Hrugs
To Avoid Giving CatsMany
drugs that are safe in people or dogs can be extremely toxic to your cat; dosages
are often very different, and cats have metabolic differences that make many common
drugs very dangerous to them. Simple Aspirin and Tylenol, for example, can
be FATAL to cats Under dosing drugs, such as antibiotics, can lead to an ordinary
infection becoming resistant to treatment. There, please DO NOT administer any
drug or medication to your cat without the specific instruction from your veterinarian.
Early,
thorough diagnosis and treatment by a qualified veterinarian will provide any
animal the greatest chance for cure or control of specific problems. One of the
greatest frustrations for veterinarians (and clients too) is to be called upon
to treat a patient which has been "treated" by an owner over a period
of time. Often home therapy allows a condition to become advanced, resistant to
treatment or the strength of the patient becomes weakened as to make it very difficult
if not impossible, to render a cure. This cure could have been obtained if care
had been sought in a forthright fashion. In these cases, the cost of treatment
is often greatly increased due to the more intensive nature of the care then required. The
following is a list of home medications that should not be used in cats.
It is not meant to be a comprehensive list, but rather to provide caution against
many medications often contained in home medicine cabinets. ACETAMINOPHEN
AND PHENACETIN Sources
Many prescription and over-the-counter brands of analgesic and antipyretic drugs
contain acetaminophen or its ethyl ether, phenacetin. Examples are Tylenol, SineAid,
SineOff, Anacin-3, Comtrex, Daytril, Nyquil, Allerest, and Vanquish. Mechanism
of action Phenacetin is metabolized to acetaminophen. Acetammophen is metabolized
by enzymes of the cytochrome P-450 series to intermediate products: nonreactive
glucuronides and sulfates (which are conjugated and eliminated in the urine),
and reactive metabolites, which are metabolized with glutathione to nontoxic mercapturic
acid (which is eliminated). If the toxic metabolites accumulate as a result of
insufficient glucuronide or sulfate metabolism or insufficient glutathione, they
are converted to toxic macromolecules that directly cause cellular death. Cats
lack glucuronyl transferase and inefficiently form glucuronic acid and sulfate
conjugates, leaving more acetaminophen or phenacetin to be metabolized to toxic
metabolites. The glutathione stores are rapidly depleted in cats, leaving a large
amount of toxic metabolites. Methemoglobinernia occurs. Clinical
signs Acute signs in cats are related to methemoglobin formation, whereas acute
signs in the dog are related to hepatic damage. Toxicity is mainly seen in cats
when even a small amount of acetarninophen is ingested (half of a 325 mg tablet
for a 3.5 kg cat); dogs can usually tolerate dosages up to 100 mg/kg. Signs include
cyanosis (which is caused by methemoglobinemia), dyspnea, facial edema (a hallmark
of acetaminophen poisoning mechanism unknown), depression, hypothermia, vomiting.
Signs may progress to weakness, coma, and subsequently death. Increased ALT from
hepatic damage may be seen. Treatment
Since the toxic metabolites bind preferentially with glutathione rather than cell
macromolecules, supplying a glutathione precursor is an important part of treatment.
N-Acetylcysteine provides the cysteine needed for glutathione synthesis and also
increases serum sulfate levels, which supplies sulfate for conjugation. Ascorbic
acid is used to change methemoglobin to reduced hemoglobin. Acetarninophen is
rapidly absorbed and reaches peak blood levels within 30 to 60 minutes; emesis
is performed immediately after ingestion (if possible), and a saline cathartic
is given. Steroids should not be given because they have been reported to cause
a dose-dependent increase in mortality. Antihistamines have been reported to be
contraindicated.
ANTIHISTAMINES
AND DECONGESTANTS (PSEUDOEPHIDRINE, CONTACT, BENADRYL, CHLOR-TRIMATON, etc.) Dosages
are not well established in cats for these drugs, and these should not be used
without
express consent from a veterinarian. These drugs can cause depression,
, hyperexcitability, , vomiting, fever, muscle tremors, rapid or depressed heart
rates, disorientation, and seizures. ASPIRIN
(ACETYLSALICYLIC ACID, SALICYLATE) Pepto-Bismol
Sources
Many analgesic, antiinflammatory, antipyretic, and anticliartheal (Pepto-Bismol)
agents that contain salicylates are sold as OTC preparations. Some keratolytic
products contain salicylates.
Mechanism
of action Acetylsalicylic acid inhibits cyclooxygenase, which then inhibits production
of certain prostaglandins, including protective prostaglandins of the E series.
