Sources & References

Every tool on this site is built on published veterinary work rather than on general web writing. This page lists what that work is, so you can check it yourself. Where a page reports a figure from a study, the study is named on that page too — this is the consolidated list.

If you find something here that is out of date or that we have represented inaccurately, please tell us. Corrections are made and dated.

About These Citations

Where we have a DOI we have verified, it is linked. Where we have the journal, volume and page reference but have not independently confirmed a persistent identifier, we give the full reference without a link rather than guessing at one — a wrong DOI is worse than no DOI, because it sends you somewhere that is not the paper. Every reference here is complete enough to find through PubMed or your library.

Clinical Instruments We Implement

Several tools are interactive implementations of screening instruments developed and validated by veterinary researchers. In each case the tool follows the published scoring rule rather than a version of our own.

• Feline Musculoskeletal Pain Screening Checklist — Enomoto M, Lascelles BDX, Gruen ME. Development of a checklist for the detection of degenerative joint disease-associated pain in cats. Journal of Feline Medicine and Surgery, 2020;22(12):1137–1147. doi:10.1177/1098612X20907424
  Implemented in: Cat Arthritis Screening Tool. The six questions and the "any single no prompts further evaluation" rule are the authors'.
• Owner-assessed pruritus visual analog scale (pVAS) — Hill PB, Lau P, Rybníček J. Development of an owner-assessed scale to measure the severity of pruritus in dogs. Veterinary Dermatology, 2007;18(5):301–308. Further validated in Rybníček J, Lau-Gillard PJ, Harvey R, Hill PB, Veterinary Dermatology, 2009;20(2):115–122.
  Implemented in: Pet Itch Score Tracker. The 2009 paper's finding that visible numerical markings distort owner scoring is why our slider hides the number until after you place it.
• HHHHHMM Quality of Life Scale — Villalobos AE. Quality of life scale for pets in palliative and hospice care.
  Implemented in: Dog Quality of Life Calculator and Cat Quality of Life Calculator.
• Tufts Animal Care and Condition (TACC) weather safety scale — Patronek GJ, Tufts Center for Animals and Public Policy, 1997.
  Adapted in: Dog Cold Weather Safety Calculator. That page states plainly that TACC was built as a neglect-screening instrument for investigators rather than as an owner walk planner, and that we are adapting it.

