Difference between revisions of "Chocolate Poisoning-Dog"

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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 ^[2], is considered the cut-off point in deciding whether or not to treat ^[2]. The concentration of methylxanthines differs between products ^[2] 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 ^[2] 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 ^[2], ^[2].
Cardiovascular: arrhythmias,tachycardia, bradycardia sometimes, hypotension ^[1], ^[2].
Respiratory: tachypnoea ^[2].
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 ^[2]. 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 ^[2]. Caffeine has a half life of 4.5 hours in dogs while theobromine has a half life of 17.5 hours ^[2]. 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 ^[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 ^[1].
Modulation of Intracellular Calcium Concentrations: ^[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 ^[1].
- Premature Ventricluar Contractions: lidocaine; iv bolus of 2mg to 6mg per kg administered slowly, after which a constant rate infusion of 20ug to 70ug per kg per minute should be given ^[1].
- Bradycardia: Atropine at a dose of 0.01mg to 0.02mg per kg ^[2].

Treatment of seizures and hyperactivity
- IV Diazepam at a dose of 0.5 to 2 mg/kg ^[1].
- Alternative to diazepam is barbiturates ^[1].
- Treating the seizures and hyperactivity should help restore normal body temperature. If animal still hyperthermic then this should be treated directly ^[1].

Correction of acid/base and electrolyte inbalances ^[2],

Insertion of urinary catheter
- Helps prevent further absorption of theobromine and caffeine across bladder wall ^[1].

Of dogs with a known history of recent chocolate ingestion but who have not yet developed clinical signs

Administration of apomorphine (0.03mg/kg IV) or hydrogen peroxide (1-5 ml/kg PO) ref 5 min vet consult in order to induce emesis and/or of activated charcoal in order to minimise further absorption of methylxanthines re 5 min vet consult

Prognosis

If treated correctly and early enough ref 5min consult the prognosis is good and a complete recovery can be expected ^[2]. For animals presenting with seizures and arrhythmias the prognosis is more cautious.

References

↑ ^{Jump up to: 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 King, LG, Boag, A (2007) BSAVA Manual of Canine and Feline Emergency and Critical Care(2nd Edition) BSAVA 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 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 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 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 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
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↑ 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
↑ 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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[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 Chapter 19, 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

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@@ Line 12: / Line 12: @@
 Chocolate poisoning results in CNS, gastrointestinal, cardiovascular, respiratory and urological signs <ref name="multiple"> Tilley, LP, Smith, FWK ()'''The 5-Minute Veterinary Consult Canine and Feline(Second Edition)''' ''Lippencott, Williams and Wilkins''</ref>, <ref name="multiples">Merck & Co (2008) The Merck Veterinary Manual (Eight Edition), Merial found at http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm&word=chocolate%2cpoisoning accessed January 2011</ref> which are evident soon after ingestion of a toxic amount of chocolate <ref name="multiple"> King, LG, Boag, A (2007) '''BSAVA Manual of Canine and Feline Emergency and Critical Care(2nd Edition)''' ''BSAVA''</ref>.
-*'''CNS:''' hyperactivity, behavioural changes, ataxia, muscle tremors, clonic seizures and hyperthermia  <ref name="multiple"> Tilley, LP, Smith, FWK ()'''The 5-Minute Veterinary Consult Canine and Feline(Second Edition)''' ''Lippencott, Williams and Wilkins''</ref>, <ref name="multiples"> Warman, SM (2007)Dietary intoxications'''BSAVA Congress 2007 Scientific Proceedings, Veterinary Programme''' ''BSAVA'' </ref>, <ref name="multiple"> King, LG, Boag, A (2007) '''BSAVA Manual of Canine and Feline Emergency and Critical Care(2nd Edition)''' ''BSAVA''</ref>.
+*'''CNS:''' hyperactivity, behavioural changes, ataxia, muscle tremors, clonic seizures and hyperthermia  <ref name="multiple"> Tilley, LP, Smith, FWK '''The 5-Minute Veterinary Consult Canine and Feline(Second Edition)''' ''Lippencott, Williams and Wilkins''</ref>, <ref name="multiples"> Warman, SM (2007)Dietary intoxications'''BSAVA Congress 2007 Scientific Proceedings, Veterinary Programme''' ''BSAVA'' </ref>, <ref name="multiple"> King, LG, Boag, A (2007) '''BSAVA Manual of Canine and Feline Emergency and Critical Care(2nd Edition)''' ''BSAVA''</ref>.
-*'''Gastrointestinal:''' diarrhoea, emesis, haematemesis  <ref name="multiple"> Tilley, LP, Smith, FWK ()'''The 5-Minute Veterinary Consult Canine and Feline(Second Edition)''' ''Lippencott, Williams and Wilkins''</ref>, <ref name="multiples"> Warman, SM (2007)Dietary intoxications'''BSAVA Congress 2007 Scientific Proceedings, Veterinary Programme''' ''BSAVA'' </ref>.
+*'''Gastrointestinal:''' diarrhoea, emesis, haematemesis  <ref name="multiples"> Tilley, LP, Smith, FWK'''The 5-Minute Veterinary Consult Canine and Feline(Second Edition)''' ''Lippencott, Williams and Wilkins''</ref>, <ref name="multiples"> Warman, SM (2007)Dietary intoxications'''BSAVA Congress 2007 Scientific Proceedings, Veterinary Programme''' ''BSAVA'' </ref>.
 *'''Cardiovascular:''' arrhythmias,tachycardia, bradycardia sometimes, hypotension  <ref name="multiple"> Tilley, LP, Smith, FWK ()'''The 5-Minute Veterinary Consult Canine and Feline(Second Edition)''' ''Lippencott, Williams and Wilkins''</ref>, <ref name="multiples"> Warman, SM (2007)Dietary intoxications'''BSAVA Congress 2007 Scientific Proceedings, Veterinary Programme''' ''BSAVA'' </ref>.
 *'''Respiratory:''' tachypnoea <ref name="multiples">Merck & Co (2008) The Merck Veterinary Manual (Eight Edition), Merial found at http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211104.htm&word=chocolate%2cpoisoning accessed January 2011</ref>.