Cat bilateral alopecia, no pruritus

Excellent question. Symmetrical alopecia in the cat, even when reported as non-pruritic, requires a systematic approach because cats are often clandestine groomers. The vast majority of these cases are ultimately due to pruritus, even if the owner never observes it.

My first step is always to differentiate between self-induced alopecia (over-grooming) and hair falling out on its own (true alopecia).

1. Confirm Pruritus with a Trichogram:
Pluck hairs from the margin of the alopecic areas and examine them under mineral oil.
* Fractured, broken tips: This is the smoking gun for over-grooming. The cat is breaking the hairs off. You are now working up a pruritic cat, regardless of the history.
* Intact, tapered tips with telogen bulbs: This indicates a true, non-pruritic alopecia (e.g., effluvium, endocrine, or paraneoplastic). This is much less common.

2. Diagnostic Plan:

Assuming the trichogram shows broken hairs (the most likely scenario), proceed with a standard pruritus workup:

Rule out Ectoparasites: Institute strict, effective flea control for all animals in the household. An isoxazoline-based product is ideal. Even indoor-only cats get fleas. Consider skin scrapes for Demodex and Cheyletiella, though a treatment trial is often more sensitive for Demodex gatoi*.
* Rule out Dermatophytosis: Perform a fungal culture (DTM and Sabouraud dextrose agar). Remember, ringworm can present in many ways and is not always pruritic. Every cat with alopecia gets a culture.
* Rule out Food Allergy: If parasites and dermatophytes are ruled out and alopecia persists, an 8-12 week strict elimination diet trial (novel or hydrolyzed protein) is the next step.
* Rule out Atopy: If the diet trial shows no improvement, a diagnosis of atopic dermatitis is likely.

If the trichogram truly shows intact hairs, the workup shifts:

* This is much more suggestive of an underlying systemic issue. Telogen effluvium (hair cycle arrest from a past stressor) is possible and self-resolving.
* More concerning possibilities include paraneoplastic alopecia (often associated with pancreatic or bile duct carcinoma) or, very rarely, an endocrinopathy like hyperadrenocorticism. This would warrant a full systemic workup with bloodwork and abdominal imaging, at which point I would collaborate with our Internal Medicine service.

In short, prove it's not pruritus with a trichogram first. Statistically, you're dealing with an itchy cat that's a secret groomer.

Colleague,

This is a classic presentation where dermatology and internal medicine intersect. While Dr. Sharma will address the primary dermatologic causes, my role is to rule out underlying systemic disease before we settle on a diagnosis of exclusion like psychogenic alopecia.

From an internal medicine standpoint, two major rule-outs for non-pruritic, symmetric alopecia in a cat are paramount:

Paraneoplastic Alopecia: This is a critical consideration. It's most often associated with pancreatic or biliary adenocarcinoma. The skin often has a characteristic shiny or glistening appearance, and the hair epilates easily. It's a "can't-miss" differential.

Endocrinopathy: Hyperthyroidism is the most common endocrinopathy in older cats and can present with a poor, unkempt coat or alopecia from overgrooming. Hyperadrenocorticism is rare in cats but can also cause alopecia and fragile skin.

Here is my recommended initial approach to investigate a systemic cause:

* Minimum Database: Start with a CBC, chemistry profile, and urinalysis. This gives us a broad overview of organ function.
* Thyroid Screen: Add a total T4 to your initial bloodwork. Given the prevalence of hyperthyroidism, it's a cost-effective and essential screen.
* Abdominal Ultrasound: If the initial bloodwork is unrevealing, this is my next step. I'm specifically looking for any mass or architectural changes in the pancreas, liver, or biliary tree to rule out the primary cause of paraneoplastic alopecia.

Only after these systemic causes have been reasonably excluded can we confidently pursue a diagnosis of psychogenic alopecia. This systematic approach ensures we don't miss a serious underlying condition.

Confidence: Moderate — need more data.