Studies We Report Figures From

• Huang L, Coradini M, Rand J, Morton J, Albrecht K, Wasson B, Robertson D. Search Methods Used to Locate Missing Cats and Locations Where Missing Cats Are Found. Animals, 2018;8(1):5. doi:10.3390/ani8010005
  Used in: Lost Pet Search Plan — the 500 m recovery radius, the 50 m median for indoor-only cats, and the recovery-rate timeline. That page also notes that the study's physical-searching finding reached only p = 0.073, short of conventional significance, because the figure is widely repeated online as settled.
• Krontveit RI, Nødtvedt A, Sævik BK, Ropstad E, Trangerud C. Housing- and exercise-related risk factors associated with the development of hip dysplasia as determined by radiographic evaluation in a prospective cohort of Newfoundlands, Labrador Retrievers, Leonbergers, and Irish Wolfhounds in Norway. American Journal of Veterinary Research, 2012;73(6):838–846. doi:10.2460/ajvr.73.6.838
  Used in: How Much Exercise Does a Puppy Need? — stairs before three months associated with higher hip dysplasia risk; off-lead exercise on soft uneven ground associated with lower risk. The page notes this is an observational study of four large breeds and should not be stretched to toy breeds.
• Sallander MH, Hedhammar Å, Trogen ME. Diet, exercise, and weight as risk factors in hip dysplasia and elbow arthrosis in Labrador Retrievers. Journal of Nutrition, 2006;136(7):2050S–2052S.
  Used in: How Much Exercise Does a Puppy Need? — free-choice feeding associated with hip and elbow conditions.
• Quimby J, Gowland S, Carney HC, DePorter T, Plummer P, Westropp J. 2021 AAHA/AAFP Feline Life Stage Guidelines. Journal of Feline Medicine and Surgery, 2021. doi:10.1177/1098612X21993657
  Used in: Cat Age Calculator — the four age-based life stages (kitten to 1 year, young adult 1–6, mature adult 7–10, senior over 10) and the note that older six-stage charts use different labels.
• Carney HC, Ward CR, et al. 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism. Journal of Feline Medicine and Surgery, 2016. doi:10.1177/1098612X16643252
  Used in: Cat Hyperthyroidism Treatment Cost — prevalence up to 10% of cats over 10, radioiodine as treatment of choice with over 95% single-dose success, the methimazole trial before definitive therapy because treatment can unmask kidney disease, recheck intervals, and the iodine-restricted diet having to be the only food. Prices on that page come from veterinary cost reporting (PetMD and others), not from the guidelines.
• Behrend E, Holford A, Lathan P, Rucinsky R, Schulman R. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association, 2018. doi:10.5326/JAAHA-MS-6822
  Used in: Cat Diabetes Treatment Cost — that some cats reach remission, that in-hospital glucose curves are not recommended for cats, and the high-protein, low-carbohydrate, preferably canned diet with 0.5–2% weekly weight loss for obese cats.
• U.S. Food and Drug Administration. Dear Veterinarian Letter Regarding Important Safety Conditions Associated with the Use of Senvelgo (velagliflozin). 2024. fda.gov
  Used in: Cat Diabetes Treatment Cost — not for cats previously treated with insulin, the risk of diabetic ketoacidosis including the euglycemic form, and the ketone and recheck schedule after starting. Remission rates on that page come from a Central Veterinary Conference research review (dvm360); prices come from veterinary cost reporting and Elanco's launch list price for Bexacat as reported by NBC News.
• International Renal Interest Society (IRIS). IRIS Staging of CKD and Treatment Recommendations, and Diets for Cats with Chronic Kidney Disease. iris-kidney.com
  Used in: Cat Kidney Disease Cost by Stage — feline creatinine and SDMA stage cut-offs, retesting discordant results, the renal diet considered at stage 2 and recommended at stages 3–4, and the summaries of Ross et al. (2006, randomized trial: no uremic crises or renal deaths on a kidney diet) and Elliott et al. (2000, median survival 633 vs 264 days).
• Boyd LM, Langston C, Thompson K, Zivin K, Imanishi M. Survival in Cats with Naturally Occurring Chronic Kidney Disease (2000–2002). Journal of Veterinary Internal Medicine, 2008. doi:10.1111/j.1939-1676.2008.0163.x
  Used in: Cat Kidney Disease Cost by Stage — 211 cats; median survival 1,151 days (stage IIb), 778 days (stage III), 103 days (stage IV).
• Grauer GF. Early Diagnosis of Chronic Kidney Disease in Dogs & Cats: Use of Serum Creatinine & Symmetric Dimethylarginine. Today's Veterinary Practice. todaysveterinarypractice.com
