Chinese dog chews linked to werewolf syndrome

Dog chews imported into Germany from China and distributed under two brand names in several European countries have been linked to the appearance of neurological symptoms in a number of dogs.

More than 15 cases have been reported in Denmark alone. An unspecified number of incidents also have been reported in the Netherlands, Germany, Finland, and Estonia.

Although the FDA is aware of the situation, an agency spokesperson informed eFoodAlert that the Center for Veterinary Medicine has not received any reports or consumer complaints of werewolf syndrome in the United States associated with dog chews.

Symptoms of werewolf syndrome can vary in type and severity, ranging from spontaneous, extreme excitement, panic attacks accompanied by howling and attempts to escape, to phases of aggression, hallucinations, epileptic seizures, and even death.

Several EU member countries and the United Kingdom have issued recall notices or consumer advisories for two brands of dog chews: Barkoo and Chrisco.

Although not distributed through retail stores in all EU countries, these chews are available for purchase over the internet.

According to an advisory issued by the UK’s Food Safety Agency, consumers should avoid the following products:

  • Barkoo kaustange natur 29 cm (570g; Batch/Lot code 1148655 MHD 04.2027 3200PF027; Bar code 4260077047292)
  • Barkoo kauknochen, geknotet natur 11cm (150g; Batch/Lot code 1148592 MHD 07.2027 3200PF027; Bar code 4260077046875 )
  • Barkoo Kauknochen geknotet 24cm (150g; Batch/Lot code 1148657 MHD05.2027 3200PF027; Bar code 4260077046899)
  • Barkoo Kauknochen geknotet mit Spirulina 12cm (180g; Batch/Lot code 1148654 MHD 06.2027 3200PF027; Bar code 4260077047261)
  • Chrisco Tyggeruller med kylling, 10 stk (Item #12457; All Use-by dates; EAN 5764630124578)
  • Chrisco Tyggeruller med kylling & kyllingelever (100g; Product no. 12324; Use by 01/12/2025; 05-01-2026; 15-03-2026; 18-03-2026; 15-04-2026; 20-04-2026; 01-06-2026; 15-07-2026; EAN 5764630123243)
  • Chrisco Tyggeruller 18 stk. – hvide (Product no. 12468; Use by 05/01/2027; 26-02-2027; 15-03-2027; 18-03-2027; 24-03-2027; EAN 5764630124684)
  • Chrisco Massive politistave, 2.stk. – brune (Product no. 12541; Use by 26/02/2027; 15-04-2027; EAN 5764630125414)
  • Chrisco Massive politistave, 2stk. – hvide (Product no. 12542; Use by 05/01/2027; 20-04-2027; 01-06-2027; EAN 5764630125421)
  • Chrisco Tyggerulle m. kylling & kyllingelever, 1stk (Product no. 12624; Use by 01/12/2025; 05-01-2026; 15-03-2026; 18-08-2026; EAN 5764630126244)
  • If you have fed any of the llsted chews to your dog, stop doing so immediately.  
  • If your dog is unwell and has been fed any of these dog chews, you should seek veterinary advice and provide detailed information to the vet about the foods and treats your dog has been fed. 


“A complete and compelling account of the hidden and not-so-hidden ways the food we give our beloved pets can be contaminated.” JoNel Aleccia, Health Reporter, Food & Nutrition, The Associated Press.

“An invaluable resource for busy pet owners” – Food Safety News

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Jerky pet treats: Anatomy of an investigation and lingering concerns

This story by Phyllis Entis first appeared in Food Safety News and is reposted here with permission.

More than 10 years after the first reports of pet and people illnesses linked to jerky treats from China, the U.S. Food and Drug Administration is no closer to finding the root cause of the problem.

From August 2007 through Dec. 31, 2015, the number of illness complaints linked to jerky pet treats included more than 6,200 dogs, 26 cats, and three people. More than 1,140 of the dogs died.

In a Grand Rounds webinar in recent days, Dr. Lee Anne Palmer of FDA’s Center for Veterinary Medicine (CVM) summarized the outcome of the agency’s decade-long investigation.

