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Health Basics

Sooner or later in your time as a foster, you will come across an animal requiring some medical help. As their histories are often mysteries to us, it's impossible to know what they've been exposed to, how many vaccines they've had, etc.

This page aims to explain what a healthy animal should look like, as well as some of the most common health issues we see in rescue. We'll also review types of medication, medicating techniques, tricks, and more.


A healthy baseline

Before you can understand what is abnormal, concerning, or requiring medical attention, it's important to understand what a healthy pet looks like. This will help us set a goal to work towards, maintain, or help us know when more action needs to be taken.

All pets will be examined upon intake into our system. These are the things that we evaluate. Normal images on the left, and abnormal or concerning things too look for are on the right. 


A body condition score refers to the animal's weight, muscle mass, and overall condition.


1-3: Underweight. 

1-2: Very serious malnutrition, possible medical causes for concern. Will require a vet plan to treat and gain weight.

3- Underweight- One of our goals will be to ensure the animal is receiving proper nutrition and caloric intake. This should be notably improvable over time.

Ribs and hips are prominent, individual vertebrae appreciable. 

4-5: Ideal. 

Last rib should be visible. Hips should be noticeable, but not overly sharp or prominent. 

6-9 Overweight.

6-7: Less concerning, may be a result of poor diet or regulation. Should be manageable and doesn't pose any immediate health threats.

8-9 Obese: One of our goals will be to ensure the animal is receiving proper nutrition and caloric intake. This should be notably improvable over time. 

Mobility is often impeded, last rib not visible, can have larger health implications long term (joint health, heart health, etc)

If at any point the animal's body condition (BCS) changes, Underdog should be alerted. Even for overweight animals, weight loss should be gradual and planned. Losing weight too quickly can be hazardous to their health. Animals with a 1-2 BCS should be weighed regularly and monitored to ensure gaining weight appropriately and to ensure we're not missing underlying health concerns. 


Eyes and noses should be clear, not puffy, and free of discharge. Some very mild reddish brown eye discharge after sleeping can be normal, but anything beyond a minimal amount could indicate an upper respiratory infection, eye infections, or other serious concerns requiring medication.

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Underdog alum Mario showing us healthy and clear eyes, nose free of dried discharge or snot, and no squinting or redness in the eyes.


Unfortunately, Mario later broke with URI, resulting in squinting and glassy eyes, severe ocular discharge and sneezing. Here he is on the way to the vet to get him feeling better.

Cats also have an inner eyelid. This should be not visible (though sometimes when sleepy, a little bit can poke through an open eyelid) and should be free of redness, puffiness, etc.


Normal inner eyelids visible due to sleeping position. Not red/swollen/inflamed.

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Visible inner eyelids, sometimes called Haw's Syndrome, can be a sign of parasites, fever, or other issues. Alert Underdog to any cat with  consistently raised third eyelids immediately.

In both dogs and cats, eyes should be clear and open without squinting. If you pull back the corner of the eye lid, the conjunctiva (the inner pinkish bit) should look normal without swelling, redness, or discharge. 


Like eyes, noses should be clear and free of discharge, either wet or old and dry. Some animals get drooly with a bit of clear dripping thin discharge when happy, but this should go away when not stimulated. Sometimes you see this when cats are really eagerly making biscuits, or when dogs "sneeze" out of excitement. 


Persistent clear or "serous" discharge can be a sign of a cold/kennel cough, allergies, or sometimes just due to hypersalivation. Let Underdog know if you see a large amount of clear nasal discharge, drippy noses, or sneezing.


Green or "purulent" discharge is never normal and can be a sign of an infection, pneumonia, severe kennel cough, or other issues needing medical attention.


The tongue and gums should be a healthy pink. Teeth start to rupture on kittens and puppies over the course of weeks 3-6 of their life, so you may see some redness and teething. If you run your finger over their gums, it should feel wet and smooth, not "tacky" or sticky (see more on checking hydration later).


