Fast-Vet

Livestock: Pain associated with trauma and intestinal inflammation, post partum pain, Post operative pain, post vaccination pain, Toothache, Muscleache, Arthritis, Fever. Poultry: Pain, Fever (Vaccination, debacking, injury etc. associated related pain 

Acetaminophen is contraindicated in cats at any dosage. Severe methemoglobinemia, hematuria, and icterus can be seen. Cats are unable to significantly glucuronidate acetaminophen leading to toxic metabolites being formed and resultant toxicity. Acetaminophen should not be used in ferrets as they may be as sensitive to acetaminophen as are cats.

Analgesic drug. Exact mechanism of action is not known. There is evidence that acetaminophen inhibits centrally mediated pain transmission via inhibition of cyclo-oxygenase (COX)-3 a variant of COX-1 found in the central nervous system (CNS). Other evidence indicates that acetaminophen may inhibit prostaglandins in some cells and tissue in which low concentrations of arachidonic acid are present.
The site of acetaminophen action may be the peroxidase enzyme component of prostaglandin H2 synthase. Therefore, COX enzyme inhibition may occur at site-specific tissues, sparing the gastrointestinal (GI) mucosa, platelets, and kidneys but acting centrally. Acetaminophen may affect inhibitory pain pathways involved in chronic
pain and neuropathic pain syndromes. Descending inhibitory pain pathways are mediated by serotonin (5-HT3). Acetaminophen can stimulate the inhibitory pain pathway mediated by serotonin, and these can be blocked by serotonin antagonists. This evidence suggests that acetaminophen may directly activate serotonin receptors. An additional mechanism of action may be by activating transient receptor potential vanilloid 1 (TRPV1) receptors. This action may play a role in some pain syndromes, but the relevance is undetermined for clinical use.
In canine studies, acetaminophen has not produced anti-inflammatory action but has been effective as a mild analgesic agent. The effects of acetaminophen are brief and not as effective as the effects of nonsteroidal anti-inflammatory drugs (NSAIDs).

The following drug interactions have either been reported or are theoretical in humans or animals receiving acetaminophen and may be of significance in veterinary patients:
OTHER ANALGESICS: Chronic use with acetaminophen may lead to renal pathologies
BARBITURATES: Increased conversion of acetaminophen to hepatotoxic metabolites; potentially increased risk for hepatotoxicity
DOXORUBICIN: May deplete hepatic glutathione, thereby leading to increased hepatic toxicity
HALOTHANE: Acetaminophen is not recommended for use for postoperative analgesia in animals that received halothane anesthesia
ISONIAZID: Possible increased risk of hepatotoxicity
PHENOTHIAZINES: Possible increased risk for hypothermia
PROPYLENE GLYCOL: Foods containing propylene glycol (often found in wet cat foods) may increase the severity of acetaminophen-induced methemoglobinemia or Heinz body formation.
WARFARIN: While acetaminophen is relatively safe to use, large doses may potentiate anticoagulant effects

Acetaminophen is well tolerated in dogs at doses listed; however, high doses have caused liver toxicity.

It causes severe toxicosis in cats because of their inability to excrete metabolites. Acetaminophen relies on conjugation with glutathione for excretion, and deficiencies in glutathione can lead to toxicity. Treatment of a toxic overdose consists of administration of acetylcysteine (see Acetylcysteine for more details). Clinical signs of toxicity include methemoglobinemia, acute hepatic toxicosis, swelling of paws, and Heinz body anemia.

Dogs do not metabolize acetaminophen as well as humans and its use must
be judicious. While dogs are not as sensitive to acetaminophen as cats, they
may also be susceptible to methemoglobinemia when given high dosages. In
dogs, it is generally not recommended to use acetaminophen during the
immediate post-operative phase (first 24 hours) due to an increased risk of
hepatotoxicity.

 high doses have caused liver toxicity.

In cats, treatment of intoxication requires prompt treatment with acetylcysteine, supportive care, and monitoring.