  Used in: Cat Kidney Disease Cost by Stage — SDMA above 14 µg/dL as abnormal, SDMA rising after about 40% loss of function in a cat study, muscle mass affecting creatinine but not SDMA, and repeating SDMA with urine specific gravity before calling it IRIS stage 1. Prices on that page come from veterinary cost reporting (RealVetCost, Great Pet Care, Wag!), not from these sources.
• Mäkitaipale J, Airas N, Engblom S, Linden J. Prospective survey of neoplastic and non-neoplastic uterine disorders in 116 domestic rabbits (Oryctolagus cuniculus). Journal of Exotic Pet Medicine, 2022;41. doi:10.1053/j.jepm.2022.01.001
  Used in: Rabbit Spay and Neuter Cost — malignant uterine tumors in 40% of rabbits over three years, about 19 times the odds of younger rabbits, findings in rabbits with no suspected disease, and removing the uterus as well as the ovaries in older rabbits.
• Brodbelt DC, Blissitt KJ, Hammond RA, Neath PJ, Young LE, Pfeiffer DU, Wood JLN. The risk of death: the Confidential Enquiry into Perioperative Small Animal Fatalities (CEPSAF). Veterinary Anaesthesia and Analgesia, 2008;35(5):365–373. doi:10.1111/j.1467-2995.2008.00397.x
  Used in: Rabbit Spay and Neuter Cost — anesthetic-related death risk of 1.39% in rabbits (0.73% healthy) versus 0.24% in cats and 0.17% in dogs. Prices on that page come from veterinary cost reporting (CareCredit, Hepper) and the House Rabbit Society.
• Yarborough S, Fitzpatrick A, Schwartz SM; Dog Aging Project Consortium. Evaluation of cognitive function in the Dog Aging Project: associations with baseline canine characteristics. Scientific Reports, 2022. doi:10.1038/s41598-022-15837-9
  Used in: Dog Dementia — 15,019 dogs; odds of cognitive dysfunction up about 52% per year of age; not-active dogs about 6.5 times the odds of very active dogs; eye and ear disorders about twice the odds.
• Seibert L. Management of Dogs and Cats with Cognitive Dysfunction. Today's Veterinary Practice. todaysveterinarypractice.com
  Used in: Dog Dementia — prevalence (14.2% estimated vs 1.9% diagnosed; 28% at 11–12 and 68% at 15–16 years), conditions to rule out, selegiline onset of 4–12 weeks and drug-interaction caution, and the diet and supplement evidence. Selegiline prices come from GoodRx and pet-pharmacy listings.
• Corral MJ, Moyaert H, Fernandes T, Escalada M, Tena JKS, Walters RR, Stegemann MR. A prospective, randomized, blinded, placebo-controlled multisite clinical study of bedinvetmab, a canine monoclonal antibody targeting nerve growth factor, in dogs with osteoarthritis. Veterinary Anaesthesia and Analgesia, 2021. summary
  Used in: Librela Cost for Dogs — 287 dogs; CBPI treatment success 43.5% vs 16.9% placebo at day 28, with bedinvetmab superior at later time points.
• U.S. Food and Drug Administration. Dear Veterinarian Letter Notifying Veterinarians about Adverse Events Reported in Dogs Treated with Librela (bedinvetmab injection). December 16, 2024. fda.gov
  Used in: Librela Cost for Dogs — approval date (May 5, 2023) and the adverse events described (ataxia, seizures, other neurologic signs, polyuria and polydipsia, death including euthanasia). The 2025 label changes come from AAHA's report on the Zoetis label update; the 1–10 per 10,000 doses reporting rate comes from Zoetis. Prices come from GoodRx and ThePricer.
• Zoetis. Apoquel (oclacitinib maleate) product label, Australian Pesticides and Veterinary Medicines Authority. apvma.gov.au
  Used in: Apoquel vs Cytopoint Cost — 0.4–0.6 mg/kg twice daily for up to 14 days then once daily, the weight-band tablet chart, and the 12-month / 3 kg minimum. Apoquel and Cytopoint prices come from published pharmacy and clinic price lists (MSPCA, ThePricer, Vetster).
• American Animal Hospital Association. FDA approves removal of some vaccine-related warnings for Zenrelia label. AAHA Trends. aaha.org
  Used in: Apoquel vs Cytopoint Cost — September 2024 approval, removal of the fatal vaccine-induced disease warning, and the remaining boxed warning on inadequate vaccine response with its 28-day / 3-month timing.
• Merck Veterinary Manual. Nutritional Problems of Guinea Pigs (pet owner version). merckvetmanual.com
  Used in: Guinea Pig Vet Costs — vitamin C requirement of at least 10 mg/kg/day (30 mg/kg for pregnant females), vitamin C loss from stored pellets, and signs of deficiency. Ovarian cyst prevalence (76–90% in post-mortem studies) is as cited in García-González et al., Veterinary Sciences 2025. Prices come from Furry Critter Network's guinea pig budget guide and one exotic practice's published price list.
