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Mycotoxicoses
Synonym(s): Aflatoxin poisoning, Aflatoxicosis, trichothecene poisoning, Penitrem A poisoning, Roquefortine poisoning, Tremorgenic Mycotoxicosis
Introduction
- These are diseases caused by ingestion of fungal toxins in food or food scraps. See also Mushroom and toadstool poisonings Mushroom poisoning.
Presenting signs
- Aflatoxin poisoning in dogs:
- Inappetence, vomiting, lethargy, melena and jaundice.
- Tremorgenic mycotoxicosis in dogs:
- Twitching, vomiting, rapid progression to whole-body tremors and seizures Seizures.
- Trichothecene poisoning in dogs:
- Anorexia and vomiting.
- Stachybotryotoxicosis in dogs:
- Contact dermatitis Skin: irritant contact dermatitis from bedding containing stachybotryotoxins.
Other mycotoxicoses in dogs
- A number of other mycotoxins have been shown to cause poisoning in dogs when given experimentally, but clinical cases have not been reported. These include:
- Citrinin and ochratoxin: nephrotoxins.
- Ergot: peripheral vasoconstriction and dry gangrene, nervous ergotism, abortions.
- Patulin: diarrhea and pulmonary edema Lung: pulmonary edema.
- Slaframine (slobbers): hypersalivation.
- Stachybotryotoxins (oral): leukocytosis and thrombocytosis Hematology: platelet count followed by leukopenia, thrombocytopenia and oral petechiae.
Geographic incidence
- Fungi are ubiquitous.
- Aflatoxicosis:
- The fungi Aspergillus flavus Aspergillus flavus and Aspergillus parasiticus can grow and elaborate aflatoxins when the moisture content of the substrate is between 15-35% and the air temperature is between 24-35°C. The fungi grow as both field fungi (infecting grains pre-harvest) and storage fungi (infecting grains and grain products in storage). Dogs have been poisoned by eating moldy grain or by eating moldy grain products, eg moldy bread. Numerous outbreaks have been reported in dogs.
- Tremorgenic mycotoxicosis:
- Penitrem A poisoning has been reported in dogs that have eaten moldy food and compost items, including moldy cheese, cream cheese, bread, or walnuts. The toxin is produced by fungi of the genus Penicillium.
- Roquefortine is also produced by fungi of the genus Penicillium. Clinical poisonings in dogs have also been associated with ingestion of moldy food, and compost.
- Trichothecene mycotoxins have been found in commercial dogfoods made with grains contaminated with various toxigenic fungi:
- Fusarium fungi are probably the most prevalent toxin-producing fungi of northern temperate regions but these and related mycotoxins occur worldwide. Colonization by Fusarium spp and toxin production can occur in the field, but some toxin production occurs in storage. Weather conditions, grain defects and moisture content are the most important factors influencing toxin production. Mild temperatures tend to encourage fungal growth and cool temperatures increase toxin production. Trichothecenes tend to be produced in toxic concentrations in years when the weather is wet and harvests are delayed and prolonged.
- Fungi of the genus Stachybotrys grow on cellulose-rich substrates, including grains, paper, and wood at temperatures between 0-40°C when there is a moisture content of at least 15% in the substrate and relative humidity not less than 90% in the immediate environment.
Age predisposition
- No reported age, sex or breed predispositions.
Public health considerations
- All these mycotoxins are also toxic to human beings. In the event of mycotoxicosis in a dog, risk to humans and other pets in the same household should be assessed.
- If a pet food is suspected as the cause of poisoning, samples should be collected and the relevant authority notified in order that investigations, and if necessary, a food recall, can be initiated.
Cost considerations
- Treatment of acute poisoning with the tremorgens, penitrem A and roquefortine, or of aflatoxicosis, may be high.
Special risks
- Dogs with aflatoxicosis may have hemorrhagic diasthesis, making them poor surgical risks.
Pathogenesis
Pathophysiology
- Aflatoxins are converted to their epoxides by a cytochrome P450 in the liver. The highly reactive epoxides bind to and damage DNA, proteins and other macromolecules throughout cells. Hepatocellular degeneration and necrosis ultimately leads to impaired liver function, including synthesis of clotting factors.
