diff --git a/UAT_PLAYBOOK.md b/UAT_PLAYBOOK.md
index 42d4cf9..f172f07 100644
--- a/UAT_PLAYBOOK.md
+++ b/UAT_PLAYBOOK.md
@@ -259,6 +259,10 @@ This means:
 | TC-API-8.9 | SSO bridge — no Better Auth session | POST /api/portal/session-from-auth without Better Auth session cookie | 401 Unauthorized |
 | TC-API-8.10 | SSO bridge — no matching client | POST /api/portal/session-from-auth with valid Better Auth session for a user with no client record | 404 Not Found, error "No client record found for this user" |
 | TC-API-8.11 | SSO bridge — returned session works on portal routes | After TC-API-8.8, use returned sessionId as `X-Impersonation-Session-Id` header on GET /api/portal/me | 200 OK, client profile returned |
+| TC-API-8.12 | Portal GET pets returns extended fields (GRO-2187) | Establish a portal session (TC-API-8.8), then `GET /api/portal/pets` with `X-Impersonation-Session-Id` | 200 OK; each pet includes `coatType`, `petSizeCategory`, `healthAlerts`, `preferredCuts`, `medicalAlerts` (in addition to id/name/breed/weight/birthDate/photoUrl/notes) |
+| TC-API-8.13 | Portal pet update — owner success + persistence (GRO-2187, fixes [GRO-1480](/GRO/issues/GRO-1480) §5.23) | With a portal session for the pet's owner, `PATCH /api/portal/pets/{petId}` with body `{ "name": "...", "breed": "...", "weightKg": 18.25, "healthAlerts": "...", "coatType": "double", "petSizeCategory": "xlarge", "preferredCuts": ["teddy bear"], "medicalAlerts": [{"type":"allergy","description":"oatmeal","severity":"medium"}] }` | 200 OK; response reflects the update with `petSizeCategory: "extra_large"` (web `xlarge` → DB `extra_large`). A follow-up `GET /api/portal/pets` shows the persisted values |
+| TC-API-8.14 | Portal pet update — non-owner blocked (GRO-2187) | `PATCH /api/portal/pets/{petId}` for a pet owned by a different client, using another client's portal session | 403 Forbidden (or 404 if pet id is unknown); no mutation persisted |
+| TC-API-8.15 | Portal pet update — invalid enum rejected (GRO-2187) | `PATCH /api/portal/pets/{petId}` with `coatType: "fluffy"` or `petSizeCategory: "gigantic"` | 422 Unprocessable Entity; pet unchanged |
 
 ### 4.9 Waitlist
 
diff --git a/src/__tests__/portalPets.test.ts b/src/__tests__/portalPets.test.ts
new file mode 100644
index 0000000..a95cb23
--- /dev/null
+++ b/src/__tests__/portalPets.test.ts
@@ -0,0 +1,267 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { Hono } from "hono";
+
+const CLIENT_ID = "550e8400-e29b-41d4-a716-446655440001";
+const OTHER_CLIENT_ID = "550e8400-e29b-41d4-a716-446655440099";
+const PET_ID = "880e8400-e29b-41d4-a716-446655440004";
+const SESSION_ID = "770e8400-e29b-41d4-a716-446655440003";
+
+const futureDate = () => new Date(Date.now() + 30 * 60 * 1000);
+
+const ACTIVE_SESSION = {
+  id: SESSION_ID,
+  clientId: CLIENT_ID,
+  status: "active" as const,
+  expiresAt: futureDate(),
+  createdAt: new Date(),
+};
+
+// A persisted pet owned by CLIENT_ID. weightKg is a string because the column is
+// numeric (Drizzle serialises numeric to string).
