Cats and dogs share a number of contagious and non-contagious diseases that can affect them, with some being zoonotic (transmissible to humans) and others specific only to companion animals. Below is a categorized, detailed list of the most common shared diseases, including their transmission, key symptoms, and notes on cross-species risk:
1. Viral Diseases (Highly Contagious, Some Cross-Species)
Viral infections are often spread via direct contact, bodily fluids, or contaminated surfaces; many have no cure, only supportive care.
| Disease | Transmission | Key Symptoms in Cats & Dogs | Cross-Species (Cat ↔ Dog) |
|---|---|---|---|
| Rabies | Saliva (bites/scratches), bodily fluids | Lethargy, aggression, paralysis, foaming at mouth, death | Yes (fatal; zoonotic) |
| Canine/Feline Parvovirus (CPV/FPV) | Fecal-oral, contaminated surfaces | Severe vomiting/diarrhea (bloody), dehydration, lethargy, high mortality in puppies/kittens | No (species-specific strains, but FPV can infect young dogs) |
| Herpesvirus (FHV-1/CHV-1) | Direct contact, respiratory secretions | Upper respiratory infection (URI), eye discharge, sneezing, fever | No (species-specific) |
| Calicivirus (FCV) | Aerosols, direct contact, contaminated objects | URI, mouth ulcers, limping (in cats); rare mild URI in dogs | Low (dogs rarely affected) |
2. Bacterial Diseases (Treatable with Antibiotics, Many Zoonotic)
Bacterial infections are spread via bites, feces, contaminated food/water, or environmental exposure; most respond to targeted antibiotics.
- Bordetellosis (Kennel Cough)Spread by aerosols/direct contact; causes a harsh, dry cough in both cats and dogs (more common in dogs). Zoonotic risk is low.
- SalmonellosisFecal-oral (contaminated raw food/feces); causes diarrhea, vomiting, fever. Zoonotic (humans can contract it from pets).
- CampylobacteriosisFecal-oral; leads to watery/bloody diarrhea, abdominal pain. Zoonotic.
- LeptospirosisContact with urine-contaminated water/soil (from infected wildlife/animals); causes fever, kidney/liver failure, jaundice. Highly zoonotic and cross-species (cats and dogs infect each other).
- Staphylococcus/Streptococcus InfectionsSkin/mucous membrane contact; causes skin abscesses, wound infections, otitis (ear infections). Some strains are zoonotic.
3. Fungal Diseases (Environmental Exposure, Zoonotic)
Fungi thrive in warm, moist environments; infections affect skin, nails, or internal organs (systemic).
- Ringworm (Dermatophytosis)Spread by direct contact with infected animals/objects (bedding, brushes); causes circular, scaly skin lesions, hair loss. Highly zoonotic and cross-species (easiest shared fungal disease).
- AspergillosisInhalation of fungal spores (soil, mold); causes respiratory issues (coughing, nasal discharge), systemic infection in severe cases. Low zoonotic risk (only in immunocompromised humans).
- CryptococcosisInhalation of yeast spores (bird feces, soil); causes nasal/respiratory signs, neurological issues. Rarely zoonotic.
4. Parasitic Diseases (Internal/External, Major Cross-Species Risk)
Parasites are the most common shared disease between cats and dogs; many are zoonotic and spread via feces, fleas, or direct contact.
External Parasites
- Fleas/Ticks: Feed on blood; transmit diseases (e.g., Lyme disease, babesiosis) and cause itching/anemia. Cross-species + zoonotic (ticks bite humans).
- Mites (Sarcoptic mange, Demodex): Sarcoptic mange is highly contagious cross-species/zoonotic (causes itchy skin rashes); Demodex is species-specific (rare cross-infection).
Internal Parasites
- Roundworms: Fecal-oral (ingestion of eggs/larvae); cause vomiting, diarrhea, pot-bellied appearance in young pets. Highly zoonotic (human children at risk of visceral larva migrans).
- Hookworms: Larvae penetrate skin/fecal-oral; cause blood loss, anemia, diarrhea. Zoonotic (larvae cause skin rashes in humans).
- Tapeworms: Transmitted via fleas/ingestion of infected prey (rodents, birds); cause weight loss, anal itching. Low zoonotic risk (humans need to ingest infected fleas/prey).
- Giardia (protozoa): Fecal-oral (contaminated water/feces); causes chronic diarrhea, weight loss. Highly zoonotic + cross-species.
- Toxoplasma gondii (protozoa): Cats are the definitive host (shed oocysts in feces); dogs/humans ingest oocysts/prey. Zoonotic (dangerous for pregnant humans/immunocompromised people); dogs show mild symptoms (fever, diarrhea).
Summary of the Most Critical Shared Diseases
The highest priority for prevention are rabies (fatal zoonotic), leptospirosis (zoonotic), ringworm (contagious zoonotic), fleas/ticks (disease vectors), and intestinal parasites (zoonotic)—all of which are preventable with routine veterinary care and hygiene.