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Building a Pet Health Tracker: The $16B Pet Tech Market

By Charles
apps petlog react-native pet-tech mobile

PetLog is our 8th Android app — a pet health and medication tracker that handles medications, vaccinations, vet visits, and weight history for 8 species. Here’s why we built it and what made it interesting.

Why Pet Tech?

The pet care industry is worth $186B globally (2025), and pet tech specifically is a $16.6B segment growing at 18% CAGR. Americans spent $35.9B on vet care alone in 2024. The average dog owner spends $1,270/year on healthcare; cats average $890.

Most pet owners track health information on paper, in spreadsheets, or not at all. Existing apps fall into two camps:

  1. Free apps with ads and data harvesting — BabelBark, PetDesk. They sell your data to pet food companies and vet networks.
  2. Vet clinic portals — Tied to a single vet practice, useless if you switch vets or have pets at different clinics.

There’s a gap for a simple, paid, privacy-focused tracker that works independently of any vet practice.

Design Decisions

Multi-Species Support

Supporting 8 species (dog, cat, bird, fish, reptile, rabbit, hamster, other) adds complexity. Each species has different:

  • Common vaccines — Dogs get rabies, DHPP, bordetella. Cats get FVRCP, rabies, FeLV. Birds get polyomavirus. Reptiles generally don’t get vaccines but need parasite checks.
  • Weight ranges — A healthy Chihuahua weighs 5 lbs; a Great Dane weighs 140 lbs. Weight tracking needs to be contextual.
  • Medication schedules — Heartworm prevention for dogs is monthly. Flea treatment varies by species. Fish medications work completely differently.

We handled this with species-specific vaccine suggestion lists that populate when adding a vaccination record, while keeping the core tracking interface universal.

Vet Visit Cost Tracking

After talking to pet owners, the most requested feature beyond basic health tracking was financial visibility. “How much have I spent at the vet this year?” is a question most people can’t answer without digging through bank statements.

PetLog tracks costs per visit with year-over-year and all-time summaries. This is useful for:

  • Insurance claims (documenting pre-existing conditions)
  • Budgeting (average annual vet costs per pet)
  • Multi-pet households (which pet costs the most)

Weight History with Deltas

Weight changes are often the first sign of health issues in pets. A cat losing 10% of body weight over 3 months needs veterinary attention. PetLog tracks weight over time with change deltas displayed between entries, supporting both pounds and kilograms.

Dark Theme by Default

PetLog uses a dark purple theme (#1B2838 background, #7C4DFF primary accent). The dark-first design is intentional — our analytics show (from Play Store reviews of competing apps) that utility app users overwhelmingly prefer dark mode. Every GriswoldLabs app defaults to dark with a light mode toggle.

Technical Implementation

PetLog follows the same stack as all our apps:

Expo 54 + React Native 0.81
TypeScript (strict mode)
AsyncStorage (local persistence)
expo-notifications (reminders)
2,031 lines of TypeScript

Data Model

The core data model is straightforward:

Pet → has many Medications
Pet → has many Vaccinations
Pet → has many Vet Visits
Pet → has many Weight Records

Each pet stores profile information (name, species, breed, birthday, color, microchip ID), and all sub-records link back to the pet via ID.

Dashboard Design

The dashboard is the first screen and needs to answer three questions instantly:

  1. Which pets do I have? — Cards with name, species, breed, age
  2. What’s overdue? — Medications due, vaccinations expired
  3. What’s coming up? — Upcoming vet visits, medication refills

Overdue items surface to the top with visual indicators. This “exception-based” design means users who are on top of everything see a clean dashboard, while users who’ve missed something see immediate alerts.

The Pet Tech Market Opportunity

Pet spending is recession-resistant. During the 2008 financial crisis, pet spending grew 5.4% while the overall economy contracted. During COVID, pet adoptions surged 15% and spending grew 6.7%.

The total addressable market for pet health tracking:

  • US pet households: 66% (86.9 million homes)
  • Dog owners: 65.1 million
  • Cat owners: 46.5 million
  • Multi-pet households: 33% (28.7 million)

Multi-pet households are our primary audience — they have the most to track and the most to gain from centralized health records.

At $4.99 with even 0.001% penetration of multi-pet households (287 downloads), PetLog generates $1,215 after Google’s cut. That’s before repeat purchases from single-pet owners.

What We Learned

  1. Species-specific data is a moat. Generic pet apps treat all animals the same. Knowing that dogs need DHPP vaccines and cats need FVRCP makes the app genuinely more useful than a generic health tracker.

  2. Cost tracking sells. In competitive analysis, the most-requested feature in negative reviews of competing apps was financial tracking. People want to know what they’re spending.

  3. Privacy matters more for health data. Pet owners who are cautious about human health data privacy extend that concern to their pets’ data. “No cloud, no accounts” resonates strongly in this category.

  4. Veterinary integration is a trap. Multiple competing apps tried to integrate with vet practice management systems. This creates vendor lock-in, requires B2B sales, and makes the app useless without an account. We intentionally avoided this complexity.

What’s Next

PetLog is signed, has a privacy policy, and is ready for Play Store submission. It’s our 8th app in the GriswoldLabs portfolio — all built in 4 days, all privacy-focused, all local-first.

The pet tech market is big enough that a simple, well-designed tracker has a viable path to revenue. Combined with our other 7 apps across finance, automotive, home maintenance, and more, we’re building a diversified portfolio of niche utility apps that collectively generate meaningful income.