+const PET = {
+  id: PET_ID,
+  clientId: CLIENT_ID,
+  name: "Rex",
+  species: "dog",
+  breed: "Labrador",
+  weightKg: "12.50",
+  dateOfBirth: null,
+  healthAlerts: null,
+  groomingNotes: null,
+  coatType: null,
+  petSizeCategory: null,
+  preferredCuts: [],
+  medicalAlerts: [],
+  photoKey: null,
+};
+
+let selectSessionRow: Record<string, unknown> | null = null;
+let selectPetRow: Record<string, unknown> | null = null;
+let updatedValues: Record<string, unknown>[] = [];
+
+function resetMock() {
+  selectSessionRow = null;
+  selectPetRow = null;
+  updatedValues = [];
+}
+
+vi.mock("@groombook/db", () => {
+  function makeChainable(data: unknown[]): unknown {
+    const arr = [...data];
+    const chain = new Proxy(arr, {
+      get(target, prop) {
+        if (prop === "where" || prop === "orderBy" || prop === "limit") {
+          return () => chain;
+        }
+        // @ts-expect-error proxy
+        return target[prop];
+      },
+    });
+    return chain;
+  }
+
+  function tableProxy(name: string) {
+    return new Proxy(
+      { _name: name },
+      { get: (t, p) => (p === "_name" ? name : { table: name, column: p }) }
+    );
+  }
+
+  const impersonationSessions = tableProxy("impersonationSessions");
+  const pets = tableProxy("pets");
+
+  return {
+    getDb: () => ({
+      select: () => ({
+        from: (table: { _name: string }) => {
+          if (table._name === "impersonationSessions") {
+            return makeChainable(selectSessionRow ? [selectSessionRow] : []);
+          }
+          if (table._name === "pets") {
+            return makeChainable(selectPetRow ? [selectPetRow] : []);
+          }
+          return makeChainable([]);
+        },
+      }),
+      update: () => ({
+        set: (vals: Record<string, unknown>) => ({
+          where: () => ({
+            returning: () => {
+              if (selectPetRow) {
+                updatedValues.push(vals);
+                return [{ ...selectPetRow, ...vals }];
+              }
+              return [];
+            },
+          }),
+        }),
+      }),
+      // portalAudit inserts an audit row after the handler; make it a no-op so
+      // the middleware does not log a swallowed error during tests.
+      insert: () => ({ values: () => ({ returning: () => [] }) }),
+    }),
+    impersonationSessions,
+    pets,
+    // Other tables imported by the portal router but unused in these tests.
+    appointments: tableProxy("appointments"),
+    waitlistEntries: tableProxy("waitlistEntries"),
+    clients: tableProxy("clients"),
+    services: tableProxy("services"),
+    staff: tableProxy("staff"),
+    invoices: tableProxy("invoices"),
+    invoiceLineItems: tableProxy("invoiceLineItems"),
+    impersonationAuditLogs: tableProxy("impersonationAuditLogs"),
+    eq: vi.fn(),
+    and: vi.fn(),
+    inArray: vi.fn(),
+  };
+});
+
+const { portalRouter } = await import("../routes/portal.js");
+
+const app = new Hono();
+app.route("/portal", portalRouter);
+
+function jsonPatch(path: string, body: unknown, headers?: Record<string, string>) {
+  return app.request(path, {
+    method: "PATCH",
+    headers: {
+      "Content-Type": "application/json",
+      ...headers,
+    },
+    body: JSON.stringify(body),
+  });
+}
+
+beforeEach(() => resetMock());
+
+describe("PATCH /portal/pets/:petId", () => {
+  it("updates an owned pet and persists the mapped columns (200)", async () => {
+    selectSessionRow = ACTIVE_SESSION;
+    selectPetRow = PET;
+
+    // Mirrors the groombook/web PetForm payload: it spreads the GET-shaped pet
+    // (weight, notes, birthDate, photoUrl) and adds the form's edited keys
+    // (weightKg, healthAlerts, coatType, …). "xlarge" must map to "extra_large".
+    const res = await jsonPatch(
+      `/portal/pets/${PET_ID}`,
+      {
+        id: PET_ID,
+        name: "Rex Updated",
+        breed: "Golden Retriever",
+        weight: "12.50",
+        weightKg: 18.25,
+        notes: "old grooming notes",
+        healthAlerts: "Allergic to oatmeal shampoo",
+        photoUrl: "pets/rex.jpg",
+        coatType: "double",
+        petSizeCategory: "xlarge",
+        preferredCuts: ["teddy bear", "puppy cut"],
+        medicalAlerts: [
+          { id: "a1", type: "allergy", description: "oatmeal", severity: "medium" },
+        ],
+      },
+      { "X-Impersonation-Session-Id": SESSION_ID }
+    );
+
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.name).toBe("Rex Updated");
+    expect(body.petSizeCategory).toBe("extra_large");
+    expect(body.coatType).toBe("double");
+
+    const persisted = updatedValues[0]!;
+    expect(persisted.name).toBe("Rex Updated");
+    expect(persisted.breed).toBe("Golden Retriever");
+    // weightKg (form key) wins over weight (GET key) and is stored as a string.
