Collie Age Calculator

Approximately 70% of Collies carry the MDR1 gene mutation, which causes a defective blood-brain barrier that allows certain drugs to accumulate to toxic levels in the brain. Affected dogs can experience severe neurological reactions — including seizures, coma, and death — from common medications including ivermectin (at high doses), loperamide, and certain anaesthetics, sedatives, and chemotherapy drugs. This is the most important breed-specific health concern for Collie owners to understand.

Prevention: Test every Collie for the MDR1 mutation — a simple cheek swab DNA test determines whether the dog is normal/normal, normal/mutant (carrier), or mutant/mutant (affected). Provide a wallet card listing unsafe drugs to all veterinary providers and emergency clinics. Affected dogs must avoid ivermectin (at herding-dog doses), loperamide (Imodium), acepromazine, butorphanol, and several other medications. Safe heartworm preventatives at standard doses exist and should be discussed with your vet.

Symptoms: excessive sedation after medication, disorientation and tremors, excessive drooling, blindness, seizures, coma, death in severe cases

Collie Eye Anomaly is an inherited developmental condition affecting the choroid (blood vessel layer) of the eye. It ranges from mild choroidal hypoplasia (often not clinically significant) to severe colobomas and retinal detachments that can cause blindness. CEA is present from birth and does not progress after about 8 weeks of age, meaning the severity at the initial examination is the lifetime severity. Approximately 70-90% of Collies are affected to some degree.

Prevention: CEA is genetic and cannot be prevented in an already-born dog. Purchase puppies only from breeders who test both parents with the CEA DNA test and have puppies' eyes examined by a veterinary ophthalmologist between 5-8 weeks of age (before the choroid develops pigment that can mask the condition). Mildly affected dogs typically live completely normal lives. Severely affected dogs with colobomas or retinal detachments require environmental management to accommodate vision loss.

Symptoms: often no visible symptoms in mild cases, reduced vision in moderate cases, blindness in severe cases (colobomas or retinal detachment), abnormal pupil appearance in severe cases

Dermatomyositis is an inflammatory disease affecting the skin and muscles that is unique to Collies and Shetland Sheepdogs. It causes skin lesions (crusting, hair loss, scarring) typically on the face, ears, tail tip, and bony prominences, along with muscle inflammation that can cause difficulty eating and moving. The condition ranges from mild skin-only involvement to severe systemic disease. It is hereditary but triggered by environmental factors including UV exposure and viral infections.

Prevention: A DNA test identifying risk genotypes is available and should be used in breeding decisions. Minimise UV exposure for at-risk dogs, as sunlight triggers flare-ups. Early veterinary intervention with immunomodulatory therapy can minimise scarring and muscle damage. Mild cases often improve with maturity, while severe cases require lifelong management. Vitamin E supplementation and omega-3 fatty acids may help reduce inflammation.

Symptoms: crusting skin lesions on face, ears, and tail tip, hair loss on affected areas, scarring and pigment changes, difficulty chewing or swallowing (muscle involvement), stiff gait, muscle wasting (severe cases), waxing and waning course

Rod-cone dysplasia type 2 (rcd2) is the form of progressive retinal atrophy specific to Collies. It causes degeneration of the photoreceptor cells in the retina, beginning with rod cells (causing night blindness) and eventually affecting cone cells (causing complete blindness). Unlike CEA, PRA is progressive and eventually leads to total vision loss. However, dogs typically adapt well over the gradual course of the disease.

Prevention: DNA testing for rcd2 is available and should be performed on all breeding dogs. Purchase puppies from tested parents. Annual ophthalmologic examinations can detect early retinal changes before obvious vision loss occurs. While PRA cannot be prevented in affected dogs, early detection allows time to train the dog on verbal navigation cues and prepare the home environment for a blind dog.

Symptoms: night blindness (reluctance to go outside at night, bumping into objects in dim light), gradually worsening vision, dilated pupils, increased eye shine, eventual complete blindness, anxiety in unfamiliar environments as vision declines

Collies have a moderately deep chest that places them at elevated risk for bloat, though not at the extreme levels of giant or very deep-chested breeds. GDV occurs when the stomach fills with gas and potentially rotates, cutting off blood supply. It is a life-threatening emergency requiring immediate surgical intervention. The risk increases with age and is higher in dogs that eat rapidly, exercise near mealtimes, or eat one large daily meal.

Prevention: Feed two meals daily rather than one large meal. Use a slow-feeder bowl if the dog eats rapidly. Avoid vigorous exercise for one hour after eating. Keep the dog calm during and after meals. Discuss prophylactic gastropexy with your veterinarian, particularly if the dog has a very deep chest conformation. Learn to recognise bloat symptoms and have emergency veterinary contact information readily accessible.

Symptoms: distended abdomen, unproductive retching, restlessness and pacing, excessive drooling, rapid breathing, pale gums, weakness or collapse