Chocolate Poisoning-Dog

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Introduction

Toxicity is due to the presence of methylxanthines such as theobromine and caffeine in chocolate.[1]. The concentration of methylxanthines in chocolate differs between products. For example the average methylxanthine content of milk chocolate is 2mg/g, while that of baking chocolate is 16mg/g. [2].

Signalment

Dog that live indoors are more likely to have access to chocolate. Also puppies are at a greater risk of eating food that is not intended for their consumption [2].


Diagnosis

Clinical Signs

Chocolate poisoning results in CNS, gastrointestinal, cardiovascular and urological signs.[2], Cite error: Closing </ref> missing for <ref> tag

  • CNS: hyperexcitability, hyperactivity, ataxia initially can evolve into muscle tremors, clonic seizures and hyperthermia.[2], [1]
  • Gastrointestinal: diarrhoea, emesis, haematemesis, colic.[2], [1]
  • Cardiovascular: arrhythmias,infrequently bradycardia but usually tachycardia.[2], [1]
  • Urological: polydypsia and polyuria may also be present [2]

Laboratory Tests

Diagnosis is usually on the basis of clinical signs and a known history of chocolate ingestion. The following laboratory tests are possible but not commonly used;

  • Detection of methylxanthines in bodily fluids such as plasma, urine and stomach contents [2].
  • Blood Glucose: Hypoglycaemia as a consequence of hyperactivity. not seen consistently with chocolate poisoning [2].
  • Urinalysis: Proteinuria, low specific gravity; not seen consistently with chocolate poisoning [2].

Other

  • ECG: rate and rhythm abnormalities

Pathology

The methylxanthines yield their effects through

  • Antagonism of Adenosine Receptors:[2] this antagonism results in stimulation of the central nervous system, vasoconstriction and increase in heart rate [2] and also diureses [2]
  • Inhibition of Cyclic Nucleotide Phosphodiesterase:[1] consequently there is an increase in cyclic AMP, which in turn leads to greater catecholamine release and their effects [2].
  • Modulation of Intracellular Calcium Concentrations:Enhanced uptake and decreased sequestration within the cell leads to amplification of intracellular calcium levels in cardiac and skeletal muscle, the net result of which is a positive inotropic effect on these muscles. [2].

Ventricular fibrillation, and other cardiac dysrhythmias are most frequently the ultimate cause of death.[3], [4]

Treatment

  • Of dogs presenting with clinical signs
    • Inital stabilisation of Cardiorespiratory System:
      • Tachycardia: beta-blockers, eg orally administered metoprolol at a dose of 0.5mg to 1mg per kg every 8 hours
      • Premature Ventricluar Contractions:
  • Of dogs with a known history of recent chocolate ingestion but who have not yet developed clinical signs
**

Prognosis

References

  1. 1.0 1.1 1.2 1.3 1.4 BSAVA Manual of Canine and Feline Emergency and Critical CareSecond Edition,2007 Cite error: Invalid <ref> tag; name "multiple" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiple" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiple" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiple" defined multiple times with different content
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 Tilley, SmithThe 5-Minute Veterinary Consult Canine and Feline (Second Edition), Lippencott, Williams and Wilkins Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content Cite error: Invalid <ref> tag; name "multiples" defined multiple times with different content
  3. Carson TL (2006) Methylxanthines. In: Small Animal Toxicology, ed. ME Peterson, PA Talcott, pp.845-852. Elsevier Saunders, St. Louis in BSAVA Manual of Canine and Feline Emergency Care Second Edition,2007
  4. Holmgren P, Norden-Petterson L and Ahlner J (2004)Caffeine fatalaties: four case reports. Forensic Science International 139, 71-73 BSAVA Manual of Canine and Feline Emergency Care Second Edition,2007