Four lines run through a Norwegian Forest Cat screen: glycogen storage disease type IV (GSD IV), hypertrophic cardiomyopathy (HCM), hip dysplasia, and patellar luxation. One is answered by a lab, 3 by imaging and hands, and all 4 have a fixed first date. Get the dates wrong and you pay twice, because a hip film taken at 8 months cannot be scored the way a 24 month film can.
The 4 lines and what answers each one
GSD IV is a single recessive mutation and needs 1 DNA sample. HCM needs an echocardiogram, since no blood test replaces the measurement of wall thickness. Hip dysplasia needs a ventrodorsal X-ray with the hips extended, read by a scorer. Patellar luxation needs a hand on the knee. A urine sample and a chemistry panel sit underneath all 4, because they catch what the imaging misses: dilute urine, protein loss, raised liver enzymes, low glucose.
Month 4: 1 swab and 1 blood baseline
Sample the cheek at 4 months for the GSD IV mutation, which is recessive, so a carrier shows nothing and an affected cat carries 2 copies. Turnaround runs 10 to 21 days at 80 to 150 USD. Draw blood in the same visit for glucose, a chemistry panel, and muscle enzymes, and keep the numbers as the baseline for every year after. GSD IV changes how the body stores glycogen, so a fasting glucose on the low side of the reference range plus a weak, tired kitten is a reason to move the appointment forward rather than wait for the next one. The DNA result states the genotype; how much the disease has progressed is a veterinary question that needs an exam, a glucose curve, and liver values, not a swab alone.
Heart: 12 months, then 2 numbers every year
Echo at 12 months, then every 12 months to age 6, then every 6 months to age 10. Ask for diastolic wall thickness (IVSd) and the left atrium to aorta ratio (LA/Ao) in writing. Under 5.0 mm and a ratio under 1.5 is a normal screen; 5.0 to 5.9 mm or a 1.5 to 1.7 ratio means a recheck in 3 months; 6.0 mm or a ratio above 1.7 means most cardiologists start treatment and recheck at 3 to 6 months. A proBNP at 40 to 80 USD is a useful screen when a cat fights the table, but a low value does not cancel the echo. The same protocol appears in the Maine Coon heart screening, and the 2 breeds share the disease family.
Hips: 1 film at 12 months, 1 final at 24
Hip dysplasia in this breed is judged from a ventrodorsal view with both hips extended, taken under light sedation so the muscles relax. Score at 12 months for an early read, then repeat at 24 months, when the joint has finished remodeling and the score is final. A Norberg angle of 105 degrees or more on both sides is a good sign; a score of mild, moderate, or severe on either side changes the plan. Films cost 60 to 120 USD, and a scored report from a registry adds 30 to 60. Mild cases get weight control and 1 gram of omega 3 fatty acids per 5 kg of body weight daily; moderate and severe cases get a surgical consult and a home with fewer stairs and no jumps from height.
Knees: 4 grades, checked at every visit
Palpate both knees at every exam from 6 months old and record 1 of 4 grades. Grade 1 slips out and returns by itself. Grade 2 slips out unaided and returns. Grade 3 sits out most of the time and can be replaced by hand. Grade 4 cannot be replaced. Grades 1 and 2 are managed with a 5 percent body weight reduction if the cat is over condition score 5, plus non slip flooring on the 2 main runways. Any grade 3 or 4, or a grade 2 with a skip in the gait, gets a surgical opinion within 4 to 6 weeks.
4 signals that show up at home
One: jumping. A cat that clears 120 cm one month and hesitates at 60 cm the next has a joint or muscle reason. Two: sleeping respiratory rate, counted 30 seconds and doubled, 3 times a week; 30 or below is normal, 40 or above needs a call. Three: weakness after 12 hours without food, or drooling and wobbling at 6 to 8 weeks old in a kitten, which points at a glucose problem rather than shyness. Four: weight, where a 5 percent shift in 30 days on the same scale is the trigger. Log it on a weight trend chart, since this breed hides 1 kg under a long coat, and check the house against the toxic plant list once a season.
Which sign buys how many hours
Four families of signs, 4 different clocks. The fastest is breathing, the slowest is a limp, and the gap between them is where most delays happen.
| Sign | Window | Call within | Probable cause |
|---|---|---|---|
| Resting breathing 40+ per minute | 10 min | 2 hours | HCM, fluid |
| Gasping, gums turning blue | none | 0 hours | Emergency |
| Weak, drooling, cannot stand | 30 min | 1 hour | Low glucose |
| Dragging a hind leg after a jump | 2 hours | 12 hours | Hip, cruciate |
| No food for 24 hours | 24 hours | 8 hours | GSD IV, GI, fever |
| Limp lasting 3 days | 72 hours | 7 days | Dysplasia, patella |
The hip score has its own clock, because a grade decides the year rather than the hour.
| Score | Finding | Next step |
|---|---|---|
| Normal | Norberg angle 105+ degrees | Rescreen at 24 months |
| Mild | Shallow socket, no limp | Weight, omega 3, 12 months |
| Moderate | Limp after exercise | Surgical consult in 6 weeks |
| Severe | Cannot rise without help | Surgical consult in 2 weeks |
Pain control after any of these uses 1 or 2 classes, an NSAID or a gabapentinoid, and both are given only on a veterinary prescription after an exam.
Costs and a 24 month calendar
Exam 40 to 70 USD, GSD IV DNA 80 to 150, chemistry plus glucose 60 to 120, echo 120 to 250, hip films plus scoring 90 to 180, urinalysis 40 to 80. Year 1 with films lands at 450 to 800 USD; year 2 adds the final hip film and runs 350 to 650. The calendar: month 4 DNA and blood, month 6 knees, month 12 echo plus urine plus first hip film, month 18 knees, month 24 echo plus final hip film, then yearly echoes with 6 month knee checks.
5 steps before the next visit
- Book the 4 month GSD IV swab and a fasting glucose in the same visit.
- Write the 12 and 24 month hip films into the calendar now, not later.
- Measure the 2 favorite jump heights and put a step beside the higher one.
- Count sleeping breaths 3 times a week and keep the 3 numbers per week.
- Weigh monthly; over condition score 5, cut 5 percent of body weight first.
Terms mentioned in this article
Frequently asked
What does the GSD IV test actually tell me?
It reads 1 recessive mutation and returns a genotype: clear, carrier, or affected with 2 copies. It does not measure how much glycogen has built up in muscle or liver. That part needs an exam, a glucose curve, and liver values, so an affected result should be followed by a veterinary workup rather than a wait and see approach.
Why take hip X-rays twice?
The first film at 12 months gives an early read while the joint is still remodeling, and the second at 24 months is the one a scorer will accept as final. A film taken at 8 months is too early to grade, and skipping the 24 month view means you never get a number you can compare with a breeding or insurance record.
How often should the heart be scanned?
Every 12 months from age 1 to age 6, then every 6 months to age 10. If wall thickness reaches 5.0 to 5.9 mm or the left atrium ratio reaches 1.5 to 1.7, the interval drops to 3 months, and at 6.0 mm or a ratio above 1.7 most cardiologists begin treatment.