- Trichothecene mycotoxins: there are almost 200 trichothecenes including T-2 toxin, diacetoxyscirpenol, neosolaniol, HT-2 toxin, deoxynivalenol (DON, vomitoxin), and nivalenol. Stachybotrys species are trichothecenes and other mycotoxins. Trichothecenes are potent inhibitors of protein synthesis and nucleic acid synthesis, and are immunosuppressants. They are directly cytotoxic causing irritation and necrosis of the mouth and gastrointestinal tract and skin. Dogs are less susceptible to oral trichothecenes due to their emetic effect.
- The mechanism of action of the tremorgenic mycotoxins is unclear. The main neurotoxic effects of penitrem A appear to be due to blocking high-conductance calcium-activated potassium (BK) channels and impairing GABA-ergic neurotransmission. Effects on the peripheral nervous system are also thought to be due to penitrem A inhibiting BK channels in muscle cells. This may cause an increase in action potentials at nerve terminals by preventing repolarisation, producing an increase in neurotransmitter release.
Timecourse
- Aflatoxicosis in the dog is usually acute to subacute (a few days) in contrast to the chronic aflatoxicosis reported in livestock.
- The trichothecenes also act within one to a few days.
- Clinical signs of tremorgenic mycotoxicosis may develop within 30 mins of ingestion, but can sometimes be up to 3 h. Recovery usually occurs within 24-48 h. In some cases, recovery may take 3-4 days but occasionally can be months.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
Aflatoxicosis
- Ural K, Ulutas B, Tunca R, Kum C, Avci H, Boyacioglu M, Guletekin M, Atasoy A (2013) Aflatoxicosis in rottweilers after eating moldy bread: clinicopathologial features and effective tetrasulphate therapy. Vet Archiv 83 (4), 403-412.
- Arnot L F, Duncan N M, Coetzer H, Botha C J (2012) An outbreak of canine aflatoxicosis in Gauteng Province, South Africa. J S Afr Vet Assoc 83 (1), 2 PubMed.
- Bruchim Y, Segev G, Sela U, Bdolah-Abram T, Salomon A, Aroch I (2012) Accidental fatal aflatoxicosis due to contaminated commercial diet in 50 dogs. Res Vet Sci 93 (1), 279-87 PubMed.
- Dereszynski D M, Center S A, Randolph J F, Brooks M B, Hadden A G, Palyada K S, McDonough S P, Messick J, Stokol T, Bischoff K L, Gluckman S, Sanders S Y (2008) Clinical and clinicopathologic features of dogs that consumed foodborne hepatotoxic aflatoxins: 72 cases (2005-2006). J Am Vet Med Assoc 232, (9), 1329-1337 PubMed.
- Furrow E (2007) The critical care of aflatoxin-induced liver failure in dogs. Vet Med 102 (10), 644-651.
- Stenske K A, Smith J R, Newman S J, Newman L B, Kirk C A (2006) Aflatoxicosis in dogs and dealing with suspected contaminated commercial foods. J Am Vet Med Assoc 228 (11), 1686-1691 PubMed.
Tremorgenic mycotoxicosis
- Kormpou F, Adamantos S, O’Sullivan A, Troth L (2018) Use of lipid emulsion in dogs with suspected tremorgenic mycotoxicosis: 53 cases. Vet Evidence 3 (2), 1-8.
- Barker A K, Stahl C, Ensley S M, Jeffery N D (2013) Tremorgenic mycotoxicosis in dogs. Compend Contin Educ Vet 35 (2), E2 PubMed.
- Munday J S, Thompson D, Finch S C, Babu J V, Wilkins A L, di Menna M E, Miles C O (2008) Presumptive tremorgenic mycotoxicosis in a dog in New Zealand, after eating mouldy walnuts. NZ Vet J 56 (3), 145-148 PubMed.
- Young K L, Villar D, Carson T L, Ierman P M, Moore R A, Bottoff M R (2003) Tremorgenic mycotoxin intoxication with penitrem A and roquefortine in two dogs. J Am Vet Med Assoc 222 (1), 52-3, 35 PubMed.
- Boysen S R, Rozanski E A, Chan D L, Grobe T L, Fallon M J, Rush J E (2002) Tremorgenic mycotoxicosis in four dogs from a single household. J Am Vet Med Assoc 221 (10), 1441-4, 1420 PubMed.
- Naudé T W, O'Brien O M, Rundberget T, McGregor A D, Roux C, Flaoyen A (2002) Tremorgenic neuromycotoxicosis in 2 dogs ascribed to the ingestion of penitrem A and possibly roquefortine in rice contaminated with Penicillium crustosum. J S Afr Vet Assoc 73 (4), 211-215 PubMed.