A mid-yawn Monty demonstrating healthy pink gums and tongue.

Pale (white) or blue gums are a sign of a medical emergency. If your foster's gums and lips look like this image, take them immediately to an emergency vet.


Rescue animals often have pretty rough teeth. As long as the teeth don't seem rotten, infected, or painful, we will typically leave dental care to the adopter's vets; as it is something that often requires long term care and treatment, is costly, and doesn't affect their quality of life, it's not a priority or barrier to adoption. Dentals are stressful and require anesthesia, so is best done after they've gotten settled in their forever homes and have a peaceful place to recover. The priority is to get them into their forever home (unless their quality of life is affected).


Your foster's abdomen should be concave. If the tummy looks bloated, it can be a sign of parasites. If it looks  very large, distended, and painful, seek emergency care. 


Cozy alum Oats has a very normal tummy.

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This kitten looks to have the parasite pot belly (or could just be very full and gassy). While not necessarily an emergency, this is good to note, and should go away with dewormers or time- if it doesn't dissipate, let Underdog know!


Breathing should be effortless and quiet. If you notice any labored breathing, that is a medical emergency! Proceed directly to the emergency vet and let Underdog know. Some mild snoring is normal, but wheezing, chest sounds, or coughing needs to be addressed.


Petunia enjoying a nap, no effort breathing.


Petunia later broke with kennel cough, and started having coughing fits. We also diagnosed a grade IV-V heart murmur. Heart issues can also cause coughing.


Animals should be active, responsive to stimulus (ie your voice/sounds/touch), and move easily. Sluggishness or lethargy can be a sign of sickness. Especially in puppies and kittens, animals should be energetic and playful.


Monty, active and playful!


By contrast, we knew Monty was sick when he was quiet, decreased appetite, and didn't want to do much besides sleep. This is alarming for a young kitten who should be hyper and crazy.

The terms vets and animal professionals use to discuss animal mentation/energy levels:

BAR: Bright, Alert, and Responsive. All is normal.

QAR: Quiet, Alert, Responsive. The animal may be shy, subdued, or under the weather, but is responding to stimulus normally and is in no danger.

Obtunded: Decreased responsiveness to stimulus. This is a cause for concern.


Common medical problems in rescue animals


Yep, it's disgusting. But knowing what's normal tummy upset, and what's problematic diarrhea is a valuable skill.

First, knowing how to describe what you're seeing helps us identify common issues. We use a 1-7 scale to help us all stay on the same page about symptoms.

2: Well formed log (ideal)

3 and 4: Soft logs

5: Soft, but with shape


1: Constipation

Usually a sign of dehydration, these are hard pellets that can be painful to pass.

This is what we like to see. Well formed, holds shape, regular "poop" color.

This is not too concerning. May be emblematic of stress, change in diet, or recovering from parasites. Ideally, will improve to a 2 level, but this is not cause for concern.

While this isn't overtly concerning, if it does not improve over time, we may need to investigate causes or solutions.

(This level is common after anesthesia leaves the system- if it doesn't resolve, let the team know)

6 and 7: Diarrhea

This is considered to be diarrhea and is indicative of a larger problem. Persistent diarrhea is dangerous, causes dehydration, and may indicate illness or parasites that may be life threatening. One bout of diarrhea after a stressful event such as transport, vet visit, or surgery is common. But if it doesn't resolve after 1-2 bouts, let a team member know immediately.

Persistent diarrhea is always a concern, especially if paired with lethargy or vomiting. Diarrhea can cause dehydration, which may be life threatening, especially to young animals like kittens and puppies. Alert an Underdog team member if your pet has more than 1 bout of diarrhea that does not improve over time.


Soft stool happens. When is it normal, and when is it concerning? The frequency and how it progresses will indicate whether or not it's cause for worry. If it's a one off, it's probably okay. But if it happens more than once and is moving closer to a grade 7 than a grade 2, that's when it's time to take action.

