Aminoglycoside Antibiotic Poisoning in Dogs and Cats

1 Symptoms

Aminoglycosides are antibiotics against Gram-negative bacteria (streptomycin, gentamicin, kanamycin, neomycin and others). They are poorly absorbed by mouth and usually injected, and most leave the body unchanged via the kidneys. They are ear-toxic (damaging the eighth cranial nerve and hearing), kidney-toxic (reducing kidney function with protein in urine) and can block nerve-to-muscle transmission, relaxing skeletal muscle and even paralysing the breathing muscles.

Ear toxicity brings dizziness, nausea, vomiting, eye tremor, unsteady gait and hearing loss or deafness. Kidney toxicity brings scant urine, no urine, cast urine, blood in urine, high urine potassium, azotaemia and uraemia. Neuromuscular blockade brings lip and tongue tremor or paralysis, limb weakness, paralysis, low blood pressure and death from heart failure and respiratory-muscle paralysis. Some animals have an allergic shock with agitation, chills, itch, hives, convulsions and coma.

2 Causes and Transmission

Causes are excessive or prolonged dosing, injection in dehydrated or kidney-compromised pets, or individual sensitivity. Oral overdose mainly upsets the gut and nutrient absorption.

3 Diagnosis

Diagnosis is based on aminoglycoside use and the combined ear, kidney and neuromuscular signs. Blood and urine tests show rising kidney values and the veterinarian checks hearing and nerve function.

4 Treatment

There is no specific antidote; care stops the drug and supports the patient. For allergic shock, adrenaline and corticosteroid and fluid therapy are used; calcium corrects low calcium, and a cholinesterase inhibitor stimulates skeletal muscle.

Nerve-repair and B-vitamin therapy help nerve recovery; fluids, potassium correction and oxygen are given as needed. Kidney-protective supportive measures are continued under veterinary direction.

5 Prevention

Use aminoglycosides only under veterinary guidance, with dose adjusted for kidney function and hydration, and avoid combining them with other kidney-toxic drugs. Monitor kidney values during treatment.

If hearing loss, reduced urine or weakness appears during therapy, stop the drug and contact the veterinarian promptly.