- Puschner B (2002) Mycotoxins. Vet Clin North Am Small Anim Pract 32 (2), 409-19 PubMed.
- Walter S L (2002) Acute penitrem A and roquefortine poisoning in a dog. Can Vet J 43 (5), 372-374 PubMed.
- Lowes N R, Smith R A, Beck B E (1992) Roquefortine in the stomach contents of dogs suspected of strychnine poisoning in Alberta. Can Vet J 33 (8), 535-8 PubMed.
- Hocking A D, Holds K, Tobin N F (1988) Intoxication by tremorgenic mycotoxin (penitrem A) in a dog. Aust Vet J 65 (3), 82-85 PubMed.
- Puls R, Ladyman E (1988) Roquefortine toxicity in a dog. Can Vet J 29 (7), 569 PubMed.
- Arp L H, Richard J L (1979) Intoxication of dogs with the mycotoxin penitrem A. J Am Vet Med Assoc 175 (6), 565-566 PubMed.
Stachybotryotoxicosis
- Coppock R, Dziwenka M M (2004) Stachybotryotoxins. In: Clinical Veterinary Toxicology. Plumlee K (ed). St Louis, Missouri, Mosby, pp 268-270.
- Jarvis B B, Salemme J, Morais A (1995) Stachybotrys toxins. 1. Nat Toxins 3 (1), 10-6 PubMed.
- Tantaoui-Elaraki A, Mekouar S L, el Hamidi M, Senhaji M (1994) Toxigenic strains of Stachybotrys atra associated with poisonous straw in Morocco. Vet Hum Toxicol 36 (2), 93-96 PubMed.
- Forgacs J, Carll W T, Herring A S, Hinshaw W R (1958) Toxicity of Stachybotrys atra for animals. Trans N Y Acad Sci 20 (8), 787-808 PubMed.
- Korneev NE (1948) [Experimental stachybotryotoxicosis in laboratory animals]. Veterinariya (Moscow) 25, 36-40. Russian. Cited in: Hintikka E L (1978) Stachybotryotoxicosis in dogs. In: Willey T D, Morehouse LG (eds) Mycotoxic fungi, mycotoxins and mycotoxicosis. An encyclopedic handbook. Volume 2. New York, Marcel Dekker, Inc., pp 471-472.
Trichothecenes
- EFSA (2011) Scientific Opinion on the risks for animal and public health related to the presence of T-2 and HT-2 toxin in food and feed. EFSA J 9, (12), 2481. Available from: https://www.efsa.europa.eu/en/efsajournal/pub/2481
- Haschek W M, Beasley V R (2009) Trichothecene Mycotoxins. In: Gupta RC (ed) Handbook of Toxicology of Chemical Warfare Agents. Cambridge, MA. Academic Press, pp 353-369.
- WHO, World Health Organization (2001) WHO Food Additives Series: 47. Safety evaluation of certain mycotoxins in food. Prepared by the Fifty-sixth meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Available at: http://www.inchem.org/documents/jecfa/jecmono/v47je06.htm
- Fricke R F, Poppenga R H (1989) Treatment and prophylaxis for trichothecene. In: Beasley VR (ed) Trichothecene Mycotoxicosis: Pathogenic Effects, Volume II. Boca Raton, Florida. CRC Press, pp 135-168.
Other sources of information
- Konnie Plumlee (ed) (2004) Clinical Veterinary Toxicology. Mosby Inc., pp 231-281.
- Puschner B (2004) Penitrem A and roquefortine. In: Clinical Veterinary Toxicology. K H Plumlee (editor). Mosby, St Louis.
- Peterson and Talcott (eds) (2001) Small Animal Toxicology. W B Saunders Company, pp 593-599.
- Gary D Osweiler (1996) Toxicology. Williams and Wilkins.
- Willey T D, Morehouse L G (eds) (1978) Mycotoxic fungi, mycotoxins and mycotoxicosis. An encyclopedic handbook. Volume 2. New York, Marcel Dekker, Inc..
Organisation(s)
- ASPCA Animal Poison Control Center: www.aspca.org/pet-care/animal-poison-control, telephone (888) 426-4435.
- Veterinary Poisons Information Service (VPIS); www.vpisglobal.com, telephone + 44 (0) 2073 055 055.