Temporary loose stool that improves over time (not concerning):

Loose stool progressing to diarrhea that does not improve over time (concerning):

  • Stress (transfer, time in a shelter, new home, car rides, vet trips, etc)

  • New diet without a slow transition

  • Surgery/anesthesia

  • Resolving parasites

  • Antibiotic use

  • Dewormers

  • Infectious illness (parvo or panleuk)

  • Parasites

  • Medication or vaccine reaction

  • Severe food allergy

  • Intestinal issues

  • Risk of dehydration/malnutrition

The next steps would be to alert an Underdog team member. If the animal is otherwise stable and happy, we may just collect a fecal sample for testing. If other symptoms are present, it could be time for a full vet exam. See more below on parasites and how to collect a fecal sample.



Pretty much every animal will have their brush with parasites at some point in their lives. Pets who have lived outdoors and have eaten wildlife are at risk for parasites, or even just gotten fleas at one point or another. While fleas themselves are a parasite, they also carry other internal parasites that can be trickier to treat or spot. Even just ingesting fleas or their waste (sometimes called flea dirt) can put them at risk for further parasites.


We prophylactically treat all animals in our care for the most common parasites. We also give them all a flea treatment to prevent future infestations. If you see live worms, no need to panic. Just let us know and we will get you the appropriate dewormer. Different worms require different treatments, so it helps if you either know how to identify the worm, or can send us a picture (yes, we know it's gross, but necessary).

Dewormers often take multiple doses to work, which is why we send another dose home with you. It's important to give the next dose spaced out appropriately to allow their bodies time to kick the intruders out. If you see dead worms in stool, don't worry, that just means the dewormer is working!


Fleas are nasty and annoying. It's important to spot the signs early to allow us to treat ASAP. You'll also want to clean any bedding and vacuum carpets to help prevent spread.

Flea "dirt" (the lower image) is the feces of the flea. You can tell it's different from regular dirt if you get it wet- it will turn red from the iron/blood waste from feeding on pets. Yuck.

Even if you don't see fleas but find flea dirt, let us know as they'll need a tapeworm treatment.

If the pet has a lot of flea dirt, ask us about safely bathing the animal (or we can do it for you) to prevent them from ingesting too much of the waste. If you see live fleas we can give Capstar, an over the counter treatment that kills live fleas. Otherwise, a flea preventative like Revolution is our go to for combo deworming and flea prevention.

If you have your own resident pets, be sure they're on a flea preventative too, as they can just as easily share this annoying bug, or pick it up if your foster brings some home with them unexpectedly.

Ticks are another common nasty parasite to watch out for, especially on dogs. They burrow into the skin and engorge themselves. Sometimes when they get larger they can be mistaken for skin tags or pimples. Look for the head burrowed into the skin.

It's important to remove ticks safely- if you find a tick on your foster, let us know ASAP so we can remove them completely and look for signs of infection or diseases. 


Microscopic parasites


While worms, ticks, and fleas are visible to the naked eye, there are many parasites that are only able to be diagnosed with a microscopic test. Usually these eggs or "oocysts" are shed by the parasite from the intestine into the stool. This is why we sometimes require a stool sample to test for more insidious hidden parasites.

While some are easily treatable, others can require longer courses of treatment and carry higher risks. For example, Coccidia is a common, easily treatable parasite. But gone untreated or undiagnosed, may result in "fading kitten syndrome"- the old school name for kittens dying suddenly without warning.

There are some parasites, such as toxoplasmosis, that has zoonotic (animal to human) transmission potential. If pregnant or immunocompromised, fostering animals in general may be hazardous to your health. Consult your doctor before taking on animal rescues.