High levels are known to directly stimulate the respiratory center (early) to
cause an initial respiratory alkalosis. High doses are also known to uncouple'
oxidative phosphorylation and may cause hyperglycemia and glycosuria. Clinical
signs The biologic half-life of aspirin is 7.5 to 8 hours in dogs and 38 to 45
hours in cats at a dose of 25 mg/kg/day. The toxic dose in cats is >25 mg/kg/day
in cats and >50 mg/kg/day in dogs. Signs are noted within 4 to 6 hours after
ingestion of a toxic dose and include depression, vorniting, anorexia and lethargy,
tachypnea (caused by initial respiratory alkalosis), and hyperthermia. The vomitus
may be blood-tinged from GI ulceration. CNS depression leads to muscle weakness
and ataxia; coma and death can occur within I or more days. Gastrointestinal ulceration
or perforation may be seen after the administration of repeated doses over several
days' duration. Anemia, bone marrow depression, Heinz body formation (cats), and
toxic hepatitis may occur. Toxic
signs may be seen at doses of Pepto-Bismol >7 mL/kg/day in dogs and cats. Two
tablespoons of PeptoBismol contain the salicylate equivalent of one 5-grain aspirin
tablet. Treatment
There is no specific antidote. The stomach should be emptied by induction of emesis
or lavage if within <2 hours of ingestion though there are literature reports
that gastric evacuation may be of value up to 12 hours after ingestion of enteric-coated
aspirin preparations. Multiple-dose activated charcoal is warranted. Acid-base
balance is corrected as needed; diuresis is instituted. Alkalinization of the
urine with sodium bicarbonate can be done to hasten urinary excretion, though
this requires intense monitoring and is difficult to achieve safely. Peritoneal
dialysis allows direct removal of salicylic acid from serum. Gastric ulceration
or perforation is treated as needed. CHOCOLATE
(THEOBROMINE) AND CAFFEINE POISONING Sources
Cooking, baking, candy, landscaping (with cacao shells), white chocolate (negligible
amounts of theobromine), sweetened milk chocolate (1/10 the amount of theobromine
as found in unsweetened chocolate, approximately 45 to 60 mg/oz), semisweet or
dark chocolate contains 130 to 185 mg/oz. Unsweetened (baking) chocolate (450
mg/oz), cocoa powder (150 to 600 mg/oz); coffee, tea, soft drinks. Mechanism
of action Theobromine inhibits phosphodiesterase, which results in increased cAMP
and release of catecholamines. Caffeine directly stimulates the myocardium and
central nervous system. It also causes a competitive antagonism of cellular adenosine
receptors. Increased muscle contractility is caused by increased entry of calcium
and inhibition of sequestration by the sarcoplasmic reticulum (mechanism unknown).
Benzodiazepine receptors in the brain are competitively antagonized. Clinical
signs THEOBROMINE A
slight increase in blood pressure is seen. Bradycardia or more commonly tachycardia
occurs, and myocardial dysrhythmias, especially ventricular premature beats, are
possible. Central nervous system excitability, manifested as nervousness, excitement,
tremors, seizures, and ultimately coma, are seen. Panting and urinary incontinence
are also possible. Death occurs within 6 to 24 hours with acute exposure. With
chronic ingestion (over several days), death may result from cardiac failure. CAFFEINE Tachycardia,
tachypnea, hyperexcitability, tremors, seizures, premature ventricular beats.
Dilatation of coronary, pulmonary, and systemic vessels may cause congestion or
hemorrhage. The lethal dose for caffeine is 150 mg/kg for dogs, cats, and people. Treatment
No antidote exists; treatment is supportive. Emesis is used and may be effective
even after several (4 to 6) hours have passed since ingestion; gastric lavage
is useful if emesis is only partially productive or contraindicated. Activated
charcoal is useful and can significantly decrease the half-life of theobromine.
Diazepam is used to control tremors, anxiety, or seizures. Bradycardia is treated
with atropine; tachycardias are treated with lidocaine, metoprolol, or propranolol.
The urinary bladder should be catheterized to prevent reabsorption of theobromine
through bladder mucosa. Fluids are given as part of supportive treatment.
HORMONES These
are often found in homes to treat many different human problems, but for some
reason, owners seem tempted to give these medications to their cats. Dosages for
most all hormones are so radically different and require such specificity of diagnosis
that one should be encouraged to resist any temptation to give a hormonal medication
to a cat. NONSTEROIDAL
ANTIINFLAMMATORY DRUGS Ibuprofen,(Motrin,
Advil, Nuprin, Vick's DayQuil), phenylbutazone (Bute, Butazolidin), naproxen (Naprosyn,
Aleve), indomethacin, piroxicam (Feldene). Clinical
signs Abdominal pain, lethargy, anemia, melena, and hematernesis are most commonly
seen with GI irritation and ulceration. If perforation has occurred, clinical
signs may include abdominal pain, perhaps a fluid wave, shock, injected sclera,
brick-red mucous membranes, and tachycardia. Temperature may be elevated or depressed.
Pulses may be bounding or weak andthready. Clinical
signs associated with acute renal failure include hyposthenuria or isosthenuria,
renal tubular cell casts in the urine sediment, or glucosuria without hyperglycemia.
Urine gammaglutamyltransferase (GGT) will be elevated. These early signs of acute
renal failure will be followed by increasing BUN and creatinine, electrolyte disturbances,
and possibly oliguria or more rarely polyuria. Occasionally, increased alanine
aminotransferase (ALT) and alkaline phosphatase (ALP) may be seen
OVER-THE-COUNTER WORMERS
are old drugs used decades ago. Most have toxicities not seen with today's modern
and safer wormers prescribed by veterinarians. Many over-the-counter womers cause
weakness, staggering, difficulty breathing, vomiting, tremors, seizures and death.
Use ONLY wormers prescribed by your veterinarian after performing a fecal analysis
to determine the appropriate wormer for the particular parasite, as different
worms require different treatments. PEPTO-BISOMOL
Because this product contains salicylate which is similar to aspirin, toxicity
and death can occur in cats. PHOSPHATE
ENEMA (FLEET) These enemas can cause serious electrolyte disturbances and cause
death within an hour or two of administration. |
