Examine the skin and coat for any lesions, evidence of parasites, or alopecia. The skin can reveal a paraneoplastic syndrome.
The crusting and fissure dermatosis of necrolytic migratory erythema (hepatocutaneous syndrome) is rare in cats and can occur
with a hepatopathy or pancreatic tumor. Exfoliative dermatosis can occur with feline thymoma. A bilaterally symmetrical alopecia
and glistening skin (Figure 4), with or without pruritus, can be seen with feline tumors such as pancreatic carcinoma, bile duct tumors, and thymoma.
Figure 4. Bilaterally symmetrical alopecia and glistening skin associated with a pancreatic tumor. (The cat's abdomen had
been shaved for an ultrasonographic examination.)
Always perform a complete ophthalmic examination in geriatric cats, as signs of systemic disease such as anisocoria, detached
retinas, or abnormalities of the fundus may be seen. Similarly, a general physical examination should be done on a cat presented
for ophthalmic disease.
EVALUATE INITIAL DIAGNOSTIC TEST RESULTS
Once you've ruled out inadequate food intake unrelated to illness (e.g. because of competition, an inability to get to food, an unpalatable diet), try to determine what body systems are affected.
The history and physical examination findings will help to localize your search. For example, if a cat that has a history
of chronic intermittent vomiting is now experiencing weight loss and anorexia and if thickened intestinal loops are noted
on examination, primary GI disease is likely.
Perform a complete blood count (CBC), a serum chemistry profile, a serum thyroxine (T4) concentration measurement, a urinalysis, and a fecal examination. It is often a good idea to keep some extra serum frozen
for possible additional diagnostic tests. Measure blood pressure in cats more than 10 years old. Perform FeLV and FIV testing
if the status isn't known or the history warrants it. Heartworm testing may also be indicated.
Complete blood count
The CBC may indicate eosinophilia associated with inflammation of the intestinal tract, hypereosinophilic syndrome, enteric
parasites, or heartworm disease. If anemia is identified, determine whether it is regenerative or nonregenerative, based on
a reticulocyte count. Cats with chronic kidney disease may have a mild nonregenerative anemia or severe anemia. A microcytic,
hypochromic anemia indicates iron-deficiency anemia from chronic blood loss, which may be observed with bleeding GI tumors.
Uremia may also cause bleeding from microulcerations. Uncommonly, bleeding may occur with severe intestinal disease, apparently
caused by vitamin K malabsorption.5 Always determine the FeLV and FIV status in anemic cats.
Serum chemistry profile
An elevated blood urea nitrogen (BUN) concentration with a normal creatinine concentration can be caused by early prerenal
azotemia, a high-protein diet, drugs (e.g. tetracycline, corticosteroids), and fever. It may also indicate GI bleeding and subsequent intestinal absorption of the blood.
If the creatinine concentration is also elevated, consider chronic renal failure.
Hypoalbuminemia may indicate renal disease, liver disease, hemorrhage, malassimilation (maldigestion and malabsorption), hyperglobulinemia,
exudative cutaneous disease, or protein-losing enteropathy. A decrease in both the albumin and globulin concentrations is
consistent with intestinal loss. Severe hypoalbuminemia (< 2 g/dl) with diarrhea suggests protein-losing enteropathy. Cats
with protein-losing enteropathy usually have GI lymphoma or inflammatory bowel disease.
Hyperglobulinemia can be seen with neoplasia and chronic inflammation. When the hyperglobulinemia is moderate (5 or 6 g/dl)
or severe (> 6 g/dl), consider protein electrophoresis to determine whether a monoclonal or a polyclonal gammopathy is present.
A monoclonal gammopathy is more consistent with lymphoma, plasma cell tumors, and multiple myeloma.
A low serum cholesterol concentration (< 150 mg/dl) may be seen with protein-losing enteropathy, hepatopathy (cirrhosis),