Difference between revisions of "Chocolate Poisoning-Dog"

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===Pathology===
 
===Pathology===
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Following absorption from the gastrointestinal tract caffeine and theobromine are metabolised in the liver <ref name="multiples"> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>. Caffeine has a half life of 4.5 hours in dogs while theobromine has a half life of 17.5 hours <ref name="multiples"> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>. In humans the half life of theobromine ranges from 6 to 10 hours, significantly shorter than that in dogs which may explain the susceptibility of dogs to chocolate poisoning REF
+
Following absorption from the gastrointestinal tract caffeine and theobromine are metabolised in the liver <ref name="multiples"> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>. Caffeine has a half life of 4.5 hours in dogs while theobromine has a half life of 17.5 hours <ref name="multiples"> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>. In humans the half life of theobromine ranges from 6 to 10 hours, significantly shorter than that in dogs which may explain the susceptibility of dogs to chocolate poisoning REF.
 +
Methylxanthines have the following modes of action.
  
−
*'''Antagonism of Adenosine Receptors:'''<ref name="multiples"> '''BSAVA Manual of Canine and Feline Emergency and Critical Care''' Second Edition, 2007</ref> this antagonism results in stimulation of the central nervous system, vasoconstriction and increase in heart rate <ref name="multiples">Tilley Smith'''The 5-Minute Veterinary Consult Canine and Feline''' (Third Edition), ''Lippincott, Williams and Wilkins'' </ref> and also diureses <ref name="multiples"> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>
+
*'''Antagonism of Adenosine Receptors:'''<ref name="multiples"> '''BSAVA Manual of Canine and Feline Emergency and Critical Care''' Second Edition, 2007</ref> this antagonism results in stimulation of the central nervous system and an increase in heart rate <ref name="multiples">Tilley Smith'''The 5-Minute Veterinary Consult Canine and Feline''' (Third Edition), ''Lippincott, Williams and Wilkins'' </ref> and also diureses <ref name="multiples"> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>
 
*'''Inhibition of Cyclic Nucleotide Phosphodiesterase:'''<ref name="multiple"> '''BSAVA Manual of Canine and Feline Emergency and Critical Care''' Second Edition,2007</ref> consequently there is an increase in cyclic AMP, which in turn leads to greater catecholamine release and their effects <ref name="multiples">Tilley Smith'''The 5-Minute Veterinary Consult Canine and Feline''' (Third Edition), ''Lippincott, Williams and Wilkins'' </ref>.
 
*'''Inhibition of Cyclic Nucleotide Phosphodiesterase:'''<ref name="multiple"> '''BSAVA Manual of Canine and Feline Emergency and Critical Care''' Second Edition,2007</ref> consequently there is an increase in cyclic AMP, which in turn leads to greater catecholamine release and their effects <ref name="multiples">Tilley Smith'''The 5-Minute Veterinary Consult Canine and Feline''' (Third Edition), ''Lippincott, Williams and Wilkins'' </ref>.
−
*'''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. <ref name=multiples> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>.
+
*'''Modulation of Intracellular Calcium Concentrations:''' <ref name=multiples> '''http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm''', accessed on 04.10.2010 </ref>.
 
Ventricular fibrillation, and other cardiac dysrhythmias are most frequently the ultimate cause of death.<ref> 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''' Chapter 19, Second Edition,2007 </ref>, <ref> 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 </ref>
 
Ventricular fibrillation, and other cardiac dysrhythmias are most frequently the ultimate cause of death.<ref> 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''' Chapter 19, Second Edition,2007 </ref>, <ref> 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 </ref>
  

Revision as of 23:19, 9 January 2011


 This article is still under construction.


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Chocolate

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Introduction

Toxicity is due to the presence of methylxanthines such as theobromine and caffeine in chocolate [1]. Concentrations ranging from of 100-250mg/kg of theobromine and 110-200mg/kg of caffeine have been reported to cause fatalities [1]. The consumption of more than 20mg/kg of total methylxanthines, the dose at which mild signs such as vomiting, diarrhoea and polyuria are induced [1], is considered the cut-off point in deciding whether or not to treat [1]. The concentration of methylxanthines differs between products [1] and therefore the number of grammes required to reach this threshold vary according to the product; in a 10kg dog 5000g of white chocolate provides the equivalent 20mg/kg dose of methylxanthines that 12-40g of plain chocolate, 83-117g of milk chocolate or 7-25g of cocoa powder does [1]. Methylxanthines are also present in beverages and foods other than chocolates [1].

Signalment

Dog that live indoors are more likely to have access to chocolate. Also puppies and dogs that scavenge are at a greater risk of eating food that is not intended for their consumption. Small breeds of dogs may reach the toxic level of methylxanthine concentration per body weight more easily [1].

Diagnosis

Clinical Signs

Chocolate poisoning results in CNS, gastrointestinal, cardiovascular, respiratory and urological signs.[1], [2] which are evident soon after ingestion of a toxic amount of chocolate [1]

  • CNS: hyperactivity, behavioural changes, ataxia, muscle tremors, clonic seizures and hyperthermia [1], [2], [1]
  • Gastrointestinal: diarrhoea, emesis, haematemesis [1], [2]
  • Cardiovascular: arrhythmias,tachycardia, bradycardia sometimes, hypotension [1], [2]
  • Respiratory: tachypnoea [1].
  • Urological: polydypsia and polyuria may also be present [1]

Laboratory Tests

Diagnosis is usually on the basis of clinical signs and a known history of chocolate ingestion [3]. The following laboratory tests are possible but not commonly used;

  • Assays for detection of methylxanthines in bodily fluids such as plasma, urine and stomach contents [1].
  • Blood Glucose: Hypoglycaemia as a sequela to hyperactivity. not seen consistently with chocolate poisoning [1].
  • Urinalysis: Proteinuria, low specific gravity; not seen consistently with chocolate poisoning [1].

Other

  • ECG: rate and rhythm abnormalities [1].

Pathology

Following absorption from the gastrointestinal tract caffeine and theobromine are metabolised in the liver [1]. Caffeine has a half life of 4.5 hours in dogs while theobromine has a half life of 17.5 hours [1]. In humans the half life of theobromine ranges from 6 to 10 hours, significantly shorter than that in dogs which may explain the susceptibility of dogs to chocolate poisoning REF. Methylxanthines have the following modes of action.

  • Antagonism of Adenosine Receptors:[1] this antagonism results in stimulation of the central nervous system and an increase in heart rate [1] and also diureses [1]
  • Inhibition of Cyclic Nucleotide Phosphodiesterase:[2] consequently there is an increase in cyclic AMP, which in turn leads to greater catecholamine release and their effects [1].
  • Modulation of Intracellular Calcium Concentrations: [1].

Ventricular fibrillation, and other cardiac dysrhythmias are most frequently the ultimate cause of death.[4], [5]

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 [1].
      • Premature Ventricluar Contractions: slow intravenous bolus of 2mg to 6mg per kg of lidocaine. Following this a constant rate infusion of 20ug to 70ug per kg per minute [1]
      • Bradycardia: Atropine at a dose of 0.01mg to 0.02mg per kg [1]
    • Once stable treat as outlined below
  • Of dogs with a known history of recent chocolate ingestion but who have not yet developed clinical signs

Prognosis

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 BSAVA Manual of Canine and Feline Emergency and Critical CareChapter 19, Second Edition,2007 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 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
  2. ↑ 2.0 2.1 2.2 2.3 2.4 http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm 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
  3. ↑ ="multiples" http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm
  4. ↑ 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 Chapter 19, Second Edition,2007
  5. ↑ 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
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