Alopecia can happen for numerous reasons. It is important to first establish if the alopecia is self-induced or spontaneous,
which can be determined by performing a trichogram and observing the hair shaft integrity. The source of the alopecia can
also be investigated by placing an Elizabethan collar on the patient and seeing if hair loss continues while the cat is restricted
The location of the alopecia can help narrow down the list of differential diagnoses. For example, caudal ventral abdominal
alopecia can be secondary to infection (bacteria, fungi, parasites) or allergies but could also be caused by urinary tract
pain or other abdominal pain.
Some additional causes of alopecia are important to consider in an older feline patient. One of the most important is paraneoplastic
alopecia. This alopecia is a cutaneous manifestation of a systemic disease, often adenocarcinoma of the pancreas or biliary
tract. Paraneoplastic alopecia is usually acute in onset, rapidly progressive, and symmetrical, affecting the ventrum and
limbs. The skin often has a very shiny, glistening appearance and can be thin, but is not fragile. Paw pads can also be involved
4. A cat exhibiting alopecia and a glistening appearance of the skin associated with paraneoplastic alopecia. Note how the
limbs and paws are also affected.
These patients often do not feel well, with concurrent weight loss and gastrointestinal signs. Skin biopsy can certainly help
with a diagnosis, but thoracic and abdominal radiography or abdominal ultrasonography is more likely to find the causative
neoplasia. If it is possible to remove the tumor or treat the cancer, hair can regrow.
Alopecia areata and pseudopelade are two rarer conditions that can cause alopecia. Both conditions cause a grossly noninflammatory,
nonpruritic alopecia. In alopecia areata, lymphocytes invade the bulb of the anagen hairs, causing a patchy alopecia; in pseudopelade,
the lymphocytic inflammation is within the isthmus, causing a diffuse alopecia.5
Other causes of alopecia in a geriatric cat include a cutaneous drug reaction, an endocrinopathy (especially hyperadrenocorticism),
anagen/telogen defluxion, sebaceous adenitis, or an injection reaction. A skin biopsy is the most important diagnostic tool
to help differentiate among the possible causes of alopecia in an older feline patient.
There are three general categories for any patient presenting with pruritus as the primary clinical sign—parasites, bacterial
or fungal infection, and allergy. However, if the pruritus is a new clinical sign in an older cat, these broad categories
can be narrowed down quickly. As has been previously stated, parasites can affect an animal at any age. Bacterial or fungal
infection can also affect an animal of any age. In fact, geriatric patients are often predisposed to these conditions because
of their age, especially if a patient has any other systemic diseases affecting the immune system.
It is especially important to look for evidence of demodicosis. Finding Demodex cati mites warrants a more thorough medical workup for a systemic disease predisposing the cat to unchecked mite proliferation.
If infection and parasites are ruled out and a feline patient remains pruritic, food allergy should be considered. It is unlikely
that an older cat would develop environmental allergies, resulting in late-onset pruritus. A strict dietary trial with a home-cooked
novel protein or a hydrolyzed protein commercial food should be performed. However, care should be taken to ensure that there
are no other medical causes that need to be considered when designing the diet trial.11
Unilateral otitis externa or otitis media
Unilateral otitis externa or otitis media in an elderly cat with no history of ear disease is most likely secondary to an
aural mass. An aggressive workup should be instituted at the initial examination. Perform an otoscopic examination to look
for any abnormal tissue in the ear canal. This may need to be done under sedation if the cat is experiencing any pain or discomfort.
The workup should include a complete blood count, a serum chemistry profile, a urinalysis, and imaging of the skull or bullae,
ideally via computed tomography, but radiography or magnetic resonance imaging are other possibilities.
Often the treatment of choice is surgery to remove the ear canal. In certain cases, if the neoplasia is not aggressively invading
surrounding soft tissue or the bone of the middle or inner ear or skull, surgery can be curative and provide a great deal
of comfort to the cat.12