• Wucherer KL, Conzemius MG, Evans R, Wilke VL. Short-term and long-term outcomes for overweight dogs with cranial cruciate ligament rupture treated surgically or nonsurgically. Journal of the American Veterinary Medical Association, 2013;242(10):1364–1372. doi:10.2460/javma.242.10.1364
  Used in: Dog ACL Surgery Cost — overweight dogs over 20 kg; successful outcomes at 52 weeks in 75% (surgery) vs 64% (nonsurgical); 27.5% contralateral rupture during the study. Summarised alongside Vasseur (1984) in a Veterinary Evidence knowledge summary.
• Vasseur PB. Clinical results following nonoperative management for rupture of the cranial cruciate ligament in dogs. Veterinary Surgery, 1984;13:243–246. doi:10.1111/j.1532-950X.1984.tb00801.x
  Used in: Dog ACL Surgery Cost — 86% of dogs under 15 kg normal or improved without surgery, versus 19% of dogs over 15 kg.
• Muir P, Schwartz Z, Malek S, et al. Contralateral cruciate survival in dogs with unilateral non-contact cranial cruciate ligament rupture. PLoS ONE, 2011;6(10):e25331. doi:10.1371/journal.pone.0025331
  Used in: Dog ACL Surgery Cost — 380 dogs; median contralateral ligament survival 947 days. Surgery prices on that page come from ThePricer and OodleLife cost reporting; the bilateral-condition insurance point comes from PetMD.
• U.S. Food and Drug Administration. Information about the Boxed Warning on Meloxicam Labels Regarding Safety Risks in Cats. fda.gov
  Used in: Solensia Cost for Cats — injectable meloxicam approved for cats only as a single pre-surgical dose, and the boxed warning that repeated use has been associated with acute renal failure and death. Robenacoxib's 3-day maximum comes from Elanco's Onsior label information; Solensia's approval study results (77% vs 67% placebo) and osteoarthritis prevalence (60% of cats over 6, 90% over 12) come from Zoetis's approval announcement; prices from GoodRx and ThePricer.
• Beam S, Correa MT, Davidson MG. A retrospective-cohort study on the development of cataracts in dogs with diabetes mellitus: 200 cases. Veterinary Ophthalmology, 1999;2:169–172. doi:10.1046/j.1463-5224.1999.00073.x
  Used in: Dog Cataract Surgery Cost — about 50% of diabetic dogs with cataracts by 170 days after diagnosis and 75% by 370 days (as cited in Williams, Veterinary Sciences 2017). Success rates, candidacy and complications come from PetMD; prices from GoodRx's published ophthalmology price examples.
• Bugbee A, et al. 2023 AAHA Selected Endocrinopathies of Dogs and Cats Guidelines. Journal of the American Animal Hospital Association, 2023. aaha.org
  Used in: Cushing's Disease in Dogs: Treatment Cost — testing only with two or more supportive findings, LDDST as preferred screen, ACTH stimulation test missing up to 41% of adrenal-dependent cases, urine cortisol:creatinine ratio for ruling out, and (via AAHA's monitoring summary) recheck timing at 10–14 days, 30 days and about every 90 days, lower twice-daily starting doses, and pre-pill cortisol monitoring. Prices come from PetMD (ACTH stimulation test) and a large online pet pharmacy's listed Vetoryl prices.
• Nagata N, Kojima K, Yuki M. Comparison of survival times for dogs with pituitary-dependent hyperadrenocorticism in a primary-care hospital: treated with trilostane versus untreated. Journal of Veterinary Internal Medicine, 2017;31(1):22–28. jvim
  Used in: Cushing's Disease in Dogs: Treatment Cost — 43 dogs; untreated median survival 506 days; two-year survival 52.2% treated vs 8.5% untreated. The overdiagnosis point comes from Carvalho et al., JVIM 2025 (doi:10.1111/jvim.17166), a survey of 2,178 responses from European primary-care vets.
• American Veterinary Medical Association. AAHA releases canine-focused diabetes guidelines (reporting the 2026 AAHA Diabetes Management Guidelines for Dogs, released September 1, 2026). avma.org
  Used in: Dog Diabetes Treatment Cost — lifelong insulin because of permanent beta-cell loss, the basal insulins degludec and glargine U-300 and possible once-daily dosing, inexpensive continuous glucose monitors, glucose monitoring as the only way to detect hypoglycemia, hypoglycemia signs and written client instructions. Cataract figures come from Beam et al. 1999; prices come from Spot Pet Insurance's dog diabetes cost guide and earlier PetPawCalc cost sources.
