In case it helps anyone else, I've listed the feline medical conditions I've encountered,
the symptoms associated with each, and a link to the relevant cat's medical page
for more details.  It's sometimes difficult to find information about some of these conditions.

Condition Symptoms Cat
Adenocarcinoma Lump on side of neck; increased snoring. Andromeda
Arthritis of spine Pain and stiffness in back/hindquarters Jessamyn

Back pain

Persistent, debilitating lower back pain. Orion

Brain abscess

Sudden lethargy; incoordination and other neurological symptoms; no response to steroids and other medication; test results and x-rays normal. Bobby
Brain tumor Sudden change in personality; behavioral abnormalities; trouble walking. Sasabe

Calicivirus, severe (probable)

Vomiting; diarrhea; lethargy; upper respiratory symptoms; difficulty breathing. Irene Adler

Cardiomyopathy, dilated

Lethargy; sudden death. Pendaran Dyfed

Cerebellar hypoplasia 

Head tremors; incoordination; balance problems. Aisling
Constipation, chronic Inability to defecate, lethargy, delay in development Flynn


No response to auditory stimuli. Aisling


Weight loss, increased water consumption; poor overall condition. Irene Adler, Jessamyn
Eosinophilic keratitis History of herpes infection in eye; swollen/lumpy area in eye. Mosaic
Eye infection/perforation Eyes "glued" shut by discharge; puncture to one eye. Penelope


Petit mal seizures consisting of urinating and meowing; grand mal seizures. Jessamyn

Feline acne

Black spots and sometimes open sores on chin; thickening of skin on chin. Irene Adler

Feline Leukemia

Recurrent upper respiratory and eye infections; two positive tests. Arivaca, Penelope
Hip dysplasia Pain and stiffness in hindquarters Jessamyn
Hypertension (probable) Sudden loss of vision. Roo
Hypertension No noticeable symptoms. Arlo
Hyperthyroidism Weight loss Tamerlane, Molly Maguire
Hypertrophic cardiomyopathy Heart murmur Sasabe
Kidney failure Sudden lethargy, lack of appetite Obsidian, Jessamyn

Liver cancer

Weight loss; lethargy; poor overall condition. Morgan
Liver, enlarged (cause unknown) None noted Jessamyn

Lymphocytic plasmacytic gingivitis stomatitis

Severe, persistent mouth infections. Irene Adler

Lymphoma, intestinal

Lack of appetite; weight loss; elevated white blood cell count; bloating. Blue Moon, Roo

Lymphoma, mediastinal

Slight lethargy; labored breathing; fluid in lungs. Arivaca, Penelope
Multiple myeloma Weight loss; very high calcium levels; high globulins and total protein; bone lesions; seizures. Arlo

Mystery illnesses

1:  Fluid in lungs; some upper respiratory symptoms.
2:  Weight loss; heart murmur.
Pancreatic insufficiency? Weight loss; chronic diarrhea Irene Adler


Persistent vomiting; lethargy. Obsidian
Pancreatitis (probable) Nausea, generalized pain, lethargy Arlo

Rattlesnake bite

Swollen paw. Jessamyn
Reaction to Piroxicam Insulin shock; acute kidney failure Jessamyn
Renal Insufficiency Frequent bouts of constipation and vomiting. Arlo

Upper respiratory infection, chronic

Sneezing, runny nose, occasional fever off and on (mostly on) for nine months. Andromeda
Urinary blockage Inability to urinate. Arlo