they'll pull their hair out. This is most commonly seen on the ventral abdomen.

And then the fourth reaction pattern is exactly what it sounds like: face and neck pruritus. So this is when you have cats scratching at their face and neck. Sometimes it can be so severe that they really excoriate themselves and end up with large wounds on their face and neck because they're so itchy.

Veterinary dermatologist Andrew Rosenberg, DVM, DACVD, shares insights on identifying 4 distinct skin reaction patterns that signal allergies in cats, from crusted papules to severe itching on the face and neck