Antimicrobials contraindicated in Antimicrobials contraindicated in canines and felines, reasons and canines and felines, reasons and

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K. Karthik, 1689

Introduction

• Antimicrobials may not act in the same way in all species of animal

• Antimicrobials- the remedy for many infectious agents- can cause serious damage at times

• Choice of antibiotic is critical• Dogs and Cats- companion animals- can over

react to certain antimicrobials.

Antimicrobials and associated problems

Antimicrobials Associated problems

Tobramycin, spectinomycin, Gentamicin

Neuromuscular & renal toxicity, oto toxicity

Chloramphenicol and griseofulvin, cefachlor/ cefadroxil/ cephalexin/ cepharadine

Diarrhoea and vomiting

Enerofloxacin/ ciprofloxacin/ norfloxacin

Nephrotocity, diarrhoea

Erythromycin/ clindamycin/ lincomycin

Vomiting, diarrhoea and hepatotoxicity

Nitrofurans and rifampin Hepatotoxic, discolour tears and urine

Ketoconazole, itraconazole Anorexia, depression, dirrhoea, vomiting

SulphonamidesCrystalluria – Sulphathiazole • Sulpha metabolized by acetylation mainly

• Acetylation reduce solubility

• Leads to Crystalluria

• More common in dehydrated animals, acidic urine (carnivores)

• Dogs- lack acetylation mechanism so problem is less.

• Counter act: urinary alkalizers, enough intake of water

Triple sulpha powder ( Sulphapyridine, sulphamerazine, sulphadiazine)- more solube

Hypersensitivity• Sulphadiazine- produce reversible

immune mediated sterile polyarthritis – Doberman

• Can occur 8-20 days after start of treatment

• Backs to normal within 5 days after halt of therapy

Sulfasalazine- for chronic colitis treatment

Colon

Hydrolyzed by bacteria

Sufapridine (Antibiotic) + 5 amino Slicylic acid (anti inflammatory)

Dose – 25 mg/ kg/day

This dose can cause salicylate poisoning in cats

Keratoconjunctivitis sicca – Dogs more prone

• Sulphasalazine, sulphadiazine and sulphamethoxazole

• Nitrogen containing pyridine ring acts on lachrymal acinar cells – cause dryness

• Lacrimation may not return to normal after discontinuation

NN44

Hemorrhagic syndrome

• Sulfaquinoxaline – as anti malarial• Vitamin K antagonist - similar to that

of coumarin anticoagulants• Rapid hypoprothrombinemia occur in

dogs • Hypoprothrombinemia can occur

within 24 hours of treatment

Cephalosporin• Cats – superinfection or anaemia• Ceftiofur in dogs - Anemia and

thrombocytopenia• Vomiting, Diarrhoea• Cephaloridine – most nephrotoxic Is a Zwitter ion

Enters proximal tubules

Affects S2 segment- renal failure

AminoglycosidesNephrotoxicity• Aminoglycosides are +ve charged

• Attracted to –ve charge of lipid layer of kindney

• Transported by pinocytosis, related to phosphotidyl inositol ( high in renal and cochlear)

• Acidic pH increase interaction and divalent cations reduce it.

• Reduced prostaglandin synthesis – low glomerular filtrate

• Initial stage- reversible; prolonged usage- irrversible

Neomycin˃ Tobramycin ˃ Gentamicin < Neomycin˃ Tobramycin ˃ Gentamicin < DihydrostreptomycinDihydrostreptomycin

Lysosomes

Mitochondria

Rupture of lysosome

Brush border cells

Ototoxicity- irreversible• Vestibular and cochlear dysfunction• Accumulates in peri and endolymph of

inner ear- elimination slow• Streptomycin> GentamicinStreptomycin> Gentamicin –

Vestibulotoxic• Neomycin>Kanamycin>amikacinNeomycin>Kanamycin>amikacin –

ototoxic• Cats more susceptible than dogs

Fanconi’s syndrome

• Defective transport of water, salts, bicarbonate, and amino acids from the kidneys; impaired tubular reabsorption.