The first hint of trouble appeared in August 2007, when bloggers reported the removal of chicken jerky pet treats from the shelves of a major retailer due to traces of melamine in the treats.

In September 2007, the American Veterinary Medical Association (AVMA) alerted its members to reports of an acquired form of Fanconi syndrome in dogs. Fanconi syndrome is a potentially fatal disorder of the urinary tract.

Later that same month, FDA advised pet owners of a “… potential association between development of illness in dogs and the consumption of chicken jerky products…” The agency reported having received in excess of 70 complaints involving more than 95 dogs. In addition, FDA received information from Banfield, The Pet Hospital suggesting an association between exposure to chicken jerky products and signs of gastrointestinal illness in dogs, including vomiting and diarrhea.

FDA investigated the reports, but was unsuccessful in finding the cause of the illnesses.

In late 2013, FDA issued a comprehensive update on its investigation, including a fact sheet for pet owners and a “Dear Veterinarian” letter requesting specific clinical data. The update triggered an immediate, massive increase in illness reports.

In 2014, FDA enlisted the help of the U.S. Centers for Disease Control and Prevention to design and run a case control study. Scientists from CVM and CDC enrolled 95 affected dogs from 31 states for the study, matching them with 261 controls. 

The case control study, first of its kind for a pet illness investigation, determined that the illnesses were highly associated with consumption of pet jerky treats from China. There was also some association with jerky treats from the United States. 

Ill dogs were more likely to be female, and small breeds were more likely to be affected than larger breeds. No other exposures were associated with the pet illnesses.

Since 2007, FDA has received reports of pet illness related to jerky treats from all 50 U.S. states, most Canadian provinces, and several other countries, including the United Kingdom, Germany, Switzerland, and Singapore, according to Palmer.

In 2007, the only way for consumers or veterinarians to report pet illnesses to FDA was by contacting a Consumer Complaint Coordinator by telephone. There was no system in place to coordinate or collate the reports. Even today, as Palmer observed, there is no CDC for pets.

In May 2010, CVM introduced the Safety Reporting Portal, an on-line form that can be used by consumers and veterinarians to report illnesses linked to pet foods, treats or medications.

In January 2011, CVM combined the two parallel information streams into a single database and initiated a weekly review of the data to identify trends. 

FDA obtained funding in 2010 to establish the Veterinary Laboratory Response Network (Vet-LIRN), a collaborative network of government and university laboratories that form the backbone of FDA’s ability to document, investigate, and diagnose animal feed, pet food, and animal drug-related illnesses. This powerful resource was activated in August 2011 and has now grown to include 43 participating laboratories.

While FDA’s efforts did not establish a single root cause of pet illnesses linked to jerky pet treats, the investigations revealed a number of issues resulting in recalls or import alerts for various problems, including:

  • Salmonella contamination
  • Residues of antibiotic and antiviral agents
  • Mislabelling
  • Melamine traces
  • Excessive levels of glycerin

The cumulative effect of these recalls and import alerts produced, over time, a significant reduction in the number pet illnesses associated with pet jerky treats.

According to a spokesperson for FDA, the number of reported illnesses associated with jerky pet treats has waned in recent years and returned to baseline levels. The agency is dialing back its use of investigative resources on jerky pet treats to focus on other types of pet food product complaints. 

FDA expects to publish a final update on its website summarizing the investigation at a future date.

Although a single root cause of the treat-related illnesses was never found, the analytical and tracking tools developed during the treat investigation have helped CVM to more quickly identify and respond to several other pet food issues in recent years. These include:

  • Pentobarbital contamination in canned dog foods
  • Thiamine deficiency in cat food
  • Vitamin D excess in dog food
  • Thyroid gland contamination of canned dog food and domestic jerky treats
  • Salmonella contamination of dry dog foods
  • Listeria and Salmonella in raw pet foods
  • Dilated cardiomyopathy and grain-free dog foods

Consumers and veterinarians who are concerned about a pet illness that appears to be linked to a pet food or pet treat should report the incident using FDA’s Safety Reporting Portal or by contacting the Consumer Complaint Coordinator for their district.