Page 341 - Problem-Based Feline Medicine

18 – THE THIN, INAPPETENT CAT 333

WHERE? PATHOGENESIS
Signs of a thin inappetent cat may be the result of any Chronic renal failure is defined as primary renal
disease process that can cause decreased body weight failure that has persisted for an extended period
and/or suppression of appetite. (usually greater than 2 weeks).
The appetite center is in the hypothalamus. Chronic renal failure is associated with irreversible

Diseases affecting the oral cavity and pharynx may structural lesions in the kidney.
cause pain or dysphagia and so decrease nutrient Chronic renal failure is the end result of many dis-
intake. Such animals will often show interest in food ease processes affecting the kidney:
but cannot eat. Inability to smell food (anosmia) will ● Anomaly: Familial renal disease, polycystic kidney
frequently cause anorexia (e.g. chronic nasal disease). disease.
Diseases of the gastrointestinal tract, liver and pancreas ● Metabolic: Hypercalcemia (from cholecalciferol
may cause anorexia, maldigestion or malabsorption of rodenticide, granulomatous disease or neoplasia),
nutrients, and therefore weight loss. ischemic injury.
● Mechanical: Chronic urinary tract obstruction (e.g.
Careful history taking regarding the animal’s environ- urolith) resulting in hydronephrosis.
ment (inside, outside; single-, multiple-cat household) ● Neoplastic: Lymphoma, primary neoplasia.
may aid in deciding a diagnostic approach. ● Infectious: Feline infectious peritonitis, upper uri-
Good history taking and complete physical exami- nary tract infection (pyelonephritis).
nation are essential, due to the lack of specificity of ● Immune: Secondary to glomerulonephritits, amy-
these clinical signs. loidosis.
● Toxic: Therapeutic agents (e.g. gentamicin, ampho-
tericin B, NSAIDs), intravenous contrast agents,
WHAT? heavy metals (e.g. lead), hemaglobin, ethylene gly-
The most common causes of the thin innappetent col and plants (lilies).
cat with few other clinical signs are chronic renal The initiating cause of chronic renal failure is often
failure, neoplasia and, depending on geographical not identified.
location, several viral diseases (FIV, FeLV and FIP).
At the time of diagnosis there is usually diffuse
Weight loss followed by inappetence tends to be a pathology of the renal parenchyma termed chronic
terminal event in many disease processes. generalized nephropathy.
Many other causes will usually have other significant Polycystic kidney disease is a common cause of renal
clinical problems that will aid the clinician in formulat- failure in some breeds of cats and has the following
ing a diagnostic plan. characteristics:
● Renal cysts may be congenital or acquired and may
affect one or both kidneys.
DISEASES CAUSING SIGNS OF A THIN ● Polycystic kidney disease is characterized by multi-
INAPPETENT CAT ple cysts occurring in both kidneys.
● Polycystic kidney disease occurs as an autosomal
dominant inherited renal disease of Persian and
CHRONIC RENAL FAILURE***
Persian-related cats, with a prevalence of at least
45% in some Persian populations.
Classical signs
● Renal cysts are fluid-filled sacs lined with epithelium,
● Polyuria, polydipsia. that generally originate in existing nephrons and may
● Weight loss, inappetence. therefore occur in the renal cortex or medulla. Cystic
● Vomiting. structures have also been noted in other organs, such
as the liver, in cats with polycystic kidney disease.