• Common in Basenji breed of Dogs

Neuromuscular blockade• Interfere with Ach release from motor ending• Not commonly seen in therapeutic dosage• When administered with general anaesthesia

and neuromuscular blocking agents.Neomycin, Streptomycin>kana>amika>gentaNeomycin, Streptomycin>kana>amika>genta• Tobramycin least

Thought on aminoglycosideThought on aminoglycosideAminoglcosides- reserved for G(-)ve infections,

used only when benefit overpowers adverse effects

TetracyclineGI upset• Anorexia, abdominal pain, diarrhoea,

nausea and vomiting (Doxycycline)• Super infection with fungi and bacteria• Cardiovascular dysfunction-

Tetracycline chelates calcium. Rapid infusion in i/v causes hypotension and collapse.

• Cats- Fever• Discoloration of teeth

Chloramphenicol

• Cats- dose-related blood dyscrasias• If treatment is nearly 14 days• Longer elimination half-life in the cat• Hypersensitivity reaction in dogs and

cats –Aplastic anemiaReversible bone marrow depression• Kittens – deficient microsomal

enzymes- inadequate drug metabolism- lead to bone marrow suppression.

• Avoided to nursing bitches, queens.

Macrolides

• GI effect• Dogs – i/v erythromycin- increase in

the electrical and motor activity of the stomach

• Increases gastric motility• Diarrhoea, Vomiting

Quinalones

Arthropathy• Common in pups and kittens• Heavy dog breeds- permanent damage to

joints• Due to chelation of Mg2+ in cartilage • Enroflaxacin @5 to 25 mg/kg for 30 days-

pupps and kittens - splitting of the articular cartilage

• Marbofloxacin, Orbifloxacin- large breeds of dogs- cats resistant to Orbifloxacin effect

Retinal degenerationAcute blindness, mydriasis- enro - 20 mg/kg a day in cats

• Difloxacin and orbifloxacin- Anorexia, decreased appetite, diarrhea, or vomiting

• Enrofloxacin and orbifloxacin- ataxia, seizures

• Orbifloxacin- hypersensitivity

Lincosamide

Anorexia, diarrhea, vomiting• Local irritation of abdominal mucosa

by oral dosing• Lip smacking and excess salivation in

cats with clindamycin

Metronidazole

Neurological disturbances- ataxia, nystagmus, seizures, tremors, weakness

• Rifampin and nitrofurans- colours urine red

Antifungal

Amphotericin –nephrotoxic• Causes renal vasoconstriction, binds to

membrane cholesterol in renal tubules• Cats more sensitiveGriseofulvin:• Hepatotoxic, CNS disturbances,

hemolytic alterations• Kittens commonly affected- inadequate

glucuronyl conjugation

Cats- terato and carcinogenic in high doseCats- terato and carcinogenic in high dose

Ketaconazole:• Hepatotoxic. Cats> dogs• Decrease libido in males-

suppression of testosterone

Renal failure Hepatic Pregnancy Neonates

Aminoglcosides Chloramphenicol Aminoglcosides Aminoglcosides

Amphotericin B Clindamycin Amphotericin B Chloramphenicol

Chloramphenicol- cats

Griseofulvin- cats Azithromycin Quinalones

Quinalones Ketaconazole Chloramphenicol Metronidazole

Lincomycin Lincomycin Fluconazole Nalidixic acid

Nitrofurantoine Macrolide Flucytosine Rifampin

Polymyxin Metronidazole Quinalone Polymyxin

Sulphonamides Rifampin Griseofulvin Sulpha

Tetracycline except doxy

Sulphonamides Ketaconazole Trimethoprim

Tetracycline Sulpha Tetracycline

Polymyxin

Trimethoprim

Metronidazole

Nitrofurantoine

Antimicrobials Antimicrobials contraindicated in contraindicated in different conditionsdifferent conditions

Safer antibiotics

Kidney disorder- Penicillin, tetracycline, cephalosporin

• Reduce the dose of drug and increase frequency

Hepatic damage- Amox, Ampicillin• Cephalosporin- next choice• Metronidazole- can be given at lower dose

Neonates- beta lacatm safe

Pregnancy safe

• Drugs safe in pregnancy- betalactam antibiotics (penicillin G, ampicillin, amoxicillin, amoxicillinclavulanic, carbenicillin, ticarcillin, and cephalosporins)- I choice

• Macrolides, and lincosamides (clindamycin, erythromycin, and lincomycin) – used in allergic patient

Fluroquinalone- not in the line of Fluroquinalone- not in the line of treatment of pregnant animalstreatment of pregnant animals.

Conclusion

• Every antibiotic has their own benefits and problems

• Selection of antibiotic according to the state of disease, species, status of the animal

• Beta lactams are safer compared to all other antibiotics in most of the situations

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