• Fall T, Hedhammar Å, Wallberg A, et al. Diabetes mellitus in Elkhounds is associated with diestrus and pregnancy. Journal of Veterinary Internal Medicine, 2010;24(6):1322. doi:10.1111/j.1939-1676.2010.0630.x
  Used in: Dog Diabetes Treatment Cost — 63 diabetic Elkhounds; first signs a median of 30 days after estrus; 46% (18 of 39) recovered after ovariohysterectomy; immediate spay improves the prognosis for remission.
• Pöppl AG, Mottin TS, González FHD. Diabetes mellitus remission after resolution of inflammatory and progesterone-related conditions in bitches. Research in Veterinary Science, 2013;94(3):471–473. sciencedirect.com
  Used in: Dog Diabetes Treatment Cost — 117 diabetic females; 6 of 57 intact females that were spayed (about 10.5%) remitted, including some that first presented with ketoacidosis; the authors recommend spaying all intact diabetic females. The intact/spayed breakdown is as summarised in Clinician's Brief. DKA hospital stay and survival figures come from Lemonade's veterinary-reviewed DKA guide.
• American College of Veterinary Surgeons. Mast Cell Tumors. acvs.org
  Used in: Dog Lump Removal Cost — mast cell tumors as 14–21% of canine skin tumors, Boxers and Boston Terriers accounting for about half, needle aspirates diagnosing them accurately in almost all cases, and grade requiring histopathology after removal. The "See something, do something" rule (pea-sized, one month) is from Sue Ettinger, DACVIM (oncology), in dvm360; proportional margins, prognosis by grade and tigilanol tiglate response rates are from a 2024 Today's Veterinary Practice review; prices come from Wag!, Hepper and CareCredit.
• Vincent AM, Okonkowski LK, Brudvig JM, Refsal KR, Berghoff N, Olivier NB, Langlois DK. Low-dose desoxycorticosterone pivalate treatment of hypoadrenocorticism in dogs: A randomized controlled clinical trial. Journal of Veterinary Internal Medicine, 2021;35(4):1720–1728. doi:10.1111/jvim.16195
  Used in: Addison's Disease in Dogs: Treatment Cost — 37 newly diagnosed dogs randomized to 2.2 or 1.1 mg/kg DOCP every 30 days; electrolytes controlled in both groups; more biochemical overtreatment on the standard dose. Label-dose cost estimates (about $475/year for a West Highland White Terrier, $2,851/year and $15,585 lifetime for a Great Dane) come from Michigan State University's description of the study; prices from ThePricer; signs, breeds and prognosis from Cornell's Riney Canine Health Center.
• Boswood A, Häggström J, Gordon SG, et al. Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial. Journal of Veterinary Internal Medicine, 2016. doi:10.1111/jvim.14586
  Used in: Dog Heart Murmur — 360 dogs weighing about 4–15 kg with enlarged hearts and no heart failure; median time to heart failure or cardiac death 1,228 days on pimobendan vs 766 on placebo.
• Payne JR, Brodbelt DC, Luis Fuentes V. Cardiomyopathy prevalence in 780 apparently healthy cats in rehoming centres (the CatScan study). Journal of Veterinary Cardiology, 2015. PubMed 26776583
  Used in: Cat Heart Murmur — murmur prevalence 40.8%, about 70% of murmurs functional, HCM prevalence 14.7%, positive predictive value of a murmur for HCM 17.9–42.6%.
• Nakamura RK, Rishniw M, King MK, Sammarco CD. Prevalence of echocardiographic evidence of cardiac disease in apparently healthy cats with murmurs. Journal of Feline Medicine and Surgery, 2011. doi:10.1016/j.jfms.2010.12.007
  Used in: Cat Heart Murmur — 17 of 32 healthy-looking cats with murmurs (53%) had echocardiographic heart disease.
• Egenvall A, Hagman R, Bonnett BN, et al. Breed risk of pyometra in insured dogs in Sweden. Journal of Veterinary Internal Medicine, 2001. Reported via a 2018 review in Clinical Theriogenology (PDF), which also supplies the 2012 Swedish breed proportions, timing after heat, 92% surgical survival, medical-treatment recurrence and feline prevalence.
  Used in: Pyometra in Dogs.
• Buffington CAT, Westropp JL, Chew DJ, Bolus RR. Clinical evaluation of multimodal environmental modification (MEMO) in the management of cats with idiopathic cystitis. Journal of Feline Medicine and Surgery, 2006;8(4):261–268.
  Used in: Cat Urinary Health Checklist.
• Olivry T, Mueller RS, Prélaud P. Critically appraised topic on adverse food reactions of companion animals (1): duration of elimination diets. BMC Veterinary Research, 2015;11:225.
  Used in: Elimination Diet Trial Planner — trial duration.
• AAFP / ISFM feline environmental needs guidelines — Journal of Feline Medicine and Surgery, 2013;15(3):219–230.
  Used in: Cat Urinary Health Checklist — the five pillars framework.