Symptoms of parasites include:

  • Vomiting

  • Diarrhea/loose stool

  • Lethargy

  • Fever

  • Elevated inner eyelid

  • Sudden tremors

  • Swollen/enlarged belly

  • Live worms around anus or in stool

  • Slow weight gain

  • "Crashing"- sudden drop in energy

  • Coughing (lungworm)

  • Ataxia (inability to walk)


We know it's no fun, but if there is a concern for parasites, we may ask you to collect a fecal sample for us to submit for testing.

Fecal samples must be:

  • Fresh (no older than 8 hours ideally)

  • Free from excessive litter, dirt, leaves, etc.

  • In a sealed package- a tied off doggie poop bag is fine, a ziploc bag, clean recycled food container, etc. Avoid anything that may cross contaminate the sample.

How it works:

  1. Collect a fresh stool sample.

  2. Tie off in a bag, put in container, etc.

  3. If possible, please label with your foster's name.

  4. Leave at room temperature- avoid setting it in warm/sunny areas. No need to refrigerate.

  5. Either a team member will pick it up, or we may ask you to drop it at one of our partner vets if it's near your home.

  6. The vet will either run an "in house" fecal test, or submit to a lab for a more in-depth analysis.

    1. An in house test will usually yield results within 12 hours. A lab test may take anywhere from 1-3 days for results.​

If the test is negative:

That's good news! However, it doesn't mean that we're completely in the clear. If there's enough cause for concern, more specific testing may be needed. Furthermore, there is a potential for false negatives; the test is just a quick snapshot in time. The parasite load can wax and wane, and we may have just grabbed a sample that didn't have a lot to find in it. Just know that it's not a guarantee of anything, but it's all just useful data

If the test is positive:

A positive result usually means that they have identified a specific type of parasite. We will treat with the appropriate medication. Sometimes it's a quick fix- another dose of dewormer, one or two topical treatments, etc. Some parasites require more intense treatments, antibiotics, or supportive care. We will always counsel you on the next steps and what to expect.

Collect A Fecal


Just like humans, cats and dogs are prone to their own versions of colds. One of the most common health issues we run into with animals pulled from a shelter setting (or any multi-animal setting) is Upper Respiratory Infections (URI), or sometimes called "Kennel Cough".


Just as the name suggests, kennel cough is the catch all term for a URI in dogs that lived in a multi-dog setting such as a kennel, a shelter, a boarding facility, a house with many dogs, etc.

Kennel cough can have many causes and refers more to the condition than the illness that causes it. For that reason, treating it can be a little tricky, as we'll need to treat for a wide spectrum of causes, as well as treat symptomatically.

For animals with a robust vaccination history, this is less concerning and they'll usually clear it with minimal support. But for stressed, immunocompromised animals, or animals without vaccines, kennel cough can be a bit more concerning and may need more supportive care.

The hallmark of kennel cough is... you guessed it, the hacking cough.

It can also be accompanied by the following symptoms:

  • Nasal discharge

  • Sneezing

  • Eye discharge

  • Decreased appetite

  • Lethargy

  • Nausea

It's important to monitor the symptoms, as we don't want any illnesses to progress into pneumonia. At the first sign of any of these symptoms, let Underdog know so we can start a treatment regimen to get the symptoms under control, as well as provide support to make sure they feel better faster.


URI mostly is identifiable by:

  • Nasal discharge

  • Sneezing

  • Eye discharge

  • Decreased appetite

  • Lethargy

  • Nausea

  • Congestion

Cats shouldn't cough like dogs do; if chesty coughing is heard, report it immediately as it could be a sign that it's progressing to pneumonia or some other larger issue.

Though with cats, you need to watch out for another URI like illness called Calici virus. This virus can result in oral or nasal ulcers, limping/inflammation in joints, and more.

URI is very serious and should be reported immediately.


Similarly to kennel cough. cats often break with URI following transport due to the stress of being crated, in a car, changing environment, etc. Stress dramatically suppresses the immune system, and opportunistic bacteria or viruses will often emerge, causing similar symptoms.


