What a single mouse bite means for a 5 kg nursing cat
A 5 kg cat that is currently nursing has a higher metabolic demand because she is producing milk for her kittens. Even a tiny fragment of a poisoned mouse can contain enough strychnine to overwhelm her system. The toxin is absorbed quickly from the gastrointestinal tract, and because it does not need a large dose to block the inhibitory signals at the neuromuscular junction, the cat can develop severe signs from one bite. The fact that she is lactating does not protect her; it may actually speed the distribution of the poison through her bloodstream.
Because the mouse was likely carrying a bait that contains a concentrated form of strychnine, the cat’s exposure is essentially the same as if she had chewed a small piece of the raw poison. The amount she ingested is impossible to measure precisely, but the clinical picture does not depend on exact grams—any detectable dose can trigger the classic muscle‑spasm cascade. This is why the short answer stresses that even a single bite is enough to cause life‑threatening signs.
Why the first half hour after ingestion is critical
Signs of strychnine toxicity appear rapidly, often within 15 to 30 minutes after the cat swallows the toxin. Early manifestations include restlessness, increased vocalization, and a noticeable tightening of the jaw muscles. Within minutes the cat may adopt a rigid, arched posture known as the "sawhorse" stance, and each convulsion can last several minutes without a pause. The rapid progression makes the initial window the most important time to act.
Call your vet or an animal poison hotline now and tell them exactly what was eaten, how much, and how long ago. Take the wrapper or the ingredient list with you. Your vet will decide whether decontamination is needed. Never induce vomiting at home. Prompt professional guidance can mean the difference between a reversible episode and irreversible damage to the nervous system.
What to watch for in the next 6‑12 hours
Even if the cat seems to settle after the first convulsion, the toxin continues to act on the neuromuscular junction. Watch for recurrent muscle twitching, a stiff gait, or an inability to lie flat. Respiratory effort may become labored as the diaphragm contracts uncontrollably, and the cat’s heart rate can become irregular. Because she is nursing, any disruption in her ability to move may also affect milk let‑down, so a sudden drop in kitten weight gain is a red flag.
Keep a close eye on her breathing sounds, pupil size, and any changes in behavior such as sudden aggression or lethargy. If you notice any new episodes of rigidity, seizures, or difficulty breathing, treat it as an emergency and head straight to the nearest 24‑hour veterinary clinic. The goal is to catch a worsening pattern before it compromises her oxygenation or leads to cardiac arrest.
How to talk to the vet and prevent future exposure
When you reach the clinic, be ready to describe the exact product that was used as mouse bait, the brand name if it’s on the packaging, and the approximate time the cat caught the mouse. Mention that she is a 5 kg lactating cat, that she has kittens, and any signs you have already observed, such as muscle rigidity or changes in milk production. This information lets the veterinarian gauge the severity and decide on monitoring, supportive care, or specific antidotes that may be available.
To keep this from happening again, store all rodent‑control products in a locked cabinet out of reach of pets, and consider using bait stations that limit access to non‑target animals. Remove any dead rodents promptly, and inspect any areas where a cat might hunt for prey. By eliminating the source, you protect both the mother cat and her vulnerable kittens from another accidental dose.
The step-by-step response, from the first minute to the vet visit, is in our Strychnine Poisoning in Dogs and Cats emergency guide.