Pancreatitis vs. FIP vs. Intestinal Tumor/Foreign Body

Hello. Please help. 5 year old MN cat (indoor only, adopted at 2 months old) - seeking input on pancreatitis vs. FIP vs. intestinal disease/foreign body.

History

- 3-4 months prior: frequent dry heaving/cough several times daily. No other symptoms, completely normal behavior. Seen by vet for asthma eval, and received depomedrol + abx injection. Lungs were normal. Suspected bronchitis.

- ~3 weeks later developed rapid onset of lethargy, anorexia, abdominal discomfort, increased respiratory rate from one day to the next. Night before onset, he did diarrhea but before was otherwise normal, eating normal, etc.

Current Clinical Signs

- Anorexia (currently syringe feeding Royal Canin GI Rx).

- Only vomited 2x since onset. No vomiting since Sunday, 03/08.

- Minimal stool (last BM on Monday 03/09, unsure if there have been more as I work + my litter box is automatic + I have another cat).

- Abdomen appears distended/firm.

- Pain/discomfort only when abdomen deeply palpated (during fast ultrasound), not light touch.

- Respiratory rate elevated (~42/min) but lungs clear. Occasional slight mouth opening/tongue out when resting.

- *NO WEIGHT LOSS. Has actually gained weighed. He weighed 12 lbs in June 2025, and now weighs 15 lbs.

Diagnostics So Far

- Vet #1 (ER) / Abdominal radiographs: pancreatitis primary Dx (lipase very elevated), scant abdominal fluid and scant thorax fluid noted (raised concern for possible SIRS).

- Vet #2 / Repeated radiographs; suspected pancreatitis + peritonitis. Aspirated sample abdominal fluid (was light pink/light yellow). Then suspected possible wet FIP (no diagnostics performed to confirm).

- Vet #3 / Repeat AFAST ultrasound, noted firm, "bunched up" intestines. Against it being FIP; another aspiration sample performed, said fluid was more bloody + A:G ratio normal). Vet's differential is foreign body vs. lymphoma/GI tumor (primarily believes it to be lymphoma). No palpable lymph nodes. Depomedrol injection administered. PLAN: Full abdominal ultrasound on Monday to confirm if there is a mass.

CBC Trends

03/07

- WBC: 7.98

- Lymphocytes: 1.81

- Monocytes: 3.63 (high)

- Neutrophils: 1.61 (low) with bands suspected

- Hematocrit: 76.5% (high from dehydration)

- Hemoglobin: 21.4 (high from dehydration)

- Platelets: 14 (low)

03/13

- WBC: 15.52

- Lymphocytes: 9.10 (increased from 03/07)

- Monocytes: 2.01 (high but decreased from 03/07)

- Neutrophils: 4.12 (increased from 03/07, now normal; bands still suspected)

- Hematocrit: 38.7% (dehydration resolved)

- Hemoglobin: 12.1 (dehydration resolved)

- Platelets: 99 (low but increased from 03/07)

Chemistry Trends

03/07

Glucose: 209 (high, from stress?)

BUN: 52 (high)

Lipase: 3,635 (so high!)

Catalyst Pancreatic Lipase: >50 (so high!)

Globulin: 4.0

Albumin: 2.9

A:G Ratio: 0.7

03/13

Glucose: 362 (increased from 03/07)

BUN: 22 (decreased from 03/07, now normal)

Lipase: 437 (normal now??????)

Globulin: 3.2 (decreased from 03/07)

Albumin: 2.1 (minimally low, decreased from 03/07)

A:G Ratio: 0.7

Current Tx

- Cerenia

- Mirataz

- SQ fluids

- Rx food

- GS-441524 (empirically treated)

1. In your opinion, does this presentation/lab trend raise concern for FIP, intestinal lymphoma/tumor (like LGITL), or foreign body obstruction?

2. Are the elevated lymphocytes/monocytes concerning for neoplasia vs. inflammatory disease? Why not viral infection?

3. Any comment on dramatic drop in lipase?

I do want to add that Pistachio does not appear to be in significant pain. He seems mildly uncomfortable at times but is mostly resting. He does still get up periodically to walk around and use the litter box. He is still making biscuits occasionally, meowing, and jumping on the bed to cuddle with me.

Any insight would be greatly appreciated. I understand it’s difficult to give a definitive opinion without abdominal ultrasound results, which may or may not reveal a mass. However, if no mass or obvious findings are present, I would be very interested to hear your thoughts on other possible explanations. Thank you so much for your time and thoughts.