In a lawsuit filed in the District of Maryland by a family purportedly exposed to an infectious disease (Streptobacillus moniliformis a.k.a. rat bite fever) from rats purchased from a Petco store which the store had obtained from SunPet Ltd., the court granted the defendants’ motion to dismiss the following claims:

assault (Counts I, VIII, and XV), battery (Counts II, IX, and XVI), negligence (Counts III, X, and XVII), products liability (Counts IV, XI, and XVIII), intentional infliction of emotional distress (Counts V, XII, and XIX), gross negligence (VI, XIII, and XX), and res ipsa loquitur (Counts VII, XIV, and XI).  Siarkowski v. Petco Animal Supplies, Inc. et al., 2015 WL 6956522 (D. Md. Nov. 3, 2015).

The court granted dismissal of the claims for assault, battery, and intentional infliction of emotional distress. The res ipsa loquitur counts were held to be mispled, finding:

a determination regarding the doctrine of res ipsa loquitur is premature, and the court will consider it along with Plaintiffs’ negligence claims, when appropriate. However, because the doctrine of res ipsa loquitur does not present a distinct cause of action separate from negligence, Counts VII, XIV, and XXI will be dismissed. Id.

The negligence claims require a consideration of what type of testing the pet store was required to perform before selling the rats, who allegedly were infected with the bacteria that sickened the owners.

According to the Centers for Disease Control and Prevention:

Rat-bite fever (RBF) is an infectious disease that can be caused by two different bacteria. Streptobacillary RBF is caused by Streptobacillus moniliformis in North America while spirillary RBF or sodoku is caused by Spirillum minus and occurs mostly in Asia. People usually get the disease from infected rodents or consumption of contaminated food or water. When the latter occurs, the disease is often known as Haverhill fever. If not treated, RBF can be a serious or even fatal disease.

People can become infected with RBF from receiving bites or scratches from infected rodents, including rats, which is the alleged method of exposure in the above-mentioned case. Pet rats have been known to transmit the disease to their owners, as reported by the CDC.

Rodents can transmit other diseases, including:

Hantavirus pulmonary syndrome

Hemorrhagic Fever with Renal Syndrome

Lassa Fever

Lymphocytic Chorio-meningitis

Omsk Hemorrhagic Fever



South American Arenaviruses


In Maryland, pet stores are required to control the spread of communicable diseases, but there are no requirements to test rodents for any specific infectious agent. If a pathogen, like Streptobacillus moniliformis, does not cause signs of disease in the host (rat) there would be no reason to test symptom-free animals.

  1. A pet store shall utilize procedures to ensure prevention and control of diseases common to and shared among humans and animals.

  2. The Department recommends that pet stores utilize the Compendium of Animal Rabies Prevention and Control, the Compendium of Measures To Control Chlamydophila psittaci Infection Among Humans (Psittacosis) and Pet Birds (Avian Chlamydiosis), and the Compendium of Measures to Prevent Disease Associated with Animals in Public Settings issued by the National Association of State Public Health Veterinarians, to ensure prevention and control of diseases common to and shared among humans and animals.

  3. A health officer shall annually inspect a pet store to determine compliance with §A of this regulation.

  4. A health officer:

(1) May delegate the authority to conduct annual pet store inspections to another specified agency such as, but not limited to, the local animal control; and

(2) Shall execute and keep on file a written agreement with the delegated inspection agency.

Enforcement. An authorized law enforcement officer or local animal control authority shall promptly enforce a written order of the health officer or the Maryland Public Health Veterinarian issued pursuant to COMAR 10.06.02.

Penalty. The owner of a pet store refusing or failing to comply with the provisions of this regulation is subject to the penalties set forth in Health-General Article, §§18-222, 18-604, and 24-110, Annotated Code of Maryland.

Retail pet stores are governed pursuant to Maryland’s Business Regulation Cod Ann § 19-701 et seq. There is no clear mandate to test rats for Rat-Bite Fever.

Based on this lawsuit, however, amendments to those laws would not be unexpected.