To an untrained eye, the signs of URI could be easy to miss. But looking closer here, you can see mild squinting of the eye, some crustiness around the eye from drippy discharge, and some greenish nasal discharge. This kitten later progressed to having pneumonia, so it's important to treat ASAP!

URI/Kennel Cough


Checking to see if an animal is dehydrated is a simple and easy indicator of health. Watch this video on checking hydration in cats and dogs.

Sometimes dehydration is mild and temporary- as long as they get enough water and moisture in their diet, many animals recover on their own, or by mixing water or Pedialyte into their food. However, if the animal is already sick, has decreased appetite, or lethargy in addition to being dehydrated, let us know- they could benefit from subcutaneous fluids to support, or in some cases, will need further vet care.

Kittens and puppies can die from dehydration quickly! Learn to check on young animals- it can be a little different than adults. Skip to about 3:40 in the kitten video to see how to assess hydration needs on young animals.

This video is a great resource for the slightly more advanced ways to check hydration status on a larger dog. While it'll take some practice to know what exactly you're looking for, they're very easy methods that give a lot of useful information.


 We recommend learning how to check gums (mucous membranes) from this video, and what "snap back" should look like. More detail/instruction available here!

(Skip to the parts about mucous membranes and skin tenting- it's very technical otherwise and not needed)

Advanced fosters- want to learn how to administer fluids? Let us know, we'd be happy to do an in person demo!

Checking Hydration


Medicating animals will most likely come up in your tenure as a foster. We'll talk about some common types of medications, how to administer them, and tips and tricks to make it easier. 

Common medications you may come across in your time as a foster:


All animals in our care will receive blanket deworming just as a precaution. We will usually rely on you to give a second or third dose, usually premeasured liquid in a syringe.


Medication not ingested, injected, or given internally is a topical. Most common topical meds are flea preventatives like Revolution, dewormers like Profender, or ear or eye medications. Sometimes shampoos can be a topical medication.

Always read all warnings on topical medication, as they can absorb via the skin. Gloves may be recommended for application.

Antibiotics (abx):

As with taking antibiotics as a human, it's important to always finish a full course for the number of prescribed days. Do not start and stop abx; if you have difficulty getting them to take it, let a team member know!

Always follow the instructions on the prescription. GI upset (diarrhea, upset stomach) is pretty common as it can kill good stomach bacteria as well (see probiotic section)

Ophthalmic (eye) meds:

In event of eye infections, some medication may need to be administered to help them heal.

Eye meds can come in liquids or a thicker ointment. If using multiple eye meds, always go from thinnest (liquid) to thickest (ointment), and allow 5-10 minutes in between application.


Antivirals help if an animal is having a flare up on an existing condition, or if the illness is suspected to be viral in origin. 


Probiotics are not prescription, and can be used to help support an animal having diarrhea after antibiotic use, stress, or during treatment for parasites.

If using a probiotic at the same time as an antibiotic, be sure to space them out a few hours apart to ensure both are reaching their full efficacy.


If you've never given medication to an animal before, it may be tricky to figure it out from scratch. Medicating cats can be especially challenging- watch the videos below for instruction on how to handle your fosters for medications.

For dogs and some cats, hiding the pill or medication in a treat such as pill pocket, cheese, hot dog, etc. may be enough. 

When putting medication into food, always do it in a very small portion that we call a "snack"- this ensures that they have gotten the full dose. 

Advanced fosters- want to learn how to administer injectable medications? Let us know, we'd be happy to do an in person demo!



Some medical issues can transfer from your foster to your resident pets, or even to humans. It's important to follow guidance on risk mitigation to your foster, your pets, and your family.

Quarantine period:

We always request that you start your foster in their own separate area. This serves many purposes, first of all being behavioral. But the secondary reason for keeping them housed separate is to ensure they're not carrying any illness that could catch to other pets or yourself. If they do break with any illness, keep them housed separately where they cannot share food dishes, water, litter boxes, bedding, etc. to prevent the spread of illness.

