Potential Explanation for Elevated ALP in Rabbits: Plastic Ingestion Case Study

TL;DR: Chronic, micro-ingestion of plastic over months was identified as the potential culprit behind persistent, isolated Alkaline Phosphatase (ALP) elevation in an otherwise healthy rabbit. Swapping plastic litter boxes for stainless steel resulted in a significant drop toward normal levels.

Maple and Mochi sitting next to a slow feeder bowl — Maple and Mochi, NZW sisters (pictured here with their plastic slow feeder bowl).

Baseline Routine Screening

In 2023, I brought home two 1-year-old New Zealand White (NZW) sisters, Maple and Mochi. I am a big believer in routine wellness bloodwork while animals are healthy to establish a baseline and catch emerging issues early.

April 2023: Mochi’s bloodwork was completely normal. Maple’s bloodwork was also normal except for a single liver value: Alkaline Phosphatase (ALP). While the standard reference range for healthy rabbits is 20–205 U/L, Maple tested at 311 U/L. Because digestive parasites are a common cause of isolated ALP spikes and were easily ruled out, we monitored her closely.

Escalation & Diagnostic Investigation

At her annual birthday checkup in March 2024, Mochi’s bloodwork was once again perfectly normal. Maple’s ALP, however, spiked dramatically to 663 U/L—more than triple the high end of the reference range.

Because all other liver values remained unremarkable, acute liver failure and liver torsion were ruled out. Furthermore, because Mochi lived in the exact same environment and shared food without any abnormal readings, parasites remained unlikely.

Line chart of Maple's ALP values over time — Maple's ALP bloodwork trends over time (2023–2026) compared to normal reference values (20–205 U/L).

Veterinary literature on isolated ALP elevation in rabbits is extremely limited. We consulted a specialist for an abdominal ultrasound, which showed no tumors, structural abnormalities, or organ damage. Given her lack of clinical symptoms, we opted against an invasive liver biopsy in favor of semi-annual monitoring.

Date	Maple's ALP Level	Reference Range	Status / Notes
April 2023	311 U/L	20–205 U/L	Mild isolated elevation
March 2024	663 U/L	20–205 U/L	Peak spike; ultrasound showed clear liver
Sept 2024	380 U/L	20–205 U/L	Dropped unexpectedly
March 2025	547 U/L	20–205 U/L	Rerose; presumed seasonal/cyclic pattern
Sept 2025	480 U/L	20–205 U/L	Slight reduction
March 2026	430 U/L	20–205 U/L	Pattern broken; did not spike as expected
Sept 2026	282 U/L	20–205 U/L	Significant drop following plastic removal

Connecting the Dots: The Habitual Plastic Nibbler

While discussing the frustrating lack of environmental explanations with our vet, I recalled one key behavioral difference between the two sisters: Maple habitually ingests plastic.

Unlike acute chewers who tear off large fragments risking instant GI stasis, Maple nibbled tiny pieces over extended periods—gnawing giant cutouts out of plastic litter boxes and chewing on plastic slow-feeder bowls left out overnight.

Plastic litter boxes showing severe chew marks and missing plastic along edges — The plastic litter boxes after extended chew damage from Maple over months and years.

Husbandry Changes & Results

To address the issue, we made two major environmental adjustments:

Replaced all plastic litter boxes with stainless steel litter boxes.
Stopped leaving plastic slow-feeders out overnight.

By September 2026, following these changes, Maple’s ALP dropped to 282 U/L—her lowest level since initial baseline testing three years prior.

Maple relaxing indoors next to a cardboard box — Maple enjoying a safe, plastic-free lounging area.

Summary & Community Takeaway

Due to the scarce documentation regarding isolated ALP spikes in rabbits, persistent low-level plastic toxicity/ingestion should be considered a potential differential diagnosis when clinical symptoms and structural abnormalities are absent. Transitioning to metal litter pans and removing plastic toys can help reduce metabolic stress on the liver.