Cat with bilateral alopecia, no pruritus, indoor only

Colleague,

Symmetric alopecia in the cat is one of our classic conundrums. The first and most critical branch point is determining if this is self-induced (over-grooming) versus a true follicular problem where the hair is falling out on its own. Cats are notoriously secretive groomers, so an owner's report of "no pruritus" must always be verified.

My systematic approach here is to first prove or disprove self-trauma:

Trichogram: This is the most efficient first step. Pluck hairs from the margin of the alopecic areas and examine them under mineral oil. Fractured, broken tips confirm over-grooming, which means we are dealing with a pruritic disease, regardless of what the owner observes. Intact telogen bulbs would point us toward a true effluvium or endocrinopathy, which is much less common.

Ectoparasite Control: Even in an indoor-only cat, flea allergy dermatitis is a primary differential for over-grooming. Fleas can easily be transported indoors. I'd recommend instituting a trial with a modern, effective adulticide like a topical isoxazoline for at least 8-12 weeks on all pets in the household.

Dermatophyte Culture: While less likely to be perfectly symmetric and non-inflammatory, dermatophytosis should be ruled out with a fungal culture (DTM).

Our path forward depends entirely on the trichogram:

* If hairs are fractured (Over-grooming): This is a pruritus workup. After starting strict flea control, my next step would be a strict 8-week elimination diet trial (novel or hydrolyzed protein) to rule out cutaneous adverse food reaction. If alopecia persists, we then consider atopic dermatitis.

* If hairs are intact (True Alopecia): Our workup shifts significantly, and I would absolutely involve my internal medicine colleague, Dr. Vasquez. This is the point to perform baseline diagnostics (CBC, chemistry, T4, urinalysis) to screen for systemic disease. Paraneoplastic alopecia or telogen effluvium would be higher on my list. A skin biopsy would also be highly valuable in this scenario to evaluate the follicles.

Let's start with the trichogram and flea control. The results will dictate our next step. Keep me posted.

Colleague,

This is a classic presentation where dermatology and internal medicine intersect. Dr. Sharma will cover the primary cutaneous rule-outs, which are essential. My role is to consider the systemic diseases that can manifest this way.

For any non-pruritic, symmetrical alopecia in a cat, especially if middle-aged or older, my primary differential is an underlying endocrinopathy.

Hyperthyroidism: This is the most common systemic cause. The alopecia can be patchy or symmetrical, and the hair is often dry and unkempt. This diagnosis must be ruled out, even in the absence of weight loss or polyphagia.

Paraneoplastic Alopecia: A less common but critical differential. It's often associated with pancreatic or biliary carcinoma and presents as a rapidly progressing, often ventral alopecia. The skin can have a characteristic shiny, glistening appearance.

Hyperadrenocorticism: This is rare in felines but can cause bilaterally symmetric alopecia and fragile skin. It's lower on my list but remains a possibility.

My recommendation is to start with a good minimum database: a CBC, chemistry panel, urinalysis, and a Total T4. This is a high-yield, cost-effective screen for the most likely systemic causes. If the T4 is in the high-normal range in a cat with clinical signs, I'd follow up with a free T4 by equilibrium dialysis.

If that screening is unrewarding, the next step from my perspective would be an abdominal ultrasound to evaluate the pancreas, liver, and adrenal glands, looking for evidence of neoplasia.

Working hypothesis only — need more data.