Your foster is likely stressed, which is a big immuno-compromiser. Allowing them time and space to decompress will bolster their immune system and if they have been exposed to anything, give them time to try to fight it off naturally.

Vaccine effect quarantine:

This is especially important if they have little or no known vaccine history. It takes time for immunity to build up in their system. Do not let unvaccinated pets meet other animals! 

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Big Boy Benny spent some time in a spacious bathroom while waiting for the results of his FIV/FeLV test, as he was an outdoor cat previously. Once he got a negative result, he was happily integrated with the resident cats and dog!

Expected timeline:

Usually it can take anywhere from 5-14 days for common illnesses to show up, and for vaccines to kick in. Most vaccines will need a booster.  If after this quarantine period you're still very keen to introduce them to your existing pets, ask an Underdog team member if this is appropriate for this animal.

How long to keep separate if sick?

This question is harder to answer, as it depends on the illness. Follow our veterinarian's guidelines and always ask before integrating pets with a medical history.

Keep your pets (and self) healthy

Always wash your hands thoroughly after interacting with a sick pet if you have others in the home. If you're going to be interacting with the ill animal and then other pets, change clothes or wear something to cover like a large apron. Be mindful of your shoes and tracking litter or germs. Disinfect frequently! We can provide you with Accel, a shelter grade disinfectant made for animal specific illnesses. 

Don't allow pets to sniff each other, share toys, bowls, litter boxes, leashes, etc. Be aware of fomites- anything you touch after touching a sick animal or person is a fomite! You can be a fomite. Be mindful of the spread of germs.


We should all be familiar with preventing the spread of disease after COVID; the same policies apply to animal disease transmission!


Every once in a while an animal may be diagnosed with a zoonotic illness, meaning an illness that can potentially spread from an animal to a human. The most common of these being skin issues such as ringworm (which is very easy to treat in people, but much much harder in animals).

Immunocompromised and pregnant people are at higher risk for zoonotic disease transmission. Be aware of the risk of taking in rescue animals, and discuss with your doctor if you have any concerns.


Maybe....don't french kiss your animals.

Philly photographer Chris Sembrot photographs owners kissing their dogs.


While parasite transmission risk is low, there is a potential for human infection from animals. Always wash your hands after handling waste or litter boxes. Pregnant people should avoid handling cat waste out of caution surrounding toxoplasmosis, which may pose a risk to fetal development and safety.

Respiratory Illness

There are some rare reported cases of transmission of illness such as tuberculosis and bronchitis. 

Skin issues

Yeast, bacterial, or fungal infections can spread from touch contact. If you notice any skin lesions on your foster or yourself, report it immediately.

Bite/Scratch Infections

The most likely way for you to get sick from your foster is from a bite or serious scratch. If your foster ever breaks skin, let Underdog know and immediately seek medical care. If treated early, there is usually little risk. However, letting a cat bite go too long can be very damaging and have lasting complications.

Use common sense

While it may be tempting to kiss and snuggle your fosters to your face, use common sense and avoid touching animals to your eyes, mouth, and nose. Wash your hands frequently, and as much as your dog may try to convince you otherwise, don't let them make out with you.


Navigating health concerns

When in doubt, never hesitate to ask. We'd rather we check it out and hear back that everything is fine, rather than wait too long.

Pictures, questions, or requests for help are always welcome! We are happy to give in home demos on medicating, handling, testing hydration, and more!

Above all else, stay calm and don't worry. Underdog is partnered with several fantastic vets who work hard to squeeze us in quickly, and true emergencies are rare. We just want to arm you with the knowledge and empower you to make the best choices for yourself, your families, and your fosters!

Taking on an animal with medical needs is so rewarding, but we know it can be a lot of work. Never hesitate to let us know if we can do anything to support you and your foster.

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