Veterinary Associations & Reference Works

For clinical framing, prevalence and standard-of-care statements we work from association guidance and established veterinary references rather than from consumer blogs:

• American Veterinary Medical Association (AVMA) — feline lower urinary tract disease, including that straining in the litter box is more often urethral obstruction than constipation.
• American Association of Feline Practitioners (AAFP) — feline life-stage and environmental guidelines.
• WSAVA — body condition scoring, nutritional assessment.
• Merck Veterinary Manual — otitis externa, the primary/secondary/predisposing/perpetuating framework.
• Today's Veterinary Practice and dvm360 — clinical review articles, including the share of canine otitis externa attributable to atopic dermatitis.
• US Food and Drug Administration (FDA), Center for Veterinary Medicine — product approvals and label safety information, including the isoxazoline neurologic warning and the 2025 approval of the first once-yearly injectable canine flea and tick preventive.
• American Heartworm Society (AHS) — heartworm testing guidance: the roughly six-to-seven-month lag before an infection can be detected, testing schedules for puppies and after missed doses, annual testing on year-round prevention, pairing antigen with microfilaria testing, and antigen-plus-antibody screening in cats. Also its position on the melarsomine protocol versus "slow kill", which it describes as a salvage procedure rather than a treatment of choice. Used in Heartworm Test Cost and Heartworm Treatment Cost.
• Itemized US cost reporting — PetMD (veterinarian-reviewed) for line-by-line heartworm treatment prices, and MetLife Pet Insurance's published figures for surgical-removal cases. Used only for price ranges in Heartworm Treatment Cost, which shows the arithmetic behind its total.
• Manufacturer guarantee terms — the published Zoetis ProHeart satisfaction guarantee, cited only for what its conditions require (testing, purchase and administration by a veterinary practice) and what it covers. It is not a product recommendation.
• Cardiac Education Group — veterinary cardiologists' owner guidance on sleeping respiratory rate (15–30 typical, consistently above about 30 warrants contact) and the ABCD staging summaries of the ACVIM consensus statements for canine mitral valve disease and feline cardiomyopathy. Used in the Sleeping Respiratory Rate Counter and both heart murmur articles.
• Association for Pet Obesity Prevention — weight and body condition data.
• Shelter medicine and neonatal rescue guidance — University of Wisconsin-Madison Shelter Medicine Program, Maddie's Fund, ASPCApro and the National Kitten Coalition, for neonatal warming, feeding volumes and stomach capacity.

What We Deliberately Do Not Use

This matters as much as the list above. During research we repeatedly encounter figures that are presented as if they came from studies but cannot be traced to one — content-marketing pages citing non-existent papers, or statistics that appear only on sites selling something. We exclude those, even when they would have made a page look more authoritative.

Two concrete examples of figures we found circulating and chose not to use: a specific daily water-intake threshold for cats attributed to a study we could not locate, and recurrence percentages for feline idiopathic cystitis attributed to a case series with no verifiable source. Where we could not verify a number, the page either omits it or says plainly that the evidence is weaker than it is usually presented to be.

How to Read Our Numbers

• Ranges, not targets. Weight charts and cost figures are bands because healthy animals and real invoices vary. We say where the variation comes from.
• Costs are US estimates and move with region and clinic type. We say so on cost pages and give the drivers rather than a single number.
• Screening is not diagnosis. Our screening tools indicate whether something is worth a veterinary conversation. None of them diagnoses, and several are deliberately built to err toward sending you to a vet.
• We name disagreement where it exists. Veterinary guidance is not always settled — the question of whether to withhold food from a pet with diarrhoea is a live example, and our page on it presents both positions rather than picking one silently.

See also our editorial policy for how pages are written, reviewed and corrected.