Parasites of Cats

Parasites of Cats

• Learning Objectives: By the end of the presentation, learn to identify parasites causing clinical signs in cats, design diagnostic plans, create treatment plans, and educate owners on prevention.

Notoedres

• Morphology: Long, unsegmented pedicels; anus on dorsal body surface.
• Hosts: Cats, rats, rabbits, occasionally humans.
• Infestation: Starts on pinnae, spreads to face, paws, and hindquarters.
• Clinical Signs: Alopecia (hair loss) and hyperkeratosis (thickened skin).
• Diagnosis: Skin scrape.
• Treatment: Macrocyclic lactones (e.g., ivermectin, milbemycin oxime), fipronil.

Cheyletiella

• Common Name: "Walking dandruff."
• Morphology: Large papal claws, M-shaped peritremes.
• Hosts: Primarily cats ( Cheyletiella blakei).
• Infestation: Survives longer off host than other mites, environment can be source of reinfestation.
• Clinical Signs: Dandruff-like appearance; irritation.
• Diagnosis: Flea comb, trichogram, superficial skin scrape.
• Treatment: Macrocyclic lactones, fipronil.

Toxocara cati

• Distribution: Worldwide.
• Morphology: Cream colored adults with cervical alae.
• Habitat: Adults live in small intestines of mammals.
• Life cycle is similar to Toxocara canis, with an exception.
• Transplacental Transmission: Does not occur
• Transmammary Transmission: Can occur in infected queens.
• Clinical Signs: Vomiting
• Diagnosis: Adults in vomit or feces, eggs in fecal flotation.
• Treatment: Pyrantel pamoate, piperazine, macrocyclic lactones, emodepside.

Toxocara cati Disease

• Severity: Less potential for death than T. canis.
• Zoonotic Potential: Can cause human infection

Tritrichomonas blagburni

• Habitat: Large intestine of cats.
• Prevalence: Common in catteries and purebred cats.
• Clinical Signs: Chronic diarrhea (commonly in cats less than 2 years old).
• Asymptomatic: Many cats are asymptomatic.
• Diagnosis: Trophozoites in fecal smears, InPouch culture, PCR.
• Treatment: No approved treatments; off-label ronidazole or metronidazole.

Cystoisospora spp.

• Transmission: Ingestion of oocysts or paratenic hosts (in dogs and cats).
• Hosts: Cats (C. felis, C. rivolta).
• Prevalence: Often results from a change in environment.
• Clinical Signs: Diarrhea, weight loss (rarely).
• Diagnosis: Oocysts on fecal smears, or PCR
• Treatment: Sulfadimethoxine.

Giardia

• Description: Common intestinal commensal organism.
• Clinical Presentation: Many cats are subclinical.
• Diagnosis: Cysts on direct smears, fecal floatation with zinc sulfate, ELISA.
• Treatment: Metronidazole (off-label).

Ancylostoma

• Transmission: Direct ingestion of infective larvae (L3), skin penetration of L3, or ingestion of paratenic hosts (rodents, cockroaches).
• Affecting species: Ancylostoma tubaeforme & Ancylostoma braziliense affect cats and dogs.
• Clinical Signs: Anemia, diarrhea, weight loss, respiratory disease (pneumonia).
• Diagnosis: Thin-walled, morulated eggs ("strongyle-type") on fecal flotation.
• Treatment: Anthelminthics (started as soon as possible, around 2 weeks of age); Macrocyclic lactones, pyrantel, emodepside.

Spirocerca spp.

• Distribution: Worldwide and most common in Southeast Asia.
• Hosts: Cat and bobcat are natural definitive hosts.
• Intermediate Hosts: Plerocercoid (aka sparganum) develops in many animals (snakes, frogs, birds—not in fish).
• Clinical Signs: Adults in intestines usually cause no disease. Vomiting, weight loss, and diarrhea are possible complications.
• Diagnosis: Operculated eggs in fecal flotation, or sedimentation, or segments passed in feces.
• Treatment: No approved treatment; praziquantel may be used off-label

Cuterebra spp.

• Transmission: Third-stage larvae acquired from rodent and rabbit burrows.
• Clinical Signs: Bots found in cervical subcutaneous connective tissue, and migration is sometimes to ocular, nasal, oral regions, and brain regions.
• Treatment: Manual removal, Topical imidacloprid or fipronil, Ivermectin.

Aelurostrongylus

• Habitat: Adults in lungs of cats.
• Transmission: Eggs are deposited in lung parenchyma, larvae cough up and are swallowed, ingested via snails and slugs.
• Intermediate hosts: Larvae develop in intermediate hosts (snails & slugs)
• Clinical Signs: Usually asymptomatic; can cause coughing, anorexia, and dyspnea.
• Diagnosis: Detection of larvae using Baermann technique or fecal flotations; rarely seen on fecal flotations.
• Treatment: Ivermectin, selamectin, fenbendazole.

Dirofilaria immitis

• Prevalence: Cats typically have 1-3 adult worms.
• Clinical signs: Asymptomatic to severe, but commonly causes Heartworm associated respiratory disease (HARD).
• HARD Signs: Intense inflammation of the pulmonary vessels due to immature worm death, and complications such as coughing, wheezing, and dyspnea.
• Diagnosis: Often difficult; low sensitivity antigen tests, antibody tests, or microfilaria check (may be transient or absent).
• Treatment: No specific therapy for asymptomatic cats; Melarsomine treatment not recommended; microfilaricidal treatment not required; annual heartworm prevention is recommended.

Paragonimus

• Distribution: Present in U.S. around Mississippi River basin.
• Transmission: Infection through ingestion of metacercariae in crabs or crayfish..
• Clinical Signs: Chronic coughing; bullae formation and rupture, leading to pneumothorax; migration to viscera and brain.
• Diagnosis: Fecal sedimentation or transtracheal wash.
• Treatment: Albendazole, fenbendazole, praziquantel.

Platynosomum fastosum

• AKA: Lizard poisoning disease.
• Habitat: Adults live in bile and pancreatic ducts of cats.
• Prevalence: Common in southeastern U.S. and Caribbean.
• Transmission: Ingesting pill bugs or paratenic hosts (lizards, toads).
• Clinical Signs: Acute/chronic cholangitis, lethargy, fever, hepatomegaly, abdominal distension, jaundice, vomiting, diarrhea, or cholangiocarcinoma.
• Diagnosis: Eggs in feces on sedimentation.
• Treatment: Praziquantel, surgical removal

Cytauxzoon

• Distribution: Common in US southeast and southern U.S., transmitted by bite of Amblyomma americanum.
• Clinical Signs: Rapid onset, often fatal; fever, anemia, icterus, pancytopenia, or death.
• Diagnosis: Organisms in erythrocytes and macrophages.
• Treatment: Atovaquone + azithromycin.