Question

the 19^th of April 2009, the Venezuelan Lechuza Carakas Polo team was due to appear in the semi-final of the US Open Polo Championship in Florida. The horses of the team were kept at the Lechuza Caracas equestrian facility near the polo grounds in Wellington, about 70 miles north of Miami. When the horses were offloaded from trailers at the polo club in the afternoon, staff discovered that some animals had died and the others were showing severe respiratory problems, incoordination and recumbency.

Even though veterinarians attending the polo event immediately rushed to provide emergency treatment to the animals, 20 of the 21 horses eventually died just prior to the event, during transport to the event, or soon after unloading at the event. One horse that had developed clinical signs was transported to a veterinary clinic but died later that evening.

Investigating the cause of death of the horses

1. investigations confirmed that only the horses from the Venezuelan team were affected and no other horses at the equestrian facility or event premises showed any clinical signs. Clinical signs observed in the affected horses included severe central nervous system symptoms, with hyperexcitability, sweating, tachycardia, dyspnea, fever and sudden death. In the morning of the day of the polo event, the horses were seemingly healthy.

If you had to lead the investigation into the death of these animals, what information would you try to gather or what type of tests would you conduct? What would you speculate could have happened

Answer 1

Since, only the horses from the Venezuelan team were affected and no other horses at the equestrian facility or event premises showed any clinical signs, we can clearly say that it was not a viral infection. If it was some sort of viral infection, normally one or two will develop the symptoms first, followed by others as the time of entry of virus will be different in other horses. But here in this case 21 horses eventually died just prior to the event, during transport to the event, or soon after unloading at the event, that is all died within a timespan of 3-4 hours. So we can clearly say that there was some sort of poisoning or contamination in their food or wrong medication was given to them. So the investigation should start from their feeding stock.

• Investigator should find out how often hay is fed and recording how much hay is provided
• An investigator should list all hay, feeds, supplements, whole grains, nutraceuticals, and whatever else the horses may have been given, and should take samples of each.
• Three identical samples of each feed component should be placed in sealable plastic bags. The bags should be labeled as to sampling date, product, manufacturer, and batch number. One bag should be left with the owner, one should be kept by the veterinarian, and one should be made available for testing. The testing laboratory should look for mold, various mycotoxins, and ionophore contamination.
• The horses of the team were kept at the Lechuza Caracas equestrian facility near the polo grounds in Wellington. So the type of bedding there should be examined and identified, An expert in water quality can sample the water that was provided to them. Tests may reveal contamination of water by algae, bacteria, or agricultural or industrial chemicals.
• The investigator should also check with the caretaker if any medication was given to the horses. If so, what medication was that? Why was it for? What was the dose? How many horses was administered with the medication? Who administered the medicine to them? From which pharmacy was that medication from? The investigator should also go to that pharmacy or the place where the medication was prepared and should check with them.

• The classic necropsy fresh/frozen sample set for suspected toxins includes:

1. Brain
2. Liver
3. Kidney
4. Fat
5. Urine
6. Aqueous humor, or intact eyeball
7. Skin or muscle if site of exposure (e.g., injection site) (Change gloves and clean collection instruments between samples.)
8. Heart blood
9. Stomach or rumen content, and intestinal content or feces (Collect these last. Change gloves and clean collection instruments in between sampling.)

• A complete history is requested to the laborotory, including any drugs administered to the animal. This enables the toxicologist to review the case to ensure the proper analysis is being performed, prevents unnecessary or unwarranted analysis, and lowers costs to the submitter.

Answer for all of these will lead to a conclusion.

According to the investigation it was found out that, vitamin-and-electrolyte cocktail was injected into these horses prior to the match. It was a generic version of Biodyl that was mixed by the pharmacy. Biodyl, a French-made vitamin-mineral supplement that is used to ward off fatigue in horses, contains vitamin B, potassium, magnesium and selenium. However, Biodyl by itself shouldn’t have been fatal. According to medical experts, Biodyl’s ingredients would cause death only if it contained a massive overdose of one of the ingredients, such as 100 or 1,000 times the specified amount. In further investigation with veterinarian it was pointed out that an overdose of selenium could be fatal to horses if Biodyl was mixed incorrectly.

While selenium is a necessary micronutrient, in excess it can cause harm. For example, orally consuming 1–5 mg Se/kg body weight orally in either contaminated water or feed is acutely toxic, while an injection of 0.2 mg Se/ kg body weight is acutely toxic. Because sodium selenite is the most water soluble form of selenium, it is likely this is the form that the pharmacy used in their Biodyl mixture. A single minimal lethal dose of oral sodium selenite in horses is 3.3 mg/kg, but a fatal injected preparation would require a smaller concentration. “There were five horses that did not get the vitamin, and those were the only ones that survived,” said team captain, Juan Martin Nero. Biodyl was administered to 21 of the team’s 26 horses. Only horses treated with the compound became sick and died within 3 hours of treatment. Other horses that were not treated remain healthy and normal. So I speculate that it was due to this injection which was improperly mixed, lead to the death of the 21 horses.