Why pregnancy doesn't change lily risks for a 28 kg dog
Lily toxicity works the same way in pregnant dogs as in any other dog—the plant's compounds attack the kidneys directly. While your Border Collie's size means she'd need to eat more than a cat to reach fatal levels, even a few chewed leaves can cause severe mouth irritation, drooling, and vomiting. The stress of those symptoms could indirectly affect her pregnancy, especially if she stops eating or becomes dehydrated.
Watch for pawing at her mouth or excessive lip-licking, which suggest the leaves irritated her gums. Pale gums would signal something far worse: internal bleeding or kidney strain. Since pregnancy already increases her body's fluid demands, any delay in treating possible lily poisoning puts extra pressure on both her and the puppies.
How lilies differ for dogs versus cats
Dogs lack the extreme sensitivity cats have to lilies, where even pollen grooming can be deadly. But their mouths and stomachs still react strongly—expect foamy drool or gagging if she swallowed leaf fragments. The bigger concern is whether she actually ingested any plant material or just mouthed it. Check the garden for torn leaves with wet edges versus dry tooth marks.
Unlike cats, where kidney failure develops within 12-24 hours, dogs usually show gastrointestinal distress first. But pregnancy complicates things: dehydration from vomiting reduces blood flow to the uterus. If she's panting more than usual or seems restless, those could be early pain signals rather than just pregnancy discomfort.
What to do in the next 6 hours
Rinse her mouth gently with lukewarm water if she'll allow it, as residual lily sap can keep irritating her gums. Offer ice cubes to lick rather than a full water bowl—drinking too much after oral irritation might trigger more vomiting. Confine her to one room with easy-to-clean floors so you can monitor any drool or vomit for leaf fragments.
Even if she seems fine now, call your vet with the approximate number of leaves she chewed (were they small new growth or large mature leaves?). Pregnancy means they may want to run blood tests sooner than usual to check kidney values, as waiting for symptoms risks the puppies' health too.
Why stress matters more during pregnancy
A poisoned dog's body prioritizes survival over pregnancy—severe vomiting or kidney stress can trigger early contractions. Watch for nesting behaviors out of nowhere, licking her belly excessively, or any vaginal discharge. These signs plus lily exposure mean emergency care, not waiting until morning.
Normal pregnancy panting differs from pain panting: the first comes and goes with activity, while the second stays constant. Time her breathing—if it's over 30 breaths per minute while resting, or she's shifting positions every few minutes unable to get comfortable, the lilies may be causing more than just mouth irritation.
The step-by-step response, from the first minute to the vet visit, is in our Safe and Toxic Flowers for Dogs and Cats at Home emergency guide.