+    expect(persisted.weightKg).toBe("18.25");
+    expect(persisted.groomingNotes).toBe("old grooming notes");
+    expect(persisted.healthAlerts).toBe("Allergic to oatmeal shampoo");
+    expect(persisted.photoKey).toBe("pets/rex.jpg");
+    expect(persisted.coatType).toBe("double");
+    expect(persisted.petSizeCategory).toBe("extra_large");
+    expect(persisted.preferredCuts).toEqual(["teddy bear", "puppy cut"]);
+    expect(persisted.medicalAlerts).toEqual([
+      { id: "a1", type: "allergy", description: "oatmeal", severity: "medium" },
+    ]);
+    expect(persisted.updatedAt).toBeInstanceOf(Date);
+  });
+
+  it("falls back to the weight key when weightKg is absent", async () => {
+    selectSessionRow = ACTIVE_SESSION;
+    selectPetRow = PET;
+
+    const res = await jsonPatch(
+      `/portal/pets/${PET_ID}`,
+      { weight: "9.75" },
+      { "X-Impersonation-Session-Id": SESSION_ID }
+    );
+
+    expect(res.status).toBe(200);
+    expect(updatedValues[0]!.weightKg).toBe("9.75");
+  });
+
+  it("returns 403 when the pet belongs to a different client", async () => {
+    selectSessionRow = ACTIVE_SESSION;
+    selectPetRow = { ...PET, clientId: OTHER_CLIENT_ID };
+
+    const res = await jsonPatch(
+      `/portal/pets/${PET_ID}`,
+      { name: "Hacker" },
+      { "X-Impersonation-Session-Id": SESSION_ID }
+    );
+
+    expect(res.status).toBe(403);
+    expect(updatedValues).toHaveLength(0);
+  });
+
+  it("returns 404 when the pet does not exist", async () => {
+    selectSessionRow = ACTIVE_SESSION;
+    selectPetRow = null;
+
+    const res = await jsonPatch(
+      `/portal/pets/${PET_ID}`,
+      { name: "Ghost" },
+      { "X-Impersonation-Session-Id": SESSION_ID }
+    );
+
+    expect(res.status).toBe(404);
+  });
+
+  it("returns 422 for an invalid coatType", async () => {
+    selectSessionRow = ACTIVE_SESSION;
+    selectPetRow = PET;
+
+    const res = await jsonPatch(
+      `/portal/pets/${PET_ID}`,
+      { coatType: "fluffy" },
+      { "X-Impersonation-Session-Id": SESSION_ID }
+    );
+
+    expect(res.status).toBe(422);
+    expect(updatedValues).toHaveLength(0);
+  });
+
+  it("returns 422 for an invalid petSizeCategory", async () => {
+    selectSessionRow = ACTIVE_SESSION;
+    selectPetRow = PET;
+
+    const res = await jsonPatch(
+      `/portal/pets/${PET_ID}`,
+      { petSizeCategory: "gigantic" },
+      { "X-Impersonation-Session-Id": SESSION_ID }
+    );
+
+    expect(res.status).toBe(422);
+    expect(updatedValues).toHaveLength(0);
+  });
+
+  it("returns 401 without an impersonation session header", async () => {
+    selectSessionRow = ACTIVE_SESSION;
+    selectPetRow = PET;
+
+    const res = await jsonPatch(`/portal/pets/${PET_ID}`, { name: "NoAuth" });
+
+    expect(res.status).toBe(401);
+  });
+});
diff --git a/src/routes/portal.ts b/src/routes/portal.ts
index 7b7b160..3f15745 100644
--- a/src/routes/portal.ts
+++ b/src/routes/portal.ts
@@ -225,9 +225,153 @@ portalRouter.get("/pets", async (c) => {
   const clientId = c.get("portalClientId");
 
   const clientPets = await db.select().from(pets).where(eq(pets.clientId, clientId));
-  return c.json(clientPets.map(p => ({ id: p.id, name: p.name, breed: p.breed, weight: p.weightKg, birthDate: p.dateOfBirth, photoUrl: p.photoKey, notes: p.groomingNotes })));
+  return c.json(clientPets.map(p => ({
+    id: p.id,
+    name: p.name,
+    breed: p.breed,
+    weight: p.weightKg,
+    birthDate: p.dateOfBirth,
+    photoUrl: p.photoKey,
+    notes: p.groomingNotes,
+    coatType: p.coatType,
+    petSizeCategory: p.petSizeCategory,
+    healthAlerts: p.healthAlerts,
+    preferredCuts: p.preferredCuts,
+    medicalAlerts: p.medicalAlerts,
+  })));
 });
 
+// ─── Customer-facing pet update ───────────────────────────────────────────────
+//
+// The customer portal pet-profile form (groombook/web) saves edits via
+// PATCH /api/portal/pets/:petId. The web payload mixes the keys returned by
+// GET /portal/pets (weight, birthDate, photoUrl, notes) with the form's own
+// edited keys (weightKg, healthAlerts, coatType, …), so we accept both spellings
+// and map each to its `pets` column. Ownership is enforced exactly like the
+// appointment-notes handler: 404 if the pet does not exist, 403 if it belongs to
+// another client.
+
+// Allowed enum values mirror packages/db/src/schema.ts coatTypeEnum /
+// petSizeCategoryEnum. Kept as plain string lists so an invalid value can be
+// rejected with 422 in-handler (zValidator failures would surface as 400).
+const PORTAL_COAT_TYPES: readonly string[] = ["short", "medium", "long", "double", "wire", "silky", "curly", "hairless"];
+const PORTAL_PET_SIZES: readonly string[] = ["small", "medium", "large", "extra_large"];
+// The web size dropdown emits "xlarge"; the DB enum value is "extra_large".
+const PORTAL_PET_SIZE_ALIASES: Record<string, string> = { xlarge: "extra_large" };
+
+const portalMedicalAlertSchema = z.object({
+  id: z.string().optional(),
+  type: z.string(),
+  description: z.string(),
+  severity: z.enum(["low", "medium", "high"]),
+});
+
+const portalPetUpdateSchema = z.object({
+  name: z.string().min(1).max(200).optional(),
+  breed: z.string().max(200).nullable().optional(),
+  // weightKg is the form's edited key; weight is the GET-shaped key. Accept both.
+  weightKg: z.union([z.number(), z.string()]).nullable().optional(),
+  weight: z.union([z.number(), z.string()]).nullable().optional(),
+  birthDate: z.string().nullable().optional(),
+  notes: z.string().max(2000).nullable().optional(),
+  healthAlerts: z.string().max(2000).nullable().optional(),
+  photoUrl: z.string().nullable().optional(),
+  // coatType / petSizeCategory validated in-handler so bad values return 422.
+  coatType: z.string().nullable().optional(),
+  petSizeCategory: z.string().nullable().optional(),
+  preferredCuts: z.array(z.string()).nullable().optional(),
+  medicalAlerts: z.array(portalMedicalAlertSchema).nullable().optional(),
+});
+
+portalRouter.patch(
+  "/pets/:petId",
+  zValidator("json", portalPetUpdateSchema),
+  async (c) => {
+    const db = getDb();
+    const petId = c.req.param("petId");
+    const body = c.req.valid("json");
+    const clientId = c.get("portalClientId");
+
+    const [pet] = await db
+      .select()
+      .from(pets)
+      .where(eq(pets.id, petId))
+      .limit(1);
+
+    if (!pet) {
+      return c.json({ error: "Not found" }, 404);
+    }
+
+    if (pet.clientId !== clientId) {
+      return c.json({ error: "Forbidden" }, 403);
+    }
+
+    const updateData: Record<string, unknown> = { updatedAt: new Date() };
+
+    if (body.name !== undefined) updateData.name = body.name;
+    if (body.breed !== undefined) updateData.breed = body.breed;
+
+    if (body.weightKg !== undefined || body.weight !== undefined) {
+      const w = body.weightKg ?? body.weight;
+      updateData.weightKg = w === null || w === undefined ? null : String(w);
+    }
+
+    if (body.birthDate !== undefined) {
+      updateData.dateOfBirth = body.birthDate ? new Date(body.birthDate) : null;
+    }
+
+    if (body.notes !== undefined) updateData.groomingNotes = body.notes;
+    if (body.healthAlerts !== undefined) updateData.healthAlerts = body.healthAlerts;
+    if (body.photoUrl !== undefined) updateData.photoKey = body.photoUrl;
+
+    if (body.coatType !== undefined) {
+      if (body.coatType !== null && !PORTAL_COAT_TYPES.includes(body.coatType)) {
+        return c.json({ error: "Invalid coatType" }, 422);
+      }
+      updateData.coatType = body.coatType;
+    }
+
+    if (body.petSizeCategory !== undefined) {
+      let size: string | null = body.petSizeCategory;
+      if (size !== null) {
+        size = PORTAL_PET_SIZE_ALIASES[size] ?? size;
+        if (!PORTAL_PET_SIZES.includes(size)) {
+          return c.json({ error: "Invalid petSizeCategory" }, 422);
+        }
+      }
+      updateData.petSizeCategory = size;
+    }
+
+    if (body.preferredCuts !== undefined) updateData.preferredCuts = body.preferredCuts ?? [];
+    if (body.medicalAlerts !== undefined) updateData.medicalAlerts = body.medicalAlerts ?? [];
+
+    const [updated] = await db
+      .update(pets)
+      .set(updateData)
+      .where(eq(pets.id, petId))
+      .returning();
+
+    if (!updated) {
+      return c.json({ error: "Not found" }, 404);
+    }
+
+    return c.json({
+      id: updated.id,
+      name: updated.name,
+      breed: updated.breed,
+      weight: updated.weightKg,
+      birthDate: updated.dateOfBirth,
+      photoUrl: updated.photoKey,
+      notes: updated.groomingNotes,
+      coatType: updated.coatType,
+      petSizeCategory: updated.petSizeCategory,
+      healthAlerts: updated.healthAlerts,
+      preferredCuts: updated.preferredCuts,
+      medicalAlerts: updated.medicalAlerts,
+    });
+  }
+);
+
 portalRouter.get("/invoices", async (c) => {
   const db = getDb();
   const clientId = c.get("portalClientId");